Jdub goes there 1981 650e rebuild

[jdub6092]

SH776 all the way, and it's not expensive to buy a good used one from a reputable powersports breaker. They just about never fail, so used is fine.
See if powersportsnation on ebay has one or two up for sale.
Avoid fakes.

I ended up getting an SH775 from Nessism
Works great and runs cool to the touch.
No room for my tool tray now, but at least the battery is charging now.

[jdub6092]

Maybe the blueing of exhaust #1 is trying to tell be something and not just a result of reduced chrome.
Went on a 15 minute ride and it blued up again. I ripped the throttle a couple of times but never got beyond 5k or 55 mph. When I took off, it responded really well, but seemed to drop off a little by the end of the ride.
It was hot enough that the steamy clearish smoke rose from the engine. Not a lot, but clearly visible.
I'm concerned that I may be running extremely lean on #1

20250322_183811.jpg What should I be looking at?
Compression check?
Valve clearance?

[jdub6092]

Compression 1 to 4: 165, 165, 155, 155
Actually pretty impressive.

Spark plugs:
20250322_194549.jpg All look perfect. No indication of lean running on #1.

[jdub6092]

Next thing to check for exhaust leak.

[jdub6092]

Tightened up the exhaust clamp on #1. It was a bit loose and will let it go and see if the splotches stop growing.
Now I'm hearing a sound almost like a playing card in the spokes of a bicycle for those of you seasoned enough to remember. Only happens when I accelerate. Goes away as soon as I let off the throttle.
Any clues as to what this might be?

[Rich82GS750TZ]

Poker or Pinochle? Could just be cam walk? Common and normal. Post a video.

[Nessism]

Getting the header pipes sealed to the head can be a challenge. You need new crush gaskets. Loosen the muffler mounts and make sure nothing is binding. First thing to tighten are the header bolts at the head. Only tighten the mufflers after the headers are seated.

[jdub6092]

Getting the header pipes sealed to the head can be a challenge. You need new crush gaskets. Loosen the muffler mounts and make sure nothing is binding. First thing to tighten are the header bolts at the head. Only tighten the mufflers after the headers are seated.

I did reuse the copper crush gaskets that had on for about a week when I decided to go the restoration route. They looked pretty good so I figured I could reuse them. I do have a lesser quality new set on hand.

Makes a lot of sense to tighten at the head before the hanger brackets. That's how I originally did it, but apparently didn't torque down enough at the head.

[jdub6092]

Decided to take the exhaust off and will change out the gaskets. Noticed all the gaskets had paint on them. Those expanding foam plugs didn't do their job!
Clearly, paint is not a great conductor of heat, but its present on all four and only one pipe was turning blue. Possibly a seating issue?

20250329_094014.jpg I have these Athena gaskets on hand that dont appear to have any copper (better heat transfer) and have ordered a copper set from Caltric that look more like OEM.
Any opinions on whether I should install these or wait for the copper ones to arrive?

I have scrubbed off the remaining paint and wire-wheeled/cleaned the exhaust ports and pipe surfaces, so just trying to decide on whether I want to ride today or wait a week.

[Rich82GS750TZ]

Those new gaskets in the pic above look just like the OEM ones I’ve always bought from my Suzuki dealer or online OEM seller. I don’t believe there’s any copper in them. If I had to guess I’d say they’re mostly aluminum. They’re supposed to crush, considerably, and as such are single-use.

[jdub6092]

Those new gaskets in the pic above look just like the OEM ones I’ve always bought from my Suzuki dealer or online OEM seller. I don’t believe there’s any copper in them. If I had to guess I’d say they’re mostly aluminum. They’re supposed to crush, considerably, and as such are single-use.

Good to know. Looks like I can go for a ride.
I was basing my assumption on the image from Partzilla.

17432773937621530047108414840979.jpg

[Griffin]

The purpose of the exhaust gaskets is to seal, not transfer heat. They seal the gap between the exhaust and a giant chunk of finned aluminum that is your main heat transfer medium.

Oem exhaust gaskets for the GS series are either aluminum or thin steel, interwound with some type of heat resistive substance. Those are what you have in the pic above and are fine. Some other brands (like Honda) often used rings made of copper tubing. Either work fine.

The key is to get a good tight seal by slightly compressing them when tightening the exhaust nuts on the cylkinder head studs (or bolts into the head, whichever set up you have). The amount of heat transferred by the gaskets themselves is insignificant.

[Nessism]

The Suzuki crush washer gaskets are aluminum. Kawasaki type look like the copper ring, crushed down somewhat before use. Worst case, I've used two crush washers before, on stubborn bikes, where I couldn't get the header pipes properly sealed to the head.

[jdub6092]

The learning continues.. Thanks for the gasket and purpose information.
Took it out for a spin with the new gaskets and while the discoloration hasnt stopped, Its now a very light yellowish purple shade. A similar ride created deep blue/purple splotches previously.
I made sure to get the pipes seated before tightening down the clamp and muffler hanger.

Still appears to have some oil burn off for a couple of minutes after I finish riding. I'll have to figure out where it's coming from. It appears like steam rising from the engine.