• Required reading for all forum users!!!

    Welcome!
    Register to access the full functionality of the GSResources forum. Until you register and activate your account you will not have full forum access, nor will you be able to post or reply to messages.

    A note to new registrants...
    All new forum registrations must be activated via email before you have full access to the forum.

    A Special Note about Email accounts!
    DO NOT SIGN UP USING hotmail, outlook, gmx, sbcglobal, att, bellsouth or email.com. They delete our forum signup emails.

    A note to old forum members...
    I receive numerous requests from people who can no longer log in because their accounts were deleted. As mentioned in the forum FAQ, user accounts are deleted if you haven't logged in for the past 6 months. If you can't log in, then create a new forum account. If you don't get an error message, then check your email account for an activation message. If you get a message stating that the email address is already in use, then your account still exists so follow the instructions in the forum FAQ for resetting your password.

    Have you forgotten your password or have a new email address? Then read the forum FAQ for details on how to reset it.

    Any email requests for "can't log in anymore" problems or "lost my password" problems will be deleted. Read the forum FAQ and follow the instructions there - that's what we have one for...

  • Returning Visitors

    If you are a returning visitor who never received your confirmation email, then odds are your email provider is blockinig emails from our server. The only thing that can be done to get around this is you will have to try creating another forum account using an email address from another domain.

    If you are a returning visitor to the forum and can't log in using your old forum name and password but used to be able to then chances are your account is deleted. Purges of the databases are done regularly. You will have to create a new forum account and you should be all set.

GS550 with 650 Block Project

  • Thread starter Thread starter msdosp1mp
  • Start date Start date
M

msdosp1mp

Guest
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
 
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.
 
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.
 
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
 
msdosp1mp said:
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
Click to expand...

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.
 
msdosp1mp said:
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.
Click to expand...

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.
 
Last edited:
Do you have the part numbers for the circlips and wrist pins? I couldn't find them on the fiche.
 
brveagle said:
You can reuse the wristpins, they are the same.
Click to expand...

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.
 
Last edited:
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
 
What size pistons do you have? Have you measured the bore yet? How come you didn't get the wrist pins with the pistons?
 
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?
 
msdosp1mp said:
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?
Click to expand...

No problem. That sounds right on track to me.
 
Suzuki_Don said:
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).

.
Click to expand...

Hmm, I stand corrected.
 
Also don't forget to change the camshaft sprockets. You can use either the 550 or the 650 cams in the 650 head. The 550 cam might have a bit more timing as they are an earlier camshaft. By '81 they were pulling back on the timing with EPA and all that. Whichever shaft you use you MUST use the 550 camshaft sprockets. They have a different number of teeth to the 650 sprockets. From memory the 550 is 30 teeth and the 650 is 32 teeth.
 
In that case, I'm going to use the 550 camshafts, as they seem to be in perfect shape for a 34k mileage motor. Are you using the stock exhaust/airbox on your setup?
 
msdosp1mp said:
In that case, I'm going to use the 550 camshafts, as they seem to be in perfect shape for a 34k mileage motor. Are you using the stock exhaust/airbox on your setup?
Click to expand...

The stock exhaust will fit OK. I am using a 4-1 which was on the bike when i got it. Use new exhaust gaskets.

The stock airbox will not fit as you will have to fit 32mm CV Mikunis to the 650 head and the airbox rubbers are too small to fit over the CV air intakes.

Buy an airbox off a 650E model and it will bolt straight onto the frame and your airfilter box will line up with it perfectly. No probs. DO NOT buy one from a 650G (it is totally different and will not fit).
 
I've already got a 4 in 1 pipe thats going to be used, but what are my options as far as individual filters? I'd really like to run the APE 005-121 as a first preference due to price, but the K&N RC-2344 seems to also be a good size. No EMGO for me :) What did you have to go through with the carburetor jetting? Dynojet?

http://gszone.biz/carbs.html APE

http://www.clemmonstrading.com/servlet/the-33381/K&N-RC-dsh-2344-(4)-2-dsh-1-fdsh-8/Detail K&N

More questions soon to follow I'm sure

Thanks everyone,
William
 
Some jetting changes will need to be made if using POD filters. I am using the stock air filter system with original foam filter so no rejetting for me.
 
You must log in or register to reply here.
Back
Top