More Tri Z wrench report questions....and Tri Z factoids

[Darius1502]

Ok...I know has been beaten to death and probably will always be beaten to death but....


1) Are the 86 and 85 cylnders the same or different? Can the wrench report be done on the 86? Or would you end up taking too much off?
(I remember reading in Dirt Wheels that the 86 got some porting mods)

2) Do you have to run high octane racing gas after the mods are done?
The mags said nothing of this in the 80's. What modifications to the report could I do so that I can just run 93 Octane?

3) For those that have done the mods...did you also cut a section of the pipe out? I was wondering if this was necessary or not.


Just pulled out my old ATV News from 1986...Yamaha press relations manaer Willie Amaradio said, 'it was billed as the YZ of our three-wheeled line. But its performance was actually closer to that of an IT (enduro motorcycle). What we wanted to do this year is make a no-compromises performance three-wheeler and to do it we made a number of change'.

Here is what they said was done:

1)piston dome has a new shape
2)small porting change actually made in mid-1985 (done to prevent piston siezures)
3)6 speed tranny
4)bigger intake tract
5)different jetting in carb
6)different rake and smaller front tire

a few more things...but it appears the porting is the same...

Thanks guys

Darius

[J.D.]

Only thing I can answer is I've been told that after Phase I you have to run 100 octane to prevent pinging, and instead of cutting the 10mm out of your pipe just throw on a DG pipe/silencer.

[mbg75]

yes the cylinders are basically the same.

after the porting work is done and the head is cut, the cylinder will need a fresh bore and piston. no sense in spending money or your time on the porting and not using a fresh top-end.

the dg pipe will perfom much better than if you cut the stock pipe

you definitely will have to rejet.

aftermarket reeds recommended, leave the stock carb and air box on. put some vents in the box or cover. for sea level use a 490 or 500 main jet.

although using race fuel can be more expensive, it's cheap insurance. mine was pinging on sunoco 94. you could try regular pump gas, all that could happen is preignition, end up burning up the piston dome, damage the head and ruin a motor that you just dumped about five hundred into in porting, piston and a pipe.

hope i didn't step on anyone's toes here. this is the set-up i am running on my tri-z for two years now. it works well. jetting is right on and the bike screams.
always starts on the first or second kick and is stone reliable.

any questions about my set-up email me mbg75@optonline.net