Engine tear down. Past experience problems or thoughts.....

[Anonymous]

Hi there....

I am fairly new to this forum. I have a 85 GS700 that was for sale but i have decided to redo the enigine. As it looks the timing chain, top rings and maybe tensioner will be getting replaced, as well as gaskets. I was sorta thinknig it would be nice to make a sticky list of past experiences with problems and helpful tips that people have came across. And i guess depedending on the responces i get to this post it will decided if thats a good idea or not. But if not I would like to hear input reguardless. Things that can be problems or whatever.

Ben

 

[brs127s]

I am currently in the reassembly of a top end rebuild. For the most part, it is pretty straight forward and easier than I thought it would be. I have had alot of help on it. I have a buddy helping me, who works at a machine shop which builds performce car engines. I also have another buddy who works on off-road bikes, ATVs, and boat motors. So a combination of the manual, several buddies, and the folks at the GSR has made this job very doable.

I replaced all the gaskets, orings, rings, valve seals, one valve, and my cam chain. I didn't split the case to replace the cam chain. My mechanic buddy loaded me his chain break/press for replacing the cam chain. My machinist buddy had my cylinders honed, milled the head, and helped me change the valve seals. We also ground the valves and seats, just to remove the minor pitting.


Get a manual, preferably a factory manual.

 

[Anonymous]

1.
Be careful taking out the cam cap bolts. They can seize and snap. And they might have been overdriven by a previous mechanic and stripped, or damaged and strip when you assemble it. Find someone who can do helicoils for you, or buy a 6m helicoil kit. Somebody, either on this list or another bike group I am on, recently said they automatically helicoil all cam cap sockets the first time they take off the head. No problems with stripping ever after.

When you put it together, use new high tensile bolts, they are worth the money. The old ones have gone through some significant temperature/work cycles and are best thrown out.

2.
Make sure you keep track of the valves so they are assembled into their original seats. This is very important.

You can make up a valve extractor with an 8inch G-Clamp and a two inch long piece of three quarter inch diameter tubing. Cut a lengthways slot in the tubing, removing about a quarter or third of the circumference. Put the clamp over the valve face and have the tube between the screwing face and the valve collett with the gap allowing you to see the collett pieces. Screw down carefully until the collett pieces are clear of the cap. Remove the two pieces and unscrew the clamp. It needs careful work but is cheaper than a $100 tool. Assembly is the reverse, but the pieces take patience to get them to stay where you want them. Some grease in the gap encourages them to stick.

The exhaust valves are likely to have some carbon squashed into the seat area. This is difficult to remove by hand but done well they probably won't need machining.

Chuck the valves into a drill press on slow speed. Hold a small wet sharpening stone against the seat area at the angle of the seat. This is not difficult and at slow speed (less than 100rpm) will not take any metal off. This is the quickest simplest way to clean off any hardened carbon. Use a small stone, about little finger size, so you can control it easily. Take it easy and it will take about a minute for each valve. A small stone is included in my dremel type toolkit, it's worth having.

You can dress up the valve seats by putting a cone of emery under a valve, facing the head, and turning the valve. You need to help the emery to turn. This will take any carbon off the seat area. Don't lap the valves with grinding paste! This is a Suzuki warning from the workshop manual. If you do any machining they only need facing with the face cutter. They do their own seating in the first few seconds of running.

3.
Have the cylinders properly honed. New rings only last the distance if they start with a newly honed surface to work against. A hand honer is not the best thing for cylinders this size - even if your mate does his Chevy V8 with one. The angle of the honing is important, and you can't measure how much metal you are chewing out with a drill-mounted hand honer.

A professional hone by a race prep mechanic on a top quality machine recently cost me $50 Oz. I turned up, he did it, I went home 50 minutes later. A great deal.

4.
If a previous owner has scratched the head getting gasket residue off, have it properly done. Once again, a wet sharpening stone rubbed flat on the head is the best way to remove gasket bits. I normally wet the stone with degreaser and it cleans better as it goes, and rinses away in water.

5.
Timing chain comes in a closed loop. Ask the store to push out one pin for you. At home you grind a pin and side-plate down with a dremel tool so you can undo the old chain. Link the new chain into the old one and pull it through. Push in the displaced pin with multigrips (it takes a bit of muscle) and set it properly by putting a small nut over the link where it will push out the other side. Crimp it again with the grips and push the pin slightly into the hole of the nut. Work the link a little until it frees up.

6.
You should not need to replace the tensioner as they don't take much load. The springs might have got a little slack but there is not much in there to get damaged or wear out.

7.
If you take the head off, and it's been a few years since it was off, replace the valve guide seals while you are at it. This is definitely worth doing. Seals seem expensive at $8.50 Oz each, until you check out Kawasaki prices. Don't install cheap after-market seals (they will start to leak in a few thousand miles), use genuine Suzuki stuff.

8.
The cam cover gasket is expensive. You can make a new one with about an hour or two of patience and a two dollar sheet of oil jointing material. Get stuff about .8mm thick. Coat each side with a well-rubbed-in smear of gasket silicone. You now have a rubbery floppy gasket that will seal, undo, seal, undo, each time you need to lift the lid to do the shims.

9.
Drain the oil before you begin. Otherwise you will have the cam area filled with oil and overflow onto the motor as you remove the cam cover.

10.
Take the opportunity to remove the battery, check its cell levels, and put it on a charger.

11.
While you have the tank off, pull each visible electrical connector apart, rub with fine emery, and refit. Do this each time you have the tank off.

12.
The exhaust pipes are fitted into the head with crush washers. Flick them out and replace with new ones.

13.
The timing plate covers a seal on the end of the crankshaft. Take off the timing gear (it probably needs a cleanup and light smear of moly grease by now) and check the seal inside. If it is weeping oil it needs replacing.

The timing unit comes off by holding the 19mm nut and undoing the 12mm nut. You will see how it is assembled as you go. Take note of which direction the cam piece is pointing so you don't assemble it timed to the wrong pair of cylinders.

When you replace the timing gear make sure that you get the thing seated into the end of the shaft properly. This is a very tight zero tolerance fit and it can be tricky to get it right.

14.
I normally use a smear of molybdenum disulphide grease on both sides of the lower barrel gasket and head gasket. This will seal them without gluing them. You need to wipe excess grease off from the area after bolting it up, and again a few days later if the heated grease weeps a little.

15.
Carbs and air box go on better if you spray them with some stuff and sit on the bike to put them on. This way you can push more easily.

I think that should keep you going for a while. Happy reading, and good luck with the bike. It's a good feeling to ride off after a well-done repair or rebuild. I started doing this sort of thing on my first bike in my high school days, thirty something years ago, and I still enjoy the feeling of successful home mechanics.


Kim

 

[Anonymous]

Things I learned the hard way:

1. If you have to separate the crankcase halves, and they don't seem to be coming apart easily, check that you've actually removed ALL the bolts. There are a couple on the top. The "cheaters" for separating the crankcase (little projections on the front) break off really easily if there are one or two bolts still holding the halves together.

2. An impact driver just might be the best money you will ever spend. I had to drill out a couple of machine screws before discovering this little beauty. Now, if a screw or bolt gives me any trouble at all, I go straight to the impact driver and it always works like a charm.

3. Again, if you do the bottom end, make sure the gear box still shifts properly every time you put something else on. It's a pain to get to the end of the job only to discover you did something wrong along the way and she won't shift.

4. Something I think made re-assembly much easier for me: Every electrical connection that I undid, I folded a little bit of masking tape over each side and labeled them the same. Also, I had a couple of big pieces of white paper on the floor of the garage. Every piece I removed went on the paper and was labeled immediately -- even the ones that seemed obvious at the time. If you've taken the engine apart a few times, and you're going to have no problem recognizing the pieces, I still think it's a good idea to put stuff on white paper (even if it's not labeled), because it centralizes all your parts.

Michael

 

[Anonymous]

Plastics baggies and a majic marker are great for keeping track of parts, bolts, screws, ect.. It's amazing how something that looks to have an obvious home when you remove it can become the mystery part when it's time to re-install it. If can't get enough detail on the bag about the part's use and placement, scribble a note and put it in the bag.
Also a digital camera is quite handy. Takes as many pictures as you can, wire routing, bolt placement (lot of the same size bolts have different strength designations on their heads), just about anything and everything. Digital pictures are great, shots are instantly available to check if they're clear and basically free so you can keep shooting until you get what you need.

 

[brs127s]

A big tip...stuff rags in the crankcase around the rods before removing any wrist pin clips, small parts, etc. I learned this the hard way. A sock works really well(it goes around the rod once and doesn't overstuff the hole).

 

[Anonymous]

Great stuff so far. Thanks a lot. I was wanting to just connect the timing chian to old one but the guy told me it was sealed circuit. ANyway So this is a common thing to push out the pin and then use same pin to replace? Id much like to do this and not split the engine. How much does it take to get the original pin out , I knowtehy have a press there at the shop, and you can squeez it back together?

P.S. Anyone know if a regular peddle bike chain press thing will work. I had to buy one of those for a old peddle bike . Ill try tonight anyway and let you all know if it works on old chain.

ben

 

[Anonymous]

This is just my view, and I know opinion goes both ways on this, but I would never fit a new cam chain except by stripping the bottom end. Why? Because by the time you've got the top end down its not much extra work to split the cases. With the engine fully stripped in this way you can also clean out the cases properly. (Sometimes when you're lifting the block, dirt can drop into the cases from the stud holes. It is impossible to prevent this happening no matter how thorough you are, unless you invert the engine.)
You can also inspect the crank and everything else while you're at it.
As I said, this is just me. Each to their own.

Also I think it was me who mentioned helicoiling the cam cap screw holes. I can't recommend this highly enough. Nothing worse than popping those threads when you're nearly finished.
I'd get an M6 helicoil kit anyway. You'd be lucky to get all the way through a rebuild without taking out at least 1 tired thread, and most of them on GS engines are M6. Having the kit there ready takes the trauma out of the issue.

 

[Anonymous]

P.S. Anyone know if a regular peddle bike chain press thing will work. I had to buy one of those for a old peddle bike . Ill try tonight anyway and let you all know if it works on old chain.

ben

The pedal cycle chain is longer between pins than the cam chain. The cam chain does not fit the holding fins of the breaker.

 

[Anonymous]

Also I think it was me who mentioned helicoiling the cam cap screw holes. I can't recommend this highly enough. Nothing worse than popping those threads when you're nearly finished.
I'd get an M6 helicoil kit anyway. You'd be lucky to get all the way through a rebuild without taking out at least 1 tired thread, and most of them on GS engines are M6. Having the kit there ready takes the trauma out of the issue.

Another trick with the cam caps that I should have put in my other stuff. The normal bolts are 40mm but the holes can take 47mm bolts. This means that you can replace the 40mm with 45mm quite safely. This gives you 5mm more thread bite without the bolt bottoming in the hole.

If you helicoil a hole the longer bolts have no advantage as they will only grip the 6 turns of the new coil.

I priced a helicoil kit today. $40 Oz for the tap/setting kit with 5 coils, and about $1 a coil in packs of ten. Cheap insurance.

Kim

 

[daveo]

when you get everything back together, fire the engine and let run till warm, shut her off and let sit 8-10 hours till ice cold, then retorque your head, you may need to do this 2-3 times, till the nuts stay at correct torque, the different co-efficients of expansion between the studs, nuts, block, and head, make this 'normalizing' desirable