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Transmission oil smoke, no cylinder leak?
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Author:  slink6333 [ Fri Aug 18, 2017 3:36 pm ]
Post subject:  Transmission oil smoke, no cylinder leak?

Hey everyone,
long story short; my '75 H1 developed a right cylinder heavy smoke problem a long while ago and the bike got put aside for multiple other projects at the time. The bike is now the primary project again and I've been getting her back to running condition.

The cases were split and the outer seals and o-ring were replaced again (not the first time for this bike). All three cylinders were pressure tested for 6 psi both vacuum and pressure, both showing no leaks at all. The problem is that I still have excessive smoke coming from the right cylinder which I cant seem to diagnose. The bike runs well otherwise (obviously the right cylinder is getting covered in oil and not running well, but aside from that). The smoke doesn't follow the carbs and remains in the right cylinder.
I am certain it is transmission oil and if I remove the check / reed valves at the bottom of the crankcase it will drip out the tranny oil. (if I then start the engine for a minute and turn it off, it will have new fluid it sucked in to drip out the bottom)

I cant seem to understand how the oil is making its way into the cylinder if the engine is sealed and passes a leak down test?
I will say that the crank has never been rebuilt, and the only option I can think of would be if the crank is so out of balance that it is letting the oil in as it turns?
otherwise, I'm at a pretty big loss for an answer and looking for any suggestions :banghead

Author:  Jim [ Fri Aug 18, 2017 3:39 pm ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

You don't really need to split the case halves to change the outer seals.

Have you wiggled the right end of the crank to see if the right bearing is shot?

Author:  slink6333 [ Fri Aug 18, 2017 3:52 pm ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

Jim wrote:
You don't really need to split the case halves to change the outer seals.

Have you wiggled the right end of the crank to see if the right bearing is shot?


True, and I have replaced them without splitting cases in the past, but i just wanted to make sure everything sealed correctly this time and was in no time rush.
I do vaguely remember wiggling around the right side when I had the cases back together and it seemed sturdy and the bearings did appear to be in decent condition.
how much play is too much? I can pull of the side covers and give it a wiggle again this weekend. Could a bad bearing cause a significant leak / smoke?

Author:  Jim [ Fri Aug 18, 2017 4:57 pm ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

It certainly could. Any play you can feel in a ball bearing is too much. If the inner bearings are OK they could make the outer one feel good unless you give it a good tug, preferably with a dial indicator to show how much it's moving.

Author:  H2RTuner [ Fri Aug 18, 2017 5:53 pm ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

What case sealer was used, please?

I only use Three-Bond 1194, works great for me.

Author:  67lotus49 [ Fri Aug 18, 2017 10:42 pm ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

About 10 years ago I had the right outer crank bearing destroy it's cage. If you have changed the right outer seal more than once already
I'd take a good look at that bearing. When my right outer seal failed it hydro-locked.

Author:  slink6333 [ Sat Aug 19, 2017 5:52 am ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

H2RTuner wrote:
What case sealer was used, please?

I only use Three-Bond 1194, works great for me.


I used permatex motoseal ultimate gasket maker, which I believe is a knock off of the three bond. Regardless, the cylinders passed the leak down test so I wouldn't suspect the sealant to be the issue, I don't think

Author:  slink6333 [ Sat Aug 19, 2017 5:58 am ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

67lotus49 wrote:
About 10 years ago I had the right outer crank bearing destroy it's cage. If you have changed the right outer seal more than once already
I'd take a good look at that bearing. When my right outer seal failed it hydro-locked.

Jim wrote:
It certainly could. Any play you can feel in a ball bearing is too much. If the inner bearings are OK they could make the outer one feel good unless you give it a good tug, preferably with a dial indicator to show how much it's moving.


I'll take a closer look at the bearing hopefully today or tomorrow. Are there any signs the bearing would be that bad other than just lots of play? It definitely hasn't exploded in the cage quite yet, but l'll try to get my hands on a dial indicator and see how bad it actually is.

Author:  triple cranks [ Sat Aug 19, 2017 7:59 am ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

Just a thought....
Maybe do the pressure/vacuum test again for the right cylinder with the crank at several different degrees of rotation? It could also be the O-ring between the seal collar and the crank. It is located right behind the pinion gear tucked under the collar.

Author:  slink6333 [ Sat Aug 19, 2017 8:16 am ]
Post subject:  Re: Transmission oil smoke, no cylinder leak?

triple cranks wrote:
Just a thought....
Maybe do the pressure/vacuum test again for the right cylinder with the crank at several different degrees of rotation? It could also be the O-ring between the seal collar and the crank. It is located right behind the pinion gear tucked under the collar.


Oddly enough, I actually did this when I did the pressure test. I rotated the crank about 120° each time and it held pressure consistently. Another reason I feel I'm going crazy here, I thought for sure that would show a leak if the crank was unbalanced.
The o-ring was replaced with the seal and I made sure to do the timeless method of spraying the hell out of everything with soapy water to look for bubbles in the o ring area, it showed nothing :|

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