DT175mx different crank lengths ! update.

[Wessie34]

I have 2 x 2k4 engines, the  crank in the one in the bike has been shortened to fit ( clutch side casing ) the other one looks right! But, the one in the bike doesn't  have room for a spring washer! Any advice / knowledge welcome,

Edited September 2, 2015 by Wessie34

[Cynic]

Shortened to fit what exactly?

You gain nothing, sure its not been mangled by somebody trying to get the primary pinion nut off?

[Wessie34]

Hi Cynic, so that the side casing goes on ! The primary drive pinion (gear) has been fitted, then the nut, no washer! Then ground down a bit! It's definitely been ground because the grind marks line up on the nut and crank end perfectly. There are also spinning marks inside the casing where the crank end touches.

 I don't want to put it back together without a spring washer, maybe thread lock might be enough but I'm confused about the crank length, just doesn't make sense. Dave 

[Cynic]

Sure its not a different crank, cranks are not made oversize and cut down, it will have been cast the same as thousands of others and then machined to micro tolerances.

Being a bit long just wont happen. Is the spacer the correct length?

I don't think I would be happy fitting it myself, there is no real shortage out there. Get another.

[Wessie34]

Well that's definitely answered my question ! They should be the same length ! It doesn't appear to be an earlier crank cos they seem to have slotted / keyed primary gear.  I don't think it's a spacer issue cos the primary drive gears are different designs too, one of them is recessed ! If you ignore the threaded bit , where the woodruff key fits, that bit protrudes further, maybe it's not fully in the flywheel, ah, now if that's possible then I'll have to strip it, bugger ! The crank is already installed as I only removed the clutch cover to blank off the oil pump but now if I can't be sure it will be safe, hey ho,  thanks for the help.

[blackhat250]

I bet hes put the pinion gear on wrong way round,  . its can be done, sits farther out, .  the correct way is recessed so nut is inside the pinion gear ,  will try and find picky ,

Edited August 6, 2015 by blackhat250

[blackhat250]

Now look at this, pinion on wrong way, note  nut on end of crank,[ way out ]

 

Edited August 6, 2015 by blackhat250

[Wessie34]

Thanks for the photos Blackhat, mine was assembled correctly but because the crank bit that the pinion sits on ( slides over) is longer someone has fitted a 5mm spacer so that it tightens, then ground down so that the clutch cover fits!

I'm guessing whoever rebuilt the crank didn't press this end in far enough! Is this even possible ? I wanted it on the road but looks like I'll have to strip the spare and check if that one is fit to use or have it re-conditioned, I just daren't run it as is cos if the nut lets go the damage will be sickening ! Thanks again, Dave

[blackhat250]

I think some engines,  have a shim on one side of crank,  [ centres the crank in cases]  my dt 400 engine didn't, nor the 250,  But I"v heard it  somewhere,

Edited August 7, 2015 by blackhat250

[Wessie34]

I hear what you say but ( sorry if that sounds dismissive ) it's about 7-8mm ! I was going to pull the spare engine apart today but haven't moved my arse out of the house yet and I have the Fazer to check over and clean yet. 

As soon as I can I'll have to pull both engines apart and I'll update anyone that's reading this ( if they should care, haha !) I first thought someone had put a different year crank in but Cynic sounds adamant they should be all the same ( which makes total sense ) thanks both of you for helping a DT newbie.

[Wessie34]

So, I have split the cases on my 175 Mx and the crank was longer!  Maybe it's from a 250, I have no idea, anyway its no use as a spare cos it's been ground down, what idiot would do that !