Author Topic: PVL Timing  (Read 41716 times)

0 Members and 1 Guest are viewing this topic.

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #45 on: March 13, 2025, 08:15:08 pm »
What's the best way to apply threebond to the crankcase without putting too much or too little on?

Offline pokey

  • Legend
  • *****
  • Posts: 1482
  • Arse .. Elbow. Know the difference
    • View Profile
    • FB
Re: PVL Timing
« Reply #46 on: March 13, 2025, 09:27:46 pm »
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.

Offline Tomas

  • A-Grade
  • ****
  • Posts: 333
    • View Profile
Re: PVL Timing
« Reply #47 on: March 13, 2025, 10:46:14 pm »
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  :)

Offline John Orchard

  • Legend
  • *****
  • Posts: 3079
  • ^^^ July 1984
    • View Profile
Re: PVL Timing
« Reply #48 on: March 14, 2025, 07:19:32 am »
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.
Johnny O - Tahition_Red factory rider.

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #49 on: March 14, 2025, 03:29:34 pm »
Thanks folks.

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #50 on: April 17, 2025, 01:36:38 pm »
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?
« Last Edit: April 17, 2025, 02:00:34 pm by 2T »

Offline pokey

  • Legend
  • *****
  • Posts: 1482
  • Arse .. Elbow. Know the difference
    • View Profile
    • FB
Re: PVL Timing
« Reply #51 on: April 17, 2025, 02:36:19 pm »
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.

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #52 on: April 17, 2025, 03:11:06 pm »
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.
« Last Edit: April 17, 2025, 03:35:43 pm by 2T »

Offline Wasp

  • A-Grade
  • ****
  • Posts: 442
  • Your Suspension Solution since 1989
    • View Profile
    • Suspensionshop
Re: PVL Timing
« Reply #53 on: April 17, 2025, 04:38:42 pm »
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 .
VMX shocks , We don't just sell them - I design and produce them individually for you since 1989.

Offline pokey

  • Legend
  • *****
  • Posts: 1482
  • Arse .. Elbow. Know the difference
    • View Profile
    • FB
Re: PVL Timing
« Reply #54 on: April 18, 2025, 08:08:30 pm »
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.

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #55 on: April 18, 2025, 09:19:17 pm »
Thanks, pokey.

I'm guessing poor installation. I'll get a new seal next week and try again.
« Last Edit: April 19, 2025, 05:45:26 am by 2T »

Offline 2T

  • Novice
  • *
  • Posts: 39
    • View Profile
Re: PVL Timing
« Reply #56 on: May 03, 2025, 06:15:21 pm »
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.