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Discussion Starter #1
Hi
OK, after collecting various parts for an engine build I ve turned direction and decided to stick with stock bore.
Now out of the collection of parts I have, definitely want to use the Koso cam and I also have the option of getting a the TB valve set with double springs put into a stock head and then ported.
What are the best piston options currently available for stock bore that would accommodate the stock valves with the koso cam or the cam and TB valves if I go that route? I really I would like to up the compression a bit also. I ve looked at the Takegawa 12.5:1 Forged piston and it鈥檚 a work of art but doubt that would work even with the koso cam and standard valves... unless someone knows otherwise馃槵

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That is a NIGHTMARE piston was my first option when upgrading, Only one person I know of that got it to work with out seizing, and that was a collective effort from member Estallings15 and David over at DHM...

I ended up going with DHM High Comp Piston with same ratio over the takegawa, but member Estallings15 is still currently running that piston hitting speeds of 80+mph

https://www.hondagrom.net/forums/7-grom-talk/40384-high-comp-piston-ratio.html
 

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Discussion Starter #3
Thanks for the heads up, guess the Takegawa piston is function over form then! The DHM piston I ve looked at before but has shown Out of stock for what must be a month now, plus being in the UK a quick turn round of spares if needed is impossible. I might have to build it up with a standard piston but wary of losing compression because of the valve overlap on the koso cam??
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So you have a couple options-

Kitaco High Compression piston which is suited for stock valves and would need fly cut for larger valves
Takegawa High Compression piston which is known to have issues in design with standard cylinder bore
DHM High Compression piston which is suited for any type of valve you would ever consider
Finbro High Compression Piston which is not the highest of compression, but still worthy

There are others I have come across on Webike but nothing else worth really mentioning. Best option by far is the DHM piston. Kitaco is a great piston but it's limited to stock valves unless you want to deal with having it machined.


Thanks for the heads up, guess the Takegawa piston is function over form then! The DHM piston I ve looked at before but has shown Out of stock for what must be a month now, plus being in the UK a quick turn round of spares if needed is impossible. I might have to build it up with a standard piston but wary of losing compression because of the valve overlap on the koso cam??
Cheers
You need to reach out to David directly on FB.. I believe he has them in stock and may not be aware his store says otherwise.
 
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