NC29 Race engine project

[stimpy]

lol
sad but true...im guilty of wanting the loom
gota race...man has gota race!
stimpy

[greggo]

After lots of head scratching, crying into my beer, and throwing hammers around the yard I think I know what caused my engine to go all mission impossible and self destruct on my ass.

I can't be 100% sure but I think one of the cam gears has moved 3-4mm on the cam. I marked them on assembly, but can't now find the marks (or be 100% i've found the marks). That would equate to 6-8 degrees I would think.

It appears the exhaust cam might have moved. For some reason though it has only resulted in valves in cylinders 2 and 3 coming into contact with the pistons. And then the inevitbale el destructo valve head falling into the engine.

Oh well, I now have a 675 to play with once the 400 is sold. And I will stay on the look out for an RVF400 to do it all again with a big bore kit.

A man needs a project.

[dannc29]

thats a shame, how many bolts did you have holding the cam gear in place? those pistons may have had a slightly higher crown or taller conrods (from manufacturing) i had .2mm difference between my tallest and shortest crown. or cam lobes are slightly larger. or valve clearance differences and also valve spring weakness

dont get the rvf. slow peice of shit. get a fast bike and make it faster. zxr or fzr. league of there own.

[stimpy]

go the 600...double the power....reliable
stimpy

[Cammo]

dont get the rvf. slow peice of shit without tens of thousands of $$'s spent on it. get a fast bike and make it faster. zxr or fzr. league of there own.

Amended.

[greggo]

Getting an RVF is not about building a race winning bike - I did say I was going to put in a big bore kit - so it's not going to be racing in a 400 class.

It's about having a project bike in the garage I can play with when I feel like it. And I want a V4.

The 675 will be running in Superstock, so will be a turn key bike. NO fiddling.

[Hot Wheels]

Right I know this is an old thread, but does the OP still have the modded nc29 nc 30 gearbox for still and if so for sale?

otherwise and help and info on what to do and which nc30 gearbox to buy and mod (if there are different types between the years)

many thanks

[PARUS]

To modify NC30 gearbox to NC29

Here is the good oil on the gearbox shaft. No the Input shafts are not interchangeable. But the output shafts APPEAR to be.


A = NC30 Input shaft
B = NC29 input shaft
C = Notice the lack of cut away on the NC30 shaft, the NC29 runs a smaller toothed gear here than the NC30 and the cut away is there to accomodate the smaller diameter gear, because you intend to use the NC30 2nd gear, DO NOT MACHINE THE CUT AWAY
D = Integral first gear, this is the bit you want the most. Press off the bearing (incidentally a common bearing is used on the VFR and CBR) at E and have the machinist cut away the integral first gear (from the bearing side) until it matches the width of the NC29 first gear. Your machinist may also machine down the section of shaft the bearing is pressed on to to match the NC29. It is pressed onto a raised collar that is different in diameter to the rest of the shaft. The other alternative is to make/find a new spacer that sits between bearing and oil pump drive that will go over the collar. You can't see the collar in the picture as the bearing is on.
F/G = Clutch mount and clutch centre nut thread. Machine down the end of the NC30 shaft to match the length of the NC29 shaft. Then have a new thread cut onto the end. The actual distance for the clutch centre splines is already correct. (or you'd be farked anyway.) This is not a common thread, and requires specialised machining (apparently).

EDIT** You can see a small oil hole on the NC29 shaft between E and F, the machinist will need to drill a similar hole in the NC30 shaft as it does not have one.

[Hot Wheels]

looking more for info on the sort of machinist used or tools they'd need as the few I've spoken to seem to think that because it'll be hardened steel they're going to struggle possibly.

plus if there were any other pointers to watch out for.

I also think I just want to check that this is possible and not too good to be true as it'll save me a fortune if it can be done.

what are the differences in ratio like, is it a big difference and which way does it change?

many thanks

[PARUS]

Does anybody know - where is greggo now ?