Tomos stalling

I changed out the muffler today and now the moped stalls when I pull up to a stop. The moped is 1993 Tomos golden bullet A35 with a 70cc kit and an amal 15mm carb. The old muffler was a two piece biturbo. It had lost its packing and the tail pipe end broke. So I replaced it with a new biturbo (same as the old) rear half (expansion and muffler).

I am guessing the problem has to do with reduced air flow through the system and maybe a back pressure problem. Should I adjust the carb to change the air intake? Or maybe adjust the idle. Any thoughts?

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Re: Tomos stalling

Will it idle in the stand?

Re: Tomos stalling

Michael Smith /

No. It'll idle for a minute (or less) then stall.

Re: Tomos stalling

Could be a whole host of issues check the wiki for Fred's guide. Engines need 4 things to run

Air, gas/oil,compression, spark

Re: Tomos stalling

> Michael Smith Wrote:

> -------------------------------------------------------

> No. It'll idle for a minute (or less) then stall.

What air filter and main jet?

Re: Tomos stalling

Michael Smith /

The air filter is the circular piece with a woven mesh on the carb. The jet is 65. It runs fine, but stalls at stops or when idling. The only change made was to replace the exhaust pipe.

Re: Tomos stalling

> Michael Smith Wrote:

> -------------------------------------------------------

> The air filter is the circular piece with a woven mesh on the carb. The

> jet is 65. It runs fine, but stalls at stops or when idling. The only

> change made was to replace the exhaust pipe.

Tried cleaning the carb yet?

Re: Tomos stalling

Michael Smith /

I cleaned the carb just a couple weeks ago (twice). So i know it is OK. I recently did a tuneup - carb clean, new gas, new spark plug and it ran good. The old muffler had lost all the packing and was open at the rear end, so it was wide open for air pressure. Could the new (and packed) muffler be a back pressure issue?

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Re: Tomos stalling

> Michael Smith Wrote:

> -------------------------------------------------------

> I cleaned the carb just a couple weeks ago (twice). So i know it is OK.

> I recently did a tuneup - carb clean, new gas, new spark plug and it ran

> good. The old muffler had lost all the packing and was open at the rear

> end, so it was wide open for air pressure. Could the new (and packed)

> muffler be a back pressure issue?

Possibly. It would run rich though

Re: Tomos stalling

Michael Smith /

That sort of makes sense. When idling, it now gets less air then before (packing is restricting exhaust air flow). Should I adjust the mix to be more lean? How can I tell the air mix from the idle screw? (i know - i'm ignorant about this).

Re: Tomos stalling

This screams air leak at the exhaust flange to me tbh

Re: Tomos stalling

Upjet upjet upjet. No its beyond me as well. (edited)

Re: Tomos stalling

♣Slew Foot♣ /

Do you go cdi or is it points if its points rerun the ground and tail.

Re: Tomos stalling

Exhaust leak for the win. Get a crush type exhaust gasket. And double check that your pipe header is quality. I have gotten some bent ones before and needed some serious grinding to make it flat enough to bolt on without leaking.

Re: Tomos stalling

Oh and flip your fuel filter. There is an arrow or words saying which direction the flow should be. And everyone of those i have had has the flow going the other way than you have it installed....

Re: Tomos stalling

> Jay Rivett Wrote:

> -------------------------------------------------------

> Oh and flip your fuel filter. There is an arrow or words saying which

> direction the flow should be. And everyone of those i have had has the

> flow going the other way than you have it installed....

That filter is installed correctly as seen in that^ pic .

So you can see what is being trapped in the filter and allowing a much bigger area for crap to be stored before having to replace the filter .

A paper filter will do a better job of filtering that that stone type .

Re: Tomos stalling

Michael Smith /

I think you are right about the air leak. I also had some engine reeving at other times which may also be a symptom of an air leak. I'd like to take off the exhaust pipe and install a new gasket but the nuts are almost impossible to get a tool on. If I can get them off, i'll go back with the deep connector nuts.

Re: Tomos stalling

♣Slew Foot♣ /

Run a hotter plug and don't gun the throttle when pulling out. Adjust idle with cable slack.

Re: Tomos stalling

Oh man I remember cyl studs... I dont know the last bike I kept those in. That could be part of it.

Re: Tomos stalling

Michael Smith /

Any good suggestions for removing the exhaust pipe flange nuts and studs?

I don't want to risk damaging the jug (breaking off a stud) , so maybe I leave the studs, replace the exhaust gasket and re-install with the deeper connector nuts.

Thoughts?

Re: Tomos stalling

You can install nuts that are easier to use if you can get the old ones off. But taking out the studs is easy. Just tighten two nuts on the stud. Make sure the bottom one is turned to tighten to the top nut since you will wrench the bottom not (lefty loosey) and this will remove the stud since the nut has no where to turn. Easy peasy. Just double check they are not welded on studs... but I think that was just a3 engines. You should be able to get an open wrench on the nuts you have.

Re: Tomos stalling

Michael Smith /

thanks

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