Shock find on ATC 70!

[GTO]

I had the pull start off check the points gap on my newly aquired ATC 70 only to find some idiot has ruined the crankshaft.
The threaded part of the shaft has split in half and the nut and washer are missing.
There doesnt seem to be much thread left that is still okay.
Here is a pic(sorry about cell phone pic quality)
Is there any way the crankshaft can be saved?

[oscarmayer]

no. you have to get a new crankshaft and split the motor and replace. if the motor is in mint working order, then it's worth the time. if not then get anotehr engine. less costs and time for sure.

[AutoXer]

160 lifan time

[Big Mike]

My 185S looks like too!! But I cant complain for $40 that I paid for the machine.

[blue27]

I would try to to save it, first get the flywheel off, use a steering wheel puller (two bolt version) and thread in to where the recoil cage bolts on. from there see if you can file the damaged raised areas off and I would then use a thread file to fix the threads and then see if there is enough thread to use when all done. They are a metric thread but I do not remember which one. Worth a try?

[GTO]

Could an engineering shop not weld a new shaft onto the end and cut a new thread?

[malibulvr]

Could an engineering shop not weld a new shaft onto the end and cut a new thread?

Probably but then it would have to be disassembled and balanced.

[GTO]

I see there quite a few 2nd hand cranks on eBay for $80 to $100 incl shipping which might be my best option and probably cheaper than engineering shop.
I see I must use a 81 to 85 crank as older ones have a different part no.

[Howdy]

Could an engineering shop not weld a new shaft onto the end and cut a new thread?

Yes, I have actually fixed one that was brought to me after it was stripped. Took about an hour or two to weld, machine and rethread it. Last I heard about 5 years ago it was still running. So yes it can be saved, but you have to be very very careful doing the fix. .

[atc500x]

Easy,remove the flywheel,cut the old thread,drill the crankshaft for a M8-1.25 bolt and tap thread in it.......I repaired many of these like this,no need to remove the motor or split the cases

[GTO]

Easy,remove the flywheel,cut the old thread,drill the crankshaft for a M8-1.25 bolt and tap thread in it.......I repaired many of these like this,no need to remove the motor or split the cases

Thanks will give it a try when I get around to it.

Also I am worried that it is not going to be easy getting the flywheel off with the shaft so flared as it is.

[GTO]

I got her running tonight, lots of smoke and cam chain noise. So I will try the to drill and tap the shaft, if it works then its time for a top end overhaul.

[GTO]

I tried to remove the flywheel last night but failed.
I had to chisel off the flared part, I ended up flattening the point of the puller but it is not a high tensile bolt so I will go and get a new bolt to fit today.
I am going to try heating it up, is this pretty safe to do so?
I will keep the flame on the crank area.

[CRAZY70MAN]

Try using a rubber mallet or a soft deadblow hammmer when putting pulling force on it.

[GTO]

I got it off in 5 minutes with some heat, cut off the end and tapped a thread and fitted a bolt.
The cam chain tensioner isn't working hence the cam chain noise when i had it running, I found the spring from the tensioner lying loose in the bottom.