DT125R ARCHIVE

Members Login
Username 
 
Password 
    Remember Me  
Post Info TOPIC: Maximum bore


DTR Respected Member

Status: Offline
Posts: 69
Date:
Maximum bore
Permalink  
 


What is the maximum bore size for the 3mb cylinder?I see that the biggest piston i found is+1.50mm.On the other hand for the 3bn is 58.40.Is there any difference in the pistons? Can i use the 58.40 piston to the 3mb cylinder?



__________________


Guru

Status: Offline
Posts: 2165
Date:
Permalink  
 

i think 2mm is the maximum over size u can go m8y not 100% tho

 

the piston in my original barrel from my bike wen i brought it was 1.75 OS so i think it had one more rebore left in it especially as the liner was starting to get a bit thin compared to the other spare barrels i have 



 



__________________

             

 



Guru

Status: Offline
Posts: 535
Date:
Permalink  
 

2.5mm im 99%, anyone?

__________________

untitled2.jpg



DTR Senior Member

Status: Offline
Posts: 360
Date:
Permalink  
 

Sorry, gotta go with Bradder's on this one. was sure you could only go 2mm os.

__________________

1990 DT125R Sm'd

Piccys - http://dt125r.activeboard.com/t40415921/1990-dt125r-sm/

1989 DT125R (offroad)

Piccys - http://dt125r.activeboard.com/t43040164/89-dtr-into-a-true-offroad-bike/



DTR Legend

Status: Offline
Posts: 3132
Date:
Permalink  
 

just found out mine has had a +1 so i looking into it and the biggest piston i found was a +2 the ones i found was +0.25 +0.50 +0.75 +1 +1.5 +2 there the ones i found

__________________
Dont Blame The Player Blame The Game


Guru

Status: Offline
Posts: 535
Date:
Permalink  
 

Sure people on here in the past have been on there 5th .5mm overbore, and one person went over that and there powervalve smashed the piston iirc.

__________________

untitled2.jpg



Nonce

Status: Offline
Posts: 519
Date:
Permalink  
 

i sold a dt with a 59mm piston im sure lol also wossner make up to a 61mm piston i think for the dt


__________________


Guru

Status: Offline
Posts: 535
Date:
Permalink  
 

Yeah noticed that with wossner, robin what you think of those wossner pistons, found one for £77 from TNT racing, im pretty much stuck on getting one now, you know if they're any good?

__________________

untitled2.jpg



DTR Respected Member

Status: Offline
Posts: 54
Date:
Permalink  
 

59mm is pretty much the limit using a powervalve as the amount you need to grind off the valve bobbin to clear the piston leaves hardly any metal left for the powervalve centre locating pins to go into, without a powervalve on a standard barrel you can resleeve and go very big bore, the wossner pistons look pretty good, i'm pretty sure the piston with the athena kit is wossner unbranded for the kit.



__________________
how do you make gifs
1988 DT125R


Guru

Status: Offline
Posts: 1053
Date:
Permalink  
 

iv got a 59mm m8 in one off mine an a standard in the other sure iv seen +2.40 floating around on ebay though

__________________
NEV


Guru

Status: Offline
Posts: 2515
Date:
Permalink  
 

This will give you an idea on the sizes you can go oversize,



I went for the 4mm O/S

__________________

 



Guru

Status: Offline
Posts: 668
Date:
Permalink  
 

ive just had a 2.5

__________________

getting there .....



DTR Senior Member

Status: Offline
Posts: 372
Date:
Permalink  
 

2.5

__________________

1999 Honda Hornet 600 - Current

1998 Yamaha DT 125 R - SOLD



DTR Respected Member

Status: Offline
Posts: 42
Date:
Permalink  
 

Hello there. Been thinking about getting a wossner 61mm piston to get the bike up to 148cc maybe do abit of porting to it aswell. Did you notice an increase in torque with the 60mm piston NEV? (by the way love the tzr hybrid build thread going well :)) The 60mm piston would make her 144cc i believe, im after abit more midrange you see as iv got a pinned valve and shes abit lacking untill it gets on the pipe.

__________________
Meadows
NEV


Guru

Status: Offline
Posts: 2515
Date:
Permalink  
 

If you are ok with pinning the powervalve full time, then yes go for the 61mm piston, but remember you also need to reline the barrel, as there wont be enough meat left on a conventional barrel liner.
As for torque aye deffo feels very torquey

__________________

 



DTR Respected Member

Status: Offline
Posts: 42
Date:
Permalink  
 

Exellentay :) Yea il be running a pinned powervalve all the time, dammit was hoping to get away with it not being relined :( oh well that will add abit of cost. Where did you get your barrel relined and bored out? PJME? and how much did it cost you if you dont mind me asking. Ta Sam

__________________
Meadows
NEV


Guru

Status: Offline
Posts: 2515
Date:
Permalink  
 

I had mine done by a local Newton Abbot bloke I always use called Brian Loram, who sent it off to an engineering firm he uses, as he hasn't got a press, he did all the stage 3 porting on it though, to just have the barrel relined and bored out cost £150.

__________________

 

NEV


Guru

Status: Offline
Posts: 2515
Date:
Permalink  
 

Oh and you also have to have the cylinder head machined out, so as to take the oversized piston, that was in with the £150 overall cost, plus the head gasket needs reaming out too.



-- Edited by NEV on Wednesday 29th of January 2014 12:25:50 PM

__________________

 



DTR Respected Member

Status: Offline
Posts: 42
Date:
Permalink  
 

well im thinking about machining the head and gasket myself at work but id need to send the bore away for relining ect. £150 eh thats not too bad you sure theres no way you could get away with using the standard liner? havent got a bore to hand yet (its in the post) would it deffinately be too thin or did you get yours relined for peace of mind? how much does he charge for porting then? id only be after the stage 1 want to do it myself really but probly better giving it to a professional if im spending £150 on a rebore

__________________
Meadows
NEV


Guru

Status: Offline
Posts: 2515
Date:
Permalink  
 

Nah you deffo need a bigger O/D on the liner to bore it out to that size, you'll see what I mean when you have your original barrel to hand.

__________________

 



DTR Respected Member

Status: Offline
Posts: 42
Date:
Permalink  
 

Okie dokie cheers for the help NEV


__________________
Meadows
Page 1 of 1  sorted by
 
Quick Reply

Please log in to post quick replies.

Tweet this page Post to Digg Post to Del.icio.us


Create your own FREE Forum
Report Abuse
Powered by ActiveBoard