engine piston check
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Like I said, the cost difference between a rebore and a hone is not worth pinching pennies over! A heat seizure has smeared the two metals together…
Also not all motorcycle engineers are the same. I’ve seen some shocking shit done by firms. If you are in the UK go to PJME for the work, not a ‘mom & pops’ corner place. The piston should of been matched to the rebore, without any movement or ‘ticking’. I’ve had places give me the same kind of fit. I only go with known, reputable places now…New gaskets every time!…
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Oh dear, you should not be reusing the head gasket, or any gasket really.
Sounds like to me, the head gasket has not sealed, it has drank all the coolant and the engine has heat seized. That bore looks pretty scuffed and at minimum is going to want a hone, but as @SpookDog says, looking more likely like a rebore.
Did you not have the temperature sender fitted when you were riding it? That should have gone into the head. Go into the radiator and stick your fingers into the top, I'd expect that to be full of two stroke oil by now so should be all slippery. Either way, you're going to need to flush the cooling system with some cleaning agent to remove all the two stroke residue, else the cooling system won't operate effectively, I'd imagine it's warmer where you are and therefore having efficient cooling is even more important.
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@erion1 Hmmm. something is not right there, definitely looks like a heat seizure to me, you see how it's scuffed on both sides, this indicates the piston expanded more than the cylinder walls. This can be down to one of two things, insufficient cooling, or too much load on the engine before it was up to temperature.
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Bud! I’m guessing that the ‘scratch marks’ are spaced around the piston in 4 places?
This is because you reused a head gasket (worst 15 £-€ you never spent!) It’s called a 4 point heat seizure. If you look up inside of the piston, the inside of the crown will be black and scorched from the heat seizure. Whether you saw it on the temp gauge or not; it overheated…Other thing is the piston shouldn’t ‘click’ back and forwards if it’s the right size. Neither should you have that amount of blow by past the rings! I think that the person who did your rebore may of done you wrong…
I’ve used old bits to keep me on the road, but never as an end plan! Even then I rode it like a grandad, never above 5-6K max, never like a ‘yoof’…
What country are you in? Somebody might be able to recommend a good motorcycle engineer to help you move forwards…
You’re going to have to put in a proper fitting piston. Why quibble about a rebore?…
If you want to ride and enjoy your bike to the max. Just fix it please!… -
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@erion1 These? I didn't know there was such a brand TBH, just looked them up and the website looks good. Encouraging they're available in .25mm increments as you get potentially twice as many rebore sizes:
Interesting they also offer a different piston kit for the '94 to '04 DTR; both kits start at 56mm (so not sure if the 1st link refers to the '88 3DB DTR as these and the original 2RH TZR125 had a 56.4mm bore as standard) but other dimensions are slightly different so there must have been changes during the '89 onwards DTR production run. Can anyone shed any light on this? Comparing the two webpages seems to indicate .5mm difference from the top of the gudgeon pin hole to the piston crown:
I always ran Mitaka and was happy with them (as long as you get the Japanese ones) but they only seem to be available in .5mm increments now.
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@HOTSHOT-III i don't think i can find mitaka piston in my country for this so i think ill go with meteor as many dt riders in my country gave good reviews about them,
btw the gudgeon pin is not coming out what could lead to that? it gets stuck as soon as it comes to the groves of the securing locks -
@erion1 When you have a heat seizure, like the one you've experienced, you've caused undue stress to the piston gudgeon holes and ovalised it. You'll probably need a tool to extract it now.
I don't think you quite understand the severity of what happened...
Worked a treat for me and was no way I was getting my gudgeon wrist pin out without it.
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@HOTSHOT-III i found a piston that i can get my hands on easy
its called TKRJ they seem to be made in jappan but it lloks to be cheap so not sure if its very good -
I think it’s caused by an Ill fitting piston ‘slapping’ around. It enlarges the hole where the pin is sitting, but creates a lip at the edges. That’s been my experience anyways
…Get a small flathead screwdriver and scrape around the hole where the clip sits. Or use wet and dry sandpaper. It’s not like you’re gonna use the piston again!
I kinda remember Meteor pistons from my past Lambretta and Vespa days. They were good I think…WHERE THE FUX YOU LIVE BUD?!
Italy?…
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@SpookDog no i live in kosovo but there are shops that have dt parts so it takes 1-2 days to get a piston, but if i want to order from mitaka or somewhere else it could take up to months, thats why im trying to see if any of u used them or have any experiences with meteor or anything as i have easy acces to them
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@HOTSHOT-III not sure about the year its a 4bl model 3mb head and 3mb00 cylinder
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@erion1 You can find out the year of the bike using Yamaha France Parts Lookup as long as the frame has a VIN Number. They seem to have information on any Yamaha product sold in Europe, I've looked up UK bikes on there before:
https://www.yamaha-motor.eu/fr/fr/service-support/parts-catalogue/
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Fux! I don’t know what to recommend. I forget sometimes how spoilt we are ‘in the west’. I’d go with the meteor piston if I was you. I wouldn’t go back to the same place that did your last rebore though, if I could find somewhere else. Get them to measure the bore, then supply the piston that fits the rebore that they do. There should be no noticeable movement in the barrel…
If you just want to get mobile again desperately, get a decent NEW head and base gasket. Lap the top of the barrel and head with wet and dry sandpaper on a sheet of plate glass…
I’ve done worse, just don’t cane the beast…Wish I could help you more…
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@HOTSHOT-III i don have a vin it only has a fin someone told me it would be easy with a vin
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