What do you all think of this, no marks or other sign of tampering at all, but the engine number seems missing. When I went to pick it up I thought it sounded unusually sweet for a 40,000km engine - it really is a peach. Could it be a factory replacement?

Nope that's how they are ... even the 3TJ's

Is there another number elsewhere to distinguish each engine from another or is that it?

Nope nothing.

But if it's running sweet then you don't have much to worry about

Give it a service. Check / rust kill the pipes. Make sure the brakes are good and it should be plain sailing ... biking

Err not exactly. I bought the bike just for the engine to fit in my micro car. With 16 inches of space for height all was looking well on the tape measure - until I took the tank cover and airbox off and discovered the carbs point straight up, adding another 4-5" to the height. Now I have a peach of an engine that will only fit if I cut a gurt great hole in the bonnet.

So that idea is scrapped, the bike's going for spares and the search for an engine continues. I wish I had put a final bid on that CB-1 last week now that went for £230 on ebay.

Ahhh - I see .... don't really want a speed hump huh ????

You need a really oldschool engine then ... a 600 Diversion or Bandit ... but they're air / oilcooled.

How about detuning a GSX-R ... or GSX600F (the flying teapot) ... they did a 400 version of it but they're a bit rare.

Where are you based ????

I'm in Kent. I think the 400 teapot is there is such a beast would be a sleeved-down 600. I am very tight for space, hence using the 400 engine.
I have a 600 diversion and have a spare engine available to me but the diversion also uses downdraught carbs though not quite as severe as the FZR. I particularly want to steer-away from aircooled because air-flow though the engine bay is restricted, it was a problem with the original engine they put a huge intake scoop on the front but not enough escape area to keep the flow up.

I'm currently thinking that I might be able to fit some side-draught carbs off perhaps the bandit/gsxr onto modified intake rubbers. What do you think of that?

It will take some power away from the engine but I don't know how much, and it might not do the floats any good.
You could fit up a big oilcooler to an aircooled engine that would help

GSX-R1100 Watercooled .... you know you want it I've got some soft cams (100 bhp) and a spare head if you do go for that.

Will you keep the 3en2 or sell it on ?

I only bought it for the engine to go in this car so if I don't use it then it'll be going. Right now I'm thinking of putting diversion inlet runners on turned pside down to reduce the height, and finding some side-sraught carbs to go on it.

I guess reversing the head is out the question .... it's more tricky on a 4 stroke. The cams would still turn at the same speed and you could possibly turn them so No1 cam lobe is No4 to get them travelling the right way round and not screw up the profiles and timing .... would that work ???

It would be interesting if nothing else