revtothelimit - motorbike forum

I was looking for a project that only needs a strip and rebuild and with a few lads in the yard racing with CRMC and two having just bought a pair of project NC30’s I thought I’d join them with a 400. Being a small bloke I went for the smallest one I could find a 1989 CBR400RR
It runs and rides and was on track only last week with a new set of tyres !
I’ll get it on the dyno and then have it stripped.

Lots to do

Strip and paint
Fork rebuild and upgrade
Shock
Brakes strip and rebuild
Engine service or tune
Race bodywork
Race loom

Hmm, not the usual choice in that class I would think-You planning on going racing this time then old boy?



P.S. 2 weeks tops

Should have made Cheesy an offer for his FZR.

Tricky wrote: Tue Jul 06, 2021 7:50 pm Hmm, not the usual choice in that class I would think-You planning on going racing this time then old boy?


P.S. 2 weeks tops

It’s a brand new class tbh, I’ll build the bike for a bit of fun doubt I’ll race it

KungFooBob wrote: Tue Jul 06, 2021 7:51 pm Should have made Cheesy an offer for his FZR.

It's his for £1200, come see it at Cadwell 23rd of July, were apparently I'm riding a championship winning ZX6R with 120bhp for at least one session.

Credit card got a hammering today.

Exhaust man primed to copy hrc headers

Powder coating man primed for wheels and a few brackets

Shot blaster for loads of stuff

ordered all seals and bearings for wheels suspension and brakes, airbox hrc copy, dynojet kit, hrc cdi, shock linkage, shock, fork kit and some service items.

Still need race bodywork and a gullarm rear wheel or two and a decal man to copy the mister donut decals

Some work today, when it came home it wouldn’t start and run. A few attempts but nothing. One of the lads in the yard wonders over with a can of deodorant and sprays it in the air intake and it fires and runs lovely while the can is sprayed lol. Not worried so I dump it inside.

Had an hour today to have a look, someone had joked it was prob the fuel pump and someone else said they don’t have one. But soon as the tank was off there it was and it wasn’t running. A quick check and no volts at the terminals. A couple minutes bypassing the relay and the pump works. Back on with tank and it starts first time and runs smoothly. I do like the whine very NC30 like. Happy with that I stripped all the road gear off lights indicators etc. Also removed speedo and modified clock bracket. I’ll refit tank tomorrow and take for a base dyno run at some point. Big box of stuff arrived so plenty to be getting on with now. 

Got the bike buttoned together for a dyno run soon. Oil and filter are fresh as is brake fluid and pads. Rear tyre is new and an 090 pro so just a front needed, gearing is already short too. Rides lovely at least in 1st and 2nd gear, so book is open for guesses on power ?

What power do they make in stock trim?

Stock they were supposed to be 60bhp, but I've no idea if that was crank or rear wheel.

So I'm going to say, 58bhp.

They're notoriously difficult to tune due to the gear driven cams.

My guess is 55bhp, anything over 60 is good, apparently you can get 90 out of an FZR, but I think 70 is more realistic, and that takes a lot of money.

I think my FZR is mid 50s, claimed standard is 60 for all the JDM 400s, my GSXR400 felt the most powerful of the 400s I've ridden (NC30, ZXR and FZR)

56 bhp for me then.

Couchy wrote: Tue Jul 13, 2021 3:43 pm Got the bike buttoned together for a dyno run soon. Oil and filter are fresh as is brake fluid and pads. Rear tyre is new and an 090 pro so just a front needed, gearing is already short too. Rides lovely at least in 1st and 2nd gear, so book is open for guesses on power ?

My dyno-eye says it'll make approximately 54.371 hp

Does it have a speed limiter, my NC31 and FZR400 had them, but my GSXR400 didn't, it just had a light that came on at 80 km/h

The fun with the JDM 400's is that they were made to make 60bhp, not restricted to 60bhp, so the cams, valves, cranks, etc.. are all designed to handle 60bhp. Getting more won't just be a pipe and jet kit

Couchie mentions the bike has seen the track before, but not if it's tuned, we might all be very surprised.

KungFooBob wrote: Tue Jul 13, 2021 4:21 pm The fun with the JDM 400's is that they were made to make 60bhp, not restricted to 60bhp, so the cams, valves, cranks, etc.. are all designed to handle 60bhp. Getting more won't just be a pipe and jet kit

Couchie mentions the bike has seen the track before, but not if it's tuned, we might all be very surprised.

A lot of them have speed limiters that cut in at 180 km/h, the easy way to get round this is to use a mechanical kmh to mph converter, this way the speed limiter cuts in at 180 mph.