I purchased a 1986 XR600R on Ebay in January 2004. It is stock, and needs more work than I had anticipated to bring it up to the performance level I'm looking for! I've been paying to store this bike since I bought it, and haven't even begun to get it up to par! At this point I really want to get moving on it! I've pretty much convinced myself that in order to be satisfied, I'm going to have to tear this bike down to the bare frame and put it back together, examining and replacing any necessary parts. I'm thinking about doing the same thing with the engine. As I said, to my knowledge this bike is currently stock! If I'm going to tear the engine down, I might as well put it back together with at least some high performance additions. I've thought about an overbore, wiesco piston, hot cam, ect. But, in the back of my mind, I have to be realistic, and limit my spending on a 1986! Would someone explain all of the aspects of "un-corking", including any re-jetting of the carbs! I've purcased a SuperTrapp for it, and a K & N air filter. This is not the first bike I've engaged in such an adventure, although it is the first XR600R! Any, AND I MEAN ANY, input will be much appreciated!

I have had my 1986 XR600 since early 1986 and it is my all time favorite. I did not like the original forks, so I installed a pair of 1987 CR250 cartridge forks and also added a pipe. This is a dual carb'd XR and was/is very fast.

When you tear down the motor check second and third gear out real close as well as the shifting forks, I have replaced third gear twice and second gear once, second gear is out again, so I just bought a XR650, which I also like, until I can fix the OLD GIRL again



Thanks Ricky! Those are inspiring words! I'm also going to be looking for some used, in good shape, parts for this bike, to help keep the re-build cost/s down where I can! Right off the bat, I'm in need of an odometer/speedometer drive! Since you've had your 1986 XR600R, and are still speaking highly of it, tells me a lot! Thanks Again! Roger.

Fistbore- I have a good friend that purcahsed an '86 XR600 new and has about 40,000+ miles on it, with original bore and no major engine work. He had been contemplating a rebuild or replacement, but loves the old twin carb design, and much more. To make a long story short, check out what I found him in the link below. It's on original tires. I almost kept it myself, but it meant more t him.


do a leak down and compression test, if they're good, don't bother with all the "high performance" stuff. my 85 was on her original top end when i sold her, still had tons of power.

the trannies are a weak point, however.

the carbs probably need new jets and she'll probably need a new ignition coil and stator.

just check everything. on a bike that old it's just a given that things'll be worn out.


My buddy built up a 660 kit on his 86 from one of the big bore companies and loves the power but has lost 3rd gear twice now and is really frustrated!!! broke the piston and marked the cylinder too.. costed a bunch!! I wouldn't add any power to it!

Hey Roger,

I forgot to mention that the back brake is also very weak on these bikes and I would not add any performance parts, as my 86 with a Header and pipe is still faster than my uncorked XR650R. Also, do you have the original digital dash that came with this bike? I guess they are hard to come by, mine still works like new. I also needed to mention that my bike has almost 90K miles on it. In the early years got lots and lots of use. You will really enjoy your Bike once you have it up and running, but like I said before, check out gears and shift forks (Dogs) real close when you go through it.


Thanks All! Please keep the information comming! It really helps to get these second opinions, and also helps me from getting "tunnel vision" on how I'm going to go about this total rebuild! Now, about these dual carbs...someone online suggested I replace them with a single carb set-up! I kind of "HHMMM'ed" on that one! What do you guys think? While I'm on the carbs, I looking for "rebuild kits" for them, assumming I don't switch to a single carb design. It seems my local Honda dealer would have to put parts together to "make up" a rebuild kit, which would be much more espensive than a pre-packaged kit. Suggestions?

Also, what do you think about the stock bore 11:1 Wiesco piston! My understanding is that this is a simple bolt on with no further modifications. Am I just going to overcomplicate things by adding this?

Just my take but this in one of the bikes they had a lot of problems with when adding hop ups.. even the 628 kit which had cams and everything. many reports of the baja where they blew up or tranny problems.. I know it sucks to have it apart and not do extra but I think this is not the bike to make hot. It's also my take that these bikes need to be used as a beeter that you don't have a lot of money in. my 98 wr 400 is much faster than the 2 86's I know of and more reliable.. those wr's now aren't worth more than 2k so to put 12 to 15 hundred into a 86 xr is just a bad call. I like the bike too but it's only worth having low teen/hundred dollars into. If you love it maybe more.....

Hello All! What do you guys think about the stock bore 11:1 Wiesco piston! My understanding is that this is a simple bolt on with no further modifications. Am I just going to overcomplicate things by adding this? Also......someone online suggested replacing the stock Dual Carb setup with the Single Carb setup! I'm leary of doing this, only because I don't know if the performance improvement would be enough to warrant spending that kind of money, especially if I went with an Edelbrock Flat Slide!

Fistbore- I've had a fair bit of experience with all XR600 models and have found a few things-

*If you think the stock power on the bike is enough, don't modify it!

*As with any bike, modifying the suspension will make you go much faster than modding the engine./

*If you must have more power, I would tidy up the inlet port and add around a 10:1 compression piston as well as rejetting the carbs to suit these mods plus try a performance pipe. This gives a good power boost throughout the rev range.

*On an '88 XR600 I had, I added a good exhaust (staintune), tidied up the inlet port and I used a stock piston but had the head decked 0.5mm or 20 thou to add more compression, (I worked out this mod takes it up between 9.7:1 and 10:1) this worked very well. The bike still revved just as well, was very reliable because there wasn't much more stress on bottom end components as the stock piston is much lighter than wisecos etc.

*If you're rebulding the entire engine, I would closely check the gearbox as well, as the earlier models were weaker in this area.

*If the whole bike is going to be in pieces, you might as well get the frame etc repainted and make it look really smick!

Hope this helps,


I just picked up a 98 xr 600. Been looking for a while for one after having a bunch of "higher tech" bikes. Love it, plenty of power. As I remember, Scott Summers left the motor totally stock in all his race xr's. There is one of his old race bikes on ebay right now and it mentioned that the motor is stock. If it is good enough for him to race stock it is plenty for me to trail/ice ride!

There is definitely no need to modify the XR6's engine unless you're riding in wide open spaces or desert racing. A stock XR600 puts out around 32-34 hp at the rear wheel and a bucket load of torque, Stefan Merriman (a world champion enduro rider) is on record as saying that around 34-35 hp is the optimum for an enduro bike- all you need to do is improve the handling and suspension and you almost have the ultimate bike it is already fast and stone reliable!

I just picked up 87 xr600. It do not run when I got it. So I have been working on it the major problem I found was the cam chain wo so worn out that the tensioner would not keep enough tension on the chain and it jumped time and bent the valves. I don't like to pay retail for my parts and found this site to be excellent for prices and parts thanks guys. I would tear down the top end and inspect the cam chain before I would ride that 86 you might have the same thing happen.

OVERHEATING QUESTION/S!!! Hello All! I've been reading a lot of your postings that seem to relate to the XR600 overheating (Mine's an '86 "Project Bike"). I'm thinking I really need to keep this in mind! Obviously, since we are talking air cooled here, about the only practical way I can monitor the engine's temperature is to monitor the engine's oil temperature. What do you guys think is the best way to do that (gauge, location of gauge, where to access oil for gauge, electrical or mechanical, etc.)? I have a few ways I'm thinking of, but I imagine you all have some "tried and true" methods! I believe a temp/dipstick combo is available, but not sure where! And, I'd rather be able to look down and see a gauge at a glance, rather than shut the bike down and pull a dipstick! Please let me know where I can get whatever you may suggest! I also feel I would like to watch the oil pressure, so if you could advise, I'd appreciate suggestions on that as well! (Sounds like I want to build a "Drag Bike", huh!) Thanks, Roger.

Hello all! Anyone have any advise on the overheating issue I have posted? Thanks, Roger.

"XR's only" has a temp dip stick that replaces the original one.

I am also in the process of having my XL600 overheat diagnosed at the shop...I will be posting the results as soon as they find a solution....

XR's only oil temp dipstick is a life saver!!! :cry: :cry: :cry:

I looked again through "XR's Only", and found that oil temp. dipstick! Wasn't expecting to find it under "chassis accessories", or whatever! That's exactly what I'm looking for! What should be the "normal" temp. range for this bike during, say medium trail and woods riding, on a 70 degree F day? What should the highest temp. be for same (as in when should I either open it up down on a long fire trail, or shut it down? Thanks, Roger.

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