Well not always does the regulator end up flush. First of all that is a starting point. I would say that most end up around flush with the case on the Non-external regulator engines.


Next if you have lots of air bubbles then you have air leak somewhere.

It could be lots of places. The regulator gasket? The carb bolts, and gasket, In fact it could even be up at the air box...this is coomon spot for a leak but will likely not cause air bubbles in the line. The quick pop or bang to a stop is not good. The mid throttle range is mostly controlled by the regulator setting. However the HS does play a role. If the HS is out 2.5-3turns then it is open far enough on a normal engine....The regulator is likely lean...but it could be lean from various reasons. Usually a bad diaphram will not act this way at all...so its likely not the diaphram but it could be the plunger stuck closed or not moving freely or it could be a piece of dirt or debris in the regulator. The little holes are easy to plug with dirt or debris.

The air bubbles could be the result of a leak or they could simply be a symptom of blocked passageway in the regulator.

Check fuel filters, make sure check valve is working the right direction to keep air in the tank... and its holding pressure in the tank. If the tank is not holding pressure then you will not be getting fuel to the regulator and this could where the "bubbles are coming from" as there is not enough fuel pressure in the tank to be running at the rpm you are asking it to run.

If its doing that lean run thing back it down right away...this si a lean conditiona nd since you are running at high RPMs 1/2 throttle then it could do the explode thing when it detonates and stops.

You advance the throttle slowly and if starts detonating then back it down...adjust the reg or HS and then bring the power back up.


The HS has a little effect on transition, the Rgeulator mostly controls it...the Low speed air bleed screw has nearly nothing to do with transition. It only fine tunes the mixture when the engine is at 2000-2400 rpm above that the air bleed screw does ZERO for the engines mixture. If you HS speed and Low speed are close to "normal settings" and are still rich of those normal settings then the regulator needs adjusted.

I had a buddy with a 110FZ and it needed 2 full turms open past flush (this is richer on the reg) to get it to run properly. Flush was a normal starting point. Once it was opened up his engine ran perfect it just needed more regualtor pressure or it would detonate on throttle up.

Low end should never be more open that 2.5-3 turns (this screw works backward as its an air bleed not a needle valve) CW is rich and CCW is lean on the air bleed low end screw.

HS should not really ever need to be richer than about 3 turns.....

Regulator is somehere around flush...but in your case it needs to be open more. If its detonation problem continues try 1/2 turn CCW on the reg and see what happens. It should get better with this course adjustment. It you go out about 1.5-2 turns and it doesn't seem to get any better at all then there is something wrong internally and it should go back for service.


Troy Newman
Team YS