Yamaha Wrench Report(Tri-Z)

[J.D.]

Has anybody every done this? Just curious, I was thinking of just doing Phase I though, Phase II seems like it's too far out there for me. Any advice and insight is appreciated, thanks

[Darius1502]

The Yamaha Wrench report sounds like a really good idea. I think that once you find a shop which can do the porting the rest should be pretty easy.

I don't know of anyone who has done mods. There was a guy in the Readers Ride section that said he had the mods done. We may try emailing him. Another good thing about the mods is that it seems that they don't take away the bottom end of the machine....which I think is great.

I hope when I get my Tri Z together its some what quick. I rode a modified 250R about 2 years ago and after riding my Quadzilla and 250cc and 500cc dirt bikes it felt like a really weak motor. A slight mid range hit...but not much else...it go boring fast.

Honestly, if I wanted a fast bike I would stick to my quadzilla or just buy a CR 500....I don't expect ATV's to be speed demons....if they are great...but to really go fast ride a dirt bike!

[mbg75]

i performed the wrench report mods on my tri-z. these mods made a huge difference in power. i drilled the hole for the second boost port, opened both up to 12 x 24. raised the exhaust port 1.5mm. i dropped the cylinder head at the machine shop and had them mill it. (i also polished the exhaust port and combustion chamber & lightly blended the transfer ports) plan on having the cylinder bored and getting a new piston. i am running carbon fiber reeds, dg pipe and silencer, and a 500 main jet w/ uni filter and stock air box. the bike has a little less on the bottom end, but when the motor comes on to the pipe it hits hard. if you have any questions, let me know. mike mbg75@optonline.net

[J.D.]

did you just do phase I, or did you go for phase II?

[mbg75]

phase 1, i didn't want to remove the air box because i do occasionaly ride in the mud. also to put the larger carb on for phase2 you need a it250 intake boot which i couldn't find at the time. as far as the porting goes, all that is requires to go from phase1 to phase2 is raising the exhaust port .5mm more and milling the head more. the most difficult part of the wrench report mods is adding in the extra boost port, because there isn't much room to drill and open up the boost port hole.

[Dynofox]

I've been thinking about having phase 1 done to my Z, but I don't know if I want to lose any of the low end. I'd say 40% of my riding is done in tight woods sections, so the wrech report might be a waste for me.

[86waterpumper]

I'm pretty sure that YTZ250N has done the stage 2 mods to his triz. He had the stage 1 ones done when we were at haspin last year, and his bike would scoot pretty good.