XR650R Carb Tuning Resources

So I've been playing with my jetting on the XRR. :dead hors:

Whats some XRR jetting combos people are running in the PDX area?

I'm running a 62 pilot, 172 main, on the 3'rd clip and 1 turn out on the pilot adjustment. Bikes got a K&N air filter, stock headers and uncorked. The spark plug looks pretty good in my opinion. I've always tried to get the plugs golden brown. Its just a lot easier with an AutoTune mapper on an EFI system...



Short of taking it in to RPM for a dyno run to see what the AFR is really doing how does one know you've got the jetting just right anyway? Just keep dropping jet sizes and go by trial and error? There's got to be some 'old wiser' method to the black magic I'm not mature enough to understand just yet but am willing to try

Here's some guidelines I used on my KTM LC4. The BRP also has an accelerator pump? which the LC4 didn't have.


http://www.iwt.com.au/mikunicarb.htm

http://www.mikuni.com/fs-tuning_guide.html

http://www.factorypro.com/tech/carbtun.html


My personal checklist:

Make sure valves are adjusted before tuning carb
Carb must be clean, choke is operating properly, and float valve is in good condition.
Make sure float height is correct

Many people suggest that reading plug color isn't helpful on a liquid cooled 4 stroke. I tend to agree. The main jet can be selected to obtain the most power at high rpm/wide open throttle. (Fifth gear full throttle what is top speed going up a hill)

dhally wrote:

Here's some guidelines I used on my KTM LC4. The BRP also has an accelerator pump? which the LC4 didn't have.


http://www.iwt.com.au/mikunicarb.htm

http://www.mikuni.com/fs-tuning_guide.html

http://www.factorypro.com/tech/carbtun.html


My personal checklist:

Make sure valves are adjusted before tuning carb
Carb must be clean, choke is operating properly, and float valve is in good condition.
Make sure float height is correct

Many people suggest that reading plug color isn't helpful on a liquid cooled 4 stroke. I tend to agree. The main jet can be selected to obtain the most power at high rpm/wide open throttle. (Fifth gear full throttle what is top speed going up a hill)

Thats awesome! Thanks a ton. Some really good reading their. I know I'm close. I adjusted the valves, installed a brand new clean air filter, went through the whole carb and cleaned, replaced all the o-rings and checked the float valve and height and put in a new spark plug. But I don't think I've followed the tuning methodology there at all. It makes perfect sense though and I'll have to give it a shot. Main jet, jet needle then pilot at their corresponding throttle positions and in that order. Shweet

The other tip I learned from Creeper at advrider.com is how to tune the idle mixture screw. Many tuning guides recommend adjusting the idle mixture for the highest rpm at idle. Creeper recommends adjusting the screw for best transitition from idle to 1/8 throttle. It is a subtle adjustment but I like that crisp response off idle. You'll be doing throttle wheelies in 3rd in no time!

It sounds like you should be pretty close, except your lean on the pilot. I would get a 68S or 70. The XRR carb does not have an accelerator pump, but works pretty good when jetted well. I would strongly advise tossing the K&N and getting a foam filter if you plan to ride in any dirt!! Here are some good sites:

http://www.dirtrodders.com/xr650r/faq.html

http://borynack.com/XR650R/index.htm

http://www.xr650r.net/

PeteN95 wrote:

It sounds like you should be pretty close, except your lean on the pilot. I would get a 68S or 70. The XRR carb does not have an accelerator pump, but works pretty good when jetted well. I would strongly advise tossing the K&N and getting a foam filter if you plan to ride in any dirt!! Here are some good sites:

http://www.dirtrodders.com/xr650r/faq.html

http://borynack.com/XR650R/index.htm

http://www.xr650r.net/

Thanks for the info. I was finally able to do a high speed run and see what it'd do. 8200rpm and 90mph is all that it had. I couldn't check the plug so I just chopped the throttle and let it decelerate and it didn't pop at all. It seams to only really pop when I'm fisting the throttle from low to 3/4 then decelerating. It'll actually back fire doing that.

I've looked high and low and nobody even knows what a 68s pilot is. I'll try a 70 with a UNI foam filter and see how that does. The plan was to street it back and forth to work for a while but I have been playing in the dirt a bit so I know that K&N isn't the best for that kind of business...

The "S" stands for smaller air bleed holes, which make it a half step richer than a non-S. I've never found one either and that is why I'm running a 70.

PeteN95 wrote:

The "S" stands for smaller air bleed holes, which make it a half step richer than a non-S. I've never found one either and that is why I'm running a 70.

My buddy just bought him self a 650R and it came with a big bag of main jets and pilots Asked real nice and he lent me the whole bag of them. I'll put the 70 in before I go for my ride this Sunday and see how she does

Here is my XR650R jetting combo which I got from 4strokes.com. I'm late to your thread here so if any of this is redundant please forgive. Im assuming you have uncorked the exhaust:

1 Replace the carb to cylinder boot with part number 16211-MBN-640.. or grind/rip/cut out the parts in your stock boot till the hole is round, not D shaped.

2 I live at 2300 feet and a 175 main jet works great from 400 to 6400 feet where I ride.

3 The Honda part number for a 68s pilot jet is 99105-MBN-0680. My Honda shop was dumb as hell about this part too, but it is a good number and it a 68s.

4 Use a needle 16012-MBN-641 and set the clip in slot 3.

5 Remove those two odd shaped parts that fill holes in the back of the skinny part of the air box. You dont have to remove the box. Warm them with hot air and they will rip out with pliers and be undamaged... tho you will never want them back in there.

Ive set up 3 650s like this and they run great and get about 35 mpg in general on/off riding. The XR650 is a forgiving motor and has so many beans it will run well on lots of carb settings. This setting is the one that I think is the most perfect... but thats only my opinion.

I bought all this stuff including the new manifold from a Honda dealer.. even tho I had to supply part numbers...dumb asses should have known.. for about 60 bucks. You can buy individual stuff cheaper I'd think but I wanted it all from one source at one time so I didnt have a lot of shipping charges. I think it has paid for itself in better gas mileage, doesn't overheat, and starts on kick one or two... all pluses of good jetting.