My 87 TT 350 has a problem, it ran great before I put it away for the winter.

[CR500123]

My 87 TT 350 has a problem, it ran great before I put it away for the winter.

My problem is it will only run with the choke on, when I shut it off I have to keep revving the engine and then it is backfiring through the carbs and head pipe. Also the head pipe gets extremely hot melting the plastic around it.

Thanks in advance.

[ttr225ttr]

umm dont runn it like that iam not sure but to me it sounds like it might be running real lean im not sure

[spratt]

Your carb needs cleaning 🤣🤣

[ovrrdrive]

Sounds like a clogged pilot jet to me. Take all of the jets out and give everything a good cleaning with carb cleaner and compressed air.

[CR500123]

First, just want to thank you guys for all the advice.

I bought some Gumout in a spray can and filled a coffee can with it. I soaked the carb in there for the whole weekend, and then I took it to work and used an ultra sonic cleaner for four hours. I used everything you can think of to make sure all the passages where free of dirt. I put it back together: same damn problem was still there!

So I thought maybe I need to check my intake manifolds so I took them to work and used helium leak detector on them and they were leak tight. I didn’t know what direction to go next. All ignition, electrical has been checked and working perfectly. It has a rebuilt head and the valves and timing is on the money.

I was just about going to give up when I saw a guy selling a set of carbs on Craigslist for a 1988 XT 350 for $40 I got them home and pulled the bowl off to my surprise they were very clean my thought was not to disturb anything on them and see if they would work.

I installed them and the bike ran great at first (until it warmed up) then the same damn problem came back!

Then I got to thinking maybe it had different jetting so I swapped the jets and installed the carbs. Three kicks and that was it, my bike runs great now the only thing I can think of is the infamous internal vacuum leak on the original carbs; MAYBE! I don’t know.

Thanks again to everyone who replied to the post.

CR500

[PumpkinHumper]

You had a plugged jet. Carb cleaner dosn't always get it. take an old throttle / clutch cable and unwind a few pieces of wire from it. Feed then wires thru the pilot jet. There is something in there. My kids TTR90 was the same way. Ran like crap all of a sudden backfiring thru the carb and suck. I cleaned the carb with cleaner and air and nothing. Ran some wire thru the jet and wala ran perfect.