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Post Info TOPIC: Crank damage - keep or replace?


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Crank damage - keep or replace?
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In the middle of an engine rebuild and have found the crank has some surface water damage or similar. Will this effect the engine if just cleaned up? I have a spare tzr 125 bottom end - should and could I use the crank out of it? I have new crank bearings, seals, gaskets and conrod set to go in.

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I wouldn't have thought you'd be able to use the tzr crank. Not a 100%

Put it this way. If you're going to do a job, do it properly. If anyone part let's you down you risk replacing everything over again. For peace of mind I'd replace all mechanical moving parts. Once I've done my rebuild I probably won't do it ever again. The way I ride and the maintenance I do ought to be enough.

If it's a job do well it's worth doing right.

That said is it a part likely to fail?

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DTR Trusted Engine Builder

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no it will be fine

just use a wire wheel in a drill to clean it all off...

try and cover the big end up as much as u can with masking tape or blue tack...

give it a good clean and oil up before re fitting

most projects iv had when they have sat in a garden for months wi no top end on the cases fill up with rain and leaves a water mark where the cranks been submerged

good clean and good to go


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I'd want to replace everything I could inside the engine. Would love to have a brand new engIne.

Zero miles on the engine.

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Right, finally anaged to get the TZR 125 crank out but damaged it in the process so that idea is out of the window. Had a look at them tho and they are different crank designs but appear to be the same size (see pics) so for future reference I reckon a tzr crank would fit a dt. Cleaned the dt crank up as suggested and it doesn't look too bad.  If money was no object i'd go down to my local Yamaha dealer and let him chew my arm off but as it is,i'm going to perservere with this crank.

(TZR crank above, DT crank below)

 



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It's not just the crank i'd be worried abouts. It's the bearings and stuff.

I wouldn't have thought the tzr crank would fit. Looks like it's wieghted differently.

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yeah the flywheels are  different shapes

stick them on some scales and weigh the cranks minus the bearing ov course biggrin



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Got new bearings and conrod kit. So what's the verdict - does the crank look useable?

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I wouldn't have thought so.

You won't be able to use the TZR crank on the DT. The DT crank is weighted completely differently. You'll cause some serious problems if you go with the TZR crank

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Gonna forget about the tzr one, what do folk think about the dt crank (bottom picture)?

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Calum122 wrote:

I wouldn't have thought so.

You won't be able to use the TZR crank on the DT. The DT crank is weighted completely differently. You'll cause some serious problems if you go with the TZR crank


 how do u no its a diffderent weight cal u wayed em??

jst coz there a different shape dont mean there different in weight

wont cause no harm at all mate

if you were worried about it been slightly out of balance to the balance shaft just remove the balance shaft, less recipricating mass on the engine may not see a power difference like or may be so .5 of a bhp  lol

the balance shaft is only there to smooth out the engine for long rides etc to make it more comfy and rider friendly, no mxers have them or off road bikes 2 strokes any way that iv seen smile



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