GS450 to GS500

[Guest]

This winter is coming to a close and I didn't get everything done I wanted to. I have a 1981 gs450l. This past winter I shed as many pounds off the bike as I could, which resulted in a 48lb weight loss. The original 450 has several leaks and instead of rebuilding it i thought I might be able to get a 500 to swap in. I know that the 500 will bolt in with a custom exhaust, but my question comes with the fuel and electronics. Will the carbs and electronics from my 450 work on the 500? The other thing i discovered was that some of the gs500 engines use an oil cooler. do all 500s have a cooler or are there some that don't use an oil cooler? and if i am leaving anything out please chime in. thanks for your help

[Mekanix]

Here we go :P

All gs 400-500 bases are the same from 1980 on, Only a few things get upgraded over the years
Clutch pushrod
clutch cable drive
clutch itself.
a few seals and gaskets.
and a few other things.
. All upgrades are backwards compatible with all engine years.

Only big differences are the obvious ones. like head and block.

In 2006 they added a different bottom half that gives it ports for an oil cooler. and hey if you can get one of those, definitely go for that one.

Oh and the 500's as well as some E model 400 and 450's have a reverse shift drum so that you can run the shifter backwards instead of forwards.

All before that are the same.

Some 500's have the recirculation ports on the front that are easily blocked off.

Carbs for the 500 are better but yours will work with a few jetting changes.

Actually they are pretty close to what you already have.

The ignitor for the 450 is different but would work.

the difference is the advance curve.

The 500 has a curve that comes on later. IT stays less advanced until the engine is reving higher.

The 450 ignitor advances sooner than that. I think the 500 would be able to use your ignitor and your advance mechanism and actually like the sooner advance curve. OR you could just use all the 500's stuff.

It all bolts on the same way and you could just use tighter springs for the 450's rotor and it would do the same job as the 500's ignitor.



The 500's ignitor has build in advance and a staic rotor.

The 450 has a dynamic rotor and a static ignitor.

For the amount of work your doing to drop a 500 in there its way cheaper to replace all the gaskets and seals in your engine.
And the performance won't be that great in comparison.

To fit the engine in there and use the the pipes the way they are you could drop a 450 head on the 500 bottom end. You would have to measure the combustion chamber volume to see what the new compression ratio would be and adjust for that but it would work.

You could drop a set of 500 cylinders and pistons on yours and be good to go with less work.


I think I've answered this one quite a few times.

Check through my past post's and you'll find some good info for the 400-500's

[pete]

Yeah... what Mekanix said

Definitely get into his GS500 thread, all this stuff is covered off very nicely

[bwanna]

Just wanted to add my recent experience. I have an '82 GS450T and swapped in a GS500e cylinder head/pistons, using the 450 gasket below the block and the 500 gasket on the top between the valve head. Was concerned about the timing as the 500 block is about 1mm taller. However, the 500 gasket is much thinner than the 450 head gasket, so that seemed to balance everything out.

The results are great. I can feel slightly more torque on the low end and a little more pull going through the gears.

If you do this, you will need to also get a timing chain tensioner to fit the 500... it is different than the 450 tensioner.

Ride safe.

[Big Rich]

Signed up in this thread as well......

Bwanna, have any pictures of the motor in the frame?

[bwanna]

I can take some, but quite frankly you won't be able to tell the difference except for the small timing chain tensioner and the imprint showing the 487cc on the front.

Everything else looks the same.

Signed up in this thread as well......

Bwanna, have any pictures of the motor in the frame?

[Mekanix]

I can take some, but quite frankly you won't be able to tell the difference except for the small timing chain tensioner and the imprint showing the 487cc on the front.

Everything else looks the same.

The slots in the fins on the sides are really the only thing to notice.

[Big Rich]

I was curious as to how the fins looked. And......I'm too lazy to pull apart my 450, 500, or 650 motors to do so.

No worries gents. I'll see it eventually.

[pete]

I wish I had've thought about this while I was rebuilding mine...

[eran_k]

what about the exhaust ports, didn't you have problem with that?

[Mekanix]

what about the exhaust ports, didn't you have problem with that?

They are only using the cylinders, not the 500 head. The 450 head will give a a beter result anyways with the 500 cams.

[bwanna]

The exhaust ports lined up very well. However, I did have to loosen up the passenger pegs to slightly adjust the mounting plate to meet the two mounting bolts on the rear of the exhausts. It worked ok.

what about the exhaust ports, didn't you have problem with that?

[bwanna]

The fins look almost identical. The tensioner is different than the 450 being smaller in size. Personally I prefer the 450 tensioner regarding design and installation. The 500 tensioner takes a little bit more to install with smaller fingers being a benefit. I actually replaced the mounting bolts with hex head stainless steal. That made it MUCH easier to install.

I was curious as to how the fins looked. And......I'm too lazy to pull apart my 450, 500, or 650 motors to do so.

No worries gents. I'll see it eventually.

[Mekanix]

What are you talking about The P.O of my bike thought that a wood screw was the best thing ever for that

Don't use wood screws lol