WL Inlet Nipple Replacement

[Rex]

Has anyone here successfully done a rear cylinder inlet nipple replacement without removing the cylinder with engine in the bike? If so I'd appreciate some tips on the procedure. I've done this with the cylinder on the bench using T. Cotten's cam rivet backup device which worked well.

[T. Cotten]

Has anyone here successfully done a rear cylinder inlet nipple replacement without removing the cylinder with engine in the bike? If so I'd appreciate some tips on the procedure. I've done this with the cylinder on the bench using T. Cotten's cam rivet backup device which worked well.

Yes, Rex...

Or maybe it was the front.

I wish you patience, careful observation and attention to detail, and mostly,.. Good Luck.

.....Cotten

QUIRAM1.jpg

[Architect]

Yes I have done it, twice. The first attempt held until it seemed like a good idea to "port" or "relieve" the inlet, started to leak again. Second attempt has been holding well since last summer. No good advice beyond what Cotten describes, we used a hodge podge of tools and methodology to make it happen, I hope to never have to do it again. The first attempt was a month long process with a lot of back and forth with Cotten. The second attempt with with a real master mechanic at his shop, about 6 hours start to finish. Good luck, but it is possible more than enough room.

[T. Cotten]

The hardest part of doing it in the chassis, Jim,..

Is cutting and crushing the old nipple to get it out safely.

The reason this is usually necessary is because often the threads of the nipple have been 'upset' at the rivet, presumeably from fierce over-torquing of the nuts.

RIVTHOLE.jpg

Twisting it out would tear new threads in the casting.

On very lucky instances, after removing the rivet I was able to take a flat-ended punch to deform the nipple inward enough that the damaged threads no longer engaged.

...Cotten

[Rex]

This one was installed @ 10 years ago with very little riding since. One of the new inlets wouldn't seal in the cylinder threads so I imposed a light vacuum to pull in a sealant which produced an air tight joint. I don't remember if this failed one was that one or not, but it's leaking all the way around not just one spot. I may try it in place, but since the bike is mostly disassembled for transmission rebuild I may just pull the cylinder. Riding season is far enough away to get it done.

I think this is the sealant I used, but drawn in after it was riveted in place. This time I'll liberally coat the threads & mating surface before installing the new nipple. If there's a better product or method let me know.

https://goodson.com/products/fluid-weld

Also if there's a cylinder thread restoration option I'd be interested. Don't want to replace the cylinder after overboring and big valve conversion.

[Rex]

Yes I have done it, twice. The first attempt held until it seemed like a good idea to "port" or "relieve" the inlet, started to leak again.

The ones I replaced looked like this when I received this engine from the expert builder (2 years, $3000). They blew massive bubbles as did the manifold joints and spark plug holes. Probably a relieving attempt.

45 manips 009a.jpg

When looking at this series of pictures it looks like I did this with the complete engine on the bench. I believe that would be easier than pulling the cylinder in the frame.

[Rex]

The hardest part of doing it in the chassis, Jim,..

Is cutting and crushing the old nipple to get it out safely.

Twisting it out would tear new threads in the casting.

Thanks for the tip, I would have made that mistake. Saved me again my friend.

[T. Cotten]

Please review the VI discussion, Rex!

http://virtualindian.org/11techleaktest.html

Beware however, that the best sealer has yet to be determined; 'Seal-Lock' requires clean, bare metal. Even parkerizing must be blasted away for its chemical bond. The only fuel-proof sealer that I was able to wick into cracks was an isocyanate urethane: TNEMEC's 'Omnithane 530', and I don't know if it still exists.

Beware also that the thin lip on the casting seals by biting into the nipple, so it must be perfect.

....Cotten

[Rex]

Yes, I have plenty of Omnithane, got it after my visit to your shop 1/28/2007, used it on the float screw last week. I had considered using that, but the data sheet indicates 250F continuous and 275F to 300F intermittent depending on the document you happen to find, and a 12 month shelf life. The green Motorcycle Mechanics Handbook Motorcycle Department Fort Knox KY 1943 has a nice temperature distribution illustration of the engine, and while it doesn't specifically indicate the temp at the cylinder inlet, the surrounding temperatures are well above 300F. If it doesn't retain its intended corrosion protection qualities that's OK, as long as it clogs up the assembly. Fluid weld is good for 3000F and while it doesn't specifically mention fuel resistance it is advertised for internal engine use @ valve seats,etc. Of course I'll do a soak in a bottle of gas test on a cured sample to be sure. Life is a just a continuous series of science fair projects, right?

[T. Cotten]

I've had Seal-Lock fail to seal, Rex,...

Unfortunately, it is intended to bond metals, not fill voids.

As far as the Omnithane shelf life, my stash is over twenty years old (when it was called 'Poly-Ura-Prime'), so perhaps today's isn't the secret sauce it was.

Otherwise, I have found it to take manifold heat excellently, even when mixed with bronze powder to appear "nickel". It is it's fuel-proof quality that made it outstanding, and if your new product fails in fuel, my prices just went up.

....Cotten

[Rex]

Mine's not new, I bought it in 2007 when you told me about it, but has since been discontinued. I won't bother with the fluid weld for this, probably what I used last time.


This is my version of the leak tester only because I had the leakdown kit which had a nice regulator for low adjustments. Leak % gauge not used for this purpose, 1/4" steel plate tapped for common sparkplug thread cut with readily available tap.

leaktester.jpeg

[Rex]

Motor's on the bench, leaking nipple cut out. Took of the heads for cylinder inspection and found a couple headbolts had oil soaked threads, all others were dry. What does this indicate?

When this was put together @ 2006 I used blue teflon head gaskets which aren't reuseable. What's the best type today?

[Architect]

I use copper head gaskets, never had an issue. I recommend cleaning all head bolt cylinder threads. I had to special order a tap, they have a weird pitch. This is the one I used:

https://drillsandcutters.com/7-16-16-hss-bottoming-tap/

[Rex]

I do have that tap, thanks for the link to the source. Do you use solid flat gaskets or the ones with the raised beads?

[T. Cotten]

The embossed India gaskets gave me fits, Rex,..

Even on cast iron heads, as they bubbled just kicking it! (If you have to depend upon a sealer, what's the point of the gasket?)

Aluminum heads used composite gaskets, and were always successful for me.

....Cotten
PS: My question to all the copper proponents: Do you want the gasket to insulate heat from the head to the cylinder, or conduct it?
I'm open to opinions, of course!