GS 450 into 400?

[Hexrod]

Hi folks! New member here, although long-time owner of Suzuki GSs. Still have my original 1977 GS400e with 35k on it.

Question: I have a line on a GS450 motor out of a wrecked bike, presumably from the 80s... Will this motor fit into the frame of my 1977 GS400?

Thanks for any advice!

Lee

 

[Guest]

I'm not a guy who has done it, but as far as I know the differences are internal and all the external aspects are the same. You will have to deal with the ignition being electronic and either move your old points plate and advance mechanism over, or better yet move the electronic ignition into your wiring system. That's assuming you get the ignition 'box' with the motor. The carburetors are the same, but the jetting will be a bit different so if you can get the carbs with the motor you're way better off.

I'm sure there's someone on the forum who has made the swap already and knows the fine details, but if you get as much of the peripheral components as you can - coils, regulator, fuel tap, and such - the better off you will be in the long run. I think the only twin motor that won't fit is the 500 and that's because of the exhaust system.

 

[Hexrod]

Thanks John! Supposedly the carbs and coil come with it - don't know what else. Will keep everyone updated!

 

[SVSooke]

I had a 2 valve 400 engine and a 4 Valve Canadian 400 side by side.The mount points are not the same,enough of a difference that you'd need to fab new mounting brackets.As far as I know the cases of the TSCC 4000 and the 450 are the same.

 

[tkent02]

If you do this, ponder the possibility of using GS500 pistons and cylinders. Easy bolt on displacement increase.

 

[Guest]

I had a 2 valve 400 engine and a 4 Valve Canadian 400 side by side.The mount points are not the same,enough of a difference that you'd need to fab new mounting brackets.As far as I know the cases of the TSCC 4000 and the 450 are the same.

Or maybe use the 450 brackets? This is my point; take as much of the 450 peripherals as you can get.

Unfortunately, I had a 400x and an original 400 frame sitting side by side in my shop but finally took the 400 frame to the recycle as it had been completely 'vultured'. Would have told the tale.

 

[Hexrod]

Well, false alarm! He's got a 4-cyl 550 motor, not a 450 twin. Ah well, thanks for your help! :>)

 

[Ric]

If you do this, ponder the possibility of using GS500 pistons and cylinders. Easy bolt on displacement increase.

If this can be done on a 400, you would have yourself a 516cc brute. B(

 

[Brandon77gs400]

I'm currently dealing with this exact issue. I have the chance to purchase a 87 450 for my 77 400 I'm wondering if the mounts, exhaust, and carbs all line up?

 

[Rensdw]

Haven't read all the posts but here is my 2 cents

The 400 engine cases are different then the 450 cases, I had my 450 frame modified to be able to put the GS400 bottom end in the frame.
GS500 cilinders will fit the 450 engine, but not the 400 engine since the stud spacing is different, camchain guides are different to.

Certainly not an easy mod!