Best stock engine?

[GreasyChris]

PK80 Ripper Kit - PORTED with Upgrades | Bicycle Motor Works

Rip it up on a REAL PK80! (PORTED Full Kit!!!) This is a full kit so you'll get everything you need to motorize a bike. PLUS, you'll receive a ton of GREAT UPGRADES at one super low price. Available only for a limited time or while supplies last.

bicyclemotorworks.com

 

[Digger]

Notice in my previous post I said I THINK I have narrowed it down. I'm still deciding. I like the long stroke, type B piston & round exhaust port of the Zeda + I had one of them when they first came out. I found a seller on Ebay selling them for $89.00 + $29.99 shipping. $119.99 total. Good price for a real Zeda. The only reason I havent pulled the trigger yet is like you said, the plating problem.

 

[Digger]

Thanks for your opinions though. Does anyone sell a good replacement cylinder for the Zeda?

 

[gary55]

Thanks for your opinions though. Does anyone sell a good replacement cylinder for the Zeda?

It's a crap shoot with the Zedas. The only one I've seen that has had consistantly good plating and port timing is the Zeda Firestorm engines from BicycleEngines.Com. Else wise I too would choose the PK80 Ripper from BMW for the G4 cylinder and high comp head. It is a short rod long stroke A type engine, so your still getting the same displacement as the Zeda with better designed transfers, larger crank cheeks for a better stuffed case, and the shorter 85mm as opposed to the 89mm rod of the Zeda should be a little lighter though I have not weighed them myself. Both have 40mm intakes and 8mm mounting studs. Either of the aformentioned suppliers are first on my list of those providing consistently good products and customer service.

 

[gary55]

But I'm a Robert. Please understand there are other people here called Robert.
If you're advising the forum to avoid a particular vendor then please include the actual trading name of the company somewhere in the thread, for those who haven't been reading long enough to know which company you mean.
I know who you meant.


So who has the best big end?

Does that make you a Bobby on a bicycle? Couldn't resist. The Runwell PK80 does seem a little smoother but both are pretty good, and with your skills and patience either would wind up great engines.

 

[FNTPuck]

This pipe is also close to the MZ pipe. It looks likes the zeda/cdh pipe but is much bigger.

80CC 66cc WC80 MZ65 Style Pipe Exhaust with Expansion Chamber High Performance | eBay

Find many great new & used options and get the best deals for 80CC 66cc WC80 MZ65 Style Pipe Exhaust with Expansion Chamber High Performance at the best online prices at eBay! Free shipping for many products!

www.ebay.com

That pipe looked good at first glance but note that the new WC80 pipe has a smaller header with a terrible angle compared to a real mz65 which sends the exhaust straight into a wall, and the welds are very poor and prone to leak. I would stay away from it and either hunt down a real MZ65 (which is overpriced and will run ~$100 now!) or even better save another $50 or so for a real dirt bike pipe which runs $150-200 depending on which one you get. I like the RM85 or KTM65 for most chinagirl builds, and bigger pipes like the YZ85 and KX85 for big bore, aftermarket jug, or race builds.

For the kit, I agree with the PK80 from BMW. Go with the ported w/upgrades if you can spare the cash since it will save you money in the long run by including not only good port work but most of the common upgrades that people will do anyway (CNC head, case mounted tensioner, OZ mag, plug boot, common sized jets, etc)

 

[Digger]

On the PK80 Ripper, is the porting done by hand or machine? What I'm getting at is, is it consistent between all the engines or is it just luck of the draw? Also I have a new Jake head I've been wanting to use. I don't know if it is a real Jake or clone. I know the Ripper comes with an upgraded CNC head, was wondering if the Jake head would be an upgrade, downgrade or about the same? Sorry for all the questions but I don't know much about modifying CG 2 stroke motors. Any tried & true advice is greatly appreciated. Thanks everyone!

 

[gary55]

Port timing is by hand. You can check what I found about this engine in the forum search PK 80 Ripper from BMW. I still haven't checked the squish gap with the provided 2mm copper head gasket, but I can't imagine Matt would go that small without a reason.

 

[Digger]

So this engine has the narrow front mount for the smaller front down tube?

 

[gary55]

So this engine has the narrow front mount for the smaller front down tube?

Yes, but if you need to go larger just use the adapter plate with the proper size muffler clamp and split metal tubing to protect the frame.
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