Fitting a 98 to 99 YZ motor in a Tri Z

[Darius1502]

I have been thinking about this idea for quite sometime.

What problems do you guys see. Ever heard of it done.

The issues seem to be:

Fuel pump vacum hose - solution: drill hole and put stem on bottom of cylinder

Reverse Kickstarter - attach rear fenders to the seat and make the whole rear end removable like an ATC 250R.

Carb Route - the carb boot is angled to the left on dirt bikes... perhaps you could find a straight boot that fits?

Exhast Route - on YZ of today the pipe snakes down the opposite side as the Tri Z. Perhaps a custom pipe.

What else can you guys think of....

Thanks,

[hondatrikesrule22]

On the head stay problem,why couldn't you just swap the heads?

[OldSchoolin86]

On the head stay problem,why couldn't you just swap the heads?

That's what I was thinking but the bores are different. The Tri-Z is a 68mm bore and the 99-01 YZ is a 66.4mm bore. This may mean nothing but it makes you wonder what is different with the jug as far as meeting up with the head.

[Darius1502]

I would want the hole motor as intended by the engineers today. Swapping heads and the head stay trouble is not that big a deal. I think Chainsaws Tri - YZ does not have the headstay...atleast I seem to recall that when it was on ebay.

[CHAINSAW]

Mine doesnt have a head stay, and its not really nessesary for a 250 motor I think. There has never been a problem with mine the way it is. Now a bigger bore motor, its suggested, because they move and groove so much, they will crack at the base of the cylinder, and blow out a hole.. (i.e. my big bore motor) If your die hard about having one, all you need is 15 minutes to make your own top mounts, to bolt up to that head.

[Tri-Z Pilot]

I think you guys have it about covered. I'm not sure, but for some reason I think the exhaust outlet on the cylinder is angled, I could be wrong though. The angled carb shouldnt be a problem, it would probably make it easier to install a pod filter.

[370banshee]

darious i thought you were doing an 89 YZ into a tri-z. or at least thats the questions you had for me in pm's was that justa typo???? i know the 83-89 engines bolt right in. thats what chainsaw, orangeshee, and myself have all done

[TimSr]

For you guys that have used YZ motors, do the TriZ kickstarter assemblies work on them, or how do you address the issue of kicking backwards? Also, do 83-89 all work with the TriZ exhaust, or does it need to be altered?

[CHAINSAW]

Mine is an 87 motor. The side cover is a Tri Zs, and the kick starter gears were swapped out. Im not sure how different they are, the YZ and Z's but mine kicks forward with no problems. The lever is a YZs thats been bent around, so it cant ever hit the clutch cover.
As for the exhuast outlet, mine is the same as a Zs. I know the 85-87s were this way for sure, but I cant give you a 100% on the 83,84, 88-91s. A Tri Z pipe will bolt right up.

[Darius1502]

Thanks for the help guys. 2strokefreak, I want to put a late 90's engine in my Z. I have looked at both the 98 and 99 motors for the YZ 250.

I figure that if I am going to do it I want a late generation motor in the Z. The same issues will present themselves:

- kickstarter
- fuel pump
-carb boot
-exhast
-lighting, etc.

I figured why not put a more modern motor in the Z then if I want I can take advantage of the various big bore kits available for the YZ such as a the 330 kits etc.

I don't know what other issues there may be, but I will take my chances. From my limited research, I have found that the motor mounts do line up. There may be other problems.

The idea of a modern powerplant in the YZ excites the heck out of me. So we will see.

[CHAINSAW]

If your looking to go big bore, its possable with a Z cylinder. Ive got an 85 cylinder thats a 370 bore, so I know its possable.

[Merriman]

If your gonna go modern, why not put a 4-stroke motor in it? Like the yzf 450, 426 or 400? They make as much HP as a standard 2-stroke, with no gas mixing.

-Exhaust would be much easier to create.
-reverse Kickstart = Flip top subframe like modern aftermarket ATVs have. Check out www.jrd-mech.com (something like that) they have flip top subframes
-Gas flow = custom tank to take the place of the air box.
-route the airbox like all others and put it by the rear shock.

[OldSchoolin86]

Yeah but they are bigger and heavier.

[Merriman]

Yeah but they are bigger and heavier.

The new 4-stroke motors?

They are not bigger (less than 1 inch in height), and almost the same weight.

My YFZ 450 motor only weighed about as much as my 85 atc 250R motor when I had them both on the bench.

a YZ dirt bike only weighs 211lb, while the yzf weighs 220lbs. You won't notice the 9lbs. The throttle and power delivery of a 4-stroke is much smoother and usable than the 2-stroke.

[OldSchoolin86]

You just said the same thing I said, they are bigger and weigh more. They also cost more to buy and cost more to modify.

[CHAINSAW]

and its highly unlikely a 4 stroke would fit into the frame. Relocating the gas tank wont work, unless its a drag race only machine. The tank will only hold a gallon, 1 1/2 at most when put up where a regular tank will go. If the frame is modded to accept the taller 4 stroke motor, well thats even less of a tank that would fit.

[370banshee]

merriman i'm sorry but putting a 4 poke into a tri-z would be like swapping 4cyls into corvettes. you can say what you want about how nice the new 4 strokes are but they way i look at it is this. it was made for a 2 stroke and that what should stay in it. tri-z's are made to be arm stretching ring dingin fast trikes. oh yeah who would wanna screw with valves, camshafts, timing chains. screw all that. darious squeeze that new YZ enigne into it then laugh at the new 4 stroke quad with your trike

[BigGreenMachine]

The new 4-pokes have lots of grunt, it would be like putting a V4 in your trike IMO but the size of the YZ450 motor makes it an awkward fit and who wants to mess with cam chains and valves anyway...

The YZ 250 and YZ450F make around 45 to 50 hp each and weigh close to the same. Personally I'd love to have a Kawasaki 450 fourstroke in my 85 Tecate or an 86 Tecate. Just because of the controlability of a fourstroke motor and contrary to what most sissies believe, cam and valve adjustments aren't that bad. Maybe someday...

[TimSr]

I think the idea of using a YZ 2 stroke motor is so you can drop it in with a minimum of welding and frame hacking. My interest in the YZ motors is simply as a replacement thats a little easier to find than a YTZ motor. I have yet to see the guy who has mastered using all the power a stock TriZ can deliver that runs properly, so Im not even interested for the power valve upgrade. I want to keep mine in operation as opposed to re-designing a whole new one. And, Im sorry, but those monster custom builds with an oversized, overweight, and overpowered motors are only good for one thing. They are useless for normal riding. Your also not going to find a lot of scrap motors from 450's laying around in the junkyard for a few hundred dollars, but even if you did, and managed to get it mounted, and build an exhaust, the stock TriZ would kill it everywhere but on a drag strip, and even there, its questionable. If you want a 4 stroke, Im pretty sure Honda built a pretty good one.

[BigGreenMachine]

I didn't mean to agree that a four stroke would be the best choice, just got carried away with ideas I want to try. A YZ motor, especially the 98 and up motors would be a great swap for the Tri-Z and if its only the pipe that would really pose an installization problem thats easy enough to solve by having a company like CT make you a custom pipe. As for lights there are kits available for the YZ that some Supermotard drivers buy to make their dirtbikes road legal.

[370banshee]

i think all of the guys in here with powervalve tri-z do drag race them i know thats what mines for

[Darius1502]

I don't want to 4 stroke motor in the Tri Z because as it was stated earlier the Tri Z is ring a ding two stroke 3 wheeler. Besides...in 2006 we probably wont have an more two strokes in production so I can do without the 4 strokes.

I will do the project but it may take some time since right now I pretty busy. The motor will be a 98 to 00 YZ 250 motor. I am exicted as heck about getting started but it will be a while.

I'll keep everyone posted. I can't believe that no one has done this. Can someone compare the cases of an 89 YZ 250 motor to the 98 motor.

Thanks,

[hondatrikesrule22]

I don't know...them 4-strokes are getting fast. I was watching OLN earlier, and there was a guy racing a 250 4-stroke with the 250 2-strokes, and he was kicking ass!

[Darius1502]

I have a YZ 400F and I can tell that while they are fast a 2 stroke 250 is much much more fun to ride.

[BigGreenMachine]

Hondatrike I hope you meant "450" fourstroke was kicking the two strokes ass cause no way will a 250 fourstroke be beating a 250 2-stroke.

[OldSchoolin86]

I don't know...them 4-strokes are getting fast. I was watching OLN earlier, and there was a guy racing a 250 4-stroke with the 250 2-strokes, and he was kicking ass!

LOL! The people on the 2-strokes had to be really sad if that was the case!

[hondatrikesrule22]

Maybe the guy said it wrong, but I could have sworn he said 250.

[CHAINSAW]

with exception to the new 450 4 strokes, a good rule of thumb. It takes double the amount of cc in a 4 stroke, to match the power of 2 stroke. Thats not no rule or anything, there are exceptions, but a lot are like that. So 250cc 2 stroke is the same as a 500cc 4 stroke. 250cc 4 strokes, can usually get whopped by 125cc 2 strokes.
Like I said, its not gods honest truth, but most of the time its that way.

[370banshee]

yeah chainsaw thats the rule of thumb. except in the case of the new 450 quads like you said. i say long live 2 strokes. what real quads, trikes, and bikes really have as a heart a premix smoking arm stretching, hold the **edited** on kinda ride. damn i'm getting all excited just thinking bout it