NC30 Lower Crankcase replacement

[L.Svedberg]

I think he means to just replace the lower half, which would be very much a deviation from common practice...remember, the cases are a set, and the main bearing journal is line bored with both halves bolted together. Bearing bore sizes won't match on an odd set of cases, and I would never dare spending that much work and cash on a bad repair like that.

I'd opt for a complete replacement engine as suggested by others.

/Lasse

[Cammo]

I think he means to just replace the lower half, which would be very much a deviation from common practice

Ah, get it now. Yes that would be a no-no!

[speedy231278]

Could you not get new bearing shells and use plastigauge to set the clearance correctly? Surely there can't be so much tolerence in the machining process that it would not be impossible to compensate and adjust to suit? Aren't the cases and crank marked with their relative sizes?

[owen_captain]

Thanx Guys, I will start the tear down soon. So here are my options.

1) Use the spare sub assembly complete and transplant the heads and other minor goodies.

2) Strip crankcase and get it welded or

3) Replace motor

I will assess once I have the motor on the bench and let you guys know the outcome as soon as I'm mobile again In the meantime, I will try and source a replacement motor (which is like gold here in Sunny South Africa )


Cap

[Neosophist]

For some reason my oringal post disappeared?

Anyhow.

It went like this.

The pieces are machiend as a set and changing just one half isnt recommened but the tolerance is so good you might not have any issue.

But you will need to check and possibly change bearing shells for the crankshaft.

Expensive, time and money. Better off changing the case if you want to rip it apart.

Lumiweld is where its at though. No need to take apart just drain the oil.



Many examples there of how to repair the block.

[tigerclaw]

Dude - hope on junkmail or olx - saw someone selling an engine in Benoni the other day for R3500 I think.. I would first see if someone can weld it in place though (ie while its still in the bike)

[owen_captain]

Dude - hope on junkmail or olx - saw someone selling an engine in Benoni the other day for R3500 I think.. I would first see if someone can weld it in place though (ie while its still in the bike)

Hey Bra, Yay a homie howzit? Looks like a engine removal or a "Lumiweld", but the latter looks like the best option. I have been getting some guys to come check it out when I have some time (lotta things happening at the moment), but also been doing some research on the welding myself. Maybe worth a try also for furture education I did have an option of a motor here in Durbs but decided to hold on till I try the lumiweld avenue as I have experience in braizing, so I'll practice on some scrap pieces till I am confident in getting it done right. No rush to get the bike running again, so I'll tarry a little .

[Neosophist]

Dude - hope on junkmail or olx - saw someone selling an engine in Benoni the other day for R3500 I think.. I would first see if someone can weld it in place though (ie while its still in the bike)

Hey Bra, Yay a homie howzit? Looks like a engine removal or a "Lumiweld", but the latter looks like the best option. I have been getting some guys to come check it out when I have some time (lotta things happening at the moment), but also been doing some research on the welding myself. Maybe worth a try also for furture education I did have an option of a motor here in Durbs but decided to hold on till I try the lumiweld avenue as I have experience in braizing, so I'll practice on some scrap pieces till I am confident in getting it done right. No rush to get the bike running again, so I'll tarry a little .

if you can braize you can use lumiweld.. its like a cross between soldering and braizing.

watch that video a few times, you can buy it in 3 stick packs.. like you said practice a little on soem scrap and then fix your engine, sand it down and repaint.

its good on genny cases which are easily cracked too.

[Morespeedvicar]

I've always fancied having a go with the ali brazing stuff, looks interesting.

[vfrman]

If it were my bike, I would either replace the whole engine with a second hand one or strip the one I have down and swap cases with the spare case you have. With the case swop I would replace all bearings and rings as well as hone the bores. but then again if I was going to go through that much to rebuild a motor, I would send it all to GForce for a big bore conversion and head work.

Of course all of this means money is no object and I wouldn't be getting rid of the bike any time soon.