I have bought an nc35 engine with a small piece broken out of the clutch side of the crank cases. My original intention was to use good bits like cams, heads and pistons in my nc30 track bike but its low miles and I am considering welding it to use complete. Has anyone compiled a list of differences in the engines? If not I can think of the following nc35 improvements:

Cams - lighter, small amount more exhaust duration
Heads - smaller intake ports, reputedly lighter but that could be the cam weight.
Pistons - lower friction, reputedly higher cr.
Gears - lower 1st, not necessarily better.
Clutch - less plates but thicker. Unknown benefits.
Flywheel - lighter?
Crank/bearings? Lower friction?

Ignition pick-ups are different too, NC30 has two and NC35 has one.

Bike_Nut wrote:I have bought an nc35 engine with a small piece broken out of the clutch side of the crank cases. My original intention was to use good bits like cams, heads and pistons in my nc30 track bike but its low miles and I am considering welding it to use complete. Has anyone compiled a list of differences in the engines? If not I can think of the following nc35 improvements:

Cams - lighter, small amount more exhaust duration
Heads - smaller intake ports, reputedly lighter but that could be the cam weight.
Pistons - lower friction, reputedly higher cr.
Gears - lower 1st, not necessarily better.
Clutch - less plates but thicker. Unknown benefits.
Flywheel - lighter?
Crank/bearings? Lower friction?

Most of the main engine differences are outlined by Honda in the sales documentation avaiable at that time, im sure theres a copy floating around on the site somewhere, it has a comparission of the cams as well as information on the valves being 1mm smaller.

The facelift / redesign was to improve road use drivability, in a sense moving away from the racebred pedigree of the earlier bikes.

It was also at this time the Japanese law changed so the bike could only make 53hp (hence them being lower power from the factory).

As far as I can tell the valves are the same size, just the ports smaller.

I am more interested in the unpublished data. For example both bikes have 11.3 compression ratio but common rumour has it that nc35 pistons give slighly higher ratio in a 30. Is this true or another misconception like nc23 wheel weight?

Not true, both pistons give the same compression ratio.

I believe nc35 pistons raise the compression in nc29 engines though.

Yes the rvf pistons in nc29's do make a good compression increase

eBay engine from Northampton by any chance?

From all the info i have read, the valves are the same, and as has been said - the nc29's benefit from rvf pistons.
The 30 and the 35 have little/no difference between the pistons. the RVf ones are very very slightly lighter.
The 35 has narrower inlet ports/ways to increase the velocity of the air/fuel and the cams have a different profile on the 35 (better) cant give exact figures so wont say what.
As said already, you have differebnt pickups and pusle generator that must be used with the matching CDI i.e. 35 puls, genny pickups and cdi must be used together.

http://hondanc30.blogspot.co.uk/2012/03 ... pdate.html

The nc35 is a more modern design but good to know the cr is the same.

And yes, its the Northampton engine :-)

http://www.honda.co.jp/factbook/motor/RVF/19940100/

RVF400 press info, shouldnt reply when im half asleep.

Intake ports are 1mm diameter smaller to match along with the camshaft and carb changes.