Suzuki 2 Strokes

Hi, new to this forum.... I've owned a 1975 GT750 for 40 years, and it looks better than I do. This year I noticed a ticking or tapping noise that seems to be from the left side (of the bike). I know it's impossible to diagnose from a description, but I'm looking for ideas from anyone who's had a similar problem. It only happens when the engine is cold, after it warms up the noise is completely gone. It's most noticeable at idle, when revved it goes away or blends in with the other noises. Otherwise starts and runs good. I haven't tried to isolate the sound yet, is the best way using a screwdriver to the ear? Thanks for any advice.

Tiny exhaust leak on left cylinder that seals when the metal expands with heat?

Thanks for the tip. I tried just loosening the exhaust clamps and re-tightening them, and *maybe* it's a little better. In any case is isn't severe, yet, hoping it stays that way. A little piston slap at 25k wouldn't bother me. I know one of the generator pickup brushes on the right side is chipped, it's been like that for years. After paying $1350 for it 40 years ago, it doesn't owe me anything, but it's painful to think about it developing a terminal illness. Another thought, I've been using Yamalube 2S this year because it's available, but I don't really like it. Any opinions on the best oil and where to get it? I know there's another category for that.... Thanks!

Congrats on having done a good job on keeping your GT750 in that good condition. There aren’t many sweet originals out there.

Wow, that bike is sweet and clean. Not many original bikes that look that good.

Slight tap could be a touch of piston slap or primary drive slack allowing a cyclic chatter. Try to get timing spot on and carbs perfectly synched.

Thanks! The picture does it some favors, but it's pretty clean. I have ridden it every year for 39 or 40 years. The timing is good, I haven't checked the carbs.

That's a lovely, clean bike, congratulations! If tightening the clamp has helped reduce the noise, it's probably the old sealing gasket which is leaking a little. Easy to replace during a rainy day.

If you do remove the exhausts to fit new gaskets, it's worth giving the exhausts an internal clean-out to evict old carbon deposits. Get a rubber mallet and whack on the seams of the exhaust, this can loosen a lot of crud that you can then pour out of the header. Then get one of those springy "drain snakes" that's for cleaning domestic drains. Fix it into the chuck of an electric drill, poke it down the header pipe and switch on, moving the drill back and forth. This scours the inside of the pipe. The pipe design causes rings of carbon to build up where the header is welded to the main exhaust pipe, and this robs power gradually. You'll be surprised at how perky the bike will feel after doing the above, and cleaning off the baffles with a wire brush (make sure the interior of the baffle tube is clear too).

Oil-wise, Yamalube is a good 2-stroke oil but if you want to change, any brand-name semi-synthetic 2-stroke oil that's for injection systems will work just fine. Look for the JASO FC or FD specification on the bottle, that's what you need. Silkolene, Putoline, Castrol, Mobil, Shell, Motul ... they're all good.