Plan for new project, 636 engine in a 400.

[steveh]

Basicly ive been toying with the idea of putting my friends 636 engine into a rolling chassis (zxr400h2) that ive got doing nothing.
Hes going to provide me with everything i need (motor, pipes, harness, carbs/airbox) for around 200quid. (his bikes written off)

Ive got to take a few measurements and maybe shift some mounts around, but im wondering what problems im going to face, ive always wanted to make somthing abit silly like this, but i wondering about over stressing the frame, swinging arm?
Is it likley to bend or break anything, will i need to do any re-inforcing? bearing in mind this is going to be a road bike.

The motors the carbed 636 motor from the older models (a1p) or somthing like that.


Has anyone done or seen this done before? any advice would be greatfull.

steve.
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Current : 06 Zx10r, 07 Wr450f SM, 74 850 norton commando, 63 bsa b40, 1962 Triton 650, 67 Triumph Tr6r, 1955 Triton 750, 1978 TY250E.

[Pete.]

I doubt you'll have any worries about stressing the frame or swingarm - consider the difference in stresses between a 11 stone and 22 stone rider!

As far as making it fit - only way to find out is either to try it or find someone who has done it before.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Frost]

Width is the main issue. The cylinders, carbs etc will be wider and the 400 engine is fairly tight anyway. The bottom end will also be wider making the front sprocket possibly poke more out of the left hand side meaning the engine might need mouting over to the right in order to keep the chain in line.

Get the engine on blocks, strip the frame and put it on top and see how things line up.

[Phoenix]

There was a guy a good few years ago who put an old Fireblade engine in a ZXR400 L chassis, he only rode it on track as far as I know so no stresses of crappy roads but after a very short period of time the frame snapped, presumably it was down to the added weight and increased torque of the engine. He welded and braced the frame afterwards and I didn't read any more issues after that but I didn't follow it for long. A B1H engine isn't going to make as much torque as a Fireblade but it's still a fair bit more than the 400 engine, no idea what the weight difference is though.

It might be worth getting some professional engineering advice though especially if it's going to be a road bike. Vibration differences could be another possible reason for damage to the frame, or difference in frame material and therefore movement/flex absorption etc engineering is complicated if done properly so just because things look fine and only weigh a few more kilos or move differently it doesn't mean it'll be ok. The difference in rider weights doesn't have the same effect as a change in engine weight, different stresses and distribution.

[Wafer_Thin_Ham]

How hard can it be?
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