A55 Airsal issues.. Help!

Jeb Zinewicz /

Hey guys,

I installed a 70cc Airsal on my Tomos A55 at the end of last season. I followed the recommended break-in routine and the bike was running fine except when I let off the throttle, I was getting a strange jerking forward motion along with a chirping sound.. I thought that the revs might be too high and that I needed to adjust the timing?

Well today I decided to give the bike a going over before summer season and I pulled off the cylinder to see If I could spot anything. The metal head gasket was partially torn off and after de-carbonizing the piston head I think I've spotted pieces of the gasket melted into/onto the piston. The rings are fine and everything else looks ok, aside from a couple scores in the cylinder head.

The only thing I can think of is that the piston might have been pushing out too far and hitting the cylinder head? Does that even make sense, or is it just the head gasket breaking that's the issue? Would a thicker cylinder gasket give me the correct clearance if it is indeed the piston?

Thanks for the help!!!

Re: A55 Airsal issues.. Help!

Is that a 70cc head gasket? I think you use the wrong head gasket.

Re: A55 Airsal issues.. Help!

Jeb Zinewicz /

Hmm, It's possible that I used the old stock a55 head gasket if the airsal didn't fit?

Re: A55 Airsal issues.. Help!

Overpriced Parts /

Use the correct gasket next time

Re: A55 Airsal issues.. Help!

Jeb Zinewicz /

Haha, yup, I think I remember that the airsal gasket didn't fit over the cylinder studs and I left the stock gasket in place! Whoops!

Do you think that would have anything to do with the jerking when coming off the throttle?

Thanks again.

Re: A55 Airsal issues.. Help!

Overpriced Parts /

Dremel the holes bigger on the new gasket

Re: A55 Airsal issues.. Help!

Jeb Zinewicz /

Right on, will do! I sandpapered the piston head so it's nice and smooth.. should be ok.

Hopefully that fixes my issue or maybe it is indeed timing that needs to be slowed?

Re: A55 Airsal issues.. Help!

Micheal H. Wrote:

-------------------------------------------------------

> Is that a 70cc head gasket? I think you use the

> wrong head gasket.

^^^^^^^^^ my guess too.

also clean the mating surface of your head it looks nicked in some places maybe its just me.

Re: A55 Airsal issues.. Help!

The jerking and lack of smooth throttle was most likely jetting on the carb. What was your jetting, main, idle, needle setting and diffuser tube? I assume you were using the stock carb.

Re: A55 Airsal issues.. Help!

Jeb Zinewicz /

Stock carb indeed. I played around with the jetting a lot at the end of last season and still had the same issue. Last I was running a 76 main Jet (I was in the 80's for break-in period), a 40 Idle and 211 atomizer. How do you change or adjust the needle setting and how much of a difference would it make?

Thanks! (edited)

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