LCGB Forums

Hi folks
Getting a bit of flutter towards WOT/ fuel starvation.

It’s with a PWK 30 mil open mouth

How do I remedy please, any ideas would be greatly appreciated.

Cheers Cgt75b

Cgt75b wrote:Hi folks
Getting a bit of flutter towards WOT/ fuel starvation.

It’s with a PWK 30 mil open mouth

How do I remedy please, any ideas would be greatly appreciated.

Cheers Cgt75b

Increase the size of carb float valve

Check the height of your float. Keihins are very temperamental in that regard. I can’t remember what it should be as I gave up on Keihins years ago.

It might not be the carb??????
Check that your fuel filler cap vent is not blocked.
Check the petcock filter isn't gunged up.
Do a fuel flow check to confirm sufficient deleivery to the carb.

Presumably the PWK has been ‘blueprinted’ to ensure no likelihood of fuel starvation

I can’t recall whether it’s part of the normal blueprint, but the float stops within the bowl should also be removed to allow more ‘gulp’

Norrie Bodge wrote:

Cgt75b wrote:Hi folks
Getting a bit of flutter towards WOT/ fuel starvation.

It’s with a PWK 30 mil open mouth

How do I remedy please, any ideas would be greatly appreciated.

Cheers Cgt75b

Increase the size of carb float valve

Do you mean the atomiser? Do these carbs have a float needle valve? Happy to be told different willing to learn

Cgt75b wrote:
Do you mean the atomiser? Do these carbs have a float needle valve? Happy to be told different willing to learn

They do, it's similar to the Delortto set up. As already mentioned, the fuel level in the bowl needs careful setting of the float hight. The float bowls are smaller than a PHBH so there is less reserve epacially if the carb is at an angle.

Warkton Tornado No.1 wrote:Presumably the PWK has been ‘blueprinted’ to ensure no likelihood of fuel starvation

I can’t recall whether it’s part of the normal blueprint, but the float stops within the bowl should also be removed to allow more ‘gulp’

I’ve removed the stops it hasn’t made any difference to be fair.

But thanks for the advice.

Cgt75b wrote:

Warkton Tornado No.1 wrote:Presumably the PWK has been ‘blueprinted’ to ensure no likelihood of fuel starvation

I can’t recall whether it’s part of the normal blueprint, but the float stops within the bowl should also be removed to allow more ‘gulp’

I’ve removed the stops it hasn’t made any difference to be fair.

But thanks for the advice.

Actually, the removal of the float stops does make a difference, but it is only a modification to allow more float needle travel.

The flow rate into the bowl itself is something that can be an issue, so please check everything out. In looking for a guide to blueprinting, this one came up & appears easier to follow than other guides I’ve used previously:

https://www.miniriders.com/threads/keih ... ods.26815/

Warkton Tornado No.1 wrote:

Cgt75b wrote:

Warkton Tornado No.1 wrote:Presumably the PWK has been ‘blueprinted’ to ensure no likelihood of fuel starvation

I can’t recall whether it’s part of the normal blueprint, but the float stops within the bowl should also be removed to allow more ‘gulp’

I’ve removed the stops it hasn’t made any difference to be fair.

But thanks for the advice.

Actually, the removal of the float stops does make a difference, but it is only a modification to allow more float needle travel.

The flow rate into the bowl itself is something that can be an issue, so please check everything out. In looking for a guide to blueprinting, this one came up & appears easier to follow than other guides I’ve used previously:

https://www.miniriders.com/threads/keih ... ods.26815/

Thanks for the link WT1 very useful indeed, I appreciate your help.