Rough start with backfire?

[PIP RC51]

I Finally got a 01 PIGGY R' and rode it for the irst time last weekend. The guy I got it from claimed it was uncorked and rejetted with the factory Honda kit, but not ridden much. When I got it, it was hard to start and ran rough but it did have old plug and gas in it. I changed oil, drained gas and added full tank of 93, new plug. This made it better but some times it still takes 8-10 kicks to spark it up. When cold it hesitates under power and when warm it backfires under decelertion.

He also added a aftermarket airfilter but did NOT drill air holes in the side panel. Does this make that much difference and could this be the problem?

Noob.....PIP

[Agent2]

Usually hard starting and backfiring on deceleration indicate a lean air/fuel mixture. Not having the air holes in the panel most likely will not affect performance on a stock xr, so I doubt that is the problem. Might want to pull the carb and see what jetting you really have and see what intake manifold you have - not sure about other states, but Cali xr650's have the restricted intake. From past experience I have found what people say and what really is can be 2 completely different stories.

[OUTERLIMITS]

Usually hard starting and backfiring on deceleration indicate a lean air/fuel mixture. Not having the air holes in the panel most likely will not affect performance on a stock xr, so I doubt that is the problem. Might want to pull the carb and see what jetting you really have and see what intake manifold you have - not sure about other states, but Cali xr650's have the restricted intake. From past experience I have found what people say and what really is can be 2 completely different stories.

I would agree with Agent2 on this. Mostly the pilot jet/needle position could be the issue. Make sure you have the 68s pilot jet.

[PIP RC51]

Thanks.

Will the jet have the number right on it? Or is there a way to tell by characteristics? And what do you mean about position?

PIP

[Maroast]

Thanks.

Will the jet have the number right on it? PIP

yep, it *should* have 68s stamped on it.... go to http://www.xr650r.us/jetting/ to see how to jet your bike...great info on that little page.

And what do you mean about position? PIP

that is the needle position...search that pigpen site for the link to a site with pictorial instructions for jetting your carb...its mad easy to do and you dont have to take the carb off the bike to do it.

can someone help me (and this dude)? the needle position effects the throttle where? Idle? mid? or full on? when I first uncorked my ride I had the clip to far down from the top (so somewhere in the throttle it was to RICH) and a to large main jet....the bike ran pretty good if you didnt hit the throttle to hard...it started first kick no problem too.....

But when you punched it, it choked for a sec then took off....after raising the clip an going down on the main jet, the throttle response was instant and the bike ran like a monster...no problem starting too.

So I *think* the needle is important for mid/ full throttle...please correct me if im wrong....

this isnt a hijack, its meant to help others (including myself) better understand carb tuning. thanx.

-tom

[OUTERLIMITS]

From what I recall, the main jet handles most everything from about 1/2 throttle on up, the needle & needle jet from about 1/4 to 1/2, and the pilot from about idle to 1/4 throttle. These are estimates and there is actually some overlap in there as well that I didn't cover, but best to stick to the basics.

PIP, unfortunately you really don't want to do a lot of changes at once because if it runs worse you really won't know what change caused it. I can tell you that I had the exact same problem with a '96 KLX650R as far as the backfiring on decel and going one up on the pilot cured it completely so I would start there. If you go to yahoo groups and join the XR650R group (it's the largest group they have for off road motorcycles) there is a ton of info there. They have section on the left hand side of the page called "files". In that is a ton of info about the XR as far as modifications and what have you. But there is also a jetting file that lists what people are using at different altitudes. From what I recall, most people used about the same jetting except changing the main jet size for different altitudes. Not sure if the 8-10 kicks to start is when cold or hot. I find this bike sometimes easier to start cold than hot. When cold, I usually hold in the decompression lever and kick it through quite a few times and maybe crack the throttle open once or twice to get some vapor in there. It seems to work well and takes less than half the kicks to light if I don't do that. Richer jetting (especially on the pilot jet) will help with starting.

As far as the airbox holes, I have them with a stock (but uncorked) exhaust, but really did not notice any difference. Could be that I ride at sea level and get a lot of air anyway.

Good luck!