wont rev clean,smoking

[dave916]

check the choke circuit on carb, remove choke plunger as it is easy to get a bit of dirt under plunger which would cause the problems you describe  [running rich ]has to be choke problem, blocked air filter ,pilot to big  if starts with no choke   any luck getting exhaust valves?

[no sub for cubes]

i stripped the carb,the choke seemed to be working last time i had it running as when i pulled it on it just killed the engine,pulled the motor out again today as im convinced there is an issue with seals or some tranny leak into the combustion,i took it for a run over a local bit of land lastnight and the gearbox has issues,1st 2nd fine third a vague(all gears are there just temperamental) and it locked up 2 3 times where i couldnt even select a gear.
when i rebuilt it i replaced the gear drum and gear change mech cos they were shagged,since then i bought this 87 motor for spares(wish id waited before spending money on gear drum and gearchange mech) and the box and selector forks in that look good and are same as my 88...so its another reason to pull it apart anyway and sort that out.
I give up trying to source the valves dave,tried everywhere,mine are useable just worn,i will pick up the search again after ive got the bottom end sorted the bloody thing running right.

[KX5Zuki]

Theres a couple people on here that can describe how to do the leak down test, but no one has decent pics or anything, so heres a link to another site that I am on, and here is a very detailed description on how to do it!

http://forums.atvdragracers.com/index.php?showtopic=3548

And yes, alot of the stuff is interchangable, I am still trying to get my hands on a kick start assembly. Soon. HaHa. Well, I hope this helps you out. Tranny fluid still seems ok? Not running low at all?

[no sub for cubes]

cheers for that kx5zuki that an excellent diagram of how to make your own leak tester,i have already pulled my motor out now and gonna strip it down to change the gearbox over,i will again look at the main seals and also check the case halves to make sure their completely flat,if your in the uk have a look on ebay there is a kick start mech on there now,wish i could help you out but i just wanna hang on to the bits i have as spares,ive spent a fortune on new bits so know how expensive and difficult some parts are to source.


                                  thanks again

[dave916]

if you are doing a leak down test you have to try and seal the little seal on kips rod ,      Did u use proper sealer on crankcase , threebond 1194 http://cgi.ebay.co.uk/Threebond-1194-1104-200g-tube-liquid-gasket-yamabond_W0QQitemZ370148148648QQcmdZViewItemQQptZUK_Motorcycle_Parts?hash=item562e8c85a8&_trksid=p3286.c0.m14&_trkparms=65%3A12%7C66%3A2%7C39%3A1%7C72%3A1689%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

[no sub for cubes]

hi dave

thanks for the additional info,as for the case sealant thats exactly what i used 3bond and i put it on generously because i had an oil leak before,its a bit of a ball ache having to pull it apart again but i will be sure to check the case halves are flat this time,dont really know what else to do,buy another set of seals perhaps and maybe use some case sealant to put them in.
it was suggested that it must be running to rich to start without the choke which is true,but ive explored all avenues and cant find any reason for that and like i said first time i got it running it was sweet until it started smoking like a bitch ,i have already pulled the motor out and this weekend will pull it apart again simply because i need to change the gearbox and selectors cos their naff,im interested to see whats lurking inside the cylinder now.

                                         will keep posting

                                             thanks everyone