1970 T250II is smoking something fierce

[lrutt]

I'm convinced it's sucking trans oil as the injector is set proper. While it's not pulling much, within a couple hundred miles there is a noticeable drop in the trans oil level.

I really really really don't want to have to strip this whole thing down, break the whole crank down, and do those center seals. Motor only has 9k and is tight and runs great. This sucks.

I don't really know of a work around other than finding some kind of oil or additive that can 'swell' the seals a bit to help out the problems. Used to be you'd see that on forkoils etc.

Doesn't seem to effect the running, but the guys behind me when we ride sure don't appreciate it.

[Suzukidave]

I am sorry to say but if the engine is drawing oil from the transmission there isnt any way around it . Also if the seal should really fail it will also draw in air that could lean out that cylinder and then bad things happen

[lrutt]

Plugs look good but a bit oily, bike runs great. Just hate to have to tear it down that far, plus break that crank apart. This will be expensive assuming I can still get all those seals.

[tz375]

If it is sucking in transmission oil as you mentioned, then the crank has to come out to replace the seals. The only question is When?

You could do it immediately - because it has to be done sometime, or you can put it off and wait for a better time or for something else to give up. if the seals get much worse, you risk crank failure or a melted piston. The issue is that none of us can predict when either of those might happen. If you only use it for short runs and time is bad, you could elect to put it off and take that risk.

If you use it as a daily driver or plan anything much more than a run to the shops, sooner might be better than later.

[GT750Battleship]

Hi,I'm sure your laws in regard to pollution are just as strict as ours !!(Australia)
It might be an idea to get her off the road & repaired,not to mention the gearbox running low on oil,further damage
Cheers,
Roger

[Vintageman]

Too much smoke is a bad thing these days

[Stinger Ian]

hello ,you May get away with just changing the two outer oil seals ...ie the centre seal may be ok for a while

[Vintageman]

My experience on these cranks (about 4 now) is all had the center seal leaking only ("smoke like crazy") for the lip intended to block gear oil was designed without a tensioning spring. The other lip facing con rod does have spring. Of course I could be wrong... leak down tests may show this.

That seal shrinks (it's really old yes!), but is not damaged otherwise. This was a new experience for me with a bad seal. Seals I have changed that were truly bad you could see damage. It smokes for the gear oil is pushed hard into the center bearing via one of the trans gears.

Knowing this , and my bike was in good mechanical condition otherwise I would over fill the gear oil to the max (until came out crankcase vent near oil pump... might even have to tip bike downhill to ensure the center seals are fully submersed ) with oil intended for high mileage, like Valvoline Max life. Has seal restorer.

But since concentration of that additive is low, I would pour 8 oz AT-205 Re Seal mixed with light weight http://www.summitracing.com/parts/ATP-AT205/" onclick="window.open(this.href);return false; (similar to what is in High Mileage oils). and let it soak for while (gently kick start once and while to flow the oil into center bearing. Not ethat this will expand all seals it touches (Kick Starter, Sprocket, clutch rod, shifter etc). Worst thing is it won't work and then just tear down and change all seals anyways.

If you plan to keep the bike it is best to have crank rebuild with new seals and at least change Big End bearing with new OEM while in there. It is really not that hard too do on that little engine. But I do think it cost me over $400 to have it crank done once I got it out(labor, new seals, BEs, shipping two ways) last time I did this.