Popping / backfire 1200c

Hi gang,

I have a 2004 1200c, .. .. bought used, .. when it got hot
it would pop through the carb and stall taking off from stoplights etc.

So, bought the full on tuners kit, .. .. rebuilt, .. even installed a new slide ( old had been drilled )
Yesterday I even replaced the manifold rubber gaskets, ..

45 / 180 jets, .. mixture screw is a 3 turns out, but doesn't seem to make
a difference where it is.
I did install the needle that cam with the kit too, .

It will pop through the carb, stumble and stall when trying to take off.
Any clutch and it just wants to die. Also seems sluggish now where before it
was quick.

It has the Screaming Eagle slip ons and K&N filter.

I tried the 46 jet, didn't help, ... replaced the plugs as well as the crank position sensor, ..

I'm about ready to push it into the lake!!

Any Ideas for help??

Curtis

I've had some similiar issues with my 06. On the freeway I switched it over to the reserve and it ran great. I ordered a new fuelvalve and am waiting on that. You might want to try switching it to reserve and seeing if it runs better, maybe your fuel valve is messed up too.

Thank you,, I saw your other thread.

it makes sense,, it acts like it's lean,,
and I noticed mine is leaking.

I already have a new one I'm going to install
and try tomorrow.

Thanks for the help,, ill keep posted

Uh oh. Mine has similar concern, sometimes its fine, some days I can't pull away from a stop without a carb fart/backfire and a stall. Very unpredictable. I have all the CVP usual stuff on order, and I have a new slide on the desk beside me, just waiting for everything to come in. Haven't even gone on a trip yet because I don't know when it may die for good. Guess I have another part I may need. Yay.

Your right, and I'll fix what I know to be incorrect before I chase at guesses, just interesting to hear someone mention something I might not have thought of. Was the gravity petcock such a bad idea from the past? Guess it could be if your float stuck.

See, this is the excellent information that can be mined from a well laid out and well supported forum. If my local dealer explained it out like this I wouldn't mind paying the rates, instead of saying "thats the way those bikes are, get used to it" when mine did the same thing I paid to have fixed after I picked it up.

I got a new Petcock from the dealer, and also replaced the cracked vacuum
line I found. It made it a bunch better, .. but still just a tick off.

Now let me say this again, FOUND the vacuum line to the Petcock split,
fixed it and it was a HUGE improvement !!

I still have an off idle stumble , and cruising at part throttle
like around 40mph, it'll pop through the carb and stumble, ..
cruise for another 1/8 mile or so, , pop, . maybe a few times, ..

but everything else is much better.

So If I can just get the little stumble gone now, .. i'd be perfect !

Curtis

In my CV kit it said to drill out the slide and use the included spring,..'

could my off idle stumble and part throttle stumble be from me not
doing that part???

Right now it has the stock slide and spring , .. new slide that has not been drilled.

well, just rode back to my shop to start the CnC machine on it's next task, ..

and, .. at a constant throttle, .. the damn thing keeps popping through the carb, ..
it'll run fine for a little, .. then, .. rrrrrrr Pop, Pop, .. rrrrrrr, .. Pop, ..
pop, ... ..

any more ideas?

Curtis

Race Flow Development

Tanks Ken,

I've done all of that, .. . loosened the cap yesterday based on your advice,..

Replaced the vacuum line, .. replaced the manifold gaskets, ..
what else is there???

This thing is driving me nuts, ..

and it's 90 and sunny, .. I wanna ride !!

Curtis

Your description of yours at the level of sputter it's at now is mine exactly. Dealer recommended a Dynojet kit which they installed and which didn't address the problem at all, then I was told that was normal. I think it is a fixable concern. I'm curious to see the difference after I install the CVP kit, and in the meantime I will be trying the gas cap idea on my ride today. Check your slide diaphragm for scorch marks, as mine showed some burns. Guess I should have express posted parts, as I'm still awaiting them. Darn me and my frugality.

i have replaced the slide, ,, exel pump, and everything else, ..
intake gaskets, petcock, vacuum hose, .. fuel, .

I find it hard to believe that it's "normal", .. ...

As a little background, .. I'm not a dummy when it comes to mechanical things.
I'm an induction engineer who works for major race teams like Star racing
pro stock motorcycle.
It's not an issue of me not knowing how to install a gasket etc.
Of course this makes it more frustrating to me because it's not making sense to me.

Where else could I have a vacuum leak?

Curtis

I'm an 18 year automotive technician with a "master" designation with my manufacturer, so I can relate to your pain/shame. Is it possible that it is a pressure wave travelling through the exhaust pipe and reverberating back to the cylinder due to the design of the baffles? I just got home from a 180km run on mine, no stall this time, but the intermittent pop was noted at 25-40mph when just lightly motoring along.

I too am running a Screamin Eagle II pipe set with a Screamin Eagle intake using a K&N filter on an original 1200 motor. If after installing CVP kit, drilling, chamfering, and polishing my new slide, and verifying no intake or exhaust leaks still results in the intermittent stall/minor pop, my next step may be octane boost in a tank of gas. Would it be possible the increased airflow/fuel with the beyond stock mods requires a higher capacity ignition coil set?

Ken,

I'll drop you my address etc in a PM,.

I'm wondering, would the popping at part throttle cruising be a lean condition?

As mentioned before I haven't drilled the new slide yet, ...

Thanks

Curtis

I guess my CVP package is delayed due to damaged in shipping, but if you resolve your issue please post your findings as it may help me diagnose mine if the CVP kit does not fully rectify my concern. Is this an issue a velocity stack would help with, or would that be only for smoothenss/power delivery at higher rpms?