First Generation Ascots > Tech Section

Wiseco Piston problem

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Slyphon:
Where were you ordering the piston from? And it sounds as though this is a manufacturer issue and not necessarily a supplier issue... Now I need to do more research in to the Wiseco Piston to determine if that's what I'll be ordering myself.

plasticadam:
Finding out a bit more about this now. The Wiseco piston is a 10.5:1 compression - the original Honda is 8.5:1. and Wiseco are suggesting this is an acceptable alternative and shouldn't require any other mods or cause starter issues. Regarding potential starting problems, this is the exact same piston for the XL500 with kickstart only, so I guess if it made too tricky to start XL owners would not be happy.
They also do a 12:1 Hi-comp version which is for serious modified bikes.
Maybe I'm getting too paranoid?

J6G1Z:
I think you will be fine at 10.5:1 compression & your bike will like it.

J.

J6G1Z:
Have you ever heard of, or seen some of the compression relief poppet valves?

I think they were originally developed for large chainsaws to ease starting. It consists of a spring loaded valve that is normally open due to the spring pressure. This allows the compression stroke pressure to escape during cranking of the starter. Once the engine fires, the pressure is high enough to seat the valve closed & hold it closed.

Most of these compression releases will require some machining of the head, plus a hole drilled into the combustion chamber to vent the compression to the valve. Here is a link to one of these types of compression release: https://www.denniskirk.com/H14197.sku?utm_source=pricegrabber&utm_medium=cse  Also it is pictured in the first pic below.

There is also one of these types of compression release that has been added to a "part" that also accepts your spark plug & threads right into the spark plug hole. That one is shown in the second picture.

Good luck
J.

plasticadam:
A bit late on the update but last week I took the plunge and asked the machine shop to do the re-bore. Fingers crossed! Hopefully get the barrel back this weekend and can finish the rebuild within  a few weeks - depending on work commitments.
Got the paintwork back yesterday - metallic black with twin red stripes -  now that does look pretty. Must get some pictures sorted and post them.

Also, I'm sorting out a few original parts for ebay UK - clocks, side panels (immaculate), headlamp and brackets. Will post them here first in case anyone's interested

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