xr 650 r too lean on high revs

hi

my xr 650 r runs too lean especially on high revs. she has a powerful low and mid range but the top end is not like it should be and i am missing 10 mph max speed.

i have a 175er main jet and a b53e needle on the third notch. everything stock, uncorked, hrc tip. she starts and idles perfect.

i checked for air leaks with a gas torch but didnt find any. where are possible/the most common air leaks? is it possible that an air leak only shows at high revs?

my spark plug is white like snow after a fast ride. after idling the plug shows a really really light brown but still too "white".

any ideas what is causing the lean mixture?

Try a 178 main jet

Did you inspect the filter screen on the petcock in the fuel tank?

Any restriction in the fuel line?

Did you confirm that the slide in the carburator is full open when the throttle is twister to the full open position?

i will check this

and i will try a larger main jet

thanks!

Any luck on the lean issue?

AURORA wrote: Any luck on the lean issue?

i think my BRP is doing alright now

i changed the coolant, the oil, the spark plug and the carburetor manifold; checked the valves; cleaned the carburetor, the gas tank and the petcock.

i use a 180 main jet now (i dont feel any difference to the 175 though)

the ceramic of the spark plug is still white but the top of thread is black. should i post a pic of it? i dont have a lot of experience with spark plug reading.

thanks a lot

regards

martin84 wrote:

AURORA wrote: Any luck on the lean issue?

i think my BRP is doing alright now

i changed the coolant, the oil, the spark plug and the carburetor manifold; checked the valves; cleaned the carburetor, the gas tank and the petcock.

i use a 180 main jet now (i dont feel any difference to the 175 though)

the ceramic of the spark plug is still white but the top of thread is black. should i post a pic of it? i dont have a lot of experience with spark plug reading.

thanks a lot

regards

Yes. Post a picture.

i am a bit late with the pic therefore you get a second one with the oil strainer screen from the frame =)





my pig now has 14000 miles on her two feet without engine problems. last time i checked the screen at ~12700 miles and it looked about the same as now.

i took the pic from the spark plug after the oil change so she idled a few minutes before (but she was already cold when i took the pic)

do i have to worry about this?

PS: sorry for the quality - the pics are from my cell phone.

What airfilter you got?
Foam, oiled etc, or a cotton-gauze clean one?

BuRP wrote:What airfilter you got?
Foam, oiled etc, or a cotton-gauze clean one?

a twinair, i guess thats the categorie "oiled"

do i see bronze coloured parts on youre oil filter?

the spark plug looks ok to me. (4-takt is grey and 2-takt is coffe with milk brown)

Sharp Ricko!
Yip, bronze parts in the oil, and that probably means the bigend thrust washers are going.

Not too good news I'm afraid......


Edit: plug looks fine, but I'd pull the crankshaft out asap. If you don't now you risk the cases, not a good idea.

do i "only" have to change the thrust washers or is there probably more that needs some love?

should i change the connecting rod too?

i heard carillo is a good adress.

can i do something to prevent this from happening again?

thanks

Send it to a reputable expert and take his advice = my advice
And yah, Carillo's a good c/rod.

But, you're going to split the cases for this - which is the perfect chance of putting all new bearings in, plus seals etc. I'd use the opportunity to renew the clutch-bushing as well then, and check the clutch plates & basket (of course), check any gears, oil pump etc etc, I'd go over it with a magnifying glass.
Your engine now is some 11 years old, a respectable age if anything, however when in use anything goes eventually. I'd rather have some 'anythings' replaced on a workbench instead of somewhere out there, but this just may be me.

thanks alot

i start searching for a competent mechanic (not that easy) and feed my pig only whats good for her.

"Europe" is a bit vague, Russia's also Europe, ditto Latvia & Greece...... but, XRsOnly do full services if you can bear the shipping cost. You could send them your crank, but re-assembly (dunno how competent you yourself are) is just as important.
Then again, you should be able to locate a local expert, they're everywhere after all.

Chief,

To determine wether or not you are at the correct fuel air mixture you must look at the spark plug ground point. This is at the base of the insoluator and the metal inner collar. Looking at the insoluator tells you what temperature range sparkplug based on your style of riding be it full throttle all of the time or half throttle all of the time.

To inspect the plug you have three choices.

Run the plug in your bike then do one of the following.

A: cut the thread barrel to inspect for a residue ring on the base of the ground and base of the insolator. This will indicate your mixture.

No residue....lean
Brown residue...exacte mixture
Black...rich


Most people get their proper fuel air mixture then go one jet richer just to add a little engine longevity.


B: get a sparkplug inspection light. Then shine a light into the sparkplug as you look through a 10 power magnification.


C:Stick a small piece of cloth or paper towel into the described area, without touching the insoluator or metal barrel, and look at the color of any or all residue.

http://www.strappe.com/plugs.html