1980 GS750L Fuel Leak

[Pete Wrigley]

Went out the other day to go for a ride. Started bike to warm it up and fuel started dripping from carbs. It wasn't the main fuel line. I was trying to avoid pulling the carbs out of fear I'd never get the bike back out on the road this year also I have never pulled carbs off a bike.

Pulling the carbs wasn't all that bad. I took my time, followed the manual and they came off in less than 30 minutes.

Looks to have been the gasket on carb 2 mostly. Overall they look good.

Ordered K&L rebuild kit K-629, 18-2592 for all 4 carbs. The bike runs fine, I really think it just needs the float needle along w/ the gasket. I'll clean everything else.

This is my first time doing this so any thoughts or advice would be welcome.

I also picked up a carb balancer kit and that will be another first.

Thanks.

[Nessism]

You might want to check the Newbie Mistakes thread linked in my signature. You could have saved a bunch of money by simply cleaning your carbs and replacing the soft parts like O-rings and bowl gaskets.

[Pete Wrigley]

You might want to check the Newbie Mistakes thread linked in my signature. You could have saved a bunch of money by simply cleaning your carbs and replacing the soft parts like O-rings and bowl gaskets.

Probably could have saved a little money but I didn't want to get caught short for parts. The tutorial looks like it will be a big help.

Thanks.

[Nessism]

Probably could have saved a little money but I didn't want to get caught short for parts. The tutorial looks like it will be a big help.

Thanks.

The issue you will have is that those K&L kits don't have all the various O-rings needed to do a full rebuild. Also, the float needle spring is weak, and doesn't hold up the weight of the float. The only float valves I've found with a proper spring in the float needle, is the original Mikuni parts, and Keyster brand.

[Pete Wrigley]

The issue you will have is that those K&L kits don't have all the various O-rings needed to do a full rebuild. Also, the float needle spring is weak, and doesn't hold up the weight of the float. The only float valves I've found with a proper spring in the float needle, is the original Mikuni parts, and Keyster brand.

Weak float needle spring? Oy vey . I'm going to try them because I have them. Fingers crossed.

Found an old video (2013) on cleaning them. Could be useful to somebody.

https://youtu.be/95nlrP-yn2I

[Nessism]

That video is half-baked. He didn't even remove the pilot screws (the caps are still installed.) And the O-rings that typically are in the worst condition are those between the carbs, and he didn't even ungang the carbs. The number one rule of carb cleaning is to NOT take shortcuts. Please follow the tutorial linked in my signature and perform all the steps.

[Pete Wrigley]

Thanks Ed.

Since watching that video so many others have popped up. IMO - you take what you can from each.

Question for you...

Would these O-rings work on a bike? I've been thinking it wouldn't be a bad idea to have an assortment around for various uses.

https://www.amazon.com/Assortment-HongWay-Professional-Plumbing-Connections/dp/B07WRF9YYC/ref=asc_df_B07WRF9YYC/?tag=hyprod-20&linkCode=df0&hvadid=385182639593&hvpos=&hvnetw=g&hvrand=9813626076777570024&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003735&hvtargid=pla-844199720376&psc=1&tag=&ref=&adgrpid=73789135610&hvpone=&hvptwo=&hvadid=385182639593&hvpos=&hvnetw=g&hvrand=9813626076777570024&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003735&hvtargid=pla-844199720376

[Rich82GS750TZ]

Don't mess around with the Amazon oring set. Just buy the correct CV set of orings from Ed (Nessism). He just recently took it upon himself to put together kits with all of the proper size orings you need to fully rebuild your carbs. Just send him a PM to get the paypal info.

https://www.thegsresources.com/_forum/forum/consumer-information/gs-parts-and-services/1703182-mikuni-bs-cv-and-vm-o-ring-kits

[Pete Wrigley]

Don't mess around with the Amazon oring set. Just buy the correct CV set of orings from Ed (Nessism). He just recently took it upon himself to put together kits with all of the proper size orings you need to fully rebuild your carbs. Just send him a PM to get the paypal info.

Took your advice and ordered the o-ring kit from Ed. Very quick turnaround. Thanks Ed!

Between Ed's and the K&L kit I think I had most everything needed.


Note.....

To anybody else doing this for the first time (like me).

Please see Nessism's first reply...

"You could have saved a bunch of money by simply cleaning your carbs and replacing the soft parts like O-rings and bowl gaskets."

Yes indeed all the hardware was perfectly fine and could have just been cleaned up.


Everything is almost back together.

I'll post results when completed.

[Pete Wrigley]

The carbs are back together, all O-rings replaced. Did a leak test with an aux fuel tank and it passed.

Decided to take opportunity with airbox off to address an issue with breather hose.

The nipple on the air box is missing. I added an breather air filter and taped over the hole on the airbox. I don't like the air filter approach.

I'm thinking of adding a threaded rod (the kind used in lamps) to the airbox to create a new nipple to attach breather box hose to. Thoughts?

[rphillips]

Sounds like a plan, anything that will hold the hose as there's no pressure anywhere around there.

[1978GS750E]

In the past, I have epoxied a plastic plumbing nipple on the airbox when that nipple was missing. Worked well for me! (The ones for PEX tubing are stout!)