Hi guys,
Over the next lot of months ( maybe year ! ) me and a few mates are going to try and rebuild a VFR400R NC30 motor, get it in a bike and ride it on the roads. I don't expect it to be a 1 ltr superbike killer but I am aiming for a running motor that rides smoothly and doesn't miss a beat, and to be fair i don't think i'm asking to much.

What i'm looking for on the forum is a little guidance, advice and just everyone to keep me and the lads on the straight and narrow, I'm not going to speak for the others but I would call myself an amature mechanic, I have no engine building experience, I understand the theory but as most on this forum know it's the practice thats the difficult part.
So I'll cut the B.S. and start the topic

To give you a bit of history to this story it all started over a year ago when i acquired a motor from a forum member, it had a knocking sound when running, straight away i expected the worst (so i wasn't going to be let down) and I presumed the big ends were probably hanging out of it, no worries i'll sort myself out with a second hand crank and we'll be rocking. Getting it back from sheffield was a bigger problem !! In steps Martin, who picked it up on his way back from Gfrance's work shop and in no time the motor was sitting on my garage floor. RESULT!

Once on the carpet Stu and I set about taking it apart to see if we could see any evidence as to why it knocked when running and once the sump came off it was all too apparent. The sump was full of bits of big end shell (which i expected) so no real surprise and I set about searching for a replacement crank on ebay. A few months pass and a replacement crank is found on ebay but once delivered I find it has also suffered a big end failure. Raging! So now I have 2 cranks, 8 rods, 8 pistons, 6 heads, 1 motor minus its crank and the wind taken out of my sails, maybe this wasn't going to be as straight forward as once believed!

I'll be brutally honest here my heart wasn't in it after that, i had my fingers in too many pies (as usual) and the project was shelved until i could find time, money, and a replacement crank. To say i was gutted would be an unstatement. Until a couple of weeks ago when i finally scored myself a good condition crank, 4 more rods and 4 more pistons. So the project is backup and running and i have a motor to build !! ye ha !! and to be fair maybe i can do something pretty sweet, i can take the 12 rods, 12 pistons and weigh them to see whats going to be of similar weights and couple that with reseated valves and new bearings i think it has the makings of a good motor and an interesting build, what do you guys think ?

Looking forward to it Royster!

I'm sure forum members could contribute a lot of knowledge to this.

I'm mechanically inept at stuff like this so it would provide me with some motivation to do something similar.

Are the cranks able to be repaired? I know with other engines you can get them welded up and reground to standard size.

Get amongst it mate! I want to do a similar thing but stick RVF pistons and cams in one just because i want to learn. The best thing about it is is that you're not relying on it to get you to work so if you screw it up it's a pain but not the end of the world, that's not gonna happen though because it's going to be a doddle

I'm not uire if the cranks can be reground as i asked before and never got an answer so started looking for a replacement. They make good paper weights and i'll maybe try a lamp outta one.

Cameron i hope this thread does spare someone on to do what i'm attempting, as i go i'll post prices of things i'm buying to show the costs involved and to hopefully give a blow by blow record of the rebuild. They if it allgoes tit's up you'll all know just how much it's cost me.....

i'd like to build a motor with RVF pistons,balanced this,that and the other, ported heads , a uk oil cooler and the rest but i wanna make sure me and my mates can buid a reliable running motor first before i think about spending money on pistons etc etc

Good luck with it mate!

I hope that you do find the time to keep us posted on how the build is going.

I think this has the potential to be a very interesting thread for those of us who have never tackled anything like this.

I rebuilt my nc30 motor about 6months back, replaced all rings/bearings/seals, everything was done slowly and meticulously and worked out well except for the honing. The problem being i did the honing myself out of desperation because i couldnt find a workshop with a small enough hone. I used a small 'brake cylinder hone', which would have been fine were the stones not as coarse as they were, the cross - hatching is obviously too deep and it burns oil. BUT, iv only done about 100kms so maybe the rings will still seat and all will be well.. Mind you some of the 08 fireblades burnt oil constantly so maybe it is a bit of an art...

Take care of every small detail, and dont skip any checks/procedures especially with oil clearances on the crank & big end bearings.. The haynes has good step by step procedures for rebuilding so follow it closely..

Im glad i rebuilt tho, one cylinder had a coolant leak and was rusting from it, a compression test probably would have revealed this sooner.

Also make sure the journal surfaces are in good condition on that crank, no scratches or unevenness, and perform all measurements the haynes suggests.. Should turn out well if done carefully...

Be watching this one with interest royster I have 1.5 NC30 engines sitting in boxes that ive been meaning to rebuild for some time. Like yourself ive never stripped and rebuilt an engine before but im hands on so how hard can it be

So it appears there is more than one bloke on here wanting to tackle this and a few that have already,excellant !

But don't worry i'll be following all advice and the haynes to the letter, i honestly don't think it'll be built in a hurry as there is no rush and money is going to be the limiting factor but as said at the bottom of each post i'll put a "spendometer" to show just whats been spent, it would give you tony a good idea if it's worth putting one of those NC30 motors together.



spendometer
so far
first replacement crank £15 , then refunded due to it being knackered
all heads (4 in total ) £70, the bike came with heads but one was donated to martin for his porting project.16 shims came withthe heads and one shim was found in the motor so i have something tostick in to measure the valve clearances
second replacement crank £50
engine casings (side covers) i've had from forever and a day.

total: £120

Get on it lad. I'll also be following this with interest - I have an engine on my floor (was on my bench for a few months) and I'll be getting this motor stripped, fettled and very likely the +2mm pistons in it from Omega pistons...

As it stands, it will take a while and I'll create a no9 rebuild thread too - going to sort the old kid out with some deep clean and TLC.

Best of luck Sir, I doff my cap in your general direction.