Tri-z leaking coolant.

[HarrisoN*]

just replaced the head gasket on my tri-z after removing it to check the jug, the old gasket was fine.

i refitted it and torqued it to yamaha manual and the right order but now i have coolant slowly weeping from the headgasket and the gearbox is filling with coolant when running.

im going to replace the waterpump seal but whats up with the headgasket? any ideas or similar experiences?

[zzmegad]

your not supposed to reuse them. The surfaces of the head and jug might not be perfectly flat also contributing to your leak. I personally have had the best luck with cometic gaskets and a quick spray of the permatex copper gasket sealer.

[barnett468]

Hello



Yeah, what zzmegad said.



SURFACE HEAD - I suggest you surface your head awhile it is off. Take a full sheet of 6oo wet dry paper, lay it on a granite counter top, clean head and mark sealing surface with felt pen, put water on paper, put head on paper and with moderate pressure turn 3 times then inspect. If anymarker remains sand until gone. It might require 400 grit if it’s warped badly.


Original gaskets.

$32.00

http://www.ebay.com/itm/OEM-YAMAHA-YTZ250-HEAD-GASKET-38w-11181-00-00-/330442187301

$35.00

http://www.partzilla.com/parts/detail/yamaha/YP-38W-11181-00-00.html

$72.80

http://www.cmsnl.com/yamaha-ytz250n-1985_model9122/gasketcylinder-head-1_38w1118100/

[barnett468]

Post correction


"anymarker" should be "any marker"


I have no edit button

[HarrisoN*]

aha i used a new gasket and cleaned it up, it was great, then i filled it with coolant and it slowly had a weep around the head. then started the bike and filled the gear box with water.

[barnett468]

Hello


Ok, thanks for the info.

Did you use a new original gasket or an aftermarket one.

Your head and/or cylinder may be slightly warped any so since it has to come back off surface head as I mentioned. Install a real Yamaha gasket ond you should be fine. Add sealer if you want.

[HarrisoN*]

i used a aftermarket one as thats all thats available here in the uk, genuine yamaha ones are available but are very expensive.

ive removed the clutch cover to change the waterpump, il then run it and see, then change the headgasket however it has stopped leaking, maybe the heat has sealed.

[barnett468]

Hello




i used a aftermarket one as thats all thats available here in the uk,

The companies I listed ship.





genuine yamaha ones are available but are very expensive.

Yes, but there comes a time when buying critical parts that only OEM is a must. Your bike was not made in China I personally wouldn't buy Chinese parts for it.





ive removed the clutch cover to change the waterpump, il then run it and see, then change the headgasket however it has stopped leaking, maybe the heat has sealed.

I doubt it. Check the head surface.

[HarrisoN*]

I know they ship but its close to $60 with shipping, the gasket i used wasnt a cheap chinese one it was a mitaka japenese one, a very respected company in the uk and many motocross shops use these gaskets. like i said its stopped leaking from the head, il replace the waterpump and check again afterits run, the headgasket wouldnt leak into the gearbox anyway and if it over pressurised it would vent rather than passing the water pump seal.

if that doesnt work i will remove the head, get it skimmend look for a oem gasket.

[barnett468]

Hello HarrisoN




I know they ship but its close to $60 with shipping, the gasket i used wasnt a cheap chinese one it was a mitaka japenese one, a very respected company in the uk and many motocross shops use these gaskets.

Sorry my friend I have bad news for you. Read the info below direct from Mitaka’s site.

Their rod kits are made 100% in Taiwan and then they have the BALLS to put them in a package with JAPANESE WRITING ON IT hoping the buyer doesn’t see the facts on their site so they believe it came from Japan, just like you believe your head gasket did. :wondering

Mitaka are now offering Taiwanese Motocross Connecting Rod Kits at Taiwanese prices.

http://www.mitaka.co.uk/CATALOGUE/MITAKA%20RODS.htm

They also can't form a proper sentence, "Mitaka are" should read "Mitaka is" plus they are not offering their parts at "Taiwanese prices" simply because they go through a wholesaler and the retailer must make a profit in the UK.






Their pistons are also ALL cast in TAIWAN. The 2 stroke ones are also machined there. 100% mfg’d in TAIWAN not JAPAN.

Mitaka Pistons

But what about the quality, where are the pistons made and does it matter, you ask ? Well yes and no. Piston manufacturing technology has not really changed in the last 30 years. It is well understood and good quality pistons can be produced anywhere in the world. Our 2 stroke pistons are cast and machined in Taiwan, whilst our 4 stroke pistons are forged in Taiwan and machined in Japan. The fact of the matter is that if you do not have a large Taiwanese content in the manufacturing process, the cost is simply going to be disproportionately high. Don’t forget that the (skilled) labour cost in Taiwan is £100 per week. The same machine tools are used whether they are used by $1,000 a week U.S. workers or €700 a week Italian workers. If the product is made in China, you should be paying a lot less for it. If you are not, then someone is making a lot of money out of you !

http://www.mitaka.co.uk/

The piston text above was most likely written by an English person as evidenced by the use of the word "whilst".






It is virtually impossible for Mitaka to have a complete head gasket set made in Japan and be able to sell it for around 15 GBP’s. I just doesn’t work that way. See link below.

http://www.ebay.com.au/itm/Top-End-Gasket-Set-Yamaha-YZ250-YZ-250-1983-1985-TRI-Z-Mitaka-/230977657059







like i said its stopped leaking from the head, il replace the waterpump and check again after its run, the head gasket wouldn't leak into the gearbox anyway and if it over pressurised it would vent rather than passing the water pump seal.

Hopefully it doesn’t leak into your cylinder so you don’t know it’s leaking and possibly damage your engine.







if that doesnt work i will remove the head, get it skimmend look for a oem gasket.

I would do my surface test first to be sure whether it’s warped or not.





From what I have seen so far it looks to me like Mitaka is a UK based company using a Japanese name in an attempt to get people to believe they are a Japanese based company or distributor or subsidiary of one selling Japanese parts. This is similar to what VESRAH does.

Just trying to help keep you from possibly being deceived.

Now how much are 2 of their head gaskets going to cost you?

[HarrisoN*]

ahh well i have never looked into a the brand just that whenever you order gaskets from your local MX/dirtbike shop they usually supply mitaka. you cant singly buy gaskets so I ahave to buy two sets, £15 each x, £30. around $25USD.

i have spare base gaskets so il pull the jug with head still bolted and then inspect the water jacket of the bore and the head, i can fill the jug with paraffin and see if it leaks over night into the waterway, if the gasket is wrong il bite the bullet and either order a oem one from the USA or find a UK supplier. but the clutch cover casing gasket is £12/$10(you can get a entire pattern gasket set for £17) so hate to think how much a headgasket will be...

[barnett468]

Hello HarrisonN




ahh well i have never looked into a the brand just that whenever you order gaskets from your local MX/dirtbike shop they usually supply mitaka.

I have learned to research any non name brand parts.






you cant singly buy gaskets so I have to buy two sets, £15 each x, £30. around $25USD. hate to think how much a headgasket will be...

Your two gasket sets actually cost 44.82 USD. I listed the price for the originals in my post 3. $32.00 USD plus shipping of maybe 10.00. If you do need a second one you would have saved $2.00 USD and a lot of work by buying original.

15.00 GBP = 22.4113 USD
British Pound ↔ US Dollar
1 GBP = 1.49409 USD 1 USD = 0.669305 GBP






i have spare base gaskets so il pull the jug with head still bolted and then inspect the water jacket of the bore and the head, i can fill the jug with paraffin and see if it leaks over night into the waterway,

Problem is, it has already leaked so when the engine gets hot and has pressure in the cooling system who knows what will happen.

Put a straight edge along the cases where the base gasket goes. Case may be warped.






if the gasket is wrong il bite the bullet and either order a oem one from the USA or find a UK supplier.

I posted the link to 3 suppliers, there is no supplier in the UK.






but the clutch cover casing gasket is £12/$10(you can get a entire pattern gasket set for £17)


The Chinese one you have should work, just seal it with Yamabond.

You are using the wrong formula for conversion, see calculator in link below.

12.00 GBP = 17.9247 USD
British Pound ↔ US Dollar
1 GBP = 1.49373 USD 1 USD = 0.669467 GBP


CURRENCY CONVERTOR

http://www.xe.com/currencyconverter/convert/?Amount=12&From=GBP&To=USD