Jdub goes there 1981 650e rebuild

[jdub6092]

Progress update.

After trying to repair the idle adjuster bracket and failing, I purchased an NOS bracket from CMSNL in the Netherlands. Really good service. Like the screw, probably the last new one available anywhere. Now I have two spare screws that I cleaned up with a M5-0.5 die. They are fine, the bracket hole was too wide. If any one needs one....

With the carbs cleaned and now immaculate with all spec jets, I bench synced them and slapped them back on the bike. Have to admit, I'm getting really good at squeezing the carbs and airbox assembly back on.

Also got the original Yuasa YB10L-A2 battery, filled it with acid, and charged it up. Now the side cover fits nicely.

Finally, I attempted to start it back up. Low and behold, the choke worked for cold start. After it warmed up, it purred like a kitten, hoping the tiger would come out.
Took it for a spin, maybe no tiger yet, but really smooth and no hesitation. Clutch much better, back brakes a little soft and need to be worn in, but front brakes are very firm. A few drips of oil coming from the drain plug. Exhaust much cleaner-no hideous gas smell.

[jdub6092]

So, I decided to pull the carbs and disassemble for the third time, mainly to check the choke circuits. I think I may have found obstructions in a combination of the tiny starter tubes and more surprisingly in the float bowl passages. Almost like degraded cardboard in one of them. One pilot jet had what looked like a grain of sand stuck in it.
Then I noticed my air pilot jets and main jets were not stock sizes. After a little research, I found that even though advertised as a fit for the 650e, the K&L rebuild kits I used were specifically for the 650g and gl models which have different jet sizes. I purchased the stock Mikuni jets from Niche Cycle. They have a nice selection of OEM jets and better prices than Jets R Us.

Buttoned everything back up and started a bench sync. Then I found the main idle adjustment screw was stripped in the idle range. So I found a replacement that took 10 days to arrive. After the initial round of bench sync and starting a fine adjustment phase, this screw also failed. Now I realize the bracket threads have too much play causing the screw to slip under spring pressure.
I found an NOS screw in Canada, but will not install it until I can repair the bracket threads. This is an M5-0.5 fine thread, so not something I have in my tap and die kit to attempt a thread repair. Not even sure it could be fixed this way.
I would really appreciate some advice on what I might do to repair this.
20250201_074801.jpg

[jdub6092]

Congrats jdub, that has to feel good after all the work you've done.
Agree on the seat but you won't have to look at it when you're riding. haha

Thanks Steve,

For only having had a basic knowledge about bikes to rebuilding/restoring one essentially down to the last screw, there is a certain sense of accomplishment. Especially when it roars back to life.
I have always had a knack for fixing things, but this is on a different level requiring patience, perseverance and focused attention to detail.
I have a bit to go, but yeah I'm pretty stoked.
Of course, I want to thank all of you on this forum who have provided encouragement, expertise and most of all your passion for motorcycles and specifically Suzuki GS bikes.

[steve murdoch]

Congrats jdub, that has to feel good after all the work you've done.
Agree on the seat but you won't have to look at it when you're riding. haha

[jdub6092]

Some good news. When starting back up right after the ride, the revs held steady. No Surging.
The sofa seat doesn't quite look right on this bike, but it is comfortable on my old arse. I did order what was supposed to be a GS650E replica.


20250110_163405.jpg

[jdub6092]

After a few more newbie blunders I won't even mention, I got the rest of the parts installed and torqued everything down. The Mighty MAX YB14L-A2 battery seems too tall and wide as I can't fit the side cover over it.
It's hard to start when cold, and the choke really only had an effect the first time. The 1-1/2 year old battery also won't hold a charge and doesn't give many cranks before it bogs down.
The exhaust smelled terrible (clearly rich) so I backed the mixture screws from 2 to 1.5 turns and it got much better. I don't have the tools to sync the carbs so I will likely take it to a shop to have it dialed in.
Anyway, I tooknit out for a 10 minute drive around the neighborhood. Kept it under 40mph and 3500 RPM.
It responded well, but not great. When I was finished there was some light almost clear smoke coming from the engine for about 5 minutes. It was pretty hot.
20250110_163715.jpg

I've been putting off painting of the fender and fairings until I know what I have mechanically.

[Griffin]

What do you think?

https://www.facebook.com/share/v/15n...ibextid=oFDknk

That sounds great. The 550 and 650 are the quietest GS engines when finely tuned.

My 650E engine is super quit. It literally sounds like a sewing machine at idle. Had an ‘80 550L that was really quiet too.

[Nessism]

What do you think?

https://www.facebook.com/share/v/15n...ibextid=oFDknk

It sounds amazing. Good job!

[jdub6092]

What do you think?

https://www.facebook.com/share/v/15nnAmLcQb/?mibextid=oFDknk

[jdub6092]

In case you didn't realize...
Routine goes...loosen the nut on the setscrew, wind the tensioner up as the pushrod is pushed inside the body. Tighten the setscrew, to hold the plunger inside. Install the tensioner onto the cylinder. After the cams are installed, and everything timed correctly, before rotating the engine, loosen the setscrew, allowing the tensioner pushrod to shoot out, removing slack in the cam chain. Back off the setscrew a full turn or so, then set the lock nut again.

Thankfully didn't have to remove it.
One note to add: After backing off the setscrew, hold it in place while tightenening the lock nut.

[Nessism]

In case you didn't realize...
Routine goes...loosen the nut on the setscrew, wind the tensioner up as the pushrod is pushed inside the body. Tighten the setscrew, to hold the plunger inside. Install the tensioner onto the cylinder. After the cams are installed, and everything timed correctly, before rotating the engine, loosen the setscrew, allowing the tensioner pushrod to shoot out, removing slack in the cam chain. Back off the setscrew a full turn or so, then set the lock nut again.

[jdub6092]

I untightened the tensioner lock nut and the slack went away.
I can see that the shaft screw tightened right along with the nut. DOH! Should have been intuitive.
Timing is still good, so no tooth jumping ocurred.
Very little room to work, so will need to dance with screw and nut, until the correct screw backoff is reached.
Maybe this should go on the list of newbie mistakes.

Since I had the cams exposed again, I decided to check shim spacing again. All still in spec, but a few got tighter.

[jdub6092]

Turns out that the cam chain goes from extremely taught to jumping a tooth or just loose. That's the click sound. I measured the links and it is well within specs. That had to be an incredible amount of force on the chain at higher revs.

It didn't do this when I rotated manually many times.
I deployed the tensioner and it did what it should. Backed the screw off 3/8 of a turn and tightened the lock nut.

Ed, I think you called it.
I do recall the guide was kind of sticky as well, but when it was closer to the head wall.

[jdub6092]

I think for sure it is something to do with the cams. I can now hear a slower click-click while it's cranking.

[Big Block]

Yikes, that sounds terrible. I hope all the valves didn't kiss all the pistons.