OzVMX Forum

Marque Remarks => Yamaha => Topic started by: Freakshow on February 09, 2010, 10:56:04 pm

Title: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 09, 2010, 10:56:04 pm

Need to put some donks together, but when i put the pins back in on weekend both seemed wider than what i wrote down, any shorter and they bind a wee bit. 

Wont take the chance, so ill run in with feeler any idea those who have books ? are they 40 thou a side ? ( and is that 1mm in real talk ? )

cheers

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: jimg1au on February 09, 2010, 11:01:13 pm

1mm = 0.03937007874in
dont you own a few manuals to check end play
cheers
jim
ps
i am still at work so i cant help you

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 10, 2010, 12:26:17 pm

so a mm is 40 thou  then, but is that the clearance.  And no i got PArt manuals and all the YZ service manuals from about 77-78.  I did have it on a yamaha chart with all the model for 74 but you reckon i can find it .....

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: ji107 on February 10, 2010, 04:27:10 pm

Axial play should be 0.4 to 0.5mm.
0,6 mm is limit

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 10, 2010, 05:19:31 pm

John, is that from the small end ?  i was just told it was 10 thou a side, so thats a bit differant to that. 

Whos actually got a book they can scan up ?

John, Did you end up using a gen big end bearing or do you have another code for an INA ?  Im taking one down to SKF this week to see if they can get some in.   

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Stan S on February 10, 2010, 05:59:57 pm

Hi, Didn't you measure the width of the wheels before you split the crank?
I don't have a manual to scan for you but I have found that most of the old Yamaha cranks that I have rebuilt over the years end up with a conrod side clearance of between 14 to 18 thou.

Stan

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: ji107 on February 10, 2010, 06:16:03 pm

From a DT2 manual, use a feeler gauge down beside the big end.

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 11, 2010, 03:20:31 pm

YEp i measured the web and it was 55.76, ( but i reckon all yams end in a 00) any how if i put it back to  that 55.76 its too tight

IF i get it down to 10 tho a side it looks a little tight to me for the oil.

IM doing the 125 ATM, but the 250 is next on the table (So while im on the hunt  i need the specs for the DT1 non reed if ther eis a differance)

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Stan S on February 11, 2010, 04:16:27 pm

Are you sure the main bearings are pressed all the way home?

Stan

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: ji107 on February 11, 2010, 05:04:22 pm

10thou either side of rod is right (total 20 thou - 0.5mm).
Dt1 and 2 are the same.  That measurement is pretty right for most early model 2stroke singles

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 12, 2010, 12:44:35 am

THe main bearings are on the outside, im measureing web to web, and inside em.  Dropped off to Ian to suss it out, rod  might be wider than normal or just needs a better truer, he measured it int he firstplace so he can figure it out, gave him 20 thou to play with, he figure it out i hope.

cheers guys

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Stan S on February 12, 2010, 08:12:46 am

I meant pressed all the way home in the cases. If there not the measurement between the bearings will be too small.

Stan.

Title: Re: Crank shaft gaps on the YZ250A and the YZ125A ( be same as DT1 - mx125)
Post by: Freakshow on February 12, 2010, 03:20:45 pm

I dont have the cases here, there at victor,  the measuement was done web to web no bearing fitted.
I was going to check them to see if they float back in there cases and face meet but in the end a guy here at work has managed to jig it back to square and it seems to have come into spec. 

Reminds me of a bloody rubicks cube,  you turn one side and the other moves, then you got the in out as well like a Gyro, any hooow seems he got the twistout and spins within a thou so thats close enough for me. its now back to 55.70 so  ill see if that fits in the case ok.

cheers Guys.