Don't skimp, buy oem!

Recently I had an issue with my rpms taking off. Very air leak-y kind of behavior. I pulled the timing rod and greased it, replaced the timing advance springs, replaced the enricher seals, replaced the throttle shaft seals,(twice!), And cleaned and rejetted the carbs. I hopedh on the bike today after the second throttle shaft seal replacement and it did the same shit. Sigh... I started going back over anything else I did this year and remembered that I replaced the carb boots over the winter. I took the probe off of my mechanics stethoscope and started listening for air. I heard it on the right side. I pulled the carb boot and set it on my work bench which was now at eye level because I was sitting in the floor. That's when I saw it. Light coming from under the boot, which should have been sitting flat. On closer inspection, there was a manufacturing defect that caused a hump in the rubber (not an euphemism). That where the air was leaking! As a quick fix I slapped a bunch of gasket silicone on that spot. Long story short, don't cheap out and buy the mikesxs boots. Go oem!

Agreed.

Similar issue with non-OEM fork seals. Just garbage... I make a practice now of always checking if a part is still available through Yamaha before I buy random stuff. It's usually the same price, shipped right to my local dealer for free. Just check via https://www.yamahapartshouse.com and take the part number to the dealership. I also hunt around on eBay for NOS stuff.

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Great idea wherearewe. I never even knew that site existed. It also helps me to support my local shop, which I'm big on.

Re. carb boots, I'm sure you've noticed by now that they are not available from Yamaha (and haven't been for many years). But the original manufacturer was ARS, and ARS boots for 447 motors with BS 38 carbs (1974-79) and BS34 carbs (1980 and after) are still available under the Tour Max label, which is a K&L Distributing house brand. They can be ordered from 650 Central or any local shop that deals with K&L. The only new boots for earlier heads that I know of are from JBM Industries. JBM also produces boots for late motors, both BS38 and BS34. JBM boots are high quality, but if you use them with pod filters I strongly suggest that you support the carburetors.

If I'm not mistaken the carb boots are a metal plate on the bottom, with a gasket between the boot and the head. It's possible to bend that kind of thing by tightening, the ends go down while the gasket supports the middle... Anyway, I'd suggest Permatex Motoseal 1 instead of the silicone, probably stand up to heat and weather better. Certainly easier to put on thin and will flow into gaps.

These ones are metal out toward the flanges but aaalllll rubber in the bottle. That was the first thing I thought, that I over tightened