GS250t not running well after oil change and valve check?

[ankersen]

Help needed.
I have a 1980 GS250t. no mod’s all stock.
Has 2 BS30SS carbs.

I was running good, then…
I thought I would give it a spring oil change and check the valve clearance (no shims on this).
Now it starts with full choke, runs up to 5000 rpm, slowly comes down and dies.
I tried to ride it when the idle was ok, then it has no power and dies.

Sometimes it will idle at 1200, then a blip of gas to 2500 rpm then it goes back to 5000.
I have cleaned the carbs (twice), replaced the O-rings (from cycleorings.com)
Replaced the intake O rings (from cycleorings.com), the intake boots look good.
Stock air filter.
New fuel line.

Bench sync’d the carbs. Looked ok.

Thank you.

 

[JJ]

Did you adjust your valve clearances in inches or millimeters?

Is the new fuel line kinked?

Did this happen before or after you cleaned your carbs?

 

[ankersen]

I cleaned the carbs after I started it up from the valves check, thinking maybe that was the issue.
Inches. .003 I think. I did check the gage to the manual.
No knik.

 

[tom203]

So this problem surfaced after the valve adjustment (but before carb fiddling), leading you to the carb work? I'd go back to valve check and doublecheck that cam lobes were in right spot and clearances were in spec.

The crazy idle makes me suspicious of an intake boot o-ring....does robert sell them for this carb boot? I'd remove one boot and check that the o-ring clearly "stands" above boot flange so it seals well against cylinder head.