Bolt it all back together and put it in the corner, lift out the rvf motor and fit it. In time you can save some monies and go see graeme France about getting a proper motor built. It's not the end of the world but you need to be asking why it happened so you don't do it again.

Was it low on oil?
Have you over ridden it, hit limiters morning, noon and night?
You haven't tried doing wheelies have you?

That's tough luck
The old money pit of NC30 ownership strikes again.

Rhory, already stripped down ready for a full diagnosis, I just have to get the clutch and alternate off an I can split the cases.

None of the above by me, although when I first bought it and changed the oil I don't remember there being as much as I drained out this time :/ its got a breakers number at the back, so wondering if the last owner was a bit of a ham fisted cunt and already blew the original motor.

Going to ring Rick tonight and see what he says to do with it, will be fitting the RVF engine over the next few days, so shouldn't be off the road too long

The number on the back is a number honda put on.

Fair enough, thought it might be a breakers number is all.

Well, at least 2 big ends have gone pop, maybe a 3rd, a fucked rod (spun the big end) and one trashed piston. Without having the cases split (not got a rotor puller to take the generator off) I can't really see whether the crank is going to be any good.

Right, getting the NC35 motor ready to put in, noticed that the rear head only has provision for the main mounts, there's 2 that are unthreaded, I think these are the ones that on the NC30 have a spacer behind them, they're pretty much the middle of the top 3.

Do I NEED to tap them out, or will it be ok as is? If not I'll try an locate the correct size tap to get it threaded.

Also, will my NC30 carbs be fine on the jetting I had before? I know the ports on the NC35 heads are smaller, so wasn't sure if I'd have to compensate for that.

Any help and advice is much appreciated

similar thing happened to my girlfriend car, bought an old ford, was running 10 40 stuff, switched to the proper 5 30 and bottom end went BANG. same thing happened to my mito last week, was running 10 40 tranny oil, swopped for thinner 5 30 stuff, BANG, bottom end. maybe just coincedance, maybe not!? who knows, but iv heard of engines getting used to a certain type of oil and then spitting its dummy if you change it. my dad s a mechanic and he s said the same thing, mostly on older , worn in engines, change somin and they dont like it. doesnt really help you though mate, just thought id tell ya lol

BillingCBR wrote:Right, getting the NC35 motor ready to put in, noticed that the rear head only has provision for the main mounts, there's 2 that are unthreaded, I think these are the ones that on the NC30 have a spacer behind them, they're pretty much the middle of the top 3.

Do I NEED to tap them out, or will it be ok as is? If not I'll try an locate the correct size tap to get it threaded.

Yes, you need to tap the rvf engine or you won't be able to bolt the front of the engine in. The tap size is M10 x 1.25 (fine). Get some good cutting compound (e.g. trefolex) and it will make the job very simple.

BillingCBR wrote:Also, will my NC30 carbs be fine on the jetting I had before? I know the ports on the NC35 heads are smaller, so wasn't sure if I'd have to compensate for that.

I imagine they'd be close enough to get the bike up and running fine.

Cammo wrote:

BillingCBR wrote:Right, getting the NC35 motor ready to put in, noticed that the rear head only has provision for the main mounts, there's 2 that are unthreaded, I think these are the ones that on the NC30 have a spacer behind them, they're pretty much the middle of the top 3.

Do I NEED to tap them out, or will it be ok as is? If not I'll try an locate the correct size tap to get it threaded.

Yes, you need to tap the rvf engine or you won't be able to bolt the front of the engine in. The tap size is M10 x 1.25 (fine). Get some good cutting compound (e.g. trefolex) and it will make the job very simple.

BillingCBR wrote:Also, will my NC30 carbs be fine on the jetting I had before? I know the ports on the NC35 heads are smaller, so wasn't sure if I'd have to compensate for that.

I imagine they'd be close enough to get the bike up and running fine.

What size is the hole and what size thread are you going for? The corect drilled hole size for an M10x1.25 thread is 8,8mm.

Depending on what you have vs. what you need, I would maybe just open the hole to 10mm and use a high tensile bolt and nut sourced e.g. through eBay.

Cammo wrote:
Yes, you need to tap the rvf engine or you won't be able to bolt the front of the engine in. The tap size is M10 x 1.25 (fine). Get some good cutting compound (e.g. trefolex) and it will make the job very simple.

BillingCBR wrote:Also, will my NC30 carbs be fine on the jetting I had before? I know the ports on the NC35 heads are smaller, so wasn't sure if I'd have to compensate for that.

I imagine they'd be close enough to get the bike up and running fine.

Excellent, it's the one that's on the block, just under the head gasket on the rear bank. I only have an M8x1.25 so used that as a pilot, and have bought an M10 one to go through again to make it the right size. So after I tap this one out I'll have mounts on both heads, the block and the lower crankcase I was wondering whether it could have worked with just the heads and lower crankcase, but guessed it would probably have been too much stress and caused things to crack.

I'll chuck the carbs on as they are, and go from there, see how it runs :)