av7 parma ajustments

when i first put my parma kit on my engine i noticed that the piston came up past the exhaust port maybe 1-2mm. I had heard about this issue on another thread somewhere so i corrected it by using 2 base gaskets cut from head gasket paper, the type with the metal mesh fused between the fiber.

my question is should i shave some material off the top of the cylinder to correct the tdc position, or should i leave it alone.

Re: av7 parma ajustments

If you are raising the cylinder up ~2mm, you are going to get terrible compression unless to do deck the top of the cylinder.

Re: av7 parma ajustments

has anyone ever done this before?

Re: av7 parma ajustments

I would shave the piston down on the exhaust a bit rather than raise the cylinder that much.

I have run into this its lame but correctable. in general the Parma has to be raise so the piston does not hit the head and for gods sake don't run the stock head gasket unless u want head leaks it looks like POS I don't trust it at all.

Re: av7 parma ajustments

i just used super thick base gasket material, which smoothed it out a HAIR, but didnt make much of a difference.

Re: av7 parma ajustments

yeah trevor, as elliot recommended shave down the piston crown on the exhaust side. i think this method is even mentioned in the 2-stroke tuning book i lent you.

Re: av7 parma ajustments

i thought about that, but the transfers were being covered up also and it seemed like alot of piston shaving.

Re: av7 parma ajustments

They call this trick...

Notched piston.

Re: av7 parma ajustments

hey, i'm on the same boat right now. piston hits head and 1-2mm shy of clearing the exhaust port and same with the transfers... i feel weary about shaving the piston down cause it seems like ALOT and it seems like it would compromise the seal of it. all this with a thick base gasket i'll try thicker but i can see it wont do much. what are you all doin about this? do all bottom ends run into the on mobys or are some just different enough to make it?

Re: av7 parma ajustments

I am running mine currently with the gaskets that came with it. But I haven't really been riding it much at all. Let me start tunning the carb and we will see.

Re: av7 parma ajustments

i just used the thickest gasket paper i had and solved the head prob but, still doesn't clear the exhaust.

how are you jetted jesse?

Re: av7 parma ajustments

I put the carb on with the Jet it has in it. Started it and ran it down the street. 100 main Jet lol! I will start with a 90 tomorrow and go down from there.

21mm phbgad



Stock 3 ball variator because I can't find a puller.

Re: av7 parma ajustments

okay so I gave it a try...

<a href="http://s112.photobucket.com/albums/n180/monkeyonagriddle/?action=view&current=parmakitwork1002.jpg"; target="_blank"><img src="http://i112.photobucket.com/albums/n180/monkeyonagriddle/parmakitwork1002.jpg"; border="0" alt="Photobucket"></a>

I still needed at least 1.5mm of base gasket in order for the piston to cover the the exhaust port at tdc. ungodly huge exhaust ports are a blessing and a curse i suppose

<a href="http://s112.photobucket.com/albums/n180/monkeyonagriddle/?action=view&current=parmakitwork1013.jpg"; target="_blank"><img src="http://i112.photobucket.com/albums/n180/monkeyonagriddle/parmakitwork1013.jpg"; border="0" alt="Photobucket"></a>

i brought the piston down to bdc and used a marker to mark how much i needed to take off. i ended up doing as close to the ring gap as i felt comfortable, and its pretty darn close.

<a href="http://s112.photobucket.com/albums/n180/monkeyonagriddle/?action=view&current=parmakitwork1021.jpg"; target="_blank"><img src="http://i112.photobucket.com/albums/n180/monkeyonagriddle/parmakitwork1021.jpg"; border="0" alt="Photobucket"></a>

It not perfect but i think itll get the job done. Theres still a little room left at the top, but i figure i'll adjust this after i find out what kind of compression im getting

Re: av7 parma ajustments

oh and i have yet to run into any piston to head clearance issues...

Am i doing something wrong? or should i not question it and be happy.

Re: av7 parma ajustments

Jay here is my new jetting.

w6 needle on the leanest setting

50 idle jet

87 main.

I will be doing more tunning and plug chops tomorrow.

Re: av7 parma ajustments

thanks for the pics trevor. How close are we talking to the ring gap.

Re: av7 parma ajustments

cool man, keep me posted, i'm still waiting on the carb... so, main jets are the same size as sha jets right? what size idle jet came in the pghb? how's the variator working?

Re: av7 parma ajustments

I have a puller on the way. Running a stock 3 ball variator and it fucking blows. Can't wait to get the vairiplus on.

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