Fuel not getting to the spark plug

Aaron Hilf /

May 08, 2019 07:59PM

Trying to get a A35 running on a 96 Tomos. It doesn’t appear that there is any fuel getting to the plug. After attempting to start several times the plug remains completely dry after I pull it out.

I do have spark on it and the carb itself is brand new (albeit a reproduction of the Dellorto 14.12).

I’m guessing it has a compression issue but haven’t been able to check it yet. Wanted to get input here before buying a testing gauge. The previous owner said it ran great until he broke the carb trying to clean it — so while he may be lying, I’m hoping it isn’t a compression problem.

Any thoughts? Or suggestions on things to try?

Thanks much.

Re: Fuel not getting to the spark plug

Garelli Master✨ /

Go to branch

stephens

May 08, 2019 08:59PM

Check the reeds. They will break every now and then. Could also be possibly crank seals also or a hell of a air leak.

Re: Fuel not getting to the spark plug

pat splat /

ggspeed

May 08, 2019 11:01PM

check fuel flow. check if carb bowl has fuel. spray some premix in spark plug hole and try to start.

sometimes the petcock gets cruddy.

Re: Fuel not getting to the spark plug

Aaron Blair /

aaronb

May 08, 2019 11:02PM

Did you jet the new carb? They don't come pre set up. Every bike is different.

Re: Fuel not getting to the spark plug

Aaron Hilf /

mopedin OP

May 09, 2019 11:18AM

Thanks so much for the guidance everyone!

Stephen – I will definitely have a look at the reeds. It's something I've seen talked about but was hoping to avoid removing the intake. Oh well.

Pat – I will try to spray some premix into the plug hole. May just need that level of help to turn over again since it's been a while. But the petcock is new and the bowl is filling with fuel.

Aaron – Do you have a link with more info on this or additional guidance on jet size? I didn't realize I would need to do some set up work on the new carb. It does have a jet already installed in the bowl – but could obviously replace it if that's your suggestion since sizing is dependent on the bike.

Thanks so much everyone! (edited)

Re: Fuel not getting to the spark plug

Aaron Blair /

aaronb

May 09, 2019 12:11PM

Jetting is crucial on two strokes. I would bet this is the issue.. The carb just comes with one so that the hole isn't empty basically...no clue what jetting u need, but whenever u change a carb you need to reset...

Somebody more familar with a35's will chime in here on what jets you should get...

Be happy that you made this post before riding it, too small of a jet and you will seize your engine..

Re: Fuel not getting to the spark plug

Aaron Hilf /

mopedin OP

May 09, 2019 12:58PM

I appreciate the help, Aaron! I'll take a look around the A35 wiki page and see if I can figure out what jet size I need.

I may even be able to salvage the existing jet in the broken Dellorto -- depending on its condition.

Many thanks!

Re: Fuel not getting to the spark plug

Aaron Hilf /

mopedin OP

May 09, 2019 09:07PM

Update — Swapped the main jet from the broken card into the new one. It isn’t stamped, so I’m not sure if it was the right size.

Sprayed some premix into the spark plug hole and tried to start it up. Still nothing.

I assumed it would start for a few seconds with fuel directly into the plug hole. Any reasons why it still wouldn’t?

Thanks in advance for any help.

Re: Fuel not getting to the spark plug

Garelli Master✨ /

Go to branch

stephens

May 09, 2019 09:57PM

> Aaron Hilf Wrote:

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

> Update — Swapped the main jet from the broken card into the new one. It

> isn’t stamped, so I’m not sure if it was the right size.

>

> Sprayed some premix into the spark plug hole and tried to start it up.

> Still nothing.

>

> I assumed it would start for a few seconds with fuel directly into the

> plug hole. Any reasons why it still wouldn’t?

>

> Thanks in advance for any help.

Does it feel like it has compression? You probably need to pull the top end at this point.

Re: Fuel not getting to the spark plug

Aaron Hilf /

mopedin OP

May 09, 2019 10:05PM

Yes, it definitely feels like I has compression. Pushes my finger off the plug hole when I kick it. Should probably just get a gauge and test it I suppose.

Could a bad reed valve cause it not to fire? Or the crank seals?

Hmmm....

Re: Fuel not getting to the spark plug

♣Slew Foot♣ /

thewhitedog

May 14, 2019 05:51AM

when you turn it over with the plug in it do you hear a whooshing sound if you do you're probably have either a case leak or a seal leak the seal leak usually is sucking in air and it stops the motor from developing the low pressure needed to open the valves in other words your moped doesn't suck right

Re: Fuel not getting to the spark plug

Aaron Hilf /

mopedin OP

May 14, 2019 09:02AM

> ♣Slew Foot♣ Wrote:

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

> when you turn it over with the plug in it do you hear a whooshing sound

> if you do you're probably have either a case leak or a seal leak the

> seal leak usually is sucking in air and it stops the motor from

> developing the low pressure needed to open the valves in other words

> your moped doesn't suck right

Thanks for the input. I'll turn it over a few times later today and see if I hear a whoosh or not. I don't think I've heard a distinguished whoosh but I'll listen for it today and see.

When you say 'seal leak' -- are you referring to the main seal? Crank seal? All of the above? Apologies if this is a dumb question -- pretty new here. Thanks much.

Re: Fuel not getting to the spark plug

♣Slew Foot♣ /

thewhitedog

May 14, 2019 10:32AM

Yeah both sides of the crank and the whole middle of the engine case if it's a gasket leak on the case you can get away with Crazy Glue

MOPED ARMY

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