Time to change wheels and ...
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Hello ! Now I will try to explain my situation with photos ( sorry for my english )))
first, I had a problem with yamaha dt lip seals ( water pump) ( the motorcycle was stopped more than half a year) , I changed it, but after that , the next day riding my bike the rear wheel suddenly blocked. Now I disarmed the cylinder and you can see whats going on. So I cant imagine why that happens , original cylinder and piston only 10000 km. And it's almost impossible to put it wrong the water pump and seal. ( or not
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The Yamaha DT 125R cylinder is sleeved ( iron ? ) can be repaired. or go for Athena )
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Can it be the fault of the oil pump ? how to check it¿ ( the engine thermostat works well.)
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?
Usualy I buy in Wemoto.com . Thank you in advance !
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@Calum thx again! do you know how to extract the power valve from the cylinder ? ( for cleaning and modify )
@Irongamer727 Ok ! )) Do you need to readjust the oil lubrication after install the Athena kit ?
Thx a lot .
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A slight rebore shouldn't affect the powervalve
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@jens-eskildsen Yes it will.
If the bore is stock (getting rarer these days and not worth assuming) then no, you're right. But once you start going over the first rebore size, modifying the valve is a must.
To save confusing, I said modify the valve just as a precaution.
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@Calum **thanks to everyone ** . One question ( maybe a little bit stupid) XD . What material the cylinder is made of ? And the cylinder sleeve ? ( Yamaha DT 125R )
The cylinder sleeve Iron?
Cylinder Aluminium ?Have you tuned Yamaha cylinder ? ( admision / exhaust transfers etc ?)
Cheers !
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@declan No, porting is going to drastically change the characteristics of a two stroke engine.
I wouldn't advise it on a daily, or on stock ignition.
You don't get something for nothing. I'm not going into it here, but the principle is, peak almost always alters performance elsewhere, usually torque.
There are exceptions where engines are poorly designed and modifications improve performance with no effect. But the end of it is, these engines are pretty well designed. When it comes to porting them, you're making a sacrafice somewhere else in the rev range for more power.
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Hello ) !
I will go tomorrow to the workshop with the cylinder for bore. I know is privileged information and long testing time but do you know where I can find information about tuning cylinder transfers, I think is good idea do something there before it will be bored. Maybe in the same workshop they do that for extra €, will ask.all this marked with color dots can be modified/enlarged : ?
at the top of ALL the transfers: (?)
so, thank you again for the help, and gas gas !
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Depending on how good your English reading is, I HIGHLY recommend Graham Bell's Two Stroke Performance Tuning.
That will give you a lot of knowledge on tuning two strokes.
I would NOT recommend porting the barrel, or altering the port timings, without a programmable CDI.
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@calum said in Time to change wheels and ...:
Graham Bell's Two Stroke Performance Tuning
Thanks for the tip Calum . also I have dowloaded the Two-Stroke TUNER'S HANDBOOK By Gordon Jennings. Time to read.
( http://www.2strokeengine.net/gordonjennings/twostroketunershandbook.php )so, for now I'm going to polish a little bit where it is needed , also the power valve , because it is very dirty.
Mitaka pistons are good ? where you can buy original Yamaha DT R parts online ( like water pump complete repair kit) ? <--- have find this official site : http://www.recambios-yamaha.com/es/dt125r/2002/bomba-de-agua.htmlThank you very much everyone, your answers are very useful.
