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.

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[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.

154426154427

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!! :beer 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.

154651

[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.

[Bryan Raffa]

you want Free HP... put a PWK on it....

[El Camexican]

you want Free HP... put a PWK on it....

Wouldn't that be classified as $220 HP?;)

[Bryan Raffa]

Wouldn't that be classified as $220 HP?;)

ya but unlocks more power and enhances the whole spectrum of the power... you can find em cheep off sleds this time of year.

[RIDE-RED 250r]

ya but unlocks more power and enhances the whole spectrum of the power... you can find em cheep off sleds this time of year.

I didn't know there are sleds that run PWK's... Good to know, thanks for the tip!

What sleds ran PWK's??

[XxMurdocxX]

I think they came on '98-'00 polaris xc 600's and 700's.

[74sickness]

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

Taking the lid off will make the engine take more oxygen in so it will even it out wouldn't it?

[RIDE-RED 250r]

Taking the lid off will make the engine take more oxygen in so it will even it out wouldn't it?

Negative Ghost Rider.... More oxygen without increasing fuel=leaner fuel/air mix.

[74sickness]

Negative Ghost Rider.... More oxygen without increasing fuel=leaner fuel/air mix.


Oh true im kinda new to this and young (16) ahah but thanks for the tip.

[pcs]

you want Free HP... put a PWK on it....

what boot would i use to run a 38 or 39 mm pwk carb

[XxMurdocxX]

I recommend using the billet intake sold in the 3ww store

[El Camexican]

what boot would i use to run a 38 or 39 mm pwk carb

I don't think the PWK comes any bigger than a 38mm. Anyone know if there is a 39PWK?

[XxMurdocxX]

I don't think the PWK comes any bigger than a 38mm. Anyone know if there is a 39PWK? yeah they make them from 28-41mm. http://www.sudco.com/pwk.html

[pcs]

i yanked one off a quadzilla and put it on my friends 250r, real woke the engine up but that engine was ported.
i saw the billet intake adapter on the 3ww store but is there any boots off other yamahas that fit and used a larger carb?

[zzmegad]

the stock z boot can be stretched by heating it, like boiling it or a torch, there some threads on it somewhere

[El Camexican]

yeah they make them from 28-41mm. http://www.sudco.com/pwk.html
Sorry, I was thinking of a 39mm "Air Striker" Those are the ones that only come in 36 & 38mm.

Thanks!:beer

[Bryan Raffa]

heat gun ..slowly heat the boot ...with the clamp as loose as is will go. it will accept a 39mm... you smell rubber burning stop with the heat..

[pcs]

ive done the boiling technique but only to stretch out a boot slightly to fit a slightly bigger carb not jump from a 32mm to 39mm.

[christph]

Good luck stretching the OEM boot to fit a 39mm carb. I'm not saying it can't be done but why not get the larger manifold? I got the larger manifold and it works great and looks good. Also consider if you are changing out jets now and then, it is much easier when the carburetor comes out with ease.

[pcs]

Good luck stretching the OEM boot to fit a 39mm carb. I'm not saying it can't be done but why not get the larger manifold? I got the larger manifold and it works great and looks good. Also consider if you are changing out jets now and then, it is much easier when the carburetor comes out with ease.
i agree with you chrisph, that is why i had ask if some other OEM boot that fits a larger carb to begin with will fit a tri z cylinder. i read that the it 465 and the yz 490 fit but not confirmed on what size carb they came with.

[XxMurdocxX]

I believe they came with a 38mm mikuni.

[TimSr]

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.

While other machines have different results, this is my TriZ experience.

If you are running a mostly stock setup, removing the airbox lid on the TriZ will make no noticeable changes, or for that matter, even with a modestly ported top end. Airflow is an entire system, and the long narrow intake into that 32mm carb works well as a low end power generator system, and the airbox is not the primary restriction. To benefit from "less restrictive airflow", you need a carb, porting, and exhaust that will utilize it, and you will find that as you add top end HP this way, you are also losing it off the bottom.

The K&N filter will make no noticeable difference other then the larger surface area doesn't clog as quickly. I prefer it for service and cleaning, but it does not enhance performance.

If by "spark arrester", you are referring to the silencer, that won't change anything other than the sound to any detectable degree. The stocker is very large and heavy, and you can drop some weight by changing it. The pipe itself, by its design determines at what RPM level your HP peaks, known as the "powerband". Most pipes don't add much in peak HP, just vary where it kicks in. The stock pipe is more top end powerband. The DG is more towards midrange.

The biggest gains to be made cheaply are in proper jetting. With your stock setup, you are almost guarenteed to be running too rich with most popular fuel mixes. I usually end up several sizes smaller on the mains, as well as dropping the needle a notch or two.

One of the cheapest and easiest bolt on performance enhancers is a set of Boysen Power reeds, which will noticeable improve throttle response, and rarely requires any jetting changes.

Porting can also noticeably improve things, but you start getting into more money, and the more engine work, the more you lose in reliability, even though with just porting, its not a lot.

My advice to anyone is to peak tune what you have before even considering serious modifications, so I think your post is on track.

[pcs]

thx for your inputs, for the intake im thinking of just redesigning one and run a open filter under the airbox cover. so im going to wait until i get a larger carb. for the spark arrestor, i ment the piece that bolts into the silencer opening. as for dg, the 2 ive seen dyno tested made less hp than stock so im not to impressed with their products so i dont plan on buying their pipe.