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Yamaha TDR 125

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kennyv50
L Plate Warrior



Joined: 02 May 2007
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PostPosted: 21:57 - 02 May 2007    Post subject: Yamaha TDR 125 Reply with quote

Hello, love the site. Just purchased Tdr 125, with engine fault.stripped and found piston blown away and slight marks on barrel wall. Now the fun. The barrel is numbered 3mb00 (y-1) and measures 56.10, the piston measures 55.9 and is marked 1.
Trying to purchase a new piston but have been informed that 56mm is a standard piston so why is mine marked 1. The barrel also appears to be standard, but with an over size piston? Next on showing two different engine rebore centers my barrel, one states that it is chromed and one states that it is not, Hence one states no to rebore and one states yes. Also are the TZR TDR and the DT125R the same engines and Whilst Haynes state that they do not cover my bike, is there one that will give me engine details on the TDR. I know that there are loads of questions, but if anyone has the answers and the time, please help!! Ken
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element
World Chat Champion



Joined: 23 Jan 2006
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PostPosted: 17:11 - 03 May 2007    Post subject: Reply with quote

I belive tdr,dt and tzr engines are the same. only differences being reeds/carb/gear ratio's.

what year tdr is it? The engine in my DT is a 3mb too
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04' DT125RE (run-a-bout) // 89' DT125R (rebuilt + supermoto conversion)
SPARES FOR SALE. 2RK TZR // 82 DR125 // DT125R/E .... PM ME...
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kennyv50
L Plate Warrior



Joined: 02 May 2007
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PostPosted: 18:37 - 03 May 2007    Post subject: Reply with quote

thanks for reply, my tdr is a 93. Problem for me is every where I go, they quote me 56mm as being std size piston, but mine is 56mm with a 1. stamped on crown, which Im taking to mean its 1mm over size.(or could it mean piston 1 from a twin set for the tdr250 ?) I notice from the haynes manual for the engines up to 1992, that the tzr and dt engines differ slightly in bore size, then the only thing which would make sence, is if a 55mm piston was available for one of the other engines and this was a 1mm oversize for one of them but fitted to my engine?
The problem I have is no one is showing an oversize piston for my tdr. So it looks like Im looking at a new/second hand barrel and piston. Does anyone know if the haynes manual covering the dt125 up to 95 cover the 3mb00 engine?
Thanks again for ur reply Element
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MarJay
But it's British!



Joined: 15 Sep 2003
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PostPosted: 19:40 - 03 May 2007    Post subject: Reply with quote

kennyv50 wrote:
thanks for reply, my tdr is a 93. Problem for me is every where I go, they quote me 56mm as being std size piston, but mine is 56mm with a 1. stamped on crown, which Im taking to mean its 1mm over size.(or could it mean piston 1 from a twin set for the tdr250 ?) I notice from the haynes manual for the engines up to 1992, that the tzr and dt engines differ slightly in bore size, then the only thing which would make sence, is if a 55mm piston was available for one of the other engines and this was a 1mm oversize for one of them but fitted to my engine?
The problem I have is no one is showing an oversize piston for my tdr. So it looks like Im looking at a new/second hand barrel and piston. Does anyone know if the haynes manual covering the dt125 up to 95 cover the 3mb00 engine?
Thanks again for ur reply Element


I'm not 100% certain that your piston is 1mm over sized.

Now, any member is free to correct me if I'm wrong here but:

I thought when they made some two strokes they measured the barrels for tolerances and then did the same with the piston. Each type they mark with a different number. I remember someone on here asking what number piston they needed for an NSR125 and someone replied saying where they could find out the correct measurement. There were three measurements based upon a bunch of tolerances which meant you had three possible markings. Logically 1, 2 and 3! Smile

I'm fairly sure your piston isn't oversized, but the best way to find out is get the vernier calipers out and measure it!
____________________
British beauty: Triumph Street Triple R; Loony stroker: KR1S; Track fun: GSXR750 L1; Commuter Missile: GSX-S1000F
Remember kids, bikes aren't like lego. You can't easily take a part from one bike and then fit it to another.
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kennyv50
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Joined: 02 May 2007
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PostPosted: 19:51 - 03 May 2007    Post subject: Reply with quote

thanks for your interest marjay and post, I have measured the piston and 55.9mm (56) it comes up, it was the lack of a manual to confirm the correct standard size, and this number 1 , stamped on the crown which has been throwing me. I suppose if I take it that the piston is a standard size, does anyone know if oversize pistons are available, i seem to be getting conflicting advice on this.
Thanks again
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Rasmus RS50
Derestricted Danger



Joined: 08 Nov 2005
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PostPosted: 08:59 - 04 May 2007    Post subject: Reply with quote

Lots of pistonsizes are availeble, check ebay, or some of of the online shops ! As u noticed the same engine is used in the DT125R TZR125 and TDR125.
Are your model the 3SH? mine is, and there are not many of them out there. They where made by the belgrada division, and not i japan, like the later models (4GW). So they are somewhat difficult, to get tech. info on. I did manage to get the complete partlist, whit exploded drawings. Only haynes i could find, is the one covering the TD125R/TZR125.
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Rasmus
Yamaha XJ600S diversion. TDR125 for the winter.
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kennyv50
L Plate Warrior



Joined: 02 May 2007
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PostPosted: 21:06 - 20 May 2007    Post subject: Reply with quote

Thanks all for posts, armed with info i have now purchased from ebay a 56.5 piston, intended for a dt125r, not my tdr, had the local engineering firm rebore the barrel, the firm who said it could be bored; fitted back together, turned on and pressed the magic button, turned over but did not start, then drained the tank only to find a full pint of water mixed with the petrol within. flushed all throu, carb as well, and tried again, great the engine fired into life and after 30 seconds of white smoke shes ticking over fine. Thank you BCF and all. However went to drop into gear and the bike stalled with a lurch, it appears the clutch is not working, thought it might be oil or lack of, so drained the old stuff. But then the drain plug/ bolt does not look right, the head end is not flanged to take a washer to seal, indeed no washer was in place plus the threaded end is stripped, and now will not hold back in place I think some one has replaced the original bolt with another, and an incorrect one at that. Does anyone have an engine stripped and could tell me the length and tread of the correct bolt?
Also does anyone have the original hand book to sell or maybe copy, Im happy to pay for the service.
Thanks again for your help
ken
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Old Thread Alert!

There is a gap of 11 years, 62 days between these two posts...

Robert321
L Plate Warrior



Joined: 19 Jul 2018
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PostPosted: 17:21 - 19 Jul 2018    Post subject: 3mb y-1 Reply with quote

Where can i find 3mb y-1 cylinder kit?
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Old Thread Alert!

The last post was made 5 years, 254 days ago. Instead of replying here, would creating a new thread be more useful?
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