swap a gs400 engine into a gs450

[Guest]

Wow that looks good wera90ex I meant it would not be a direct swap on with little work. But anything is possible!

I thought about using the whole gr top end. As in: taking the cylinder block and pulling the sleeves out. Shorten the block on the bottom end about 8mm and deck the head as much as possible to compensate for the big combustion chamber. Use the GR pistons and get it all to work and look like it was made like that
Then I decided to just take the sleeves and go camakazy 4 valve on it :P


What happened with the timing chain and the extra long center channel on the GR head ?
Was it long enough ?
Did you have to weld up the front and back of the head ?
How did the crank hold up?
Did you do anything to the top end oil jets ?
what CP ratio did you end up with ?
How was the vibration with the new pistons
How hot did it run ?

Keep the info coming, I'm really interested in everything you did there

[jfman]

WERA90X: got pix of the trackbike?

[wera90ex]

Wow that looks good wera90ex I meant it would not be a direct swap on with little work. But anything is possible!

I thought about using the whole gr top end. As in: taking the cylinder block and pulling the sleeves out. Shorten the block on the bottom end about 8mm and deck the head as much as possible to compensate for the big combustion chamber. Use the GR pistons and get it all to work and look like it was made like that
Then I decided to just take the sleeves and go camakazy 4 valve on it :P


What happened with the timing chain and the extra long center channel on the GR head ?
Was it long enough ?
Did you have to weld up the front and back of the head ?
How did the crank hold up?
Did you do anything to the top end oil jets ?
what CP ratio did you end up with ?
How was the vibration with the new pistons
How hot did it run ?

Keep the info coming, I'm really interested in everything you did there

That cam chain tunnel was the first thing I thought I'd have problems with. It's JUST on the edge. Didn't weld anything.
I just used the 450/500 timing chain with the 450/500 sprockets.


Cranks held up just fine. The key to keeping the crank in good shape is don't over rev. It will break on the right side rod journal. Only had 3 break in 25 yrs. My fault entirely.
Kept the same oil jets. They're just for crank/rod bearing pressure anyway.
On CP ratio, I don't really know. Never bothered to figure it out.
I was more concered with lifting the head/cyl off the bottom end due to stud stretch. Which at street speeds it's probably not too much an issue but at the track your WFO.Used APE studs.
Vibration isn't a problem. Even with the 83 mm pistons. Only vibration problems I've had is when I removed the balancer. Don't do it. That motor will want out. Ran great! But broke the frame.
Heat: It gets hot as hell but never melted anything. Even when I used some $25 a gal. dragon **** for fuel.
When I've put all the different combos together I normally clay the top end to make sure everything is going to fit. Degree the cams and double check piston to valve clearances. Don't really worry too much about the bottom end they're so over built. But that's one of the things I love about these bikes.

[wera90ex]

WERA90X: got pix of the trackbike?

This one s got the GR cams in it. Use it to teach at track schools.

[wera90ex]

Here's a different race bike. Don't use it much.

[wera90ex]

My business card.

[wera90ex]

warning! warning! Just remembered something, if you use the GR 650 pistons in the 450/500. You have to fly cut the pistons for valve clearance. Nothin' big ,about what you have with a GSX400 piston.
Also, You'll have to shave some under the wrist pin to clear the crank. I'm sure I have some pics somewhere I just have to find them.
Sorry,Some of these mods were done 20 years ago and it's a bit hard to remember. Don't worry, it'll happen to you youngins too. Your mind will turn into a fine kitchen tool.....................a sieve. RG

[Guest]

What was the best combination you've made ?

[jfman]

sweet bikes!

You need to stick around some more as theres many things we can learn from you.

[wera90ex]

What was the best combination you've made ?

The white GS 500 was the best all around performer.
'02 gsxr 750 front end,3.5 wheel,'92 GSXR 600 aluminum swingin' arm/w Penski shock,600 lb spring,4.5 wheel, 555cc motor w/.417 megacycle cams,shim under and 39mm Keihin CR specials with Yoshi exhaust.
As much as I loved ridin' this bike it just wasn't fast enough for the tracks I was riding and the classes I was running in.

[Big Rich]

warning! warning! Just remembered something, if you use the GR 650 pistons in the 450/500. You have to fly cut the pistons for valve clearance. Nothin' big ,about what you have with a GSX400 piston.
Also, You'll have to shave some under the wrist pin to clear the crank. I'm sure I have some pics somewhere I just have to find them.
Sorry,Some of these mods were done 20 years ago and it's a bit hard to remember. Don't worry, it'll happen to you youngins too. Your mind will turn into a fine kitchen tool.....................a sieve. RG

Sorry I'm late to this thread, but what interferes with the GR pistons exactly? I'm not sure I'm understanding why there would be valve clearance issues.

[Guest]

Wow how did I miss this thread???!!!

Wera... mate I love your business card... which combination is that one?

[jfman]

Why is it that the whole GR650 motor doesnt work?

What does the GR650 actualy share with a gs500/450/400?


Also about the GS 500 engine: mekanix said the shift drum is reverse, wich doesnt bother me it would have built-in GP shift. BUT is the rest of the stuff compatible(besides the head) the electronics are compatible or do the old electronic bolt into a gs500? the cases are the same and they will mount up?

[Guest]

Why is it that the whole GR650 motor doesnt work?

What does the GR650 actually share with a gs500/450/400?


Also about the GS 500 engine: mekanix said the shift drum is reverse, wich doesnt bother me it would have built-in GP shift. BUT is the rest of the stuff compatible(besides the head) the electronics are compatible or do the old electronic bolt into a gs500? the cases are the same and they will mount up?

The GR motor doesn't bolt right up and its too tall to fit in the frame.

But if you want to make it fit there are ways

It doesn't share anything really except for the camshafts and sprockets. Those can be easily swapped out to any of the other bikes but the cam profile isn't that great. Its got lift but really low duration compared to the 500.
Maybe a few bolts are the same but for the most part its a one of a kind beast.

The gs twin base after 1980 is the same up until 2004. Same case and parts. Although some are upgraded a bit with better bushings. The clutch was upgraded and the pushrod was made a two piece.

2004 + have a different lower case to allow for an oil cooler.

The shift drum is one difference, but really it doesn't matter but you do have the choice of which ever one you want to go with.

The oil pump on the 500 got new higher ratio gears for more pressure/volume.

The electronics are a one or the other kind of thing. Use the mechanical advance with the ignitor that doesn't do the advance. Or use the stationary rotor that has the advance curve built into the ignitor. The only difference between the 500 and any other one is how soon it advances. But you can put the plate on any twin 80+ engine and it will fit and bolt up like it was stock.

That means that the gs500 ignition and parts are a direct replacement and upgrade for the gs400-450.