GT250k Wont run

[malky]

this GT250K is doing my swede in,
rebuilt motor new crank seals etc rebore but cant get it running properly - it will start on the bump and run then six times out of ten will go first kick and then - nothing - got spark and fuel but it just will not go - checked timing several times carbs float heights checked - running out of ideas now - never been stumped by a two stroke before - other thing is it seems to keep getting a lot of fuel in the crankcase as when it does eventually start on the bump it pours out of the exhausts - am I missing something simple here?
Mal.

[ConnerVT]

Fuel in the chambers can be bad float needle/seat, or possibly a hole in the float.

[sportston]

Fuel in the chambers can be bad float needle/seat, or possibly a hole in the float.

I second that. Also could be dirt in the carbs stopping the float valves from sealing. Do you have inline fuel filters? Have your carbs been cleaned thoroughly on a high pressure water or air line?

[jabcb]

Could also be caused by a bad vacuum petcock or a manual petcock that was left in the “on” position.

[malky]

thanks for the input guys- petrol tap is working fine - looking like its bad carbs going to try and get hold of a set of 250M units which are a bit more refined with better idle set up than the K ones - also have leak off pipes on them - don't suppose anyone has a pair kicking about have they?
Mal.

[dollydog]

hi malky, i've got both sorts, all sonic cleaned and rebuilt with new jets. if you want 250a [non flanged carbs], then you might have to wait a couple of weeks while i refurb some. plus you will need the flange rubbers, which i don't have. the ramair 250's are my forte pm me for details.
cheers, dd.

[dollydog]

hi mal, i've pm'ed you twice, but for some reason they are both stuck in the outbox and not showing as sent.
don't know why? forum must be having a bad day
cheers, dd.

[malky]

the saga goes on ,
bike now runs and goes like the clappers - starts first kick but still have a strange problem in as much as it will not run on the right cylinder only when it comes to set tickover speed etc - it will run and idle on the left cylinder no problem but even if the bike is running and I pull the left lead off it struggles and just stops - carbs are all good float heights etc spot on all jets clean - really at a loss with this - anyone got any thoughts before I start looking at coils and the like
Mal.

[jabcb]

Make sure the battery is good and has a full charge.

[Craig380]

Will it run on both cylinders when it's on the choke? If it does stay alive on the right pot on choke, then it points to a pilot circuit problem

[malky]

No it starts on choke but only on the left cylinder - knock choke off and the right chimes in - does this on three different sets of carbs so I can't have a pilot problem on all of them surely - was going to try swapping the carbs over by using a longer balance tube to see if it was any different - bowls are on the correct carbs and little choke jet in the bowl is clear - this bike is just spinning me out !!!!

[alanr]

swap plugs over and see if any different.

[malky]

Tried that - makes no difference - going to try another set of coils on it next

[tz375]

If it starts on left side with choke, that side is lean and when choke is opened the right side kicks in, suggests that there's an air leak on the left side and that the right side is jetted a touch rich.

If, as you say, it makes no difference when you change carbs over, that suggests the intake is leaking or maybe even the base gasket. Pressurize the left side and spray soapy water around the base and intake and look for bubbles.

[dollydog]

you should be able to see if the base gasket[s] are leaking, but the head gaskets are a different matter. did you retorque the heads down after first running it? did you use crappy pattern head gaskets that don't squash? i still agree with jab about the airleak somewhere, but i'd start at the top of the engine and work my way down - starting with the head gaskets. if all else fails, bring it to aberdare next month and i'll fix it for you
cheers, dd.