Hey I have a 50v and was wondering about what would be best to run a 70 cc head kit on my engine ?

I know there is post already about this

I have the head ported and milled with WIKI instruction, I could port more and get a little more but it’s a just a fun zip around thing

Also I have a 15/15 Sha carb and a 55 t rear sprocket and also the 12t front .

With the stock gearing it goes 39-40

My question is would it be worth it split the bottom end and do crank up with new crank bearings and piston and head kit

Or just re tune and ride the stock engine , thanks

Re: Av7

If you can do Bearings, seals and gaskets do it

Re: Av7

Ok definitely can do that

so just refresh the bottom end

And just hold of on the complete rebuild / upgrade ?

Re: Av7

Probably you mean 70cc CYLINDER kit - which will give you more torque because of the larger bore. You will also want to go for a aftermarket exhause so the engine can breathe, and a new intake and larger carb...

Current set up you would want to set your timing to 1,5mm BTDC if you dont have that set already, also derestrict the exhause if you did not do that (oh yeah and check if the new intaks with the 15mm carby is not restricted where it transitions from round to rectangle)

You might also want to consider stuffing the counter springs on the lower engine mount, that would give a bit of tunability to the variators actions.

If she is running goodly at themment then you may want to consider getting the gasket seal bearings for the carter and hold off. If the bearings are not complaining and you have no sign of a vacuum it would be a good task to leave alone until you decide you really want to kit the engine (or the AV7 decides to develop a vacuum leak).

Re: Av7

Yeah I was thinking the 70 kit and have been reading all the info about them ,

I swapped from the 14mm bendy intake to the 15mm short when I did the carb

and I port matched it to the cylinder and when I ported it . It has been running perfect since the port job

I will just have to check the time of the engine

Also did carbon removal of the exhaust and unrestricted it also .

What head would you recommend for the 70 kit a stock head squish probably is not correct for the bump in size and compression thanks .

Re: Av7

I know at least two people who had the big end bearing fail on a stock AV7 crank with mild 70 kits. Both bikes were running good and had miles on them with the stock cylinder.

Part of me thinks it has to do with the fact that the stock air filter is a rain funnel and if they get left outside they often have water in the cases when you buy them, but its definitely not a coincidence, since just about no other moped has that issue.

personally, i replace the crank when i kit av7's.

the airsal kit with a 16 SHA, stock pipe, stock everything else, makes a great setup. goes 45 with tons of torque, doesn't shake too much (its not turning high rpms) and they are reliable as fuck. its one of those 'magic recipe' moped builds.

Re: Av7

Mike McScoutington /

If you're considering picking up a kit gimme a shout. I have a 74cc Parma, matched cases with new bearings and seals, an ER3 variator, and pull start just sitting on my shelf. I would be willing to let everything go for a good price.

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