GS550 with 650 Block Project

[msdosp1mp]

Hello all, I've decided that it would be best to talk about this here, instead of under "Technical Info".

What I've got is a 1977 GS550B with 34K well maintained miles on it. I read something on here about installing a GS650E cylinder block and pistons on top of the GS550 crankcase. I have the correct pistons and jug, but am still trying to determine if its possible to use the 550 head, or if I should find a 650 head as well. Also, what carburetor choices are available to me at this point? And, do the 550 wrist pins and clips work with 650 pistons.

I want to do this on a budget and keep it realistic too.

Any input is GREATLY appreciated.

Pistons: 50 bucks for all 4
Block from low mileage GS650E: $35

[Suzuki_Don]

I have replied on your other thread about the head and wrist pins.

The only carbs to use are the CV BS32SS constant velocity type. They were used on all 550, 650, 750 and 850 motors from 1980. Although the jets and needles will be different in each case. Best to pick up a set off a GS650. Be aware that the GS650G and the GS650E have different jets and settings. So if you pick up a set off a "G" then rejet to the "E" specs.

The VM type carbs that are currently on your 550B will not fit the 650 head. I have done the swap too.

[msdosp1mp]

Where might I find a set of compatible wristpins and clips? I've tried ebay, but don't really feel like purchasing an entire set of used pistons and such.

[tkent02]

They are available from Suzuki or any of the online vendors.

[msdosp1mp]

I'm going to probably ask a bunch more questions as this goes on, but are the valve covers the same for the 550 and the 650? I'd like to retain as many parts as possible.

Thanks,
William

[Suzuki_Don]

I'm going to probably ask a bunch more questions as this goes on, but are the valve covers the same for the 550 and the 650? I'd like to retain as many parts as possible.

Thanks,
William

It depends which 650 head you use. Halfway through the production run on the 650 they changed the head slightly to accommodate a different valve cover with an extra bolt near the front cam chain run to stop a weeping oil leak that used to develop on the 550 and early 650 heads. If you use the early 650 head then the 550 valve cover will fit. no probs.

BTW don't use 2nd hand (used) circlips in your pistons. You MUST use new ones.

[brveagle]

Where might I find a set of compatible wristpins and clips? I've tried ebay, but don't really feel like purchasing an entire set of used pistons and such.

You can reuse the wristpins, they are the same.

bikebandit has the clips.

I have done this swap before.

use the 650 head and make sure you use a 650 head gasket. In all honesty, It's easier if you buy a 650 top end/motor complete.

Also, there will be some dremeling that you will need to do to get the sleeves to slide completely down into the cases. But don't worry, it's just minor.

[msdosp1mp]

Do you have the part numbers for the circlips and wrist pins? I couldn't find them on the fiche.

[Suzuki_Don]

You can reuse the wristpins, they are the same.

Don't like to disagree, but the wrist pins are not the same. The bore on the 550 is 56mm and the 650 is 62mm, so the wrist pins are different lengths and have different part numbers.

The part number you need for the 650 wrist pins is 12151-67001 (550 is 12151-08001).

The circlips are the same part on both motors. Part number 09381-16001.

Use the wrist pins that came with the pistons. If you don't have pistons yet then purchase the 1mm oversize ones and bore the cylinders accordingly to acieve a 700cc capacity with a six speed transmission.

[msdosp1mp]

Thank you for looking up those part numbers for me, is there a better way for me to go about doing that? I've already got the jug and the pistons, but just lacking the rings, wristpins, and circlips.

How are yall's bikes configured?

Thanks again

[Suzuki_Don]

What size pistons do you have? Have you measured the bore yet? How come you didn't get the wrist pins with the pistons?

[msdosp1mp]

I have a low mileage jug thats a standard bore, and I got some NOS STD pistons that didn't come with pins or circlips. I'd like to just hone the bore and stick the standard size pistons in. Is that going to be a problem?

[Suzuki_Don]

I have a low mileage jug thats a standard bore, and I got some NOS STD pistons that didn't come with pins or circlips. I'd like to just hone the bore and stick the standard size pistons in. Is that going to be a problem?

No problem. That sounds right on track to me.

[msdosp1mp]

So I started tearing the motor down yesterday. I've also stuck my carburetors on ebay for anyone who's interested. Here are some pics.

http://s111.photobucket.com/albums/n153/msdosp1mp/GS550%20Rebuild/

Thanks for all of the assistance!

[brveagle]

Don't like to disagree, but the wrist pins are not the same. The bore on the 550 is 56mm and the 650 is 62mm, so the wrist pins are different lengths and have different part numbers.

The part number you need for the 650 wrist pins is 12151-67001 (550 is 12151-08001).

.

Hmm, I stand corrected.