Author Topic: yz490 piston (Read 2980 times)

noisy toy · « **on:** January 11, 2014, 05:30:54 pm »

Has anyone seen a port like this in a yz490 piston before? good or bad? I will attempt to post a pic.....
cheers, shane.

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noisy toy · « **Reply #1 on:** January 11, 2014, 05:58:23 pm »

noisy toy · « **Reply #2 on:** January 11, 2014, 05:59:25 pm »

aha it worked! helps when you copy the correct link.....

Lozza · « **Reply #3 on:** January 11, 2014, 11:01:12 pm »

Makes no real or measurable difference except for maybe making the skirt a tiny bit weaker

motomaniac · « **Reply #4 on:** January 13, 2014, 10:50:42 pm »

its for more top end power .I wouldn't think that it was a good idea on a bigbore for motocross.

Lozza · « **Reply #5 on:** January 14, 2014, 02:59:20 pm »

Any ideas how that port would make more top end HP?

vandy010 · « **Reply #6 on:** January 14, 2014, 05:21:37 pm »

Dont know much about big bores but we did this mod many
years ago on a mates YZ80F and it made a big improvement.
I thought it was mainly to provide extra lubrication/cooling to the
small end and was more of a bottom end power mod???
Anyone else?

Lozza · « **Reply #7 on:** January 14, 2014, 06:31:24 pm »

Did similar things a dynoed them back to back and found no difference in the output of the engine.

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Author Topic: yz490 piston (Read 2980 times)

noisy toy

yz490 piston

noisy toy

Re: yz490 piston

noisy toy

Re: yz490 piston

Lozza

Re: yz490 piston

motomaniac

Re: yz490 piston

Lozza

Re: yz490 piston

vandy010

Re: yz490 piston

Lozza

Re: yz490 piston