1982 GS550 to 650 Rebuild

[Sci85]

Ok, so here's the background...Last winter I bought a non-running, flat black, 1982 GS550M for $380. I spent the winter rebirthing the bike. I did a complete tear down, frame powder coat, etc. Rebuild thread is here:

http://www.thegsresources.com/_forum/showthread.php?t=185189

So, after I got it all back together it ran but not real well. The only thing I did to the engine was set the valve clearance. It also pop out of 2nd unless you babied it in that gear. This summer it developed a bottom end knock. That coupled with the tranny issue meant I was in for a major rebuild at some point. Well, like probably most of you guys, I decided to go for the rebuild even though I've got way to much money in this thing already

So, looking for a little more ponies, I bought and attempted to swap in a GSX 600F motor in. Well, it fit in the frame but the rear of the engine was way more compact than the 550 so getting the sprockets to line up was not going to happen without major frame surgery and that was not going to happen.

Anyway, so I decided to do a 650 head swap onto the original 27K mile 550. So i pulled the engine a couple weeks ago and found the the crank was rubbing against the case on the stator side as well as at least a 1/4 inch gap on 2 of the rod big ends. Dang! A new crank was now on the list...

At this point I'm contemplating cutting my losses and moving on. Fortunately my luck was about to change. I managed to sell the carbs I bought for the GSX 600 for almost what I paid for the 600 motor, oil cooler, starter, generator and header. So that was good. I used that money to buy the 650 cylinder and a set of used pistons.

Then, I sold the 600 motor for twice what I paid! Things are really looking up now. Then just today, I found a complete lower end with tranny off a GS550L with only 390 original miles on ebay for $160.00. Yes, that's three six zero. At first I thought it was repainted it looked so clean until I read the description. Sweet!

All I have left to do now is find a good 650 head and some new rings and I will be ready to start the rebuild process. I plan on documenting as much detail as I can since the information about this swap seems to be distributed across a few different posts and is not consolidated or in depth enough for me.

I know everyone likes pics so here we go...

The bike!


No problem flossing here! This is the original 550 crank big ends.


Original upper case half...


Quick question - can anyone recommend a good machine shop in the St. Louis area where I can get new guides installed or valve work done?

[tkent02]

If your new engine is that good, I'd run it as a 550, at least until this winter.

No point in wasting riding weather over it.

[Sci85]

I heard that and if it was a complete engine, I might have done that but it's only the bottom end. Luckily all tha parts are coming in. All I have left to source is the 650 head, rings and gaskets. I figured I can get it back together in time for some good riding before it gets cold. And with the extra oomph from the 650.

Hopefully I can pull this off without mucking it up. I have never done a multi cylinder rebuild before!

[Sci85]

So, I got the new 550 bottom end in and it look amazing. The factory paint is still intact, the crank turns free and smooth, all the big ends are good and I'm stoked. I also bought the clutch from the same guy. The basket has ZERO marks on the clutch plate tangs. Amazing. I also got the 650 cylinder and head in which I've started to disassemble.

Here's the new lower end. Look how clean those journals are and how clean the starter cavity is!



And here I've started the necessary grinding required to fit the larger bore 650 Cylinder sleeves into the 550 lower half. I had to grind both the front and back as well as the sides to gain the needed clearance.



Tomorrow I hope to have the valves removed from the head and cleaned up.

[dark7068]

awesome, I will keep an eye on this one for sure. maybe if my parts aren't gone I will finish off what the PO started with the swap.

[Sci85]

Well, I've been busy collecting parts and knowledge. The lower end I bought was so nice I had to paint the top case and head so it wouldn't stand out so much. I also got all the valve seals off, chambers cleaned, new seals installed and head and cylinders painted. Tomorrow we start putting together the cases.

Removing the keepers and valves using the GS forum taught home made tool. Love you guys!


Cleaned up chambers and ports. I used a dremel with a soft wire wheel that worked great. Although the little wire wheels don't last very long beats scrubbing.


Freshly painted lower case half. I used Duplicolor high heat silver. Looks pretty close to factory.


Freshly painted head with all the valves resinstalled. Set aside some time when putting the valves back in. Getting those little keepers back on is a PIA. I ended up using a pair of self closing, long nose tweezers and globbing the valve stem with grease to hold the keeper in place. Regardless, it still took me a good hour to get them all done.



Freshly painted cylinder. I decided to go black on the cylinder to set off all the silver. I think it's gonna look good once it's all together.


And that's it for now. It's sleepy time and I need it...

[Sci85]

Okay, I've been busy getting all the parts I need for final assembly as well as learning and reading. I broke a piston ring the other day accidentally so now I'm down again for another week or so. I have gotten the bottom end together and everything ready for cylinder and head once the remaining parts come in. Feels like this is taking forever!

Bottom end done.



I still can't believe I got this lower end for $150 bucks with only 390 miles on it! Take a look at the stock oil sending unit. That's the original unit if you can believe it. Amazing!


While waiting on the parts so I can get the rest of the motor together, I decided the factory wheels just didn't suit me. So, out come the paint cans. Here's my initial color scheme on the front wheel. What do you think?



That's it for now. Thanks for looking and any feedback.

[Super]

Great work so far! And great pics too. Keep up the good work and looking forward to the end result.

[Sci85]

Ok, so I ordered the SH775 series regulator as a preventative measure since my bike still has the stock itty bitty unit and for 60 bucks, it's crazy not to right? Anyway, I needed to find a place to mount this honker since there was no way it would fit into the factory location. Since I will not be using the stock airbox, I fashioned a metal plate to replace the stock lid and mounted it to that. I think it will work nicely. I also ordered the Triumph connectors for 10 bucks which saved me some wiring time and this one is nicely made.

Hoping my rings come in today so I can get back to work on the engine!!

[Sci85]

More progress! After a ton of help from Suzuki_Don, I finally got the cams in, slotted, and degreed to 105/107 lobe centers. Engine in place finally. Finally! Everything was going smoothly until I went to put the left hand side cover on and noticed the clutch push rod was bottoming without hitting anything. Uh oh. I started a thread on that. Hopefully it's nothing major. Anyway, the mandatory pics...

[Caferacernoc]

Wheels and engine are looking great!

[Sci85]

Thanks man. This bike has really been a labor of love. I have a ton of time and money in it to date but I gotta tell ya, comments from the community really help. And, it's just one fun little bike so it's worth it. And yeah, that engine, at least the bottom end, was super clean. I still can't believe someone bought a gs550 and only put 390 miles on it over its life. Luckily I am the recipient of that preservation. Wish I could have gotten the whole thing though. The 650 head, pistons and cylinders was a pretty good find too. They only had 6k miles on them. So all in all, I've got an almost new motor now for basically 350 bucks including all new seals, Orings and gaskets. Great deals are out there if you are patient.

[Sci85]

Been working hard to get the baby Kat back on the road before the cold sets in but looks like I may be just a couple days too late. Temps dropping fast now. Doh!

Anyway, I got the engine all back together, carbs in, new filters on, 550 header expanded to fit the 650 port (need 650 exhaust gaskets still, using the 550's for now), electrics wired up, new R/R wired in, and attempted to fire her up but the battery was bad. Dang cheapo Walmart battery. Didn't even last a year. I also had to replace all the cover and oil filter gaskets as there were leaks everywhere.

So, went down and got a new 200 amps AGM battery (man this thing is HEAVY but it turns the motor like it was a single), squirted some ether into the new K&N's, and bingo! she fired right up. She actually ran pretty good considering I have no way to sync the carbs and the pilot and main jets are all that I changed (thanks for the advice Don!). She idles pretty decent enough. I did hear an exhaust leak on #1 due to using the smaller 550 gaskets instead of the 650's which are on order. Can't wait to get the final jetting set and the carbs synced (still looking for someone in STL area with a sync tool as I'm out of project funds). Sounds so much better than the jacked up 550.

I attempted to put her into gear and see if she would take off but for some reason, even though the clutch feels real good at the lever, she jumped forward and thankfully the garage wall stopped me haha. So, I gotta take a look at the clutch tomorrow and figure out why it's not engaging. I did put in a new one and a new clutch cable. Feels great at the lever though so not sure what's up with that. Hopefully just an adjustment is needed and I didn't forget something during reassembly. Here's the only pic I got today. Will post some more tomorrow.

[tkent02]

550 header expanded to fit the 650 port (need 650 exhaust gaskets still, using the 550's for now),

Can you explain this please?

[Sci85]

Sure. For some reason, Suzuki decided that the 650 heads exhaust hole needed to be physically larger than the 550's head even though the valve and actual port is the same size. So, assuming you are wanting to use a 550 header, which is what I have, you need to expand the header where it bolts up to the head. Also, the exhaust port gaskets are larger for the 650 head as well. I followed Suzuki_Don's idea which consisted of slipping a 1.55-1.6" OD pipe over the existing 550 header ends and welding them up. Don has pics in one of his threads on his rebuild. I will see if I can find it.