I'm back again looking for any input as to what could be the problem. 97 zx7 with stage 1 DJ jet kit , full muzzy exh. Float bowl mod. I have tried everything to get this bike to run right. It accelerates flawlessly, starts up fine, idles fine. When I try to just cruise at a steady rpm , it pops through the carbs and sputters. It also will pop through the carbs while warming up with the choke on about every 8 to 10 seconds. I just did a leak down test and to my surprise all cylinders tests perfect and even. I have synced the carbs at least ten times now. I have put a different set of carbs from a known good running bike on it. I have adjusted the vales and checked the cam chain and tensioner. The only thing that was slightly suspect was that the chain had a very small amout of play between the cam gears. The manual says there should be no play at all but it seemed pretty tight. I have also tried reversing the float bowl mod and still nothing. I took off the carb boots and inspected them and put a bit of sealer around the o-ring just to be sure. I have also taken the complete wiring harness out and opened it up completely and checked every connection. Soooo, now that I can rebuild my bike without a problem I just need to know how to make it run right. I am down to my last clump of hair to be pulled out. Any one, any help, please.

 

Sounds frustrating!

If there is one thing that Kawasaki could never get right, it was their cam chain tensioners. It happened to my 750 before. I fixed my problem by putting on a manual cam tensioner, and it ran SO much better afterwords.

I noticed that with a loose cam chain, the bike will run fairly smooth until you hit bumps in the road. The road bumps shake the loose chain enough to off-set the timing, which could cause a backfire, or stutter.

 

When did the back firing start? Was it after the installation of the dyna jet?

 

I don't really remember when the backfireing through the carbs started , it may have been after the dynojet but it was running bad before it as well.

 

stupid question, are the carbs synched?

 

did the DJ kit change the piot jets? if it did, which they usually do, then you have to readjust the pilot mix screws,( i am not referring to the main jets, but DJ usually replaces the pilots, and then you have to bore out the lead plugs and adjust the pilots screws, if not it runs so rich it wont run except at top end, it take that far to clean out the rich mix, and its this rich mix thats poping in the pipes

 

Any feedback mario66

 

I have adjusted the mixture screws at least ten times , sometimes lean and other times more toward rich and resynced the carbs after each time with little to no improvement. It just still pops through the carb at lower rpms and won't cruise at say 4k rpms steadily, no matter what gear i'm in. It still accelerates without missing a beat though. Some one suggested that maybe something is wrong with my ECU but i'm not sure that I believe that . Also some days it runs better than others and I have learned to avoid riding in such a way as to allow it to pop. It is really driving me crazy though.

 

Might sound stupid but did you check the spark plugs

 

and or wires