1991 KX125 restoration project...

[Reckless]

Havnt asked any nz wholesalers but cant find a complete crank. Found hotrods big end bearings, seals and conrod kit...?

Anything else id need? What about the bearings in gearbox? Dont really wanna replace every moving part just for the sake of it but id be pissed if they failed

Hey Chop, The bearings in the box, any wear on the dogs and the crank shaft bearings and seals are probably more the points you'll find the most deterioration rather than the big end. So if you gonna spilt the cases best to have a look at the lot.

You probably won't find a new crank shaft it is quite rare to have to! A kit is the normal way! You split the halves off the pin, then press them back together over the new rod and bearing. Then the tricky bit is to get the correct tolerances on width and aligning the halves up. This is best done by someone with experience and a well set up rig and dial gauge. Its either right or wrong!

It is usual to do all or nothing. You basically decide to split the cases and do the lot because the big end needs replacing or you have a gear box problem? You wouldn't necessarily do the big end just for the sake of it, if you had a gearbox problem either unless it looked bad.

The big end will have alot of side to side standard its the up and down (or slop in the bearing) that's of concern. If it looks all good and the box was changin gears etc fine, I don't think I'd touch it till it needs it, unless you just wanna do the lot for piece of minds sake!
Just my 2c hope it helps!

[CHOPPA]

Hey Chop, The bearings in the box, any wear on the dogs and the crank shaft bearings and seals are probably more the points you'll find the most deterioration rather than the big end. So if you gonna spilt the cases best to have a look at the lot.

You probably won't find a new crank shaft it is quite rare to have to! A kit is the normal way! You split the halves off the pin, then press them back together over the new rod and bearing. Then the tricky bit is to get the correct tolerances on width and aligning the halves up. This is best done by someone with experience and a well set up rig and dial gauge. Its either right or wrong!

It is usual to do all or nothing. You basically decide to split the cases and do the lot because the big end needs replacing or you have a gear box problem? You wouldn't necessarily do the big end just for the sake of it, if you had a gearbox problem either unless it looked bad.

The big end will have alot of side to side standard its the up and down (or slop in the bearing) that's of concern. If it looks all good and the box was changin gears etc fine, I don't think I'd touch it till it needs it, unless you just wanna do the lot for piece of minds sake!
Just my 2c hope it helps!

Yeah mate very helpful thanks!! Yeah if i open it up then id be inclined to do everything....

Full gasket and seal kit, rod kit including big and little bearings and crank pin and main bearings only $136 but then i gotta get gearbox bearings and someone to do it and balance the crank. Im pretty fussy though so i might be better to bite the bullet!!

[Reckless]

Yeah mate very helpful thanks!! Yeah if i open it up then id be inclined to do everything....

Full gasket and seal kit, rod kit including big and little bearings and crank pin only $136 but then i gotta get gearbox bearings and someone to do it and balance the crank. Im pretty fussy though so i might be better to bite the bullet!!

I think the main reason we sometimes don't always do everything in a 2smoker like in a car engine or four stroke bike is they are so simple to strip down each time.
Your call Choppa, but be prepared on a bike that vintage to have to replace a few bits in there that maybe could have still gone for ever, especially if your fussy.
But then you'll know its done. Your probably thinking best to fix it now rather than after it breaks as its an older bike! Better be a keeper this bike after this much work!! LOL!!!
Cheers mate cya out there!

[barty5]

Yeah mate very helpful thanks!! Yeah if i open it up then id be inclined to do everything....

Full gasket and seal kit, rod kit including big and little bearings and crank pin and main bearings only $136 but then i gotta get gearbox bearings and someone to do it and balance the crank. Im pretty fussy though so i might be better to bite the bullet!!

If you pull it down take out all the bearing and take them to the local bearing shop they should be able to supply most of them. Most automotive bearings are V spec. Same thing ive done to all the bikes ive rebuilt works out heaps cheaper beats payin for a (dealer) labeled box. You may find the odd one they cant do though.

[barty5]

just priced up a Prox rod kit they retail at $209 but sure could shave a good chunk of that. A full crank can price in the morning but lookin more like a good $400 normal retail.

[CHOPPA]

Cheers guys! Bugger it, it looks mint so ill leave it! Never used to replace any bottom end bearings in my race bikes till they siezed lol Dont intend to ride this much cause i have the 450 anywho

[Reckless]

yeh mate have a look at the crank shaft seals if you get keen though. If they leak you'll loose fuel pressure up through the transfer ports. Thats bad for performance. If you take the clutch basket or whatever off to do this you can have a good tug on the end of the crank shafts to see how the big end bearings are and if there is any side movement as well. Then you'll have done pretty much all you can without splitting the cases apart.

[CHOPPA]

yeh mate have a look at the crank shaft seals if you get keen though. If they leak you'll loose fuel pressure up through the transfer ports. Thats bad for performance. If you take the clutch basket or whatever off to do this you can have a good tug on the end of the crank shafts to see how the big end bearings are and if there is any side movement as well. Then you'll have done pretty much all you can without splitting the cases apart.

Thanks for your help!! Cheers mate, i just heard back from the previous owner and the bottom end has been rebuilt at some stage so that has helped me make my decision! Back together it goes!

I cant believe the condition of inside this 18 yr old engine, no where on the clutch basket and everything looks mint! Bore is score free powervalves are mint, the old piston looked like brand new and it has new carbon reeds

[cheese]

you're probably that lucky guy that got the bike after the previous owner spent heaps on it.

[oldskool]

Probably owned by one of those people who likes to admire their bike, dreams about it, but hardly ever rides it.

[barty5]

Probably owned by one of those people who likes to admire their bike, dreams about it, but hardly ever rides it.

Are you picking on cheese or hemex???

[Hemex]

Probably owned by one of those people who likes to admire their bike, dreams about it, but hardly ever rides it.

Are you picking on cheese or hemex???

haahaha... 8 hours in the last 5 weeks... I'm leaving this non-riders club..

[cheese]

Well its a bit hard to ride my bike from China now isn't it.

[oldskool]

Well its a bit hard to ride my bike from China now isn't it.

because it keeps breaking down!

[Hemex]

Well its a bit hard to ride my bike from China now isn't it.

We'll start a 2 man team and show these oldies what riding is all about... give me a year... hahahaaha

EDIT: oldies = Oldstools and the GNCC winner for age group 35-39...