Top end rebuild

[pregrid]

At the risk of getting flamed for asking this let me preface this thread my saying I've just spent WAY too much time looking for the answers to my questions, can't seem to find a quantitive thread to do the deal. OK...............

Barrel, pistons, and head should be back soon from the machine shop. I only wanna do this one time. So........I need some input on gasket sealing procedures from the bottom up. Sealer/no sealer, center punch, yada yada yada. Could be some help to someone else down the line. I also promise to document what I did and how it worked out. So....fire away.

 

[XSLeo]

Over at the Garage they had a thread "leakless xs assembly"or something close to that. Took you step by step through the assembly of the engine.
Leo

 

[pregrid]

Over at the Garage they had a thread "leakless xs assembly"or something close to that. Took you step by step through the assembly of the engine.
Leo

Meh, not enough info. We have three sealing surfaces here: barrel to case, head to barrel, and top cover to head. I guess I could use my 40+ years of experience with auto mechanics, but if you screw up on a car you don't usually need to pull the motor back out to fix a problem. Maybe I'm just over thinking this thing.

 

[jayel]

what drives me crazy are these #7 o-rings, looks like they go on top of the bushings on the outer four studs but no cut-out for them, do they just go between the cam cover and sealing washers? weren't on mine went I tore it down, didn't have the cylinder spigot o-rings either, that and the .25 pistons makes me believe it's been down before

 

[pregrid]

what drives me crazy are these #7 o-rings, looks like they go on top of the bushings on the outer four studs but no cut-out for them, do they just go between the cam cover and sealing washers? weren't on mine went I tore it down, didn't have the cylinder spigot o-rings either, that and the .25 pistons makes me believe it's been down before

those o-rings go on the tubes you put in the top cover after the rocker shafts are installed, as in the orange thingies here........

 

[jayel]

ok, nice pic, since my bushing seem solid in the cover I see no need to replace those

 

[retiredgentleman]

pregrid;

For the engine case to the cylinders, just install the gasket, no sealant.

For the cylinder head I used the head gasket, but added a thin bead of Three Bond 1104 around the camchain tunnel and around each of the 4 outer stud holes.

For the valve cover, no gasket is used, just use Three Bond 1104.

Cleanliness is super important. Use something like lacquer thinner to clean the surfaces just before assembly.

Make sure the camshaft bearings are pushed fully inwards (with the camshaft centred). You want to have equal amount of camshaft showing at each end. This is so that the oil seals will fit properly when the camshaft end covers are installed.

Torquing also super important. Use 30 ft-lbs for the 8 large 10 mm studs, 14 ft-lbs for the 4 8 mm bolts and the 2 under the spark plugs, 7 ft-lbs for the 1 bolt at the back centre. Re-torque several times after some miles are put on (leave the top engine mount off).

as Leo said, read the "Leakless Assembly over at the "Garage".

 

[retiredgentleman]

pregrid;

Here is how I installed the pistons/cylinders.

The following method makes installing the cylinders/pistons very easy.

Install the inner wrist pin circlips into both pistons at the same time you install rings and then put the pistons fully into the cylinders from the bottom.

Install cylinder base gasket. Rotate the engine to stand on its nose, so that the cylinders/pistons can slide onto the studs horizontally. Slide the cylinders/pistons down the studs,feeding cam chain as you go. I used a clamp to hold the conn rods just below the cylinder bottom. Tap the pistons down until holes line up for the wrist pins. Install the wrist pins and outer circ clips. Remove clamp and slide the cylinders fully into the crankcase. Rotate engine so cylinders are vertical again. Carry on with front camchain guide, camshaft/bearings etc.

With this method, you're not fighting with the weight of the cylinders and less chance of the camchain falling downward.

 

[pregrid]

^^^Now THAT's what I'm talkin' about. Thanks!! And I'm very anal about cleanliness.

As clean as this looks, it ain't yet..........

 

[pregrid]

Retiredgentleman: Do you replace the washers under the head nuts with brass ones?

 

[5twins]

Yes, definitely replace those outside 4 rubber/metal washers with brass or copper ones (the original steel washers are fine for the inner 4). They're like the #1 cause of 650 head gasket leaks. I used copper from the big GS Suzuki fours because Mike wasn't selling the brass ones at the time of my rebuild.

For the head gasket, small beads of sealer around the cam chain tunnel and 4 outside oil flowing stud holes are extra insurance against leaks. My gasket developed some slight weeps along the front edge after several seasons so I now include a strip of sealer across the front, connecting the cam chain tunnel to the outer stud holes. It's indicated in yellow below. Do both sides of the gasket, of course .....

 

[pregrid]

Cool, thanks!

 

[racerdave]

5twins and/or retired: What about using spray on copper coat on the entire head gasket? Thoughts? Are there any particular brands of gaskets that seem to be best?

 

[5twins]

I've never tried the copper coat so I can't say. Vesrah and O.E.M. head gaskets are supposed to be better than the Athena one. The Athena head gasket is thicker which may cause a slight reduction in compression and power. I don't know. I asked 3M about it and he doesn't think it makes any difference but Grizld1 does.

 

[retiredgentleman]

Retiredgentleman: Do you replace the washers under the head nuts with brass ones?

Yes, I used the copper washers from 650central on the 4 outer studs......................they work perfect.

 

[retiredgentleman]

5twins and/or retired: What about using spray on copper coat on the entire head gasket? Thoughts? Are there any particular brands of gaskets that seem to be best?

Sorry, no experience with spray on copper coat.

I used the Athena head gasket for my top end re-build, and it has worked well.

 

[pregrid]

Yes, I used the copper washers from 650central on the 4 outer studs......................they work perfect.

So, any reason not to use the copper (or brass) washers on all 8?

 

[tonyc]

I used them on all eight.

 

[5twins]

You don't need them on the inner 4 because they don't flow oil. Plain steel are fine there. Spend the money on something else, lol.

 

[sivarTi]

I'm going to add a question onto this rather than start a very similar thread. My barrel to case is leaking a bit, not a ton but it does leak. Also I need to do the chain guide as I'm getting platic in my filter. I was going to order the gaskets and guide but what about the O ring kit? Is it a waste of 16 or so bucks from Mikes or should I order it at the same time. I don't plan on doing any real rebuilding of anything. I just want to get rid of the leak and platic bits in my oil. Thanks