free hp for a tri Z?

[pcs]

so ive been getting familiar with my tri z and looking around the site for some free or cheap hp before i take the cylinder off for porting. i was thinking removing the spark arrestor from the muffler and removing the lid off the air box to let the motor breath a little better. just wanted to ask if anyone else has done this and what type of jetting changes were done if any. from reading old mag articles, the air box set up is really restrictive on the tri z so any mods to breathing yielded nice gains. any inputs will be appreciated.

[wisconsinite]

removing the airbox cover will make quite a difference, but be sure to re-jet your carb or it can lean out and cook your motor!

[christph]

It is not exactly free, more like 50 bucks, but K&N still makes an air filter for the Z. That will get her breathing easier. If you are going to get her ported be sure to google the "Tri-Z Wrench Report." It is an article written back in the day about hopping up the Z and it includes advice on porting. I took their advice and added an additional boost port and the performance gains are impressive. Here are some before and after pictures of my cylinder.

[badass350x]

If you have a spare air box or dont mind cutting yours up,,, what I did on my build is cut the whole box off except the flange that the air cleaner clamps to as well as the mounting area where it bolts to the frame, that way its completely open under the air box cover!

[pcs]

thx for the inputs, i did find the k/n tri z air filters for around $40 on flea bay. i think im going to pop off the air box lid for now, any thoughts on what size to go up on the main/pilot jets?

[pcs]

duplicate post

[RIDE-RED 250r]

It is not exactly free, more like 50 bucks, but K&N still makes an air filter for the Z. That will get her breathing easier. If you are going to get her ported be sure to google the "Tri-Z Wrench Report." It is an article written back in the day about hopping up the Z and it includes advice on porting. I took their advice and added an additional boost port and the performance gains are impressive. Here are some before and after pictures of my cylinder.

Interesting... I have a 250r cylinder that has an oversize sleeve and those additional boost ports...

PCS: I would start out 2 sizes richer on your main after pulling your airbox lid.... Never hurts to start out safely rich at first after altering intake and exhaust.

[74sickness]

My 200x was running lean and i took of the airbox lid and its almost perfect and sounds better too, I love it.

[badass350x]

My 200x was running lean and i took of the airbox lid and its almost perfect and sounds better too, I love it.

So it was running lean and it even runs better with the lid off????? now its really running lean!!!!!!!!!!!!!!!!!!!!!!!!

[Tri-Z 250]

Interesting... I have a 250r cylinder that has an oversize sleeve and those additional boost ports...

Honda cylinders came stock that way. The Wrench mod can change the motor into a more boastful snappy unit great for race motor...but not needed to have a hard running Z, stock head with a DG and proper jetting. With all the mud around here, I keep the lids on.

[RIDE-RED 250r]

Honda cylinders came stock that way. The Wrench mod can change the motor into a more boastful snappy unit great for race motor...but not needed to have a hard running Z, stock head with a DG and proper jetting. With all the mud around here, I keep the lids on.

Maybe some of the later cylinders did then. I know for a fact that my stock '85 cylinder does not have those boost ports.

You just learned me something!! Thanks man!

[El Camexican]

This is a photo of the stock boost ports on a early 90's WR/YZ 250. If I ever port another Tri-Z cylinder I'm going to try and duplicate these ports.

[Tri-Z 250]

naah you can say it...it's a Honda. I think that WR/YZ head pretty much in a nut shell is the mod. Do look at the exhaust port for leads or possible alteration ideas. If I remember those weren't power valved yet...or am I wrong?

[pcs]

Interesting... I have a 250r cylinder that has an oversize sleeve and those additional boost ports...

PCS: I would start out 2 sizes richer on your main after pulling your airbox lid.... Never hurts to start out safely rich at first after altering intake and exhaust.

you are definitely right
no mud where im at plus even with the lid off the airbox cover still provides protection to the filter.

[El Camexican]

naah you can say it...it's a Honda. I think that WR/YZ head pretty much in a nut shell is the mod. Do look at the exhaust port for leads or possible alteration ideas. If I remember those weren't power valved yet...or am I wrong?

No power valve on the Tri-Z and the size of the Tri-Z exhaust port is a lot bigger than the power valved port on the WR/YZ, but there are also two small ports as well as the main one on the WR/YZ. My Tri-Z exhaust port seems so wide I thought the ring would get caught on it, but so far so good. I wonder what % of the circumference of a cylinder can be open before there is a problem with the ring snagging, anyone have an idea? I assume the smaller the circumference of the cylinder the greater the % of the circumference can be dedicated to the exhaust port. The mod for the Tri-Z exhaust port is to raise it a bit. I suggest only 1mm because if you go more you'll likely need to shave the head a little to get the compression back.