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Need help from xr600 experts.

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So my story goes that I'm bored with racing my local series and I want to do something a little different for next year. I decided I'm going to buy a newer XR600 and set it up Scott Summers style and do some whipping up on the guys in my Expert A class next year. I have done similar in the past with an XR400 and won my 4stroke B class and had a blast so I can't wait to do the same on the big 600.

So here is where I need the help. I've been searching the forums and you guys have some SICK XR600's. So what years do you guys recommend and why and what should I do to make it super reliable. I also want to trim as much weight as possible and as far as engine mods go I want to keep them very light with a good aftermarket exhaust as well as a better carburetor. I think I'm going with WER for the suspension, does anyone have experience with there stuff? How about lightening the flywheel?

Thanks in advance for what I'm sure will be awesome advice.

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Ya gotta be a little patient. Sometimes it takes a bit for a reply.

I'll take a stab at a couple of your questions.

As far as preferable years, I would say 1991-2000. The bikes were pretty much the same through these years.

XRs as a rule, are already super reliable. Keep clean oil in it. Check and clean the air filter regularly. Check the valves once in a while. Clean and lube the suspension componants occasionally. Ride. Smile. :busted:

As far as taking weight off, I don't have a clue. :busted:

Carburetors. I've had good experiences with both the stocker and Mikunis.

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I can't remember what webpage it was, but ut talked about the tricks simmers used when he raced. One was a stock exhaust mod and opening up the air box. But if you go after market on the exhaust that would eliminate his trick. One thing he talked about was trimming the bottom of the front fender to allow more air flow.

Not sure how far you want to go, but when you horror anything, the trick is to make it suck and blow as much fuel as possible. The old say holds true that there is no replacement for displacement, so you have a good platform with the big thumper.

That being said, and as you probably know, a good rider with a great handling bike will whoop to nuts off an average rider with way too much horse power. Maybe a good stop for you would be rebuilding the front forks and shock. I bet those items would make a rider of your caliber much happier than just raw power.

But if you want horsepower, talk to Headtrauma. I think he runs an aftermarket pumper carb.

But even with that new carb, jetting and exhaust, the stock engine would not be able to maximize the increased intake and exhaust capability.

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I digress and got way off track.

Aftermarket exhaust should shave a few pounds. Same with wheels and hubs if you want to that route. You will chew them each race, but aluminum sprockets save some weight. Stick with the smaller tank and only use the amount of fuel you need for a race. A big desert tank filled means you have the potential of carrying about 7 to 14 pounds when you cross the finish line.

Shed the kickstand and use aluminum foot pegs. Not much savings there but every little bit can help.

A lot of guys run with bark busters. If you trust yourself in in the thick stuff, keep or take them off. That is about a pound.

Check brake discs. We are really splitting hairs at tis level, but some are lighter than others.

If I was going to ride a GNCC then personally, I would focus on suspension. I bet a pretty stock ride, with your ability would be money better spent than the horsepower route.

Just my two cents. Good luck this season.

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Thanks for the reply. As far as the engine is concerned I will most likely just be tearing it down and making sure it's in good shape internally and put a stock compression wiseco piston in her. I will do an after market exhaust for the weight savings more than anything and the carb for ease of starting and smooth power delivery. I have been kicking butt on a kx250f so I'm sure the XR will have plenty of power. I know the suspension is going to be the make or breaking point of this project and usually I do my own revalving but I don't have much experience with the XR suspension so I will save some time and send it out to WER for a revalve.

How about shaving some weight off the flywheel? HAs anyone done that to help the beast get through the RPMs faster?

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Thanks for the reply. As far as the engine is concerned I will most likely just be tearing it down and making sure it's in good shape internally and put a stock compression wiseco piston in her. I will do an after market exhaust for the weight savings more than anything and the carb for ease of starting and smooth power delivery. I have been kicking butt on a kx250f so I'm sure the XR will have plenty of power. I know the suspension is going to be the make or breaking point of this project and usually I do my own revalving but I don't have much experience with the XR suspension so I will save some time and send it out to WER for a revalve.

How about shaving some weight off the flywheel? HAs anyone done that to help the beast get through the RPMs faster?

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If your racing hare scrambles / enduro do not lighten the flywheel ...... and run the stock camshaft , motor has great tractability

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If you want a kick ass XR600, here's what you need to do, in my opinion.

Replace the front forks with a USD conversion. Something off a CRF or KTM.

As for the motor, it needs pepping up.

Replace the piston with a higher compression.

Replace the cam, I don't recommend Hot Cams.

Fit up a pumper carb. 41mm would be best.

These are your best bang for the buck.

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WER is an excellent choice for the suspension. You will not believe the difference when you get the redone forks and shock back on the bike. Factory Connection also does an excellent job. Keeping the engine stock is a good move, in good tune there is plenty of power available and reliability is not impaired. A pumper carb is a significant improvement, but kinda pricey, worth it as far as I am concerned. An aftermarket muffler on the stock engine will provide little if any performance gain, but will save some weight.

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This is something I am sure you already know but gearing will also help you out. I think the stock gearing really bogs her down at low rpm. So, work that for the expected scramble terrain.

You know the deal. For tight courses add in the front and drop in the rear. If you know the course will have Long open runs...do the opposite.

Another obvious idea, but may be a better work around than messing with the flywheel. I personally feel the engine has decent HP and torque, but also understand a racers desire for a little more.

God bless fossil fuels, the internal combustion engine and that American desire to always want to tweak it a little further.:lol:

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This is something I am sure you already know but gearing will also help you out. I think the stock gearing really bogs her down at low rpm. So, work that for the expected scramble terrain.

You know the deal. For tight courses add in the front and drop in the rear. If you know the course will have Long open runs...do the opposite.

Another obvious idea, but may be a better work around than messing with the flywheel. I personally feel the engine has decent HP and torque, but also understand a racers desire for a little more.

God bless fossil fuels, the internal combustion engine and that American desire to always want to tweak it a little further.:smirk:

Actually ya got that backwards. :banghead::cheers: For tight courses, drop in the front and add in the rear. The opposite for long runs. :lol::)

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If you want a kick ass XR600, here's what you need to do, in my opinion.

Replace the front forks with a USD conversion. Something off a CRF or KTM.

As for the motor, it needs pepping up.

Replace the piston with a higher compression.

Replace the cam, I don't recommend Hot Cams.

Fit up a pumper carb. 41mm would be best.

These are your best bang for the buck.

I'm doing the pumper carb for sure. Is there a 41mm that comes with everything for a direct bolt on? I've been reading the thread about fitting the CRF carb but it seems like it would be a jetting nightmare. As far as the cam goes I had originally thought about keeping the stocker because of the good bottom end power delivery but I'm finding some cams with nice grinds that should add bottom and mid.

I was going to install one of the lower compression aftermarket pistons because I had read that Scott Summers claimed the lower compression piston kept the bike from having excessive engine breaking. I guess as long as I'm on the throttle it wouldn't matter :lol:

WER is an excellent choice for the suspension. You will not believe the difference when you get the redone forks and shock back on the bike. Factory Connection also does an excellent job. Keeping the engine stock is a good move, in good tune there is plenty of power available and reliability is not impaired. A pumper carb is a significant improvement, but kinda pricey, worth it as far as I am concerned. An aftermarket muffler on the stock engine will provide little if any performance gain, but will save some weight.

Yea the WER site even talks about the XR as being one of the bikes they have a lot of experience with. I had originally thought of doing the USD swap but the more I read about the 91+ cartridge forks the more I think they may suite my needs. Our terrain in tight single track with loads of roots and rocks and I believe the built in flex from the smaller forks will help absorb some of the punishment. I've been tuning the twin cartridge forks for a few years now and they just never feel as plush in the super rough stuff.

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Actually ya got that backwards. :cheers::smirk: For tight courses, drop in the front and add in the rear. The opposite for long runs. :lol::banghead:

zrexr is correct :)

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But if you want horsepower, talk to Headtrauma. I think he runs an aftermarket pumper carb.

I wish! I'm still running the stock Keihin PD. It's not a bad carb, but I think a Mikuni HSR42 would be better. :lol:

I'm doing the pumper carb for sure. Is there a 41mm that comes with everything for a direct bolt on?

Sudco sells a complete kit for the XR600 with a non-MX FCR41. It's not cheap. No one ever seems to regret going with a pumper carb, though.

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I had originally thought of doing the USD swap but the more I read about the 91+ cartridge forks the more I think they may suite my needs. Our terrain in tight single track with loads of roots and rocks and I believe the built in flex from the smaller forks will help absorb some of the punishment. I've been tuning the twin cartridge forks for a few years now and they just never feel as plush in the super rough stuff.

The revalved/resprung stock forks worked best for me. I had an HRC628 with WP suspension front & rear and a stock 600 with stock suspension redone by Factory Connection. The suspension on both was top notch, but I preferred the redone stock suspension (SRC fork brace on the forks) a little more plush & controllable on roots & rocks. The only bad feature of the stock forks is the low underhang.

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hey not to hijack, but creeky di you have more details on your suspension setting?

I upgraded to 98 cartridge fork on my 88 and it was a nice improvement, I also added a brace(rsw) and that is noticeable on ruts, roots and technical stuff..

But I feel I am undersprung(180lbs) as I have significant brake dive and feel like I am sagging too much upfront...

Any other details?

I am planning on a revalve upfront soon but thought about cutting my springs to add stiffness a bit to try it out...If I screw up I can order some nice eibachs or something.

Out back I will be upgrading to a resprung and revalved xr650l shock...should be a great improvement over my 88 stocker, which works but suffers from a crapped out spring and bounciness..

thanks and keep the details and thread going!

christian

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hey not to hijack, but creeky di you have more details on your suspension setting?

I upgraded to 98 cartridge fork on my 88 and it was a nice improvement, I also added a brace(rsw) and that is noticeable on ruts, roots and technical stuff..

But I feel I am undersprung(180lbs) as I have significant brake dive and feel like I am sagging too much upfront...

Any other details?

I am planning on a revalve upfront soon but thought about cutting my springs to add stiffness a bit to try it out...If I screw up I can order some nice eibachs or something.

Out back I will be upgrading to a resprung and revalved xr650l shock...should be a great improvement over my 88 stocker, which works but suffers from a crapped out spring and bounciness..

thanks and keep the details and thread going!

christian

I am 175#. With everything stock, the stock fork springs with Spectro 10W oil @ 4.5" worked well for me. As for the compression clickers, it worked for me anywhere from the halfway point and the hardest setting depending on the riding conditions. Aftermarket springs are an improvement but best results are obtained with the springs and revalving together. If you want to experiment with stiffening the stock springs, try inserting a 1/2-3/4" spacer made from PVC pipe. I have heard that cutting the spring can help, never tried it. On the rear, set the sag at 4-4 1/2 " , put the compression and rebound clickers in the middle and experiment with different settings until you are satisfied.

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thanks creeky will do

Ill try just the spacer thing first even if it only helps with initial sag and stuff...

I dont have a manual anymore as the site I downloaded it from doesn't have an active link anymore...

So I read somewhere that the shock out back should be 20 clicks out on comp and 20 or so out on rebound...

I had them both way in..

I wanted to start stock settings then play around...but Ill try the middle for now.

Clickers on my fork are now 3 out from full hard...they where at 8(stock?)

anywhoo

Ill play around..

Cant wait for my revalved shock to show up though...I need traction!

cheers and thanks!

christian

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Actually ya got that backwards. :banghead::cheers: For tight courses, drop in the front and add in the rear. The opposite for long runs. :lol::)

I better keep this post around for reference if I ever change mine. Better yet, I better just keep it stock so I don't mess it up.:smirk:

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