Tzr, piston, wemoto

Rikstation · L Plate Warrior Joined: 29 Jun 2005 Karma :

i recently purchased a piston kit for a yam TZR 125R from wemoto (https://shop.wemoto.com/index.dyn?oid=5834005)
it was slightly slimmer than the one I’ve replaced and flatter on top.
i get no luck when trying to start the bike and there is no compression coming from the exhaust. is this because of the piston?
i think it is, but i would like a second opinion.
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Yam TZR 125R

Klause · World Chat Champion Joined: 25 Apr 2004 Karma :

You did put the piston ring on the piston didn't you? Laughing

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Current bikes: 1960 Triumph 5ta x2, TTR600RE, KTM200EXC, Cagiva Elephant 900ie.

Rikstation · L Plate Warrior Joined: 29 Jun 2005 Karma :

yeah i didnt forget that, if you look at the pics your see my two pistons differ in shape. i can only think this is the problam. would there be anything else that would stop the the compression.
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Yam TZR 125R

cagiva gezzer · World Chat Champion Joined: 17 Mar 2003 Karma :

If the original piston isn't damaged, then you've got two very different pistons.
If your engine is (part) piston ported you're going to get a very reduced intake cycle which WILL mess with the running of the engine.

btw - bore looks shagged.
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"because one stroke isnt enough and four strokes waste two"

Rikstation · L Plate Warrior Joined: 29 Jun 2005 Karma :

yeah the original one (the one laying on the floor is damaged, thats why i got a new one.
an although the air intake may be reduced, i should still have atleast some outake right?but i have none.
i have taken my bore to a garage and i should have a new genuine piston tomoz. the guy there said it was shagged aswell, but it should still start as it is though, right?
if not let me know so i can get it sorted before i fit the piston.
cheers
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Yam TZR 125R

simon1221 · World Chat Champion Joined: 28 Jul 2004 Karma :

I just got a piston kit from wemoto, even though it is for the older tzr it all works fine, so they aint all crap.

Are you sure you dont have an import or something that would mean they differ in size?

That is one rusty conrod, and you should have oiled the rings before you put them in also.

Is the tzrr engine is different from the tzr engine?
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DNA50 (sorry) ->> TZR125l >> GPZ500S

simon1221 · World Chat Champion Joined: 28 Jul 2004 Karma :

Have you exhausted all methods of starting the engine, as the spark plug will get pretty oily the first few attempts?
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DNA50 (sorry) ->> TZR125l >> GPZ500S

Rikstation · L Plate Warrior Joined: 29 Jun 2005 Karma :

I think the tzrr starts from 94 mine is a 96. I once ordered gaskets they wouldn’t fit, they only worked on models up to 93. so the engine must be different. The bike is an import, I assumed they all were from 94. if this is true the piston would have to be the right one. I have had a look at the spark a few times. That did not seem to be a problem.
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Yam TZR 125R