Just rejetted, ran great, now won't start...

Alright here's the lowdown...tomos a35, just put on a estoril pipe, and an intake to get the carb out from under the frame. I also took out the air box and am running some panty hose for a filter.

Took a while to find the right jet but ran great with a 76. Now all of a sudden, it's not starting. If it does start for a second, I have to have the throttle wide open and then cuts right back off. Great spark, seems to have good compression if I do the finger test. Anyone got any clues? I'm at a loss for what else to try!

Re: Just rejetted, ran great, now won't start...

did you check fuel flow at all points in the system? petcock, fuel line, inline filter if you have one, banjo/banjo filter, main jet, diffuser... i have had similar problems and a good carb clean did the trick. also, read the troubleshooting guide on the wiki.

Re: Just rejetted, ran great, now won't start...

Yup all freshly cleaned and read the wiki.

Re: Just rejetted, ran great, now won't start...

I took it apart to check and the bowl was full of fuel.

Re: Just rejetted, ran great, now won't start...

That doesn't mean the engine is necessarily getting fuel - the fuel also has to travel through the jet and diffuser. Both clog easily. If you're stock I assume you have an SHA since it is a Tomos A35. My bike with an SHA was bogging, dying and generally running shitty even after I "cleaned" the carb. Then I really blasted out the diffuser with carb cleaner then compressed air. No more problems. I'm still pretty new to this myself, but I've learned from experience that the carb often isn't as clean as you think it is. Take the time to get every little part of the circuit, not just the main jet. And run an inline filter!

Re: Just rejetted, ran great, now won't start...

Inline filter huge. petcock filter suck. had this problem on my stock bing when i was at anything but mid range my ped would die. Found an air leak and a peice of sand restricting the fuel flow inside the carb. i know i'm odd and soak my carb in fuel. Also compressed air is the best blasting though every port and hole. easy enough to pull a spark plug and see what fuel your engine is actually getting. also SEEMS to be good compression really doesn't mean much. could be dissipating around the ring or a hairline crack very easily. found this to be an issue on my lawn mower. just my 2 cents. Enjoy. Best of luck.

Re: Just rejetted, ran great, now won't start...

Overpriced Parts /

Possible seize? and now you have bad compression .

Re: Just rejetted, ran great, now won't start...

I never felt any seize...could it of happened without me noticing?

Re: Just rejetted, ran great, now won't start...

Overpriced Parts /

Yes funny this summer I saw few puch kstar 70 cc kits/engines that few weeks after they were kitted didn't run good with bad idle .

The kids/guys swore they weren't seized and never felt anything. Soon After taking apart they both were seized in some way with bad scoring.

One just needed a clean up and a new piston. The other one was too bad to fix,

Couldn't see no damage from taking off just the head .

Most damage was in the bottom/underneath of the piston/cylinder.

Re: Just rejetted, ran great, now won't start...

Restrict airflow, down jet a few...you are getting to much air..

Re: Just rejetted, ran great, now won't start...

If I'm getting to much air would just upjetting work?

Re: Just rejetted, ran great, now won't start...

Yes, and fucking with the needle and mixture screw (if applicable)

Re: Just rejetted, ran great, now won't start...

I'm still at a loss, tried everything.....the only thing I can think of is that the jetting is off but if that's the case, why would it have ran seemingly well for a day?

Re: Just rejetted, ran great, now won't start...

Okay so I randomly got it to start and held it at wot and it revved up and down, up and down, up and down all while at wot.

It also seemed to be spraying fuel from pipe. Is this mean too rich?

Re: Just rejetted, ran great, now won't start...

Well a 6 is a pretty large jump from the stock 53 for just a pipe and intake. I don't own a tomos but a few of the guys here recommend a starting point to be about a 57-58. You are likely very rich although it may not be your complete problem it is likely a large portion of it. I would suspect that the bike running for one day could have been because the engine was warmed up prior to the jet change and is not doing well with cold starts or running in general. Have you tried to replace the stock jet and start the bike? I would not ride the bike in that state but it should start and idle pretty well if not a bit lean.

Re: Just rejetted, ran great, now won't start...

I haven't tried going that far down. I'm also running panty hose as a filter so it's getting a lot of air. You think even with that filter set up I should try and much smaller jet?

Re: Just rejetted, ran great, now won't start...

Yes, I run a polini "race filter" had to tune the jets for this monster air flow. Gas is explosive, yes, but only in the right mixture to much air or to much fuel = no go.

Re: Just rejetted, ran great, now won't start...

Lukas McWhorter /

Mine does this from time to time and I don't know why.

Anyway, confirm you have spark, and after you know you have spark just spin the hell out of the engine with a good electric drill until it runs.

Don't ask me why, but it works every damn time and I bet you the next time you start it it'll fire up soon as you bump it over compression.

Re: Just rejetted, ran great, now won't start...

I went to the garage and down jetted all the way back to a 58 and still no start.

However I did notice a black liquid (couldn't tell if it was oil or fuel) that had dripped down the crank from the engine. Not a lot but enough to puddle. Does that mean the engine is flooded? Maybe that's why it's not starting?

If it is flooded, what should I do?

Re: Just rejetted, ran great, now won't start...

My conclusion is that you have and exhaust leak and the high jet is compinsating for it.

or

The black liquid might be used up and spat out tranny fluid from behind the sprocket.

Re: Just rejetted, ran great, now won't start...

What makes you think exhaust leak? It's got a brand new gasket on it so what else could fix that? thx for the help!

Re: Just rejetted, ran great, now won't start...

Could be leaking transmission fluid.. could be a crank seal, which is where I would go seeing that you are having issues starting and even once running it surges up and down. If it's leaking anything, go in there and find out what is leaking.

Re: Just rejetted, ran great, now won't start...

Sounds like a carb clog. I would seriously think about jetting for a real air filter, you'll be happy you did later on.

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