Recent Posts

51

Tech Talk / Re: PVL Timing

« Last post by 2T 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.

52

General Discussion / Re: Any old boys still here ?

« Last post by crossedup2 on April 23, 2025, 04:22:54 pm »

Brett

You beat me by a month. ( You started in June 2007, me in August). Not the oldest but certainly close to it. And yes at our age we can all be cheeky.

We have crossed paths somewhere, possibly a Classic Dirt I think. You were on your way North if I remember correctly for some action in QLD, then home.

I still check in to see if there is any new / old stuff happening.

It's still a great reference for knowledge and wisdom. Any Google search on old bikes brings up links to this information.

I'm hoping to make it to the world MX at Hidden Valley in Darwin later this year. Possibly riding up there to watch but we will see.

Keep the chats coming. Never boring!

Peter B

53

Spaniards (Bultaco, Ossa, Montesa etc) / Re: Ossa flywheel nut.

« Last post by Dungar Pilot on April 22, 2025, 06:41:21 pm »

Hi Everyone,
It has been a while since working on an OSSA, my memory tells me there is a shock absorbing spring on the end of the crank? Most bikes have springs inside the clutch basket,  OSSA do things differently!

Photos would help you cause.

54

Spaniards (Bultaco, Ossa, Montesa etc) / Re: Ossa flywheel nut.

« Last post by PeterC on April 22, 2025, 08:27:02 am »

I assume it is a Femsa flywheel. You will need a flywheel holder too stop flywheel rotating, undo nut, remove washers andbthen use cirtect flywheel puller

55

General Discussion / Re: Any old boys still here ?

« Last post by brent j on April 21, 2025, 09:37:54 pm »

I still look in here occasionally but there's so much online stuff now that never used to around.
I started off following Graeme Mc when he had the "PETSHOP" site as I had an XT500 I was building up for VMX.
He had a VMX group page on YAHOO which was where I heard about Ray Ryan's passing. I joined this site as soon as it started and living in the top of nowhere this was my VMX lifeline.
The Turkish hackers had their go, and most people rejoined.

This site gave me the opportunity to find interstate events and when the chances arrived to travel to compete. I battled for last place up and down the East coast for 10 years or so and met a lot of people and was shown some great hospitality.
The trips have stopped (10-15,000km trips with accom and cost soon add up) but I still ride every chance I get.
The priority moved from VMX to Vintage enduros and now vintage trials.

I'll be cheeky here and say I must be one of the longest, continuously standing members. A lot had enough over time and left the forum but did return.

56

Spaniards (Bultaco, Ossa, Montesa etc) / Ossa flywheel nut.

« Last post by olddirtbikes on April 18, 2025, 09:39:20 pm »

  Hi Folks, can anyone tell me the correct way to undo the flywheel nut on a 1974 Ossa Phantom 250 please???
    Thanks, Alan

57

Tech Talk / Re: PVL Timing

« Last post by 2T 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.

58

Tech Talk / Re: PVL Timing

« Last post by pokey 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.

59

Tech Talk / Re: PVL Timing

« Last post by Wasp 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 .

60

Tech Talk / Re: PVL Timing

« Last post by 2T 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.