PVL Timing

[2T]

What's the best way to apply threebond to the crankcase without putting too much or too little on?

[pokey]

Spare nozzles are pretty handy. Cut the nozzle on a 45 degree angle or whats comfortable for you to hold while working on the engine. Then on the tall side nip a small Vee out of it so its about 2mm wide. Thats how wide your sealant will be, the height will squish down giving you a full cover of the case surface. Wider surface needs a wider Vee. Squeeze too hard you get more sealant travel too fast and you get less. Do a few practice lines so you get the feel and squish it so you can see how wide the bead ends up.

[Tomas]

What's the best way to apply threebond to the crankcase without putting too much or too little on?

I was going to use a screwdriver the other day but could not find it. So I just used my own finger to smear it on 

[John Orchard]

What's the best way to apply threebond to the crankcase without putting too much or too little on?

I put a drop on the end of my finger, enough to cover about 60mm at a time. Always applied 1104 like that.

[2T]

Thanks folks.

[2T]

I have just reassembled my motor and a leak down test has air coming out the stator side crank seal on the inside where it wraps around the crank shaft.

When I disassembled the motor, I inspected the area around the stator and there was no sign that oil/fuel had been leaking from the seal. Makes me think I've got something wrong during reassembly. The seal is new and genuine Yamaha.

Can anyone suggest what's gone wrong?

[pokey]

What pressure did you use to test? I ask as over pressuring can damage a new seal. You can get lucky and reposition the seal lips if not ton on assembly. I recall your previous issue with the seal not fitting thus not sealing.

[2T]

Was very careful with the pressure, pokey. Took it slowly to 5 psi and it dropped fairly quickly. With a soapy water mix sprayed over the seal the leak was very evident around about 50% of the surface.

I now see that assembly lube or grease should have gone on the crank surface before the seal was fitted and I didn't do that. It went on dry. Could that be the problem?

Re: seal fitting. That was on the clutch side. This side was a much firmer fit when I installed it. I also used a wipe of threebond.


Am about to remove the spring off the seal and see if I can inject some oil or assembly grease under the lip.
Update: Still leaking.

[Wasp]

In my opinion , any sealant on a seal is only insurance . If the tolerances or surfaces are not correct , any amount of sealant can not fix that problem. In theory , it should not leak , even without sealant . But of course we always apply a little for security. Crank bearing tolerance is also worth checking , just a thought .

[pokey]

Sounds like your test method was fine

The options are

Poor installation method.
Old stock shrunk seal
Worn case/shaft

The more i read of the history the more i would be looking at the case. Spun bearings can do that.

[2T]

Thanks, pokey.

I'm guessing poor installation. I'll get a new seal next week and try again.

[2T]

For those interested, I've solved the leaking crank seal problem.

The seal I removed had some small notches on the inner lip, possibly caused from not lubricating the shaft before installation. I also had a good look at the shaft and casing, and they look in very good shape.

I followed up with a leak-down test with no leaks from the seal but a leak from the decompression valve thread (a drop from 5psi to 3psi over three minutes). I fitted a tight-fitting o ring over the valve thread and that solved the problem. I still had a leak but found it was coming from the air inlet fitting on the leak-down tester, so I've had a win. Onwards!

Thanks to those who helped out with advice.