Jetting XR650R

Another question for you BRP gurus.

I just installed a White Bros E series silencer and want to know what jetting I should be running. I'm getting alot of popping on decel and a very slight hesitation when I WFO the throttle...

Fully uncorked 2000 XR650R, WB silencer w/12 discs and spark arestor, Aftermarket air filter, at aprox sea level. (stock header)

I'm running a 65 and a 172 jet with the clip on the 2nd possition on the needle and 3 3/4 turns on the PMS screw.

Thanks guys!

What altitude & temps are you running? Your pilot jet should probably be increased to a 68s or 70 and then the fuel screw will need to be adjusted.

175~178(back plate off)on the main, 70s on the pilot, 68s will work

What altitude & temps are you running? Your pilot jet should probably be increased to a 68s or 70 and then the fuel screw will need to be adjusted.

I got a 68 sitting in front of me... anyone seen my screwdriver? :thumbsup: Alt is around sea level, temps from 80-100*

Any idea how many turns on the screw?

175~178(back plate off)on the main, 70s on the pilot, 68s will work

I think I'd like to keep the back plate (spark arrestor right?) on... :thumbsup:

it still might take a 178 sence your at sea level.

If you're at sea level or less than 1000', richen it up a bit. I'm at 650' elev. and run a 180 main, 68 pilot and have holes in the airbox/sideplate. Everything else is uncorked by the book, running stock head pipes and HRC exhaust tip with the spark arrestor screen and internal cap removed. The small diameter stock head pipes provide a really good low end snap, and with the HRC tip modified for better flow, will even give a decent top end, but not as good as the larger diameter aftermarket pipes. I prefer the chunky, snappy low end response so I use the stock pipes.

LL.

Any idea how many turns on the screw?

You should adjust your pilot/fuel screw and then adjust the idle speed at your riding location for the best results. Before adjusting the pilot/fuel screw, make a note of where yours is adjusted by turning it all the way in and counting the turns in until it stops (do it gently), but be careful when it stops and don't crank it tight because you can easily damage the screw's seat and then you might be really screwed. Put it back to where it was and make a note of how many turns out it was. To adjust the pilot/fuel screw, first make sure sure your engine is fully warmed up, then set the pilot screw to 1.5 turns out. With the engine idling at the 'correct' idle speed, turn the pilot screw clockwise until the idle slows. Then turn the pilot screw counterclockwise until the idle slows again. Make a mental note of how many turns you made in between the low idle points. Then turn the pilot screw half way between the low idle points to finish the adjustment. If you turn the adjuster counterclockwise and the idle doesn't drop down, then you need a larger pilot jet. If you turn the pilot screw clockwise and the idle doesn't drop down, then you need a smaller pilot jet, but this procedure won't work so well if you have your idle is turned up too high to begin with. After adjusting your pilot circuit, re-adjust your idle speed if necessary to the correct spec. If your off idle throttle response is as good as you've ever felt it when you whack open the throttle from idle while the engine is under load (while actually riding your bike), then you're done. If there's more hesitation than usual when you whack open the throttle from idle when the bike is being ridden (under a load), then turn the pilot/fuel screw 1/4th turn inward to see if that improves your throttle reponse. If it doesn't, try another 1/4th turn inward and see if that makes it better. If it gets worse in this direction, then turn it backward in 1/8 or 1/4 turn increments until you have found your best off idle throttle response.

Is your exhaust tip completely stock or has it been drilled out for better performance or is it the HRC tip?

Great info guys, Thanks!

I run at sea level in CA. When I installed my "E" series with 12 discs and the quiet core I was running a 180 main and 68s pilot. After additional mods (header, airbox mod) I was running a 185 main and 70s pilot. My bike loved it, the bigger pilot took away the flat spot on the low end from the airbox mods and even after dropping the bike it started pretty easily. I forgot to include this was with the UNI filter.

I also, ran the 185 main, 70s pilot, holes, uni and XR's only header. I swear by the 70s! the plain 70 pilot is better then the 68s....

Ok, I think I'm mostly done... I'm running a 172 main and a 68 pilot, 3rd clip on the needle and adjusted the screw like you guys said... that combined with being fully uncorcked, a UNI filter and the WB E series S bend my fat girl is running like a champ!

I may try taking a few disks out, but the decel popping is gone, she rolls on strong and pulls hard though the gears.

Thanks guys! :thumbsup:

When Honda designed and built this engine, I wonder if they knew it was going to be THE motor to have! I've ridden alot of different bikes, but the 650R engine is IT man! Totally Freakin' Rips!! XR650sm.jpg

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now