Engine number - C029424
Frame number - KH250B-007755
Can this be correct ?? The log book states it was first registered in 1977.
What is it ? could it be a 250 with top end or is it a 400.
The guy wants to sell and was asking what it would be worth ??
Frame numbers for 1976 KH 250-B1 commence 000001
Frame numbers for 1977 KH 250-B2 commence 008601
Engine numbers for 1972 350cc(S2 Mach11) start S2E00001
Engine numbers for 1973 (S2A) start at S2E28226
Engine numbers for 1974 400cc (S3)start at S3E 00001
Engine numbers for 1975 (S3A)start at S3E14300
Engine numbers for 1976 KH400A3 start at S3E026300
Engine numbers for 1977 KH400-A4 start at S3E033601
Engine numbers for 1978 KH400-A5 start at S3E042801
Going by the info. you provide, it ain't an S3. The frame, as has already been shown above, is KH250B1 (1976/77 era). The engine number has been got at, as it shouldn't start with a C. It could be the original KH250B1 engine with those numbers, but with a bodged prefix, but the crankcases would need to have been machined to take 400 barrels. Alternatively, it could be a KH400 engine (A3 model of the same era), again with a bodged prefix. Checking if it has 400 barrels and CDI would be a start. Can't speculate much more without more info. or pictures. Clearly it's a bitsa, so value is more based on the value of its parts as opposed to it being a genuine S3. You don't give any indication of condition, but assuming it is not restored and at best tidy, then we're talking hundreds of pounds only.
Nigel, been thinking, and it seems clear, (as S2Gerald points out) that the engine number is either incorrectly stated or has been doctored, either way the numerics are close to a 1976 400 A3 era engine number range .
I also agree that its 'worth what its worth' as spares, depending on the bikes overall condition
Hmmm well to be absolutely correct (Or as well as you can!)
The Frame is a 1976 KH250B1 Model
(Numbers are for Frame KH250B-000001 to 008601)
And as for the Engine could well be off a A3 KH400 - But are you sure that it is a 400?
This is probabaly a Stupid Question? But is there a 400cc or 250cc cast into the Cylinder? - Otherwise it could well be the Original KH250B1 Engine ( Numbers for B1 are S1E 028801 to S1E 038401)
with the S1E Prefix ground out?
It is definately a 400 engine, he bought it in the early eighties and it has been sitting in the shed ever since. Engine still turns over, but has not been started for some 25 years. Nothing is standard all chrome is rusty. Paint is lime green with black side panels (KH 400 badges).
Probably best to advertise on evil bay and see what comes of it.
Smokie wrote:Hmmm well to be absolutely correct (Or as well as you can!)
The Frame is a 1976 KH250B1 Model
(Numbers are for Frame KH250B-000001 to 008601)
And as for the Engine could well be off a A3 KH400 - But are you sure that it is a 400?
This is probabaly a Stupid Question? But is there a 400cc or 250cc cast into the Cylinder? - Otherwise it could well be the Original KH250B1 Engine ( Numbers for B1 are S1E 028801 to S1E 038401)
with the S1E Prefix ground out?
Ta Ta Keith
There's a distinct echo in here Keith!!! I've said all that already. I put 1976/77 as a '76 B1 may well have not been registered until '77. If looking for engine cc, it'll be 249 or 401, but then the 400 fins and heads are quite different from 250.
and it seems clear, (as S2Gerald points out) that the engine number is either incorrectly stated or has been doctored, either way the numerics are close to a 1976 400 A3 era engine number range 
