CBR400RR track bike serious engine problem

[adeyrob]

Hi, new to the forum and seeking a little help with my not very well NC29 track bike which I recently bought to have a bit of fun on.

I've so far managed 2 track days on the 400RR, the first at Oulton Park, and then a two day event at RAF Valley on Anglesey a couple of weeks back. Unfortunately the engine blew on the last lap of the last session at Anglesey so now have a project in rebuilding it, and may bee seeking advice from more experienced 400 owners.

Not had chance to strip it down yet, but it still starts and runs but sounds like a bag of spanners in the engine though. It suddenly lost power and developed the above sound when I put the power on full coming out of a fast right-hander, so clutch in just in case, and coasted in to a run off area, engine still running. Had to get a lift home to pick up the Ducati for the second day of the session......

The bike was owned by a bike mechanic who had used it as his track bike for over four years with no problems (he's moved up to a CBR600RR track bike now). The bike is standard, no tweaks, other than an HRC box, so will rev 500 above red line before it hits the limiter, K&N filter, has a quick action throttle and after market end can + track bodywork with all the unnecessary bits removed for weight savings. Oil & coolant checked prior to track day and was fine, the oil had done 1 previous day, so would have been changed after this one.

Been looking on ebay for second hand engines for either exchange or parts, but not seen anything yet. I have been told that the "Jelly mould" CBR600 (87-90) is a drop in replacement, has anyone done this? if so do the 400 carbs fit and are they sufficient for the extra capacity, jetting etc? Would rather keep it at the 400 as it's great fun, but if the engine is beyond cost effective repair I'd up to the 600 if possible as quite a few available on ebay.

Any help or advice appreciated.

Cheers

[Gimly56]

The CBR600 engine isn't a 'drop-in'. Pretty sure you have to do a few chassis mods to get it to fit??

If you search the forum you will find a couple of build threads on the 600 in 400cc frame project.

If I were you I'd rebuild the current 400 engine and at least you will know what you've got beneath your legs!!

[tanuki]

to get any engine to fit in the 29 chasssis is a masssive job.

It will fit into an NC23 chassis far easier but still needs some cutting and welding to the frame, then there is the loom, airbox, exhaust etc

Drop the motor and split the casings and take it from there.

[adeyrob]

Cheers for the reply, going to stick with the 400 engine and get stripping it hopefully next week, not had chance yet!

[EmilyPip]

I'd be keen to hear how you go with this!
I have a VERY similar story! I got only 2 track days out of my bike too before a nasty engine sound rocked up. I swang it past my mechanic while still on the trailer and he said the oil pump has become loose in the engine - he didn't split it though, just from the sound.
I'm half keen to try and rebuild it although I feel that's beyond my skills/parts/tool limit here in Australia.. I do want to split it before giving up entirely though.. Otherwise I'm just on the hunt for a spare engine to drop in.
Good luck!
Emily