Gasket or not?

[Mick Taylor]

Hi all, I took my Classic out for a 30 mile spin to the pub and back last night and it is running like a watch, super smooth and responsive, it would be near perfect if the forks didn't chatter ......but that's an incurable issue as I understand it and not the subject of this post.

One of the alloy air transfer ports leaks a small amount of thin oily brown fluid....it always has done.

20181014_140059_resized (720x1280).jpg

I can find no mention of a gasket in the parts book......nor on the AN exploded diagrams.

I'd like to fix this leak on an otherwise dry engine......I have a pair of O rings to hand, what is the sealing arrangement where the leak is?

Mick.

[Richard Negus]

There's never been a gasket there, so your sealant of choice.
ThreeBond, aka Yamabond, or RTV silicone works for me.
There's an O-ring where the elbows join to the frame; a smear of RTV there doesn't come amiss.
R.

[Mick Taylor]

Thank you Richard, at least I know I can definitely fix it now.......much appreciated .

Now....if you could just recommend a fix for the rattling front forks.......

Mick.

[Richard Negus]

Now....if you could just recommend a fix for the rattling front forks.......

Mick.

Mick,
As a Saab dealer once said to me about a noisy gearbox, "Yes Sir, they all do that"
Doug Hele came up with a fix using shims to reduce movement of the damper piston and reduce the rattle. AN may still have some, 48.0263 Shim .005", although there's a strong chance they'll need cleaning.
R.

[Mick Taylor]

Doug Hele came up with a fix using shims to reduce movement of the damper piston and reduce the rattle. AN may still have some, 48.0263 Shim .005", although there's a strong chance they'll need cleaning.

I hadn't heard of that before......you are right, AN do have some in stock so I'll order a few, thank you.... .

That's a job for a dark winter day......scented by fork oil, what could possibly go wrong?

Mick.

[Mick Taylor]

Resurrecting an ancient post on air transfer ports.......my left side port always leaked a little oily brown fluid, so I tried the high temp silicone as suggested and it cured it.....for a while.

Recently I noticed my idle speed is slightly elevated by a couple of hundred rpm and it was suggested it may be the air transfer ports allowing air in at the rotor housing joint, and as it happens...... this time both sides are leaking a little oily fluid, so the RTV fix was temporary.

I removed the left port casting today and all that was left of the silicone gasket was a very thin band hanging onto the inner edge of the casting....on the actual gasket surface, almost no trace at all.

Happily, inside the port I've opened it's spotlessly clean.....I'm thinking of using a smear of Wellseal this time as the silicone failed; is there any reason I shouldn't use this?

Mick.

[Mick Taylor]

Further to my last, having given it some thought I've ordered some thin, (0.4mm) high temperature gasket paper to make up a pair of gaskets...... I think this problem will just reoccur unless I do something more than just spreading sealant, so the plan is a gasket with a thin smear of whatever sealant seems best at the time. How I wish they still made Hermetite gold..

If it works (or fails) I will report back......presumably I can't be the only person with this problem...

Mick.

[BlackIP2]

Yes, I have a similar issue with my right hand port, but I think mine might be aggravated by having removed the small cover a few times (it's held down by one of the transfer port bolts) to access the vacuum pipe etc. I would have thought all the other bolts fixing the transfer ports would have been enough to still completely seal the facings, but obviously not - unless removing that one bolt and none of the others might cause the slightest of warps?
Anyway, I am looking at a way to fit that small cover to a bracket without having to remove the bolt every time, and will also see how successful you are with the gasket.
Cheers
Mark

[Mick Taylor]

Further to the gasket saga, I made a pair up using 0.4mm gasket sheet intended for stationary engines (high temperature) gave each one a very thin smear of Hylomar both sides and refitted the transfer ports; the extra 0.5mm does fractionally raise the casting of course and I found I had to bolt down the engine end first to slightly compress the gasket before fitting the frame bolts, but they all went in just fine.

I also found the rubber vacuum hose fitting at the fuel tap end of my vacuum line was cracking, ordered a new one from Andover only to find it comes without the rubber adaptors despite the parts book showing it as a single unit...happily, lots of old British cars seem to use an almost identical part.

Come the moment to start it, today...it wouldn't fire; long story short, no spark. For no particular reason I pulled all the fuses one by one to check...all good, but when I put them back I had excellent sparks and it started straight up. If anyone could throw any light on that to suggest what might be going on I would appreciate it as electrics are not my strong suit....it only seems to happen from cold.

Out and about for 20 miles or so, the hot idle was still too fast and sounded like two single rotors competing against each other, a distinct throb throb idle with a momentary pause.....five minutes or so with the screwdriver and she now idles at 900rpm and sounds like a single unit, with an unbroken silky smooth and steady idle, she also starts instantly when hot.

No leaks from the new gaskets, early days of course, but fingers crossed it's a fix.

[Mick Taylor]

Update on my home made gaskets for the air transfer ports on my Classic. Rode out to Hastings and back today, about 60 miles in total and it got fully up to temperature in town.

Not a trace of leaking from either transfer port, it's so nice to have a spotless engine at the end of a run....and, maybe unconnected, but the idle has improved, it's now a steady 800rpm with no hesitation.....so for me at least, gaskets have worked.

Mick.

[BlackIP2]

Good news on that Mick.
I took my right transfer port off to re-seal it and I've done around 100 miles or so.
However, the bike's up on the bench again as I have to take the carbs off to replace leaking float chamber valves.
And I have to remove that bolt that holds the engine cover in place, but guess what, the port is leaking again!

Leaking air port.jpg

I can't believe you and I are the only ones to suffer this issue, but I will try your gasket cure. Can I ask where sourced your gasket material from please?
And how did you you get your transfer ports so clean and smooth, or is that how all Classics are?
My ports are quite rough at both joint ends, which I suppose could just be the result of a hard-worked ex-police IP2?
Cheers
Mark

[Mick Taylor]

My bike has always had this problem, however I've been out on it over the last two days and I still have zero leaks from the transfer ports so at the moment I consider it cured.

I used this stuff as it's intended for high temperature applications.......and I bought the thinnest available.

https://www.ebay.co.uk/itm/Stationery-E ... ctupt=true

Or.....just copy and paste this description into the ebay search field.

Stationery Engines high temperature gasket sheet material paper BS 7531 Grade X

Mick.

[BlackIP2]

Thanks for that Mick.