85 Tri-Z

[jsmstorm]

A buddy of mine picked up an 85 Tri-Z this weekend for $200. Looks good but needs a new top end on it. Ok so now my question.... I haven't checked the bore with a micrometer yet, and the top of the piston doesn't say shit all it has on it is a W. Just trying to figure out what the hell this W is for on the top of it. Also what would be the cheapest place to get a new piston kit for it?

[rm250dude]

u got any pics? by the way nice avatar

[FPMXer]

There should be some #'s on the inside of the piston. If you only found a "W" on the dome then it could be stock or a Wiseco. Here is Wiseco's chart for Yamaha.

http://www.wiseco.com/PDFs/Catalogs/CB07/YamahaATV.pdf

[2twin350s]

Excellent buy.
The stock bore size was 68mm.
If there are no numbers,all you can do is mic it, to get the current size.

CHECK the WATERPUMP.They fall off the shaft and,the engine overheats and fries the topend.Hate to see you put a new topend on and smoke it.Waterpumps are still available from OEM.

A lot of places carry top-end kits,all for about the same price.Probably about 150 to get the piston and gaskets.ETC.

I am into the Tri-z's pretty heavily,and I have sources for many great aftermarket parts,info for swapping newer parts, V-force 3 cages etc etc.
Check out my site.There are some Tri-z parts I sell and stock Etc.
If you need anything,drop me a line.
Many times,I can beat magazine prices for parts too.
www.cosmicquads.com

[climb any hill]

Good score!!! Did you try RJATV for that top end kit?

[jsmstorm]

No I haven't yet climb I think the only place I have checked so far was rocky mountain.... I'm going to have to mic it out tonight. I don't see anything on the piston at all besides that damn W. I will check out that water pump for sure tonight also. The dude that he got it from was a pilot for the army and I guess the dumb ass put this motor in because the old one was fubar. Well he went to iraq for 6 months, came back didn't even change the gas let alone check anything else on the thing and went to glamis, and blew the skirts off the damn piston..... Is there anything besides the waterpump that I should check before we fire it up after we get that piston swapped?

[2twin350s]

Well check the trans oil,obviously.
The waterpump seals go bad and leak coolant into the bottom end.
The waterpump sucks on them.
I generally buy them new,drill a hole thru the plastic impellar and shaft,then drive a roll pin thru them.That way,they never fall off again.
You may want to have the jug and head decked while apart.
They tend to get warped and not seal at the headgasket from time to time.
While the jug is off,check the vacumm fitting at the base of the jug.Make sure it is tight in the jug.That is the vacumm line that pulses the fuel pump.They tend to get loose, and suck sand and dirt the engine and cause vacumm leaks.

They only other thing,I would say is a good idea to do, is delete the factory t-stat.
You can unbolt it,and remove the stat and run without it,or just get some fittings at the hardware store and make a t-junction.
That is located between the rads in the lower hose.You cant miss it.It is a big bulky thing,that does not need to be there.
Also the coils had a tendency to crack,and short out on the frame.May just want to check it while apart.Blaster coils work,and Warrior coils will work too.

[jsmstorm]

Yea I was wondering about that thermostat shit but wasn't sure and now I know. Thanks man I will be sure to check all that out tonight.

[jsmstorm]

Are there any other parts besides coils that will swap between other bikes and a tri-z?

[2twin350s]

Well,I have a huge list of things.I will try to cover the simple ones.

ALL these are direct bolt ons unless I state otherwise.No modding needed.

Banshee rear axles and bearings and sprocket hubs and wheel hubs all fit.Direct bolt ons.If you use the banshee or warrior rear hubs,you will have to run banshee or warrior rear rims too.The stock tri-z rear hub used a blaster bolt pattern.Banshee sprockets fit the tri-z as well as the chain,they just take different amount of links.
Warrior rear shock fits.

2004 YFZ 450 quad rear brake rotors fit with some slight enlarging of the mounting holes.
You will also have to shim the rear caliper over 3/8 of an inch to fit the YFZ 450 rotor to the rear rotor hub of the TRI-Z .
The YFZ 450 rear rotor will go directly on the front hub no problems.
87,88,89 warrior and banshee front brake pads,fit the Tri-z.

Older 300ex rear hubs will go on the rear axle,and you will gain 4 inches of width,and you can run honda rear wheels then.

83-86 yz 250 dirtbike clutches and baskets fit the Z.
Banshee thumb throttle with a 86 tri-z cable fits,and will delete the factory 85 fulcrum box ,in the 85 cable.(that was a factory recall in the day)

Banhsee front and warrior front master cylinders fit.Banshee rear master cylinder fits,but you have to transfer the lower adjustment knob that fits the tri-z brake pedal.Banshee swingarm bolt fits the Z also.
Banshee,and blaster voltage regulators fit the tri-z.

Atc 250R front fenders will fit the tri-z.

TRX 250X kickers will fit the tri-z,but you have to shave about a 1/8 inch off the kicker near the screw,so it does not scrath the clutch cover on the Z.

That is all I can think of right now,or feel like typing.There are other things,but they require some modding.
You can give me a call anytime for info.My number is on my website,I posted earlier.