[Tatanka]

Transam1, Like several other GL!500 owners on here, I've been through this. Mine symptom was a surging/oscillating idle. What I learned in the course of doing the job was that the 1500 has an extensive and critical vacuum system and that the heart of it is located at the bottom of the carbs = the 2 "isolators" (rubber boots that connect the carbs to the two intake pipes) and the 4 primary vacuum lines that come out of the carbs, two from each carb. All the other vacuum lines are secondary to those 4 hoses. The problem with the GL1500 design was a thin rubber mat on top of the engine (purpose unknown to me) and all 6 rubber components mentioned above are UNDERNEATH it, meaning they bake hard under there and hard rubber doesn't seal properly.

We'll glad to help as you get into it, including useful tools and tips like removing the radiator fans for accessibility to everything. Our Super Moderator Fossil92/Bill has a good tutorial by Jim Martino that he can post a link for, too. It's a bit time consuming, but the results are worth it. Can't really synch carbs if there are ANY vacuum leakages. Now my idle is dead steady and the acceleration is great. My mileage averages about 40mpg.

 

[Tatanka]

Fossil/Bill: I KNEW once I mentioned the rubber boots under the carbs, "insulators", that you'd HAVE to go back in to replace them, kicking yourself in the ass the whole time for not doing it when you were in there before! I knew this because it's exactly how I felt when I went back in to replace them, too!:snork: Sure was a hell of a lot easier for having left much longer primary vacuum hoses!

Transom: Your GL1500 is 6 years older than mine. If it has also spent its life in the Southwest it's a sure bet that all those components are about the consistency of Bakelite by now. I'd also replace the 1 gasket across the middle of the carbs while in there. Might even be good to replace as many secondary vacuum lines as you can. The fresher the tighter; the tighter the better.

 

[Tatanka]

Where are you sourcing these parts from. i.e. Insulators, gaskets, boots etc. ?
Thanks

OEM from Honda only. If you have no decent dealer near you with a parts counter, you can order on line from Western Honda and others.

 

[Tatanka]

Thanks, I was on Steve Saunders site and I'm hearing there was a TSB issued that states to raise the pilot and main jet size. Anyone aware of this or where I could find the info ?
Thanks

I have not heard of this. Before I concerned myself with changing the carbs I'd make sure there were NO vacuum leaks and that the carbs were adjusted to original spec. Gotta establish a "baseline" condition.

 

[Tatanka]

Found the insulators at cyclemax also found the sub and cruise filters that I will change. What gasket in the middle of the carbs are you referring to ?
Thanks

Well, in my '95's carb set there is a gasket across the middle of it just below the air horns, horizontally.