650R backfiring!!
 

My XR650R has a bad habit of backfiring when I'm kickstarting it, and I'm just wondering if anyone can give me some good advice on how to stop/reduce this. Thanks for your time. Ed

Hi Ed,

My opinion is reach of fuel...by me was the same when i changed the main jet,so my advice.....try to do a new carburetor sinchronization and the problem will be fixed I hope!

Cheers,
Simon

Ed,
Do you know the starting sequence for the XR ?
Has yours got a decompression lever ?
Does it backfire once it's started ?
Is it from hot or cold ?
How old is the bike ?
Just in case-------- use the decompression lever to get the piston just past top dead centre, that is pull the lever in, slowly push on the kicker until you feel a resistance and take it slightly past. Do not open the throttle, in fact don't even touch the throttle, then give it a good kick and let it idle for a short time before opening the throttle and then in small increments until the engine revs cleanly.
Cheers
Ian:thumbup1:

2002
 

Bike is 02 model.
Never backfires once started. Runs beautifully.
It does have the decompression lever.
Running on BP Optimate (98) at present.
Will clean the valves and put in new spark plug this week.

Ed

synchronise the carb with what? migrating wildebeest? what do you synch a single carb with? I used to do it with banks of 4 carbs

back to the question: are you flooding the engine? if it runs well once started, I'd guess you're flooding it by using the throttle while kicking it. only use the throttle if you need to clear a flooded engine eg after a tumble - pin the throttle wide open for 6-10 kicks then resume normal starting sequence which means finding TDC and then, leaving the throttle alone, kicking it through TDC. use the decompressor to nudge it past TDC if you like, but then give it a good kick. getting the choke setting right helps - mine can be a bit of a bugger. oh, and every now and then random XR650Rs will lose compression. I assume its the decompressor sticking, but I've seen it on several bikes.

and stop wasting your money on 98! that bike will run fine on 80+ octane cut with all sorts of shite without rejetting/plug-chop: they're bloody great!

Many thanks!
 

Thanks a lot, guys. Your help much appreciated. Have got a new IMS tank arriving soon and can't wait to fit it. Ed

Rich since you mention it.....

Is it okay if I use Oct 92 instead of Oct 97?

Its for my Dommie? And my Austin Mini Clubman....:confused1:

Petrol has gone up 30%!!:( This week!!:thumbdown:
:funmeterno:

I wouldn't know about your clubman, but wouldn't want to risk the damage to valve seats etc

the dommie engine powered my XR650L with dodgy rubbish, no worries. I tried diesel, but found pushing the bike back to the garage was a bit of a drag. I did find some "petrol" that pinked a bit under load so I backed off and didn't do any harm.