Good high temp alloy putty?

[John Orchard]

Hi Gentlemen,

I want to do some reshaping of aircooled 2-stroke ports, mainly inlet & transfers, Lots of different aluminium putties on the market, JB Weld seem to have a large range (appears about 5 different specs) and not super expensive, the JB Weld product that seems to have good strength & heat resistance is their 8297 product, has a good 'set time' and 'cure time', this is the one I am considering.

I have read some good reviews on JB Weld 'original', I have used, and seen used Devcon (the inlet port floor on one of my Kawa ZXR750 Superbikes was Devcon'd, it was a missile), Devcon seems a bit pricey, and I wonder how it would stand-up to thick applications?

What say you Guy's, recommendations?

I'd still be interested in any suggestions of an ex-port filler also, maybe you might use the same product in both cooler & high temp applications?

Thanks in advance for any input that can assist me, regards, John.

[djr]

Hello, my only experience is with JB weld.
There are really only 2 types , the slow hardening "original" type, or the fast hardening "Kwik" type.

The slow hardening one is better, more durable, and will withstand a higher temperature, but tends to flow unexpectedly when hardening - you spread some on and get it to a rough shape that you want, but an hour later it has flowed away from where you want it to be !

Can't comment on Devcon, as I have never used it, but it seems to have been popular for decades

[sleepy]

I use Devcon FasMetal 10 with good success. I would think the biggest problem in a 2 stroke exhaust port would be getting it to stick to the oil/carbon impregnated metal but unless you are trying it on the bridge I would think the temperature may not be a problem short term.
Never used JB weld but is meant to be quite good.

Just looked on the box and the devcon not recommended above 120 Deg. The gas temp would certainly go above that but would the metal temp go above is the question.

[John Orchard]

I would think the biggest problem in a 2 stroke exhaust port would be getting it to stick to the oil/carbon impregnated metal but unless you are trying it on the bridge

I'm looking at modifying unused NOS cylinders.

[pokey]

JB Hi temp, Devcon  etc are all quite good for engine mods but the exh port gets pretty damn hot  and your better off with a a TIG and a port grinder. I dont need to say but i will that getting the surface clean is the key for epoxy to key. Acetone works well.

[sleepy]

JB Hi temp, Devcon  etc are all quite good for engine mods but the exh port gets pretty damn hot  and your better off with a a TIG and a port grinder. I dont need to say but i will that getting the surface clean is the key for epoxy to key. Acetone works well.

I'd agree that welding is the best but for experimental testing the epoxy should last long enough for a few quite blasts in the back yard and once the shape is proven then start welding. What could possibly go wrong?