Mikuni 41mm flatslide kit from XR's only

[beezerjoe]

I am considering buying this kit for my '89 XR600R. I've gone through the engine it has a 10.5 piston,K&N filter, and a slip on 4" supertrapp. The stock carb has been rebuilt and is jetted proper but still leans out real bad and won't idle. What I would like to know is have any of you had good or bad luck with this set up? Does it live up to the advertisment? Does it mount up without alot of hassel? How close was the jetting out of the box and so on.

Thanks for any info you can provide. Joe

[Billahjack]

I bought a Mikuni from XRs only and they said that they jetted it. Their jetting spec sucked and it took forever to get more jets. Most motorcycle shops don't carry jets for that carb. I ended up trading it for an overpriced set of radiators.

The only good thing was the accelerator pump.

I hope you have better luck on the XR600R.

[martinfan30]

I am considering buying this kit for my '89 XR600R. I've gone through the engine it has a 10.5 piston,K&N filter, and a slip on 4" supertrapp. The stock carb has been rebuilt and is jetted proper but still leans out real bad and won't idle. What I would like to know is have any of you had good or bad luck with this set up? Does it live up to the advertisment? Does it mount up without alot of hassel? How close was the jetting out of the box and so on.

Thanks for any info you can provide. Joe

i went with the keihin fcr 41 pumper on my 650L. i put a 160 main, 55 pilot and this thing rips! very happy with this fcr. BUT, 490.00!!?

[litng1]

beezerjoe

My 92 XR is like yours now.Except mine is 11-1 comp.I run the stock carb with a 168Main and it starts great for me.It also runs great.Im not a pro but I dont think you need the fancy carb.What jets you running in yours.

[daddyk]

I have a '89 with the Mikuni flatslide,it's not a pumper. Its been a very good carb easy to start,idles clean,pulls well up top. It's not as much fun as the Edelbrock on my '94, not the same snap off the bottom. It does pull better on top than the Ed.If you can't get your stock carb to work right it would be a good way to go.

[beezerjoe]

beezerjoe

My 92 XR is like yours now.Except mine is 11-1 comp.I run the stock carb with a 168Main and it starts great for me.It also runs great.Im not a pro but I dont think you need the fancy carb.What jets you running in yours.

I have a '89 with the Mikuni flatslide,it's not a pumper. Its been a very good carb easy to start,idles clean,pulls well up top. It's not as much fun as the Edelbrock on my '94, not the same snap off the bottom. It does pull better on top than the Ed.If you can't get your stock carb to work right it would be a good way to go.

After reading these two posts I pulled the stock carb back off mainly because I couldn't remember what jets I had in it.I took all apart checked all the passages again checked the numbers and found a #62 in the pilot and a#160 in the main.The main on mine sounds like it might be alittle on the lean side but that won't cause the problem I was having with the pipes glowing red at an idle. What I found to be the culprit was the idle screw that I got with the Keyster carb overhaul kit. It was bigger at the metering part of the screw than the one that was originally in the carb from the factory. Good thing I'm a pack rat and keep alot of my used parts. I reinstalled the original idle screw and now it starts like a dream. sounds like I should change out the main jet since the intake and exhaust is no longer stock.

Thanks alot guys for helping me go from this:rant: ? to this:thumbsup: ?

[Kawabuggy]

Your main jet is probably pretty close. Your bike should have come stock with a 152MJ. If you are at a 160-that is a pretty significant jump over stock.

I would recommend leaving the MJ alone, and getting a 68S pilot. This will have the greatest increase in bottom/low end performance. It should also help the bike to run cooler, & start easier.

[beezerjoe]

Your main jet is probably pretty close. Your bike should have come stock with a 152MJ. If you are at a 160-that is a pretty significant jump over stock.

I would recommend leaving the MJ alone, and getting a 68S pilot. This will have the greatest increase in bottom/low end performance. It should also help the bike to run cooler, & start easier.

Thanks for the tip.? It actually starts pretty easy now and seems to runwell up the street. It sounds like it would worth giving it a go. Definetly won't hurt. How radical is the cam you installed? Was the pilot jet part of requirement to get the cam to work on the low end or is this just good policy to help the engine out? Thanks again.

[goblin127]

I've got the XRs mikuni set up on my L and its been better than the stock hands down. Starts easy in the cold something it would not do before.

[Kawabuggy]

I changed to the 68S pilot at the same time that I swapped the cam. No one told me that I should, but I knew the stock 62PJ was just not going to work. I also switched to a full after-market exhaust, and a UNI air filter so I figured it would be safe insurance. After running the bike with all the new components I checked the plug and it was a nice caramel color just like it is supposed to be.

From reading on this web site and on others (4stroke.com) changing the PJ was mentioned as almost a necessity. I fully agree! My bike went from a dog down low to an explosive monster. With all of the changes it is hard to quantify which specific part made the most difference, but together, the package works very well.

Your bike may be different than mine, so carefully check your plug after making jetting changes.

[beezerjoe]

Very cool Kawabuggy I'm going to look into the pilot jet. The only question I have now is does Honda carry this part or is it an aftermarket item?

Thanks again.

[Kawabuggy]

Beezer, the 68S can be purchased directly from Honda. The catch is you have to tell them that you want a 68 pilot jet for the XR650R.

Here is the Honda part number: 99105-MBN-0680. Good luck!

[beezerjoe]

Right on Kawabuggy. I'll let you know how it works out ?