Bigger engine for 85 GS550E? What will fit?

[NoBars]

I have always thought this would be a cool swap, the tricky part if I remember correctly is having enough room for the carbs, that is why 2 barrels were used originally.

[dogal123]

Hi Guys have just found this thread and I'm glad I have. I was thinking on putting my GSX750 engine into a GS750 frame which I have just bought, and it looks from this thread as if it will fit:-D Cm113 if i can ask, you mentioned you had put additional bracing on the frame, if you did could you give more details please, it would be much appreciated, also did you weld on other mounting points. I'm going to try and build a real cafe racer style bike.Thanks!

[cm113]

As far as putting the engine in the frame, there are no additional mounts or braces needed. I used all the stock mounting locations from the frame and made brackets/spacers to mount to the new engine. You would be suprised at how similar these engines are once you started measuring. Plus the weight savings is incredible. I can place and pull the late model 750 engine by my self. However, I can't pick up the GS550 engine without serious problems with the old back:-|

Mine will also be a cafe styled bike when completed. So I want it to handle as well as possible. That is why a braced the frame (added gussets, etc.) Anywhere that looked like there would be stress, I added a brace (if I had room). All this braceing should help the chassis feel alittle more planted when the speed goes up. Plus, my 550 frame was built with the idea that a 40+ hp engine would be setting in it. I figure if I more than double the hp, the frame would need some extra bracing to stiffen it up.

You have alittle bit a room once the engine is in the frame. So you can place the engine in crooked if your not careful. Basically it comes down to getting the engine position that allows for the sprockets to be aligned, the header to fit and the gas to clear as best it can. Yes, there is some problems getting the carbs to fit on with a stock tank. My tank will modified for knee pockets anyway so that won't be a problem. From the pictures of the other bike on this thread, it appears that type of tank my have more clearance than the one I am using? One other thing, on the 550 frame, I have to pull the oil pan to get the 750 engine in or out of the frame. Since you don't pull the engine very often, this is not a problem either.

hope some of this helps.
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[dogal123]

Yes it helps a lot. Much appreciated. I have a GSX750F and I'm planning on transfering the engine and front end to the GS750b frame, I know there's a bottom head stock bearing change required, also have a katana twin shock swing arm which will fit, and I'm going to flip the clip ons and get them machined, so it has the distinctive low handle bars, thats the plan any way :-D no doubt it will have changes along the way. Thanks again for the info.

[cm113]

Actually, If I am not mistaken, the GS750 used the big bearing on the bottem of the steering stem. If so, that is the same bearing your GSX750F uses. Should be a direct bolt up and go swap. I could be wrong?

later,
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[cm113]

Just wanted to post a progress pic of my little hybrid cafe racer. Engine is going in today (GSX-R750). Still not decided on a tank yet or a color for the wheels, but it is starting to shape up. I am thinking a '78 GS400 gast tank to get a more narrow profile? And I have also thought of a early '80's GS1100 tank with the knee pockets? Also still looking for the perfect set of rear shocks. Want some that look retro, but are still functional (and are 14" eye to cleavous). See what ya think.

later,
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[Tarbash 27]

How about an RG500 motor??!!!!!!!!

Good luck with the exhaust on that, let alone finding one of those motors

[Nerobro]

I've always wondered about a GT750 or a GT550 motor.

[johnnay]

dunno how I missed this thread - good job on a great idea - you might want to look at ZRX shocks, I believe they're 14". I'd go outside and measure exactly for you, but it's snowing and I'm a wuss...:-D

[Nerobro]

Brveagle and I both have ZRX shocks on our GS550's already.

I think I may have started the trend ;-) they're L O N G. I'll measure them tonight for ya.

[cm113]

Thanks.

I have thought about the ZRX shocks and that was my original plan. However, my swingarm is off a 81 GS1100 and requires the cleves (sp?) mount on the bottom. A set of a Honda CB750 supersport (later model) would work great, or a cbx. They measure about 14.25" which is about what I need. Unless someone has a neat way of attaching to the cleves mount on the bottom (and keeping the shock close to the frame), I guess the ZRX shocks are out

Have a good one.
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