Whats up with this main jet situation?????

[Darius1502]

Took my carb apart and there was a 320 main jet in the Tri Z. I learned that a 470 is stock.

My plug was oily black at 320 so I:

cleaned my air filter and installed a 310. Now the plug is tannish, mocha brown.

The only mods on this Z that I know of are:

1) Boyessen reeds
2) DG silencer (no pipe)
3) open airbox lid and K and N filter

Whats going on here guys??

I don't want this thing to detonate!!

Darius (man the troubles never cease!)

[twgranger]

470 is not the main jet for all tri-z's 470 is the right main jet for the tri-z (N) it says it on the front of the frame. The tri-z (S) main jet is 360 i think.

[KASEY]

DO YOU HAVE KEIHEN JETS IN YOUR MIKUNI???? i know that they look the same and #'S ARE WAY DIFFERENT ,,,, maybe?

[Darius1502]

Last night I went to bed thinking that the 86 must have come stock with a smaller main jet.

I just need to look at my manual and don't have it here.

Thanks guys...sorry for creating a crisis every 5 minutes!!

darius

[Tri-Z Pilot]

Yeah the 86's (s) models had different carb settings, 360 main I think. I dont know why the 85's had a 470 (mine has 470), what could be so different about the engines that you would need a radical main jet change like that?

[Darius1502]

The motors have different porting. Denn is gong to compare the 85 and 86 cylnders. There is a difference in the power of the two bikes. In 86 Yamaha made some improvements. I don't think the 86 has the wrench report mods on it...but Yamaha may have done a few things to give it more power.

After all if they knew how to do it with the wrench report and recognized it was a problem...why would they just leave the 86 alone?

Darius

[Tri-Z Pilot]

I thought that porting didnt affect your carb settings?

[Darius1502]

You are probably right. I am not the carb expert. I know that the 86 has a bigger intake boot that mounts on the carb.

Who knows....as long as I am not going way out of the ballpark. My plug looks good too!