Well I thought I fixed the backfiring with the #4 spacer,it worked fine after I put it in yesterday, I went to town today and it's back in all it's noisiness,the same as it ever was,now what? any ideas guys ?

Make sure you have no intake or exhaust leaks and slowly turn out the slow mixture screw to see if it helps. Mine pops a little and I'm not too concerned about it. It's never popped when shutting it down.

Good luck, after all I've done to mine, the popping still comes and goes. No exhaust leaks. Screw set right where it should be. Runs great!! Except for the occasional annoying POP between shifts. I really think it's an atmospheric thing. Humidity and such.

Lancer, it's like you say, pop and Crackle,no gun fire type noice. what is the correct setting for the idle screw?
that's the one on the right side ,right? the thumb screw on the left I just adjust it to get a nice idle ???
in the past I have owned nothing but singles,none of them back fired at all (500cc was the biggest)

not seeking to hijack mick's chain but I thought a sign of leanness was a pop as you shut the throttle too, but my plug is a little on the sooty which everything I've understood is that it means it is running rich!

whaaaat?

mick - what color is your plug? maybe that'd help with advice out there.

owners man states to go to a hotter plug(ngk dpr7ea-9) if "plug's insulator is dark"...anyone tried this?? os split fire??
mick try search for "lancers' easy carb tuning" it helped my decell pops along with better throttle controll on my part,she doesnt like havein it snaped shut( elev. 4k + less O2)..also think i remember a post from a fellow savager whose air mix screw( on right side one behind the brass plug, idle screw (throttle valve stop screw) is where the throttle cable attaches to the carb) had vibrated out of adjustment ... good luck let us know what you find

I experimented with a post-mod bike to find the "ideal" setting of the air screw ( the one under the sheet brass plug).

I did notice that popping frequency would come and go between the various adjustments, never going away completely but being much more frequent in the richer settings than in the leaner settings.

Your sooty plug and pipe indicate you are running "richer" which is what the idle speed method tends to give you when you use it to adjust your air screw.

Turn it in by the 1/8 turn increments and run it a week at each setting.  Don't bother with measuring gas mileage, that always seemed to have more to do with my wrist than with the air screw setting, but do record your pipe color and how the bike accelerates and runs generally.  And the popping and backfiring of course.

You will find differences exist and you will wind up at a setting that maximizes what is important to you.

Oldfeller


PS, is your air filter clean?   A plugged up air filter can make you run richer all by itself.

I notice mine pop's more on humid days.  Humid days have thinner air, means rich mix popping.  Same if you pop more in higher elevation.