TT600R won't start(but once we tow it, it runs perfect)

[wonky]

One of our TT600R's has decided it doesn't like starting. It got progressively worse over about a week until now we can't start it with the kickstarter at all and have to tow it, then bump it in 3rd gear. Once we get it going it runs as usual, although he has to leave the choke on for a little longer than usual. When its hot, ie within 10-15 mins of stopping it will kickstart.
Theres an intermitent medium pitched knocking noise its started doing as well. I'm not sure if its a valve or something nastier. The knock is in time with the rpm.
I'm thinking the starting problem might be a blocked pilot jet but haven't stripped the carbs yet
Any other ideas from the wisemen?
Cheers

[mph4]

split carb, rubber?

[aukeboss]

I would also think it has something to do with the idle mixture. The TT6 is pretty sensitive to that. Indeed, inspect the intake rubbers. Also, try the following: turn out the idle mixture screw out half a turn and try to kickstart. Maybe even a full turn or 1 1/2 might solve the problem. This would be a clear indication that the mixture is becoming leaner which is normal with wear and tear.

Auke

[Breed1229]

sounds like a lean mixture problem, or valve lash, or even a combo of the two. As stated a bad boot will couse a lean mix also.
Please let me know what you find, also if the pilot was blocked it would not idle well if at all, good luck man

[smokinrider]

i would suggest strip and clean the carbs as a starting point. if the bike previously run fine dont adjust anything. youll just end up not knowing where you are and have a hell of a job sorting any problems.

i have noticed that the american contributors to these carb related questions seem to go straight for the adjust this, change that, fit bigger this ect. rarely is the problem that complicated.

if it was running and then stopped it isnt going to be the size of the main jet or any other jet size issue. it soundls like the carb is running a bit lean due to a blockage of some sorts. my dr regually needs a carb cleaning as i use it a lot in mud, every time i strip it there a lot of dirt in there despite inline filter and filter on the taps.
the knock sounds like preignition caused by a lean mix.

clean the air filter whilst your at it and make sure all breather pipes ect are clear. i would put money on a bit of sludge in the pilot jet circuit, remember to count the turns on the pilot screw and replace exactly the same when rebuilding.

after this you could check the valve clearances and the decompressor cable adjustment. fit a new sparkplug as well whilst your there.