'82 Yz80

[Bateman147]

Hi -

I'm going to be working on a YZ80 for a friend (I don't have it in hand yet). It's in a YSR chassis, and used for mini roadracing. It apparently has a later model cylinder and piston for a larger bore. The owner thinks that makes it close to a 90.

I'm looking for advice/specs on tuning this combination. I'm assuming a 1mm squish band at the approx. angle of the piston crown (5 degrees or so) will be correct. Any help with suggest port heights, cylinder head volume, etc would be greatly appreciated. I'm quite familiar with Honda RS125 roadrace engine tuning, but don't have any experience on this particular engine.

The pipe the owner says he'll be buying for it is from Team Calamari. I don't have specs on the pipe yet, but should soon. I'm assuming it will be run on VP C-12 fuel or the equivalent, but I will confirm that prior to working on the bike.

I really appreciate any advice anyone can give.

Thanks!

Michael

 

[SuzookKING]

I am familar with the YSR's as my son & I have 2 of them. :yeehaw: A CR80 conversion (his) and a YZ125 conversion (mine).

Depending on where he will be riding it I would go for something similar to what the karting world uses (not being a tuner this is heresay so if this is far off someone correct me, otherwise confirm with a better source, before toasting some parts)

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196° exhaust and 136° on the main transfer
pick up blow down area and also a little top end power by widing the exhaust port a couple of MM above the point when the transfers open.
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This was given to me by a redneck kart tuner

I myself am going to have Eric do a cylinder/head for my son, mine has plenty of power since switching to a modified TZ125 pipe.