82 GS650G with lots of problems

[Guest]

First I want to say thank you for all the help I've already gotten from this forum. It's been extremely helpful as I now come here before a project rather than using the Clymer manual.

This thread is going to follow my attempts to repair the numerous problems I'm having with an 82 gs650g. So far the list of repairs needed includes

• Rebuild top end of engine
• Cleaning and rebuild of carbs
• Cleaning and lining of gas tank
• Petcock repair
• Replace/repair exhaust
• Seat repair
• Side cover replacements
• Upgrade Electrical system - Long term

I'm already well underway with the project. The tank, carbs, and cylinder head are all off the bike. The carbs have been disassembled and have been taking their turns in carb dip. I've spent hours fishing strange plastic bits out of the tank. And I've bought a replacement cylinder head as mine didn't come off the bike in the greatest of shape.

Which brings me to my current issues which is rebuilding the 'new to me' cylinder head. Sense it's from a different bike I think it's best to just do a full removal of the valves, inspect the seats, etc. I've seen several post on here about doing valve work and they usually say the the manual is a bad example to follow, I tried to watch the valve video on Bikecliff's site but the link is dead. Is there another guide around for doing valve work?

[MechMessiah]

Petcock rebuild for 82 650 pt1

I had some free time this past weekend to do a little bit of work on the bike. Rebuilding the petcock is one of the first things I tackled mostly because I didn't have much time and it seemed like a pretty quick job. I discovered that the petcock was bad when I removed the carbs for cleaning and I couldn't shut off the gas flow. Every position on the petcock let gas free flow from the tank.

I know the standard suggestion is to just replace the petcock with a new one when it goes bad, especially sense you can't buy replacements filters separately. But my filter is still in good shape so I'm gonna take a stab at the rebuild.


So I'm starting with the tank already drained and off the bike. Removing the petcock is pretty simple as it's only held on with two bolts.


Now that you have it removed from the tank the next step is to remove the old filter. Now these filters can't be bought separately anymore so If you're filter is still in good shape and can be reused be careful with this part. The filter comes out if you pull straight up but can sometimes get stuck from rust, in that case just wiggle it back and forth a bit until in slides out.


Once you have the filter off you can look down where it was and see the plastic valve the controls the flow of gas. Be sure to note the location of the hole in the valve with the position of the switch\lever on the front of the petcock.


Next you'll want to use a small pair of pliers or flat head screw driver to gently pry up the clips that hold the switch in place.


After the clips have been released you can pull the switch from the main housing. Be careful as the switch is spring loaded. If you have trouble getting the plastic valve out try this, remove the spring and O-ring from the switch and then put the switch back in the housing and turn the valve between the Reserve and Prime positions and that should loosen it up so that it just falls out.


With the front half disassembled now you turn to the back half with the vacuum diaphragm. All you need to do is remove these four screws.


Be careful for another spring that is loaded behind the vacuum diaphragm.

End part 1.

[MechMessiah]

Petcock rebuild for 82 650 pt2

Start part 2.


Now it's time to rebuild! And while you have the whole petcock disassembled it's also a good time to clean it up. I soaked mine in carb dip for a bit and used an old tooth brush for the caked on stuff.


I started the rebuild with replacing the top O-ring. As soon as I finished putting it on I realized that it probably would have been best to wait sense I'm not putting it right back on the bike. Oh well.


Next I replaced the O-ring for the switch. I always use a little oil to help install new O-rings.


With the new O-ring in place reassemble the whole front valve in it's proper order and install back into the petcock.


Now replace the old gasket and vacuum diaphragm with the new ones and install the spring between the new diaphragm and backing plate. Then just screw the back of the petcock onto the main housing.


Now all that's left is to put your fuel filter back on. Here's a before and after of how mine turned out.


Sense I still want to clean and line the inside of the gas tank I'm gonna keep this guy in my favorite storage and organizational devise, a ziplock bag! I seriously love using these things. I have my whole 650L, that's being completely rebuilt, in these.

Well that's it for my first update on this project. I also had time to pull all the valves from the used cylinder head I got off ebay so that will be my next update.

[Steve]

The tank, carbs, and cylinder head are all off the bike. ... And I've bought a replacement cylinder head as mine didn't come off the bike in the greatest of shape.

You did not mention whether you removed the cylinder block. You should. Removing the head, no matter how careful you are, will disturb the seal on the base gasket. It would be a shame to get it all put back together only to find the base gasket leaking and you will have to tear it all apart again. If you got a complete gasket kit, you already have the gasket. If you don't have a kit, it's only about $10 for the gasket. Compare that to the $200 or so for another OEM gasket kit, not to mention the time and effort involved.

Is there another guide around for doing valve work?

The valve removal guide is one that needs to be updated, anyway. My son and I made that video, which showed a piece of PVC pipe that had a window cut in it for access to the valve keepers. I have since updated my tool to a 24mm deep socket (3/8" drive) that has about 1/3 of the skirt cut away for keeper access. Use a 6" C-clamp and the socket to push the valve spring retainer down, remove the keepers, release the clamp. Repeat as necessary.

Installation is just a little more than the usual reverse procedure. I put a dab of grease on the inside of the keeper, then use a pencil magnet to hold the keeper while I put it up to the valve. I then use a hooked scribe to push the keeper into place. Slide the keeper around to the back side of the valve, repeat with the other keeper. The dab of grease holds them in place until you can release the clamp.

I know the standard suggestion is to just replace the petcock with a new one when it goes bad, especially sense you can't buy replacements filters separately. But my filter is still in good shape so I'm gonna take a stab at the rebuild.


So I'm starting with the tank already drained and off the bike. Removing the petcock is pretty simple as it's only held on with two 10mm bolts.

Those are actually 6mm bolts with 10mm heads, so be careful with your terminology when going to the hardware store.

Not sure that I see the proper washers under the bolt heads. They might be proper, it's hard to tell. There should be a washer with a rubber lining in the hole that helps seal the bolt head to the petcock.
There is a name for that type of washer, but I can't remember it. You might be able to find them at a GOOD hardware store.

Here's a before and after of how mine turned out.

The generally-accepted success rate for a petcock rebuild is about 10-15%. With the apparent care (and documentation) that you have shown, I hope that you are in the "successful" few.

[BigD_83]

That's a nice writeup.

It appears the petcock is in okay shape; I thought it might be soft and cheesy internally based on its outward appearance.

if you can't find the proper gaskets for under the petcock bolts at a hardware store, they are available through parts vendors. I believe they run in the $4.00/ea range. They might be less in the US market.

[MechMessiah]

You did not mention whether you removed the cylinder block. You should. Removing the head, no matter how careful you are, will disturb the seal on the base gasket. It would be a shame to get it all put back together only to find the base gasket leaking and you will have to tear it all apart again. If you got a complete gasket kit, you already have the gasket. If you don't have a kit, it's only about $10 for the gasket. Compare that to the $200 or so for another OEM gasket kit, not to mention the time and effort involved.

I have not yet removed the cylinder block. I was really hoping I wouldn't have to as I didn't want to deal with the piston rings but maybe it would be best.

The valve removal guide is one that needs to be updated, anyway. My son and I made that video, which showed a piece of PVC pipe that had a window cut in it for access to the valve keepers. I have since updated my tool to a 24mm deep socket (3/8" drive) that has about 1/3 of the skirt cut away for keeper access. Use a 6" C-clamp and the socket to push the valve spring retainer down, remove the keepers, release the clamp. Repeat as necessary.

Installation is just a little more than the usual reverse procedure. I put a dab of grease on the inside of the keeper, then use a pencil magnet to hold the keeper while I put it up to the valve. I then use a hooked scribe to push the keeper into place. Slide the keeper around to the back side of the valve, repeat with the other keeper. The dab of grease holds them in place until you can release the clamp.

Thanks for the info but the Clymer manual was good enough for this one. The only tricky part was getting those old seals out.

Not sure that I see the proper washers under the bolt heads. They might be proper, it's hard to tell. There should be a washer with a rubber lining in the hole that helps seal the bolt head to the petcock.
There is a name for that type of washer, but I can't remember it. You might be able to find them at a GOOD hardware store.

Seems like those were lost by a PO. Sounds like a great idea though. I'll pick up few when I can.

The generally-accepted success rate for a petcock rebuild is about 10-15%. With the apparent care (and documentation) that you have shown, I hope that you are in the "successful" few.

Me too man!

[MechMessiah]

Valve Removal 82 gs650

Sense the petcock didn't take much time to rebuild I also had time to pull all the valves from the cylinder head I got off Ebay. I had to buy the replacement head after 5 bolts snapped and one threaded insert came completely out. Buying a replacement head was the cheapest option for the repair.

With a proper spring compressor the job is pretty quick and easy. One thing to keep in mind before you begin is that you'll want to keep all the components of each valve assembly together and to avoid mixing parts so it's important to have a way to keep things organized. My personal preference is Ziplock bags.


With the cylinder head already off the bike the first step is to pull the valve bucket/tappet. I used a small flat head for electronics under the shim to lift the bucket just enough so I could get a grip with my hands.


With the bucket out of the way you can now place the spring compressor on the valve.


Once the spring compressor is on simply turn the handle of the compressor until the spring is depressed far enough to let the two keeper halves fall out. Use a pair of needle nose pliers to grab the keeper halves through the windows on the compressor tool. After you have the keepers you can remove the compressor tool or set it up for the next valve.


When the keepers fall away from the valve stem during the last step the valve it's self may fall right out of the head, it may also stay in the head. If it stay in just give it a little push downward and it will slide right out. Just be ready with something to catch them either way and keep their fall to a short distance.


Now pull out the spring retainer and both valve springs. Make sure to take pictures or note the direction the springs came out as they will need to go back in the same direction. If you look at the springs you will notice that they are coiled more tightly at one end then the other. This is what you need to be aware of.


The next step is to remove the old oil seals. These are not reusable so don't worry about damaging them. They can be quite tricky to get off. The trick is to use a pair of needle nose pliers and grab onto the shoulder of the seals. Then twist it in a circular motion to break the old seal loose. Once it is lose you can simply pull the seal straight up and off.


With the old seals out of the way you can now lift the spring seat out from the bottom of the valve shaft. Grab your needle nose pliers again and use them to simply lift the seat straight up and out.


Now just repeat the process for the rest of the valves until you have an empty cylinder head. And remember to keep the parts of each Valve assembly separate.

Well that's it for this update. Next order of business is to get all these parts cleaned up.

[MechMessiah]

That's a nice writeup.

It appears the petcock is in okay shape; I thought it might be soft and cheesy internally based on its outward appearance.

Thanks, man. It's actually two different petcock's though. The rebuilt one started in much better shape.

[MechMessiah]

Valve Lapping

I've got the head and valves all cleaned up now and ready for the next step of lapping the valves. Here's the first one ready to go.



I'm going to use the DIY breather hose idea from cowboyup3371 on bikecliff's site. It's really easy to make and works great.


Here's the first valve again now with some fine grain lapping compound around the face and oil on the stem.


Next you place the valve back in its journal and then place the DIY tool against the bottom of the valve and start the drill. It's really helpful to use a finger on your free hand as a kind of backing plate for the spinning valve.


It should only take a short time to lap the valves. If you spend more than a minute or two without seeing much results then replacements might be a better option.


So that's one valve done and 7 more to go.

[MechMessiah]

Bad Valve Cylinder

Well after I finished lapping all the valves and moved on to reinstalling them in the head I ran into a little problem. The last shim bucket I put back seized up and would not come out or even spin in place. So I pulled all the other valves again and found the last vehicular machine shop in Baltimore and dropped the head off. A few days later I picked up the freshly separated parts from the shop and got to work on the head.


My solution was to find a socket that was slightly smaller than the bore of the valve cylinder, and tape some 400 grit sanding paper to it using double sided tape. Then I attached the socket to my drill.


I worked the socket in a circular and up/down motion along the cylinder walls to try and keep an even bore. I only ran the drill for short burst of 15 sec or so and kept checking the bucket in the bore to keep from over doing it. Once I had the bucket sliding and spinning like all the others I switched the sand paper with some cloth and grabbed the shop vac to clear all the dust. It worked out pretty well and now I finally have a fully assembled cylinder head!

[MechMessiah]

General update 6/30/16

I've finally had the time and money to make some real progress with this bike. I've got the the Cylinder Head, Chain Tensioner, Petcock, and Carburetors cleaned and rebuilt. Well, I do still need to replace two Float Bowls for the Carbs due to the drain screw threading being bad on them.



I also was able to fabricate some plugs for the gas tank so I can de-rust it. I'm hoping they'll be reusable sense I also have to de-rust the new tank I got for my other 650 that's going through a full rebuild. I still need to do a bit more research though before I'm ready to tackle the gas tanks.



So the next update is gonna be a little out of order. Just realized that I didn't cover pulling the Cylinder Block. Oh, I've also decided to add one more repair to the list. I'm gonna drop the oil pan so I can make sure there's no surprises sitting at the bottom.

[MechMessiah]

Pulling/Inspecting Cylinder Block

Pulling the Cylinder Block is pretty straight forward and easy. The main things to look out for are dirt or the Cam Chain falling into the Crank Case. The Cam Chain isn't as big of a deal as you can hang it from the frame but if it does fall down you can fish it out with a paper clip. The dirt is a bit trickier. I like to use a shop vac to help keep the dirt and old gasket bits from falling down. If you have some small attachments it can get any dirt/gasket that does happen to fall down and land on the ledges in the case, like the cam chain compartment. However it is just best to thoroughly clean the engine before hand.



So if you already have the Cylinder Head off grab a rubber mallet and knock the block a few times to break the seal with the old base gasket. Once the seal is broke and it's lose just lift it up, with an occasional wiggle now and then until you're clear of the studs and pull the cam chain out. That's it.



After the Cylinder Block is off you'll want to stuff some clean rag in the Crack Case openings around the Pistons and Cam Chain. If you're leaving the Pistons on at this point you may need to rotate the Crack Shaft to get enough room to stuff the rags in.



My first priority after getting the Cylinder Block off was to check the Piston Rings and Cylinder Walls. All of the Piston Rings were in fantastic shape, well within the specs!



As for the Cylinder Walls, I think they look good. But to be honest I'm not really sure. This is the deepest I've ever been into an engine so if anyone with more experience wants to chime in feel free. If they do need to be honed I could also use a recommendation on the type of flex-hone to get. 64mm seems the best size for these cylinders, and 320 grit is the most common mentioned on this site but what abrasive material should it be?

I really want to get this engine back together soon rather than later. I don't have a garage and keeping this thing outside with the engine insides exposed just makes me uneasy, especially since Baltimore has very humid summers. I've got it wrapped up as best I can with two trash bag over the engine and two covers on the bike plus the rags in the crack case. I was hoping to have the thing back together by the 4th but a major F-up by my bank kept my finances in limbo most of this month.

[MechMessiah]

General update 07/05/16

So much for getting the top end back together quickly. My parts order that included the wrist pin circle clips got delayed due to a few other parts on the order being back ordered. I guess I can use this time to focus on the Gas Tank which I've paid very little attention to so far. I'm planning to use common White Vinegar for de-rusting the tank. I picked up 4 gallons a couple weeks so I think the only other thing I should need at this point is baking soda to neutralize the acid of the vinegar.

[MechMessiah]

Piston & Cylinder Installation

I finally got my parts order in and have been making some real good progress over the past few weeks. I also got a lot work done on the gas tank while I was waiting on the parts, but more on that later. For now I wanna get this engine back together.



So the first order of business was pulling the pistons. That went pretty easy with a small pair of needle nose plyers to get the circle clips out. The wrist pins came out without much fuss either. The ones that didn't slide right out just needed a little coaxing with a deep wall socket that was a little smaller diameter than the wrist pins.




Here's the piston all cleaned up and re-ringed. I was able to reuse the old rings as they were all well within the specs. You can also see my plans for ring compressors, just hose clamps and strips of plastic from a soda bottle.




Before I put the pistons back in I wanted to clean up some of the rusty studs that gave me so much trouble when I was taking the cylinder head off. I poked all the studs through a trash bag to keep the top of the case clean and then wrapped the worst of the studs in bits of paper towel that were dipped in Evapo-Rust. I let that sit for 30 mins or so then used a wire brush on them. They came out much better and hopefully will make this all much easier if I ever have to do this again.




Now to start getting the pistons back on. I used assembly lube on all the contact surfaces of the moving parts and then put one circle clip in the piston so the wrist pins would have a back stop.




With one clip already in all I had to do was pull the wrist pins out just enough to slip the pistons onto the connecting rods and push the pins right back in. Then just install the second clip. I was surprised at how easy the clips would go in but that assembly lube probably deserves most of the credit.




The pistons have all been installed, the ring spacing triple checked, ring compressors are in place, and the rags are out. Time to get the cylinders on. I've also got my homemade holding fixtures in place. I just made them with some scrap wood and then wrapped them in tape to prevent any little wood chips from going in the crack case.




And here are the cylinders ready to be installed. I used twist ties to keep the base gasket snug against the bottom but I also made a rookie mistake here by installing the cam chain tensioner. It ended up costing me some time and almost costed a base gasket but thankfully the twist ties came to the rescue. With the chain tensioner already on I didn't have enough clearance to get the chain guide in and when I started to lift the cylinders back off the gasket was getting caught on the threading of the engine studs, so I ended up putting more twist ties on the outside edges and saved myself a base gasket.




Remember how I said the chain tensioner cost me some time? Well thanks to that delay I wasn't able to beat the freak summer thunderstorm that popped up right as I got the two inner pistons installed. I got the whole thing covered up before any real rain started and thanks to some repurposed photography equipment I was able to get back to work after a few hours pause. You can also see the oil and mallet I was using on the cylinders sitting on the lawn chair.




And the cylinders are finally on! It was such a relief to finally see them back on the bike. Once I was sure they were properly seated I gave the engine a few good cranks and everything was moving nice and smooth.




I also got the cylinder head back on and torqued down to spec but I wasn't real concerned with getting pictures at that point. The thunderstorm was kinda nice because it cooled down from high 90s to low 80s but then it also brought out the mosquitos so I had to wear long pants and shirt to keep those bastards off me. It was also about 11:30 by the time I started torquing down the head and I can't even remember what time it was when I finished with the last nut. So here's what she looked like right before I put the cover on for the night.

[Steve]

Not bad, but it really should look a bit more like this:




.