Hi compression piston and destroking?

[speedpro]

Yeah, the problem is that the centre and end bits are the same diameter. The only way to get the big end bearing on is to split the cage which would seem to be a problem. My pin has a 2mm bigger centre section and the offset is only .75mm so I can fit the big end bearing straight on.

[richban]

The off set crank pins were actually of good quality, but it was the pins split bearings that failed on Rich, twice.

Yep correct. I would just go the old fashioned way and offset the pin in the crank. The Akunar hi end pistons ($25US)ish are great. I have been abusing one for 2 years. If you can find one that fits its a good option.

[husaberg]

While looking for a piston for Kicka i came upon this site.
no idea re the quality but the price can't really be argued with.
They cover a wide rage of suitable sizes.
They also pistons for 4 valves in various sizes.
http://jvtscooters.com/index.php?pag...mart&Itemid=29

http://jvtscooters.com/component/sea...it=20&start=60

For my money for a Honda single i would stroke the engine as it is so much easier and the comp is more tidy and in reality a 2 valve Honda single won't rev enough to make use of a short stroke anyway. Simply to get a high comp with a large valve head such as the Honda will compromise combustion and require too much ignition advance to be practical. A stroker with a 185/200 crank i believe will be faster and cheaper as well. 4 valves are a different story of course.

[husaberg]

It does seem a bit pricey just for the piston and clips. Consider that I got a new chrome bore cylinder complete with forged piston, rings, pin, clips, and gaskets from Taiwan for US$87.70 and a 3.5mm longer stroke crankshaft for US$122.80 + freight of US$43 it would seem worth your time doing some serious research for another source. The cylinder is a lot nicer looking casting than the original Yamaha as well and the piston "looks" good as gold.

I had came upon a (Taiwanese i think) site that also had a lot of Honda stuff z50 crf50 etc and even had some some 2 stroke stuff a while back. Mike what site were you dealing with?
I had a wee look in the favorites lists on my browser but the site i was snooping around isn't leaping out at me.

[speedpro]

Yamaha Cygnus bits here:

http://tdmotor.en.alibaba.com/search...ext=motorcycle parts for cygnus

or just check on the "alibaba.com" site

[Drew]

2) I recently heard a story about a guy who tried using bog on top of pistons to raise the compression in his Cortina. No actual word on whether it worked or not...

(2) only a cortina owner would try something like that.

The guy who bogged the pistons was known as "Booger", and he's a bit simple.

Just to clarify, NO, it didn't work. It ran...ish. But not on all cylinders, since chunks of bog got stuck in valve seats holding them open.

[husaberg]

Yamaha Cygnus bits here:

http://tdmotor.en.alibaba.com/search...ext=motorcycle parts for cygnus

or just check on the "alibaba.com" site

Thanks not the one i was thinking of i will try to find the one with the Taiwanese MB100 cylinders and other stuff in Hindsight it could have been Vietnamese.

[speedpro]

This one?

http://gzfuhui.en.alibaba.com/produc...0_50_5MM_.html

[husaberg]

This one?

http://gzfuhui.en.alibaba.com/produc...0_50_5MM_.html

Yes and no. The site was a manufacturers or distributors site def a website rather than one like alibarba it had all sorts of stuff to buy rather than have made.
Pretty sure in hindsight it was Vietnamese