Valve Shims

[Guest]

Adjusting the carburetor mixture screws doesn't seem to affect the idle, and it still revs high, but doesn't stumble at 5,000 RPM anymore. I've tested for air leaks, and none presented themselves. The tach needle bounces a bit, and when I push the choke all the way in, it dies, even after running for a minute with the choke out.
This leads me to believe the valve shims are out of whack.
When I order new shims, should I get ones that have the same number on the underside as the ones currently in the engine?

 

[tom203]

If you can?t get this critter to idle nicely after warmup, and if it needs a bit of ?choke? at all times and if mixture screws don?t seem to do much.....your carbs aren?t clean enough yet.
Skip the valve stuff.....till later. When you check clearances, you often find that new thinner shims are needed. No sense buying new ones till you know what you need.

 

[Guest]

I also don't have a carb sync tool yet, so I haven't been able to properly wrangle that into a happy medium.

 

[cowboyup3371]

So buy a carbtune and get started on it. Until each step is done properly all you will do is chase your tail. Read up on the procedure for doing the valve adjustment. The steps are on Basscliff’s site (http://members.dslextreme.com/users/bikecliff) and email Steve for his spreadsheet

 

[Guest]

Just ordered a carb sync tool earlier today. Let's hope it's that simple, I really don't want to crack that case... because I've never done it before, and I'm worried about botching something.

 

[Rich82GS750TZ]

I’ve read that it’s useless to try to tune your carbs until after the valves clearances are properly adjusted.

 

[Agemax]

I’ve read that it’s useless to try to tune your carbs until after the valves clearances are properly adjusted.

You are correct. Carb synch and pilot screw adjustment is the very last job to do after ALL the other routine maintenance tasks have been completed, including shims,spark plugs,air filter, ignition timing. (and of course, carb cleaning)

 

[tom203]

Just ordered a carb sync tool earlier today. Let's hope it's that simple, I really don't want to crack that case... because I've never done it before, and I'm worried about botching something.

It won?t be that simple.....your carbs aren?t clean yet and the sync tool doesn?t work miracles .
For now ,skip the fancy stuff and clean the carbs properly. A good careful bench sync will get you real close, or good enough for engine to run nicely.

 

[Guest]

I have the tools the clean the carb, I know to do the sync afterwards.

 

[Rich82GS750TZ]

ZPS,
was this statement our yours in regards to valve adjustment?
"I really don't want to crack that case... because I've never done it before, and I'm worried about botching something."

I think you're getting hung up on the carbtune, IMHO. You don't need it now. Maybe later when you get the bike running and want to fine tune.

Yes go ahead and clean the carbs, and bench sync them. You need to do that. But you need to know that the valve clearances are in spec before you bother with fine tuning the carbs with a carbtune. If you need to decide between buying a carbtune or a valve cover gasket and a few shims, go for that gasket and shims. Get the spreadsheet from Steve and open up the top of your engine. Yes, it's scary the first time. After that, you'll wonder what all the fuss was about.