Jump to content

Tuning Moster carburettor


Recommended Posts

I am sure this topic has been covered before . I can not get pop off pressure or reset pressure from Vittorazzi so I have just looked at other engines and took an average from that. I also set the lever height from walbro site.

  I start at factory settings then open low screw till it offers to bog down on rapid acceleration then weaken it again till I get a nice fast clean response on acceleration. The hi screw is set over time to give a nice spark plug colour.

  Can any body tell me how they set up there carbs and its probably the same for all 2 strokes with Walbro 32 carb? 

Link to comment
Share on other sites

What lever height are you using - is it 1.45mm?

What pop-off pressure did you settle on?

I`ve never been able to find a definative answer either, and am thinking about 10 - 12 psi?

How are you measureing your pop-off - with one of the dedicated pop-off pumps/gauges - does it work OK?

Do you take the mixing chamber cover off that side of the carb when checking pop-off?

I`ve never been entirely satisfied with my measurements as i think either i`m doing it wrong or the extra tubes to/from the primer bulb is affecting my measurement...

Like you my high speed adjustment has been done over time to get a nice `rich tea biscuit` colour on the plug and by throttle response and `feel` when on the ground.

My low speed i do mostly by ear/feel: starting with the factory 0.25 turns out it`s easy to tell when it`s rich because it `four strokes` and jumps around a lot on the rubber mountings.

Too lean and the idle races and the engine exhaust sounds `weak` - also it may even stop as the fuel is used up in the mixing chamber. At this point it`ll probably hesitate when blipping the throttle,too.

I go mid way just before the engine start to bog/hesitate when the throttle is snapped open, or get to that point then open up a tad.

I think i`m just under one-quarter turn out on the low and just over one turn out on the high.

The Vitorazzi factory settings made my Mosters` plug BLACK and i was getting 6L/h, it`s now down to under 4...

This is not advice for carb adjustment for any other motor - always set your own carb to your particular engine!!


Edited by Hann__
i edited it
Link to comment
Share on other sites

Thanks for both replies Hann. Lever setting 1.45 mm below carb body ( no gasket). Pop off 10--12 psi but must not leak at 8 psi. I do use a home made set up which is a pressure gauge same as refrigeration engineers use a tee piece and a small hand bulb with some tubing. I do it with cover off carb so I can see if needle valve is leaking at 8 psi. You must have some petrol in carb to wet needle valve.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.


  • Create New...