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The DR200 power plant build up -> DR-Z125 frame thread.

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I scored a DR200 motor sans kick-start, electrics, shifter and the remains of a parts bike this past weekend. Let me tell you, getting the bike was half the adventure, but that's a story for another time.

So, my step-son (14) pulled it out of the bike and he started disassembly. I had this crazy notion that we could stick his kick-starter on that motor and do a compression test, but we noticed that partial disassembly would be required because the head plug was missing. Then we noticed the bolts that hold the jug onto the case were missing. So we figured investigating would be a good idea.

The rocker cover came off with little effort except for one bolt that required around 75 ft-lbs of torque to remove. A piece of the rocker cover had been busted off and lodged near the valve. The rocker arm looks like it's seen better days.

The cam chain was not on the sprocket, but is in the case. I've got to fish it out and see if it's ok or not.

Otherwise, it seems fine! There's no up/down play in the big end bearing, there is side to side, but this is normal, although my kid is really concerned about it. I'm not. There's no sign of anything bad with crank bearings. The jug looks like a light hone would do it some good and a new piston.

I'm a happy camper.

So, the next question is "what to do now?"

Some research so far:

Carb:

DR200 Replacement Carb Which One - I like the TM-28

Perhaps "klintech" upgrades? I think he means Kientech.

Piston:

LT230 for +CR?

237cc Big Bore? Really? Maybe

Repairing what we've got:

Can anyone confirm the head/cover are a set?

Stick with the DR-Z125 Head?

Misc:

I am not reading the hundreds of pages of the ADVrider thread.

Some good advice from 500XC, but I'd like to see how it turns out.

Unbelievable!

Hyosung 4 Valve head? - I think I read that before.

TE450 head? - that's a new discovery, more research will be required. That's a Hyosung ATV, not Husqvarna.

This might be one of those times when there's TOO many options.

Some specs on the DR200:

Cylinder height (thanks Bruce!) 82.25 mm

Stock Bore X Stroke: 66 x 58.2

More info/progress will be coming later, including pics.

Edited by Smacaroni
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I've lurking this forum for some time now, planing on building a conversion of my own in the near future (parts are piling up) Unsure what path I'm gonna head down in the engine dept... Would like to go BIG Look'n forward in seen you and TwoWheelTom's 200 builds!!

Subscribed!!

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Stock DRZ125 head might not be too bad and it's cheap (you already have it.) It will definitely raise the CR . the ports are not too bad but the vales are a bit smaller.

Hyosung head ?? Who wants to go first ? Come on Tom

http://cgi.ebay.com/ebaymotors/06-07-08-09-Hyosung-Gt-250-Gt250-Cyllinder-Heads-Good_W0QQcmdZViewItemQQhashZitem3a582c4374QQitemZ250587399028QQptZMotorcyclesQ5fPartsQ5fAccessories#ht_3179wt_1167

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I´ll forget about that head, NO modern 2cyl/4v/2cam.Hyosung Head will bolt on.

What i saw myself doing it was from a : 1996 cruise /1Cam (maybe other single cyl.models from that time: XRX etc.); even the cam chain adjusted tighly.

This is the aspect of that engine :

http://cgi.ebay.de/Motor-Hyosung-125-ccm-8115-km-Laufleistung-aus-Unfall_W0QQitemZ180484009161QQcmdZViewItemQQptZMotorrad_Kraftradteile?hash=item2a05af6cc9

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For 16 Euros, I'd do it. However, $199 w/o covers is a little too pricey and I agree, the dual cams are going to be a really unlikely bet.

Okie dokie, some pics:

rocker arm which has seen better days and the inside of that chip which made me wonder if the cover bolt would come out in one piece.

dsc02785e.jpg

it was so tight, it stripped off part of the threads from the bolt.

dsc02783a.jpg

The cam could be better, but could be a lot worse.

dsc02782k.jpg

The cylinder doesn't look too bad.

dsc02790x.jpg

Anyone ever measured a GN250 head? http://cgi.ebay.com/ebaymotors/SUZUKI-GN250-GN-250-CYLINDER-HEAD-VALVE-ROCKER-COVER-88_W0QQitemZ290417464628QQcmdZViewItemQQptZMotorcycles_Parts_Accessories?hash=item439e3ad534#ht_500wt_956

Or an LT250? http://cgi.ebay.com/ebaymotors/Suzuki-LT250-LT-250-Quadrunner-cylinder-head-engine_W0QQitemZ250582813262QQcmdZViewItemQQptZMotors_ATV_Parts_Accessories?hash=item3a57e64a4e#ht_500wt_730

I think they might be the same part.

And bless this ebay seller who took a bunch of measurements for me without me even asking!

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=170450802738&ssPageName=STRK:MEWAX:IT#ht_2686wt_756

(note this is for showing an exemplory ebay seller, not saying that it would work! but I can dream, can't I? Oh, yes, I will be puling out my micrometer tonight!)

Edited by Smacaroni

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Dear Smacaroni: Sorry to be funkiller but let me warn you : GN250/LT250/LT300 family Engines have Nothing to Do , with our DR125/DR200/LT125/LT185/LT230 ones.

GN250 has the Cam Chain on the rigth side; to start with, vs DR200&others on the left!. Cam wont fit(its longer). Its PistonPin is 18mm vs 16mm DR200/LT230.

Dont think it´ll ever bolt on.

The Biggest Engine of our family-that I knew of- was the rare LT250S(built in 1987/1993?) -Bore 68.50 mm Stroke 67.mm-,with its 72mm max 0verbore piston. its Cam is a cheap upgrade(96$:Alphasports.com) to LT230s one: torqueyer&better top end(more lift&Duration?), not positive about its Duration or PistonPin figures, as I´ve never seen one in my country.

I, in your stead, would rebuild your own DR head: its porting&valve size are a better starting point for any monster performer project, I´ll put a couple new rockers and Cam; and then, listen to how noisy are those worn Cam journals.(oil pressure softens its chatter).

-I made a makeshift with my worn/noisy XT600 CamJournals that worked!. : I put the head cover over a flat marble table with 150-sandpaper on it; and then, rubbing it flat for a looong while, check when tired ,beware not to seize the cam if you go too far.

-Have a look at this :

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=230427804097&ssPageName=STRK:MEWAX:IT

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Ah! most important! : check that that Oil Pump works properly!. (your damage is down to =1/oil starving, or 2/faulty/clogged oil pump)

To check it : You dont need to start the engine, just turn the crankshaft till the oil is spilled over the head(rigth side cam), if so : you`ve flow ; pressure is another bussiness.. .

As many others have said before :LT230s upgrades are the way to go with a DR200, I´ll take a look at ATV forums about compatability/interchangeability.

forums.atvconnection.com, ATVrider etc.

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Oh yes, without a doubt I will be checking the oil pump and cam journals, if both parts were worn the exact same way I'd just call it old, however, the fact that one is severely deteriorated and the other shows a for lack of better terms, "groove" where no groove belongs tells me there was something bad going on.

I'm not going to invest this kind of money only to have it come apart 0.001" at a time.

But, this is also how I manage to pull off most of the stuff I do, buy cheap, drive way too far, invest a lot of elbow grease and brain cells instead of shelling out $2,000 for someone else to do it.

I bet the oil filter looks like a sequin gown.

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Hey Smac, thanks for including my bit of hair brained cheapness in your thread!

The 250F muffler was just something that fell into my lap (literally - quite painful), and since I'm working with a full sized frame, fitting will be easier than with the DR-Z frame.

The selling points were it was quiet and USFS/ Canadian Forestry approved, and I had actually repacked it 3 hours of run time before I bought it.

The diameter is a great deal larger than the stock DR200 head pipe, or the old DR250 twin header's joiner pipe even. I'll be porting the head for sure, but since I tore my rotator cuff trying to wrestle a knotheaded horse into a horse trailer, the DR200/ RM125 has been pushed to the backburner over the DR125.

I'll be sure to start it again right after I go back to work.

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The big bore 230 kit is a pain in the butt if you ask me. I would go high compression piston in the stock DR bore(66mm). If you go big bore, the squish band on the stock 200 head is seat up for 66mm, so you will have to take the head to a machine shop to have it enlargened. (That goes for the lt230 head as well). After that its just a sleeve and bore away....once you get the piston fly cut to clear the valves.... After all this, the compression will be lower (due to all the machining needed to get the piston to match the head, valves etc...) Next step will be to fill and blend the head to raise the compression back up. Which brings me to my next point/question...does anybody know what the correct squish should be? Im hearing in the 50 though range, but that is comming from a bunch of two stroke guys... Im thinking higher compression stock bore and a good cam would be the good way to go at this point. I ordered up some head and base gaskets from the lt250s (very rare, but has a 72mm bore, so I wont have to custom cut some gaskets to fit) What a pain! Ill take some pics when the gaskets show up and Im finishing assembly. Im thinking the big bore is more of a pain than its worth...

Tom

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EDIT: After looking at the 72mm dr200 piston.....DAMN!! What in the heck am I doing? Thats the way to go!! Crap...why do I always do this....

Tom

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I took some more measurements last night.

The crank case bore is 72.53mm. It appears there is plenty of room to make this grow. However YOU have to make it grow, either split the cases and bring it to a machine shop or take out the grinder and run the risk of dumping lots of metal flakes in the crank sump.

The sleeve OD is approximately 75.75mm.

The exposed part of the sleeve at the base is 24.91mm high, in my cyl, it was recessed a good 0.75-1.00mm above the base of the cylinder.

The cut away "height" (turn the cylinder upside down) on the flat part was 15.22mm from the cylinder base. I did not measure the circumference of the transition.

The exposed part of the sleeve OD is 71.83mm. The thickness of the wall at this point is 2.95mm.

The bore on mine is 65.75 mm, so this is obviously a stock cylinder.

Bore to cam chain slot inside wall is 10.90 mm

Cam chain slot dimensions 16.75 X 78.88 mm

I don't know if these will be of any help to anyone else in the future, but there they are. They're also recorded for posterity so when I lose this sheet of paper in front of me I can find them again.

Oh, and as far as that GN250 cylinder. I'm not convinced that it's unworkable. I think that if I could get my hands on an unmachined casting it's entirely workable, the problem of course, would be getting that unmachined casting. The stud holes are in the wrong locations. I am not at all deterred by the right/left hand cam chain bit. I think it would be feasible to simply relocate the cam chain tensioner to the other side and rotate the cylinder 180 degrees.

The hard part is getting the unmachined casting!

As far as the 16mm vs 18mm wrist pin, it's not unheard of to use a spacer, I already had one designed in my head. I would probably go with stainless because it's harder than "normal" steel but still can be machined. It would cost more, but not excessively more to do it this way. It probably really doesn't matter THAT much, but I tend to overengineer things in such a fashion that the most expensive component will break before the cheap ones. It's a backwards approach, but that's how I roll.

The alternate, probably better route is using the 72mm piston mentioned earlier.

So that's out. 👍

Just a sleeve is probably not a great idea since the GN250 cylinder is only 74mm tall, compared to the 82mm DR200. Then again, it is only 8mm... The really difficult part would be the GN250 cylinder referenced in my first post, the sleeve base diameter is 79.5mm.

Does anyone have any info on this mysterious 72mm sleeve? You obviously can't just bore the factory one over since the base will completely go away. DR250 (non-Z) maybe? I can't seem to find a manufacturer for one.

Oh and is it possible that somewhere there's a roller rocker for this bike? That would be sweet.

Research continues...

Edited by Smacaroni

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LT230s upgrades are the way to go with a DR200, I´ll take a look at ATV forums about compatability/interchangeability.

forums.atvconnection.com, ATVrider etc.

Are these the ones you're thinking of?

Quadsport Help

LT230s Help

Quadsport mods (spoiler: there some good and some bad, i.e. one user who thinks a longer con. rod can handle greater RPM, the opposite is true)

Cam discussion (begins on second post)

And LT230 Big Bore - lonely thread, no responses.

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Im gonna call powroll on monday, but as it sits, I believe the 72mm dr200 piston is out of the question. (I dont think they make it anymore??) I had to machine my cases to get the sleeve to fit. I had the sleeve cut down (as far as length goes) so it would match the stocker. I have a PM in with Norcal (he said he had some 72mm pistons back in that post) we will see how that goes. It may be possible to get Powroll to make another batch if we can get a couple of guys to commit to buying. Im betting if you called LA sleeve or any of the piston companies, the sleeve should be fairly easy to come by. My 71mm piston from la sleeve came with the sleeve, then you had to bore to match piston, so they really are not very specific. I bet they have a grip load that should work.

Tom

Tom

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Ah...

BTW, that LT230->260 kit makes the DR200 a DR224.

At 71mm, that's 230.425

72 is 236.962

Which is a very respectable increase over 199cc.

Back to that old adage, "horsepower costs money, how fast do you want to go?"

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Are these the ones you're thinking of?

Quadsport Help

Yep, strange as it is, that a thread migth have more than 800 pages !.. . so many topics in it.. .and jumbled.. . but interesting if one takes the time to read it thoroughly.

I agree with TwTom, a High CR Wiseco Piston and a good Cam, can make a Huge difference for a DR200. Once modified air filter&Jetting&Exhaust.

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we used the 200 cyl and sleeved it for 72mm pistons,i think i still have two 72mm pistons that are 14:1 comp.these are set up for the lt230s head that we milled.i will have to look for the pistons we are back doing import drag racing and all my time has been putting motor together.also you will not be able to run the 28mm pumper carb its way to tall.we were going to go with a bigger carb any way so it was not a problem,we went with a 32mm.are motor runs very well we putting out right at 30hp. also i would have to check if the pistons would work on the non stroked 200

Edited by norcalklx

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Research is nearly complete. I've got one remaining question that will either make or break what I'm planning.

Who has put a LT230 piston into a DR200 or perhaps 125 cylinder? I like that 70 and 72 mm piston, but I'd like to build something with greater replacement parts availability, which is why we'll be happy with the 67.5 mm piston. The fact that the piston is cheaper and boring is less than buying a sleeve and swapping it also is a consideration.

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