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183 lb XR200

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I'm old and skinnny with two bad wrists so I needed to build an ultralight playbike. My regular ride is an XR650R/CRF450 hybrid that weighs 275 lbs. Big fun but too much heft for a 55 year old 155lb aging adolescent with bad wrists.

I spend winters in an RV park in the middle of a national forest in Florida so I didn't have access to my nice workshop. here's what I tossed together in my 8x12 shed

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Quick specs,.. it started as a BBR framed CR85 to XR200 conversion I found on craigslist for $1400 It has the full Powroll stoked, bored, cammed, light flywheel etc. I extended the swingarm, and built up some super light full size wheels with trials rims and tubless trials tires. Final weight is 183 lbs all fluids but no gas.

Its 100lbs lighter than my uber trick XR650R and is the same size as a stock XR200 with way better suspension. Oh yeah its pretty fun..... the stroked 218 motor and 6 speed is magic, the CR suspension is great and the trials tires are like riding on duct tape. The trails look the same but I feel 20 years younger.

Edited by woodsryder
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About time someone did something like this. Good job getting the weight down.

Swiss

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Thanks guys, there's another 10 -15 lbs in there I could chase out but it would require a new frame, swingarm and careful component selection. This was just a quick way to get mostly there without having to hand fabricate everything. the BBR frame is blingy but not very light and niether is the aluminum swingarm.

I already learned that weight loss has an increasingly dramatic effect the lower it gets. It may be 50 lbs lighter than a stock 200 but it feels like even more. I learned that the XR200/CRF230 motor is an amazing package and the cr85 and other minis have close to the same suspension travel as big bikes. I learned that trials tires have amazing grip and a soft ride. The combination is game changing,.. we almost need to start a new category for sub 200 lb bikes!

As I get some time on this bike and refine the ergonomics, I'll probably start over with a custom frame. KTM 85/105 forks, shock, hubs, brakes etc are beefier than the CR stuff and even lighter yet. I learned a lot about wheels and can build even lighter next time. I'm pondering a frame kit that would result in a 175 lb play bike using hand picked components. Similar to the BBR or Service Honda hybrid bikes.

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According to BBR a couple of years back, the aluminum frame to fit the XR200 engine was suposed to be about 2-3lbs. lighter than the Honda CR125 frame. A good chrome-moly frame would weigh another couple of lbs. lighter depending on how much you wanted to stress it. If you wanted to build it to handle a 260lb. Gorilla doing Triples on the local MX track then you need to add back those couple of lbs.. If not then you can build it lighter!

The forks from the KTM 85/105 are within ounces of the CRF85/150 forks and the wheels are the same when built with the 21/18" sizes. The KTM 85 hubs are some of the lightest around, compared to some of the "trick" aftermarket stuff they are just as light or lighter. Of course, using the minibike wheels built up you have to use fewer spokes. Yamaha had some 32 spoke front and rear rims that they worked with that are full sized and will lace up with custom spokes. I've weighed and measured all of this stuff.

Not sure if you are using a factory Honda tank, they are fairly heavy compared to something like Clarke aftermarket but Clarke doesn't make some of the smaller late model tanks. If you switch to the older style center tube top frame, you can lose about 2-3lbs. with the tank change.

Heavier spring rate springs are going to add some weight both front and rear. I don't know if there is an aluminum arm that is lighter than the mini arms? The KTM 85 arm is 21" long but doesn't use a linkage (some weight savings). KTM clamps use a bolt on bar clamp and don't require heavy adapters. Knobby rear tire is generally a fair bit lighter than the Trials rear. But you say that you really like the Trials!

Many of the stock XR200s weigh less than 220lb so your current bike is closer to 37lbs. lighter than stock, not 50lbs. as you stated. Button mag can take off about 3-5lbs. from stock depending on which magneto you have and if you can get it working well. No advancer on the Button mag but you CAN use the XR200 trigger (which does have the ignition advancer) to fire the Button mag CDI. I am working on the best solutions for that on my big Honda.

I have thought about trying to squeeze an XR200 engine into a KTM 85 chassis and add the large rims, but it would be a tight squeeze around the carb/shock. Custom frame would fix that. Would probably be right around your 175lb. target.

Air forks would take a couple of lbs. out, but you might want the reliability of springs? Tubeliss rear might take another lb. off the back wheel. About the same on the front wheel.

Lots of Detail work would take some additional weight off.

You are getting there keep it up!

Swiss

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Great input Swiss!,.. i think this mini BBR frame is just a cut down version of the full size frames so that accounts for the 2-3 lb difference. It weighs 16.5 lbs and the swingarm is 7 lbs. Its chunky thick and overbuilt. I know I can do better with chrome-moly, I build concept cars, race cars etc. I want to lose the linkage and go with a PDS style KTM105 shock or an ohlins made for linkageless. A braced chome-moly swingarm will be stiffer and lighter. The swingarm and frame on my 180 mph TZ750 is lighter than this one.

The KTM 105 forks are just early full size forks from the late 90's so they can handle anything. The KTM hollow axles are WAY bigger than the CR stuff and the hubs and brakes are lighter too. I used a YZ80 front hub because it looks tiny and has 32 spokes to fit the trials rim. Turns out the CR front hub looks bigger but weighs the same and has only 28 spokes which would need a custom drilled rim. The YZ front rotor saves weight because it only has 3 spokes and I trimmed it further yet. The ktm rotors hubs and calipers would be the lightest.

The trials front rim is the lightest there is. Sun rims are next, excels are the heaviest. The rear trials rim is tubeless and a bit thicker so it weighs the same as an excel but saves over a pound for no tube. Front tubes are just over a pound and I'm skeptical the Tubeliss system really is lighter for $100 but would like to confirm. The rear tire is already tubeless and radial.

The trials Michelin X-lite tires are as light as the lightest knobbys made. I have weights for probably 50 tires and all types of rims. My full size wheel and tire sets added only 5 lbs total to the bike compared to the mini stuff and I could have done better on the rear but I got impatient and used the heavy CR85 hub. Talon and other aftermarket hubs are all heavier than stock. I have a set of trials hubs and they are the lightest but would need much work to adapt. I'm away from my machine shop during the winter so did the best I could for now.

The airbox was stupid heavy so I trimmed away 90% and used a pod type filter with splash shield probably saving 2 lbs. The tank is a BBR special and must be 1/4 thick so its crazy heavy. I'll move the seat back 2 inches later and fabricate a larger and lighter alloy one

So right now I have a heavy tank, frame, swingarm with linkage, exhaust and rear hub. I see 8 lbs easy in those items so 175 looks very possible.

My next effort will go like this. KTM forks, axles, hubs and brakes with custom frame and KTM or Ohlins linkageless shock. Turns out the mini shocks are not much smaller or lighter than full sized ones. I have 25 brand new surplus Ohlins cannondale shocks made for no linkage. Morad Trials rim on front, Sun rim on rear both with 10 ga spokes. 428 O-ring chain, I might use an old alloy Elsinore tank and go for the retro look? Target 175 lbs or better?

Tires are the biggest weight obstacle. The trials radial tires are squishy soft and ideal for a light bike. Full size tires carcasses are way too stiff and heavy because they are designed to survive a fat guy riding a KLR650. On this bike you could probably run them flat? I may try shaving the knobs and even carcass on an old tire to save weight,.. gotta find lighter 2 ply tires. I may try removing some knobs from a trials tire to cut weight and open up the tread.

I weighed everything while doing this and could share if you want anything. I would like weights on KTM hubs, forks, brakes, shock and frame for comparison. I havent looked at the engine yet for weight savings but do have a list of all the Honda flywheel weights that will fit. VERY interested in the mag options. Looking for an alloy kickstart lever and auto clutch I can adapt. Air forks would require extra volume to be right so add some weight back for reserviors and I hate to lose reliability. They also have more seal friction with the presure. Also trying to avoid high dollar Ti stuff but the rear spring would save a good chunk of weight.

The shortcut would be to rebuild a KTM105 or CRF150R frame to fit an XR motor, then extend the swingarm and fit big wheels,.. should end up right about where I am now. The KTM has shock to carb issues with the XR as you already know. I thought about offering modded frames like that but a new one would be better, lighter and wouldn't have compromised ergos.

I'm just so blown away by the handling, wish you could ride it. That XR 218 motor has such usable power delivery and dropping another 35+ lbs makes it feel stronger yet. I need to ride a CRF150R but am told you have to flog it to get the power and it has a very short fuse before rebuilds. Can't beat an old simple XR for a playbike.

Edited by woodsryder
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Woodsryder,

Lots to discuss, will post back and forth with you some in private emails, but keep this thread going. First of all, the KTM 85/105 forks are not just the earlier 43mm forks. They are about 3" shorter in overall length and about 1.5" shorter travel. In other words they are the same 43mm tube size but redesigned specifically for the mini bikes. Still they are plenty stout for woods riding. The front axles are much larger than the smaller 12-15mm Japanese parts. They are a full 17mm axle with an even larger shoulder on one side and identical to some of the earlier bigger bike KTM parts. I know because I have an older KTM 125 axle to compare it to and they are identical and both tubular. They also clamp on both sides of the fork legs which makes for a stronger assembly.

You can make a non-linkage swingarm that will probably be about 2lbs. lighter than the aluminum arm that you have now. Snail cams in aluminum are the lightest adjuster method for building the arm. Trials shops have aluminum aftermarket snail adjusters in various axle sizes that will work just fine. You can even get them in trick anodized colors.

There are some Ti springs out there that will fit and work. Comes to mind the Ti rear springs that Yamaha had on their MX bikes a few years ago. I have one on an Ohlins single shock in my shop. Since they came off of larger 125/250 MX bikes they will have higher spring rates which will be fine for a conversion like this and a non-linkage design.

What are the weights of the Michelin X-lite trials tires?

The front Tubeliss system will NOT lose you any weight. If you want to lose weight on the front you need to go Ghetto-tubeless! That will be to NOT run the inner high pressure tube, just cover the spoke nipples with stick on dots and then wrap the inner rim with tape. People have used Duct tape, and electrical tape etc... Something to seal the spoke nipple area. Some have used a semi-hardening sealant brushed over the spoke nipple area. Then lever on the tire, add some of the newer Super Slime and pump it up enough to seat your beads. Lower the air pressure to your desired low amount and ride it.

Now you need one thing for your rim, a good tire valve. You can make one by cutting out a tube and glueing it into place in the rim, you can get one of the ones with the rim liner strip from Tubeliss, or you can take your rim and thread the valve hole for 1/8" pipe thread and screw in an aftermarket air fitting right into the rim. Plug or seal the rimlock hole if there is one and use 4-6 sheet metal screws on each side of the rim, screwing through the rim and into the tire bead. That is Old Skool and works fine to keep the tire beads against the rim on a non-tubeless rim. (DO NOT USE SCREWS THAT ARE LONG ENOUGH TO SCREW RIGHT THROUGH THE TIRE BEAD! MEASURE THE BEAD THICKNESS AND THE RIM THICKNESS AND USE A SCREW THAT IS JUST UNDER THAT LENGTH! HA!HA!) Although the rubber on the steel screw would probably seal the threads from air leaks, there is no reason to take the chance on a leak. Screw the screws into the tire while the seating pressure is high and then lower the pressure to riding levels. That will prevent the screw from pushing the tire bead away from the rim as you screw it in.

This will work on both the front and rear rims and will save additional weight over the Tubeliss design. Note: this may make a really thin Trials rim fragile to rock hits! Do NOT make your holes in the rim close to the rim edge, measure and make them where the screws will enter the thickest part of the tire bead.

On the auto-clutch, I think that Chuck has checked and they weren't going to make them for the older XR200. I just looked at their Rekluse website and don't see any of them for the smaller bikes except for the Z-Start Pro for the CRF150R. I don't believe that this would work for the XR200 based engines. You need an EXP type of clutch to work in the 200 basket. I have discussed this with Chuck and there is probably some room on the bottom of the inner clutch basket to machine it thinner and allow another friction disk to be addrd to the 200 basket. That would be necessary because the EXP or DynaRing type of clutch is going to take the place of about 3 friction plates. There MIGHT be an option, actually two of them. One, I understand that the RevLoc designs might be in production in Australia, they were more tolerant of smaller production numbers and fitted more engines. The other is to build your own IF you have the machinery and talent. One of the guys on ThumperTalk did just that for his little trail bike engine.

Button magnetos, the rotors weigh under 6oz. and the stator and backing plate about 12oz. so just over 1lb. without lightening holes/machining. (mine is lighter) Note: the reduction in weight would be the same as lightening the crank and will allow the engine to rev quicker but reduce the Trials Bike total bottom end Plonk at idle speeds. A tradeoff that you need to decide if you want to make. It doesn't bother me as long as the engine responds sharply when asked to off idle.

As far as riding, I rode my XR200 at 176lbs. back in 1980 when I put my XR200 engine into my older twinshock 125 custom frame. I do know what it is like. Feels more like a Hyper-Powered bicycle than a motorcycle. Puts a GRIN on your face with each ride! There have been a couple of custom bikes based on the little Honda 110 horizontal engines and a production bike the Sikk that were in the 150-165lb. range. But with about 1/2 the HP of the XR200/218 engines.

Swiss

Edited by Swiss

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OK Chuck!!! That one is LIGHT!!! And pretty too. Lots of good work and very custom. Not sure how it would work as a trail bike but for Trials it is pretty neat with the 250cc Thumper engine. Of course, they also started with a bike that was sub-200lbs. to begin with!

Swiss

Got me a new LARGE Photo file started! HA!HA!

Edited by Swiss

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Just got them all saved to my hard drive. You NEVER know when Web sites disappear and all of their photos/data with them!

Chuck, do you know what the Montesa/Honda 250 engine weight is?

Swiss

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No I don't know the engine weight but I do have comparison weights on the same scale for the 315R and 4RT. Almost identical chassis with different engines; the 315R is a water cooled 250cc reed valve 2T with a carb, no power valve and a heavy flywheel. One quart fuel each bike:

4RT 172 lbs

315R 164 lbs

So that implies an 8 lb heavier engine in the 4RT. They each also have, within a lb, the same weight on their respective front and rear wheels.

For tight technical trails they are as fast as most other bikes but riding style is different compared to a trail bike. I usually trail ride the 315R in 4th gear and fan the clutch or use use 3rd for slower stuff. The handling is very light and with only 6" of suspension travel the bike just doesn't do big hits very well. I've been told the twin spar aluminum frame is quite stiff compared to some of the lighter Trials bikes so from that they should be a better trail bike than some of the more flexible Trials chassis'. I've ridden the 4RT and it feels like a 4T and is nice for trail riding, but I still prefer the 315R for really slow gnarly stuff, the 2T motor is smoother on the bottom end.

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Swiss I'll get back to you via e-mail too. Got some questions about crf230 engine stuff too.

I didn't know the KTM mini forks were shortened, I hope there's still clearance for a 21 inch tire? The CR forks may be bordeline for a big guy but at 155lbs a lot of the kids riding minis weigh more than I do. The CRF150R upsized the axles and I know it needed it because my front one was bent when I got it. The KTM forks look like the best choice for big guys but much less available on ebay.

Ti is half the weight but only one third the stiffness of steel. Not the best choice for everything but it makes great springs. I think dirt bikes are the next thing to see a lightweight revolution. I've been through it with bicycles and trials bikes are leading the charge right now for motorcycles. Its just a matter of time before it gets to us. Unfortunately that trend always comes attached to the tendancy towards high dollar bling. Bicycles were and still are really bad about covering up some awfull engineering but lots of billet bling and carbon fiber because that's what sells. My MTB cost me $5000 to build15 years ago, I don't want to go down that road again. My focus is to simplify and lower parts count, hence the old air cooled carbed engine. I want to stay away from billet bling and Ti but the spring is the one exception I may make.

The X Lite tires weigh 7.39lbs for the front, the lightest knob i could find is a Dunlop MX31 or a Michelin M12 both at 7.6 lbs. The tubeless rear X Lite seems heavy at 11.9 Lbs but the lightest 18 inch knobby I found was 13.2 plus tube. I found specs for an IRC trials pro at 10.75 but am finding published weights optimistic. The search continues for light tires. The trials tire is big, tall and squishy, its like adding two inches of suspension travel. Add more air and it doesn't get stiffer, just taller,.. very strange tires. I hate to get silly with tape and slime to save one lb. A bottle of slime weighs a pound.

I was hoping to find an EXP type auto clutch for something that shared plates with an XR but that's a longshot. I'm surprised they don't make one for the 230 since its a good starter or wife bike. After riding it I don't see the need as much with that tractable power and slick gearbox. My flywheel has been lightened but I don't know how much yet. This site gives flywheel weights for various XR 200 models http://vincentcrabtree.co.uk/XR200.aspx Stock for mine is 3.95 lb so big savings could be had but I don't know if I want to go all the way down to 6 oz.. for woods riding? I have removed flywheel weight on every bike I owned and it usually makes less difference than people make out. I sawed off the crank end on my roadracer and ran total loss ignition, I felt that one. I would have to ride something to decide if I can lose more flywheel.

I've been watching the attempts at sub 200 lb bikes and not impressed by most so far. Just don't want to have less power than I have now.... just don't want to use $1200 mtb downhill forks or bicycle wheels,.. don't want skinny tires or limited suspension. i just want everything but lighter. Seriously the one change I do like is the shorter wheel base and lower seat.

I think there would be massive appeal for a 175 lb XR200 sized air cooled playbike that's NOT a $10,000 rich kids toy like the BBR stuff. I think you should be able to buy a frame kit, bolt on some ebay stuff and ride away at 175 lb for the same or less than the price of a 250 four stroker.

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Well, first of all I can't say that I like the new format for replying to posts where they cut down the earlier posts so that you can't see all of it by scrolling the page to make sure that you reply to the longer posts.

Anyway, I have enough screen space to set the reply window and a note window with the copied and pasted text side by side and answer that way. Solution but extra work! HA!HA!

Yes, the KTM mini forks are shortened. Otherwise you would have a full sized set of 43mm tubes and clamps weighing about 4+lbs. heavier than those CR85/CRF150 forks that you are comparing them to. I don't have a set of the full sized KTM 43mm forks but I do have an older set of 4054s that are comparable if just a little lighter. Same basic travel and similar weights. The lengths of the KTM 85/105 forks are just about identical to the Honda mini forks. Same lengths and travel. Difference is that the KTM forks come with a taller upper clamp and when the fork tubes are dropped about 1/4" in the clamps there is still plenty of clamp to hold them securely. Also as I mentioned to Chuck, switch to Button or Shallow headed 6mm Allen bolts to hold the fender. The other option is to go for the $$$ Euro lower leg extensions just like the ones that are available for the CR85/CRF150 forks that drop the axle 1" lower than the stock bottom pieces of the fork tubes. As I said, the main axle of the KTM 85/105 fork is 17mm and the larger shoulder that clamps into the right side fork leg is 21mm. Much larger and stronger than the Honda mini axle.

As for availability, that depends on how you go about it. EBay is still one of the best sources for the forks and maybe the rear shock. However, it seems like one of the buyers is buying up many of the sets that are offered for reasonable costs (still more than the cheaper Honda units) and then reselling them for higher costs. Basically working on controlling the prices by cornering the market. One option is to buy a good condition used KTM and sell off all of the parts that you don't want on EBay. In parts most cycles are worth a lot more than the entire cycle. Two ways to do this, you can buy a used bike or even go for a brand new one if you can get a deal on it and then sell the stuff to be used as "spares" for someone's new racebike. The newest KTM is said to have the latest/trickest suspension that they have done yet! Just takes more work on your part to sell off the parts without discounting them by selling everything together. That way you also get the complete brake system and any additional parts that you might want/need from the donor KTM. Including the disk brake rear wheel which you can convert to 18". The KTM swingarm looks really nice and is 21" long but might need to be lengthened to have much adjustment on an 18" wheel and certainly would need some extension to fit that monster diameter Trials tire that you are running.

Prices have already been rising over the last 10 years or so, and as our economy has problems everything seems always more expensive. I just did a basic price sheet on building a Vintage Honda XL350 full race engine and the numbers put it at over $3700 without custom head port work and exhaust system or assembly/labor costs. That would include an auto-clutch at $400 however as part of the added costs.

Back to the light weight XR ideas. Lots of Bling/Trick means $$$!! If you think that the prices on the KTM 85/105 forks on EBay are high, look at their brand new prices from KTM! You can do a little Ti for things like engine studs for a reasonable cost IF you can do your own threads on a lathe and buy the rod stock. That is if you figure your own labor costs at $0.00... Small 6mm Ti bolts/screws don't save much weight for their cost. Try aluminum 6mm button heads if you can use them for things like sidecovers etc.. The parts on that Montesa/Honda Trials 4RT would be incredibly high! But I saw lots of Anodized Aluminum bolts on the engine!

Tires!! I have a Dunlop 80/100/21 D756 in the garage that I will be putting as Ghetto Tubeless on my XL350 and it weighs 7lbs.3.5oz. The inner tube that I had in the front wheel was 1lb.3oz. so a Tubeliss front kit would not have saved more than maybe 3oz. maximum. So my front knobby is lighter than your X Lite Trials by a couple of ounces. It is big and wide enough for a good lightweight bike and good traction.

On the rear you weighed your X Lite at 11lbs.14.4oz. My Dunlop 120x18 weighs 13lbs.4oz. But I need the big 120 to work with the 50 or so HP that my big engine will crank. A weight that I have on a Michelin 130 M12 was 12lbs.7oz. so just about 8oz. heavier than your Trials tire. I am sure that most all of the knobbies will have stiffer sidewalls than your X Lite tires do. I suspect that a 100x18 Michelin M12 knobby might get close to your rear X Lite tire weight if you needed a knobby and ran it tubeless.

In my part of the country, where Mesquite and sharp desert rocks can poke holes with regularity and more than just one at a time the Slime is a requirement whether you run tube or without. About 10-12oz of slime is what I have seen recommended for a full size rear tire. The NEW Slime is rated much better and longer lasting than the older stuff. It is also MUCH harder to find! I had to order it from an offroad bicycle shop out in CA!! Not your Wal-Mart Slime!

I checked the Aussie company that is making the DynaRing and they also don't show anything yet for the CRF230 or the XR200. If they made a DR or an EXP that would fit one of them it would work with both since they do use the same clutch plates. As Chuck and I have discussed, it might be better to see if the primary drive gear and clutch basket from the 230 would interchange with the XR200 parts. The 230 already has an extra clutch plate and the primary ratio is better for transmission life. The altered ratio would reduce the torque going into the tranny. It has been mentioned that the Aussies would be willing to do some custom units, so maybe they could be talked into a DR for the 230 that would fit the 200? There is a BIG market in Brazil for 230 stuff where they make LOTS of the 230s... But the CRF230 doesn't have the kickstarter and the clutch basket might not work? Anyone have them to compare?

What you are calling your "flywheel" is your magneto rotor. Yes, I have seen the website with the different rotor weights. It is up to you if you like the lighter magneto rotor or not. I doubt that your rotor was lightened more than 1lb. So you are still running about a 3lb. EXTERNAL rotor. The button mag is a micro sized 6oz. INTERNAL rotor which means that it has WAY LESS mass effect when accelerated than an External unit of even the same weight. The button mag rotor is only 2" in diameter. As I said, I am working on making it a good ignition unit. I am not done with the set-up yet. Mine is machined down to 4.5oz.

I also have watched the work done to achieve sub-200lb. weight bikes and I think that yours is one of the success stories. As you said, there is more that you can remove from it, a little at a time. Do yourself a favor and make a complete list of all of your weights currently and what you can replace them with to save some ounces. You will be surprised. My list of mods worked out to almost 1 1/4 page in length and a lot of pounds total. When I built my old SL/XL145 bike back in the mid-'70s down to about 176lbs. I read an article in I believe it was Cycle World (can't find it anymore) where they took a TL125 engine and put it into a custom Trials bike with a Sammy Miller frame and lots of trick stuff! They claimed it was super light at about 183lbs.! And for the day and time it was also Super Expensive Bling! But Popular Cycling came had done articles on the old SL100/125 bikes for MX racing that used heavier longer travel suspension and were lighter than that very expensive project bike and much less expensive. You can always spend $$$ for Rich Kids Toys and often not get the best that you could build with some knowledge and skill. I think that with some work and information about what to do and how to do it you could easily build sub-200lb. bikes using the XR200/230 based engines and some frame and suspension kits. You have already done it. Your frame kit was kind of expensive for a starter, but you didn't buy it new which helped a lot I am sure.

Swiss

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Tyler, a google search will turn up good and bad info on trials tires. Just remember its not the trials tread pattern that makes it special, its the carcass and compound. Having said that a cheapo trials/universal tire will dissapoint you but a modern competition radial tire will amaze you. There's nothing better than a good trials tire for new england woods riding.

Swiss, I just copy your whole message to the reply window and deleet as I address each paragraph.

I have an aftermarket top clamp that raises the bars and moves it way forward, also allowing the tubes to be run 1/4 low in the wide clamp area. I removed some metal on the bottom clamp to raise the fender. So far no contact but i haven't had the springs out yet to confirm full travel.

I drew up some lower fork leg extensions but didn't have to go there, can you give me the source? None of the mini swingarms will fit any 18 inch tire . The KTM cast tapered swingarm is harder to extend than the CR's straight extruded one. Its a bad idea to weld on them without heat treating after but I took the risk and reinforced the joint. I would never sell a modified aluminum part, steel is best. That's why BBR overbuilds their frames, to avoid liability. The rear Michelin S12/M12 tire is the shortest 18 incher I found at 25.8 diameter vs 27 for some tall tires.

I want simple and favor the old school xr's. Today people want modern engines, fuel injection and lots of bling. I'm too stubborn to build something i don't like even if its profitable.

I'm finding tire weights off the web are unreliable and I think its because two of the same tires can vary by a pound or even two. I'll bring my scale with me when shopping. I may even spend an evening with a tire groover whittling excess rubber off a tire to see how far I can go? I think its best to start with a soft compound hard terrain tire. The front tube I have was only 1.05 lb so weigh before buying and get a smaller size when possible. Michelin changed their tire sizes and don't have a 100 rear anymore. i'm told the new 120 is the same size??

I'll look into the new slime. Trials guys paint it in their tires to use less of it. I just need to get a 230 engine to see what swaps are possible. its common for Honda to change primary gearing as an engine evolves to reduce loads on clutch and gearbox. I hear the heads don't fit but can be fitted??

The CB 100 has an internal rotor that fits but that's all I know. I would just have to feel the effect before going that light on flywheel weight. It will probably be Ok? Who makes your magneto?

Here's some links to light bike attempts both pretty lame

http://motocrossactionmag.com/Main/News/WE-RIDE-THE-WORLDS-LIGHTEST-CRF250--4148.aspx

http://www.dirtrider.com/reviews/dirt_bike/141_0911_fmf_racing_199lb_2008_ktm_250_sx/index.html

I only have $2000 invested in my BBR but was very lucky. It cost the guy $9000 to build in 2001 and had $1000 in engine parts? I only paid $1400 because the cam chain was slapping and the adjuster wouldn't work so it sounded scary. Some people have more money than brains and I'm here to take advantage of it.

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There's a ton to read in this posts, so forgive me if it's already been posted. A couple things stand out to me, first I didn't see anyone mention an AC Racing aluminum sub-frame. They are a bit lighter and you did mention the brakes, but you actually need to use a CR250/450 twin piston caliper, which you will need an adapter. The stocker single piston caliper doesn't stop the heavier bike and someone that is 50lbs heavier than it is intended for. Other options: A built XR100 Conversion will save a ton of weight and have more horse power, but less torque. But you will have many more options in building the motor. Plus the CRF150RB everyone seems to think it requires more maintenence, but I've owned mine ofr a couple years now and the only thing I've ever done was adjust the valves once. (besides oil and filter changes). It takes a bit to get them jetted perfect, but mine is spot on and flat out screams. With a Flywheel weight and a few other things they make a pretty good trail bike. There was a guy that put larger wheels on his and he loved it. But my conversions weigh in at about 165lbs. and that's without using any ti or even trying to go super light.

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