Hey guys,

Just finshed installing the Jardine pipe and some new jets a few days ago. Holy nuts is it loud. I really wasnt expecting that at all.

Anyway, I started off with a 145 stock main jet which with the new pipe and K+N, I immediately upped to 152.5. The bike was backfiring on decelleration like hell I adjusted the idle mix screw and seemed to reduce the backfiring, but still prevalant and loud at times.

After riding it over the course of a day, the bike seemed a bit rich on the top end, so I swapped out the 152.5 with a 150. Midrange to top end performance is great. Its like a totally new bike, but i still have the darn backfiring on decelleration or throttle roll off. I checked the header bolts to see if they were loose and tightened them up, thought maybe that was the prob.

The bike was still backfiring, so I thought ok its too lean I'll try to up a pilot jet to 55. I rode to work this morning and the bike is still doing the same thing backfiring and popping on decelleration. I've kinda gotten the hang of holding the throttle in such a way to avoid the backfiring but I shouldnt have to do that. Does anyone have any ideas of what i can try now to eliminate the backfiring?

Thanks for the help.

what did you do for the mid range (spacer/needle) ?

You are doing that correctly.

you should also check to make sure you have not crimped either side of the intake boot. An air leak at the intake causes a backfire like an exhaust leak.

I'm with Jim on this one. Check the fit from the header to the muffler for leaks. Mine was leaking like a sive but I wasn't aware of it. An easy check is to put some soapy water where the muffler and header attach to each other then, with the engine idling, cover the muffler outlet with something. I used a potatoe but you can use anything. I was shocked when I saw all the bubbles coming from under the muffler clamp.

Helmut

Thanks for the help guys, I think the exhaust might have been leaking. I did the whole cover up the end of the pipe and soapy water bit but I didnt see anything. So just to make sure I put some silicone sealer around the connection and tightened the hell out of the clamp.

This morning I drove to work and voila I wasnt getting any backfires on decel or at least nothing major, occasional put puts. Now what seems to happen is backfiring on upshift from 1st to 2nd, all other gears seem ok. Am I running too rich now?

Well i finally fixed the bike.

I ended up pulling the intake boot off and reseating it properly so i was sure there were no leaks there. Then I pulled the header bolts out and put some locktite on them and put them back in. No leaks at the header. Bike was still backfiring at this point but not as badly. I pulled the top of the carb and shaved my 1/2 spacer prob down to about 1/4 maybe a little less. Then I adjusted the mix screw which is at about 2 1/2 turns now.

Been riding the nuts out of the bike now for 3 days and the backfiring is gone, the bike is also a lot more responsive now. I'm thinking the additional spacer shave must have helped. It still backfires but very rarely and it doesnt sound like a gun shot.

Thanks to everyone for their assistance. Much appreciated.

If you go w/ the loctite, replace the bolts w/ something stronger than the factory garbage.  like grade 8s.  If you can find them in metric.

On the other hand, how do grade 8s do w/ thermal expansion?  Anyone know?  Same as regular steel?  or pot metal?