85 tri-z engine troubles, 2T experts needed for comment please!

[dma550]

hey guys

Our 85 tri-z is giving us troubles. It was part of a shady trade deal, we traded a 350x for it. X was in much better shape, and this owner was not truthful about the Z. Oh well, I'm putting that behind me and going through it. So far we've done the carrier, front wheel bearings, forks, fixed a split in the case and are working on exhaust.

For the most part the engine was a good runner - it does load up but can be pretty crisp and feels like most of it's horses are still available. It does smoke A LOT, I mean a lot for a 2T. My son and I have KTM XCW woods bikes and its profound how much it smokes. All blue smoke, and spooge, and I suspect Jetting is way off, or jets are clogged.

So here's the new thing: My son ran it hard on a hot day, and it started puking oily water out of the thermostat. It dumped all over the cylinder, see pic. It was a gray gooey mess, didn't look like coolant, but when the water dispersed a jelly like oil was left behind. Could be clutch oil I guess. We drained the coolant and there wasn't much left, but it was not contaminated, it was definitely old 50/50 mix. We replaced the coolant and ran it hard again. Now, there is a bogging at mid-high range which seems unrelated, but does look like a fuel starvation problem.

So, I guess it's time to take the carb off and ID the jets, and make sure the floats aren't sticking. I also think popping the head off to see if the head gasket is ok is good too. Anyone suspect the water pump/water pump seal or Tstat?

I'd love to hear from someone for next steps. We have about 4 hours riding it and about 30 working on it so far!

233930

[newby200x]

Have you rebuilt the waterpump yet? The seal is notorious for leaking.

[DohcBikes]

Water pump seal is bad, allowing gear oil to mix with the coolant.

Hopefully YTZdrew, El Camexican, Mosh, or another Tri-Z guru happens along shortly with details.

[dma550]

Thanks guys - yeah I did suspect that seal. The gear oil is slightly gray vs. the caramel color it went in as. We didn't know if it was clutch material or coolant. Do you guys know if the there is a better impeller for this? I remember reading someone sold a billet one, or maybe it's one from a Banshee or other engine.

[newby200x]

I've heard of billet impellers, but have not personally seen or used them. I've seen a few posts about pinning the factory impeller to the shaft. Just drill a hole through the impeller and shaft and put a roll pin in. The shaft is very hard though, you will need a bit suitable for hardened steel. The seal is not hard to change.

[jonolanracin]

While you are replacingseal just buy a new oem impleller they are about 45 on boats.net and its well worth it to replace it at same time as seal and i would go on and replace the right side crank seal while you got clutch cover off its only 12 dol and simlpr to change that could be your excess smoking problem

[yaegerb]

hey guys

Our 85 tri-z is giving us troubles. It was part of a shady trade deal, we traded a 350x for it. X was in much better shape, and this owner was not truthful about the Z. Oh well, I'm putting that behind me and going through it. So far we've done the carrier, front wheel bearings, forks, fixed a split in the case and are working on exhaust.

For the most part the engine was a good runner - it does load up but can be pretty crisp and feels like most of it's horses are still available. It does smoke A LOT, I mean a lot for a 2T. My son and I have KTM XCW woods bikes and its profound how much it smokes. All blue smoke, and spooge, and I suspect Jetting is way off, or jets are clogged.

So here's the new thing: My son ran it hard on a hot day, and it started puking oily water out of the thermostat. It dumped all over the cylinder, see pic. It was a gray gooey mess, didn't look like coolant, but when the water dispersed a jelly like oil was left behind. Could be clutch oil I guess. We drained the coolant and there wasn't much left, but it was not contaminated, it was definitely old 50/50 mix. We replaced the coolant and ran it hard again. Now, there is a bogging at mid-high range which seems unrelated, but does look like a fuel starvation problem.

So, I guess it's time to take the carb off and ID the jets, and make sure the floats aren't sticking. I also think popping the head off to see if the head gasket is ok is good too. Anyone suspect the water pump/water pump seal or Tstat?

I'd love to hear from someone for next steps. We have about 4 hours riding it and about 30 working on it so far!

233930

water pump seal is going out, and I would be willing to also bet your clutch side crank seal is out. I would pressure test the motor.

[RIDE-RED 250r]

When oil mixes with coolant and is heated and agitated by the normal operation if the cooling system, what comes out will not look quite like oil or coolant. By what you are describing, you most certainly have trans oil mixing with the coolant...

All of the previous posts contain sound advice, I recommend following it. :)

[sledcrazyinCT]

I see a recommendation for a new impellor. Here is a billet aluminum one

Here is a link to ones for sale on EBAY http://www.ebay.com/itm/1983-1987-Yamaha-YZ250-Billet-Water-Pump-Kit-Waterpump-Impeller-Shaft-w-ARS-Seal-/232042674710?vxp=mtr


I bought one the other week and hope it will be a big improvement for reliability when I get my Z project together

[jonolanracin]

Im sure the billet impellers are fine but the one in our race bike is a 30 year old oem that still works fine so i just see no sense in spendind triple for a billet when a oem will last atleast 30 years lol

[Queef Chief]

While you are replacingseal just buy a new oem impleller they are about 45 on boats.net and its well worth it to replace it at same time as seal and i would go on and replace the right side crank seal while you got clutch cover off its only 12 dol and simlpr to change that could be your excess smoking problem

Every single time I've had a Tri-Z issue, Darren has been spot-on with his diagnosis.
Definitely one of the gurus on this site.


Sent from my iPhone using Tapatalk

[sledcrazyinCT]

Im sure the billet impellers are fine but the one in our race bike is a 30 year old oem that still works fine so i just see no sense in spendind triple for a billet when a oem will last atleast 30 years lol

Considering the cost to rebuild an engine another $80 to upgrade over plastic impeller is cheap insurance. I have also read too many horror stories of engine failure from water pumps on these trikes. Pretty common occurrence of these plastic water pump impellers failing resulting in ruined motors if you use the search feature on 3ww.

[dma550]

You guys are the best, thank you for the quick reply. I ordered up the parts, and for the first time ever every part I needed was in stock and has shipped. This was probably the one shot at winning a jackpot I'll get this lifetime, I probably wasted it on parts! Thanks again.

[RubberSalt]

I've had 1 situation where it wasn't the water pump seal that caused the problem. Head gasket was blown. The pressure pushed passed the seal and mixed coolant/oil. That sucked. I ended up pulling the coolant hose off, sticking balloons on the head where the hose hooks up and another on the pump. Doing a leak down made them fill with air.

Both gasket and pump seal got replaced.

[YTZ drew]

All sound information above. As for the durability of the stock Tri-Z pump impeller, I can only comment with my own experience. When I got my Tri-Z, the previous owner told me he rebuilt the top and and melted it down about an hour later, then never rode it again. When I tore it down, the plastic impeller was just sitting inside the water pump housing, detached from the shaft. Nothing really holds it on there, the shaft is just knurled inside the molded plastic. I'm usually quite happy with OEM parts, but a billet impeller sounds like like a good investment to me. Kind of like buying quality tires, brakes, and lunchmeat. Like the Boar's Head guy says, compromise elsewhere.

[jonolanracin]

I am deffinatly not saying the billet is not a great part but if you temp light operates like it should theres no reason to burn up an engine from water pump failure when my temp light comes on i stop before any damage . anytime i build a new tri z engine that ive never been into it gets all new seala and a oem impeller so ive never had any problems with oem

[RubberSalt]

I suppose a cheap alternative would be to drill a hole in the impeller and shaft so it can be pinned.

Tossing ideas out there.

[YTZ drew]

I am deffinatly not saying the billet is not a great part but if you temp light operates like it should theres no reason to burn up an engine from water pump failure when my temp light comes on i stop before any damage . anytime i build a new tri z engine that ive never been into it gets all new seala and a oem impeller so ive never had any problems with oem

I truly believe that the oem impeller is capable of delivering 30 years of trouble free service. I'm just a scaredy cat about certain things, and I honestly don't know which way I'm going to go when I build my Z. I'm still in the parts gathering stage, and on a budget to boot, do the oem price is much more attractive. What to do, what to do........