Timing

[1fastZ1slowridr]

I took my Z to the shop and had cams (stage one hot cams intake and exhaust) and a piston (wiesco 13.5:1) put in. I got it home and before i tested it out i put on a full hmf and big gun rev box. when i brought it to the shop it ran fine and had a fmf slip on. when i tested it out it ran like **** and spits and sputters on top end. so i played with the jetting. after i tried multiple combination of jets i figured it wasnt getting any better and tried the stock rev box and nothing changed. it sounds like its hitting a rev limiter similar to the reverse rev limiter. now the question. could the timing have anything to do with this. any help would be really appreciated.

[duke416ex]

Timing could be affecting it, did they not jet it at the shop, and I would just call them to see what they say bout it.

[400exrider707]

We have been trying to figure this Z out for the last couple of weeks. What 1FastZ1Slowrider forgot to mention that is when the bike starts up and is just sitting there in neutral it runs fine. It revs strong and sounds completely normal. Its only when you are riding it, will it start to act like this. We are running out of time and possibilities here. We were thinking electrical, but we had someone run over the whole quad and he said everything was getting power where it needed to be. Im totally baffled by this. We have tried a million different jetting combos and nothing seems to help or make it worse so I dont know. We have tried lid on, lid off, upped the pilot, went between a 150 and 175 main and everything in between. Someone please help! We have a big race this weekend and need to get this thing going. We're definitely going to call the shop today, but we would rather do it ourselves as the shop is looking more and more incompetent. Thanks

[bwamos]

Sounds like it's off a tooth.

My 330ex was doing that. When I reassembled I managed to set the timing chain 1 tooth off. Not sure how I did it.. it's not exactly rocket science.. lol. But, when it was off it would sputter and sometimes ping when it was under heavy loads.

I'd bet you are having the same issue.

[duke416ex]

I owned a z400 for a very short time, but never did any mods to it. What it the stock jetting and what jetting combos did you use? Also, have you adjusted the fuel air screw any?

[400exrider707]

We have tried nearly every jetting combo together and nothing made it really any better. We went from a 148 main to a 175 main using mikunis and dynos. We upped the pilot to a 25, and we tried almost every clip position on the dynojet needle. We tried the big gun cdi, the stock Cdi, the HMF Full, the FMF slip-on, lid, no lid, you name it we tried it. Nothing. We are ready to set this thing ablaze at this point:mad: We are open to ANY suggestions as to what the problem might be. We are starting to lean more towards timing at this point now, but all the work was done by a reputable shop, so I would hope they did this right. We are probably going to pull off the cover and look at the cams tomorrow and see if we find anything. This is getting really aggrivating!!!:mad: :mad: :mad:

[duke416ex]

Did you call teh shop? Since tehy did the work I would have had them fix it before I even messed with it. If they are very respectable, they are gonna want to make it right. The jets don't have any blockages do they, and I know it sounds stupid, but is the choke on, if not what does it do with it on?

I would say the timing chain is off one tooth. it is kina easy to figure it out. just bring it up on its comp stroke and see where things lie.