Carb sneezes and shuts bike off.

[bonesaw]

Problem: right carb sneezes and stumbles the bike to a stall. Idle is low because of the cam and if I set my idle any higher I get a hanging idle on deceleration.

Why would one sneeze? Improper adujstment of the mixture screw?

Tried dead cylinder method, the right carbs mixture screw is facing the backbone of the front frame loop and I cannot access the screw while the carb is on and running...


Air leak tested with wd40


Plugs look rich on the threads but a little white on the top of the insulator. The rest of the insulator looks tan/darker.

Specs:

1980 xs650
750 bigbore
Performance cam
Pamco
HHB PMA
PWK Flatslide carbs with pancake pod filters
Pandemonium ya mama open exhaust.
Billet intake mounts

Any insight helps.

 

[TwoManyXS1Bs]

A couple things to try, just to get diag info. Do these separately.

- Readjust right intake valve clearance to 0.010"-0.012"
- Retard ignition timing about 2°-3°

Note any changes...

 

[bonesaw]

A couple things to try, just to get diag info. Do these separately.

- Readjust right intake valve clearance to 0.010"-0.012"
- Retard ignition timing about 2°-3°

Note any changes...

......I think I set the valves this spring to stock settings,forgetting that there where different clearances for the cam.

 

[bonesaw]

Okay,adjusted my valves to the cam specs. Shot timing with a light to varify.

Starting to think it's my pamco Hall effect ignition or my coil?

Bike runs when throttle is pulled and dies sometimes on decel. Always the problematic right side of the bike.

Pull plugs and they look okay, They are however wet when the bike misses and dies...

 

[bonesaw]

A couple things to try, just to get diag info. Do these separately.

- Readjust right intake valve clearance to 0.010"-0.012"
- Retard ignition timing about 2°-3°

Note any changes...

Thanks for the reply,I'm really at a loss with this thing. I put so much money into it and get nothing in return.half the fun is building it,but I'm getting no play either..

I retard'd the timing 2 degrees and the problem was still there,if not worse. I advanced the other way 2 degrees from where it was initially at.. It seemed to improve at idle but once on the road it still sneezed on the right side and killed the bike at a stop light. I'm thinking its electrical?

 

[XSLeo]

Did you get those PWK carbs from Mike's? If so set them on a shelf some where and put on good carbs.
I am running Ninja ES500 carbs on my 75 750. Never ran better.
There is a many page write up on them.
There is also a many page write up on those PWK carbs. Those from Mike's are a bored out 28 mm PWK knock off.
Leo

 

[bonesaw]

Did you get those PWK carbs from Mike's? If so set them on a shelf some where and put on good carbs.
I am running Ninja ES500 carbs on my 75 750. Never ran better.
There is a many page write up on them.
There is also a many page write up on those PWK carbs. Those from Mike's are a bored out 28 mm PWK knock off.
Leo

What is your opinion on the mikunis?
That and possibly a new ignition/coil are on my next list

 

[bonesaw]

Just noticed my petcocks are both leaking while shut off. Could this be an issue?

 

[bonesaw]

Switched plug wires and a different time I switched carb bodies.still sneezed/coughed on the same side.

Thinking partially clogged petcocks (gravity fed)

Also re checking my valves,for the 45th time.