KH250 A5 Oil Leak / smoke issue

[Robbo749]

Hi folks, I've been a member for a few years but am not a regular contributor - apologies. I need the groups' expert wisdom and experience on a possible problem I have with my triple:-

symptoms - some evidence of an oil leak on right hand side of bike, under cases and along the expansion chambers. Its not coating the tyre but there is enough to be concerned. Initially I assumed that it was 2-stroke oil leaking somewhere from the old pipes, but eventually concluded that the clutch casing was leaking, and duly found little gearbox oil retained when I checked everything over and reseated the casing. There is a good amount of smoke on throttle on the right hand (offside) cylinder until the bike has run for a while and warmed up properly. As im havent run 2 strokes in my earlier years I cant decide if the on throttle puffs behind me are normal or gearbox oil being drawn in. Otherwise the bike runs very well and ticks over nicely - its a damn fine ride! Its still on the standard bore / pistons at circa 16k miles.

Initial diagnosis thoughts:- the crank end seal is either shot or not seated properly, drawing gearbox oil in on the compression stroke and blowing out of the cases on the firing stroke.

Questions
- does the diagnosis sound correct?
- any other diagnosis suggestions?
- what is the risk of running it like this (albeit keeping the gearbox oil topped up!)
- how easy is it to change the seals without taking the engine out / splitting cases? and if so any special tools needed other that pullers and picks?
- any gotchas to watch for?

thanks in advance
Mark

[Wolfie]

Your diagnosis sounds good and it is a regular cause of the RHS smoking more than the other two... You can change the seals in situ, but it is a quite brutal method.

Put three (or four) self tapping screws through the seal and they will push out the seal (against the Bearing cage), then tap in a new seal slowly and carefully, it may lose a little of the edge seal on the inner edge. Loosening the Casing nuts at that side may (or may not) make it a little easier.

As for your escape of oil, the place to take extra care when fitting the Clutch cover is at the three way junction between upper and lower cases, and the Clutch cover gasket, put some extra sealant there. Or the Kickstart seal could be weeping.

[scouse]

This might sound like a strange thing to say, however smell the right hand exhaust smoke
If it doesn't smell like 2 stroke then the crank seal or the O ring that's failed.
They are both easy to change without splitting the cases.
Hope this helps

[Robbo749]

Great help gents, thanks! I sense a quick flit to Z Power in the offing!

[Olde Coney]

Great help gents, thanks! I sense a quick flit to Z Power in the offing!

For any parts you should try here first

https://kawasakitripleparts.com/?v=79cba1185463

[Wolfie]

I did miss that you said it smokes until warm, if the smoke does disappear then you can probly discount the seal, it would persist all day with a dud seal.

Smoke that clears is often a sign of leaking check valves in the oil lines, allowing oil to drain into the bottom end until it is thrashed clear..

[doodah]

Also when the crank seal is shot ,it will aerate the gearbox oil so it will go white and foamy and leak out of the gearbox breather

[Robbo749]

Thanks both. Haven’t seen any aeration in the oil or symptoms. Re less smoking when warm, generally it only smokes when going from off throttle to back on the throttle and then goes back to “normal” on a steady throttle. I don’t seem to be losing 2 stroke oil from the tank so I have discounted the check valves to date.

Short term, I think the answer is to set all the levels, clean the cases, ride it and monitor changes.

Have had a look at the shop manuals and apart from oil pump tinkering it seems relatively straightforward to get at the seals behind the primary gear