TWO Broken Rocker Arms. GS700E.

[kingofvenus]

I have 700 cams in mine. Haven't made a pass with it since, so i don't really know. And there is the carbs and some porting so.....

[kirkn]

Well, the project proceeds slowly.... (the past two weeks were spent getting the family boat ready for 4th of July boating excursion - jeez, you think MOTORCYCLES are expensive...)

I've disassembled the "accessories" - clutch, ignition, drive sprocket and cylinders & pistons, then pulled the motor out. With all the other stuff removed, it was really a pretty easy task. One man and one floor jack.

The pistons, rings and cylinders all look great! No scuffs or marks or stuck rings or anything. You can still see the original cross-hatch marks near the bottoms of all 4 cylinders. I haven't mic'd anything yet, but I suspect it'll all be OK. New rings and a honing ought to do. Odometer reads 14k miles.

Peeking into the camchain cavity, all looks good, too - no chewed up sprocket or evident damage anywhere.

Curiouser and curiouser as to what caused that broken cam chain and two broken rockers...

I'll degrease the cases then split 'em and see what I see.

Kirk

[kirkn]

Well, progress continues very slowly. All I've managed to do is degrease the motor and order $450 worth of new parts this morning!

Now that several other projects are out of the way (son's motorcycle and a Ninja 250 I just scored), I should be able to make some progress.

Next is split the cases.

Chuggity chug....

[kirkn]

Hey, Kirk, how 'bout an update? Well, OK, if you insist...

A lot of time has passed, and quite a bit of work has got done, although still not complete yet.

I flipped the engine upside down and removed all the stuff accessible from the oil pan area, removed all the bolts from the bottom and from the top and pulled up the bottom case half from the top half. The crankshaft remained in the (upside down) top half, but the transmission came up with the bottom half. Nothing fell apart or bounced off into dark corners.















Next was lifting out crankshaft with rods, the transmission shafts with gear clusters, then the transmission shifter bits. So far, so good. Lots of crap from the destroyed cam chain tensioner faces, but everything else looked very good and everything spun freely as it should.

[kirkn]

I bought a new camchain and new tensioners, front, rear and top, and a complete gasket kit. Cleaned everything thoroughly - cases, crankshaft, transmission bits, shifter bits, etc. Then, I just began putting it all back together again, reversing the steps that it came apart in. Actually, I had recorded each step as I went during disassembly. Something like 100 individual steps I wrote down. So, it was just a matter of reversing the steps and following the manual for torque values, etc.

Crank back in, transmission and shifter stuff back in, gaskets and O-rings where they go and case halfs back together again.

[kirkn]

Next came the top end.

All the bores looked and measured good as did pistons and rings and the motor only had 14000 miles, but I ordered new standard piston rings anyway. A light hone in the bores to refresh 'em and put it all back together. One step at a time and it all goes together nicely. Proper end gaps, proper ring orientation on the pistons, new circlips, and we're good.
















And, at that point, engine goes back in the frame! Woo Hoo!






Now, I'm just kinda bolting on all the 'accessories' on the bottom end, cleaning and refurbishing as I go - clutch, ignition, stator, sprocket, etc.

Next will come cleaning and lightly refurbishing the head. 12 of 16 valves weeped acetone from their ports into the combustion chamber, so I'll remove the valves, clean the chambers and ports and lap the valves back in. Then the head goes on and cams, etc. then carburetor overhaul and, and, and...

Still a lot left to do, but at least it's not going backwards!

[rapidray]

Change the oil pump!!! After all that crap went throught the motor, CHANGE THE PUMP! What kind of assembly lube are you putting on all of the bearings before you put it together? Ray.

[kirkn]

Well, I didn't change the pump, but I did clean it out. It was beautifully clean when I took it off and checked, as were all the oil passages and various orifices. But, I flushed it clean and reassembled it and it's back in.

As for assembly lube, on the crankshaft I used some kind of molybdenum paste. I don't remember what brand. On everything else, I'm just using plain motor oil.

[BassCliff]

Hi,




It's starting to look like a motorcycle again. The pictures are great. Thanks for sharing.



Thank you for your indulgence,

BassCliff

[49er]

You've taken a very methodical approach to this project. Well done.

Just one observation. You don't appear to have checked on the condition of the big end bearings or their crank journals. I would have thought that it would be prudent to do this, plus replace the big end cap bolts with new ones.

I suspect that slack cam chain tension has caused the failure. I have seen the results a loose chain can cause internally on a spare 850 engine. Did you notice any gouge/groove marks in the cam chain tunnel in the head?

IMO, the only thing that prevented a broken chain on my engine was the fact that the idle sprocket between the cams kept the chain stable around that part of the engine.

You can safely replace a cam chain without splitting the cases, provided you invest in a decent joining/peening tool. IMO, manually hammering the link pins to peen them, is a receipt for disaster.

[chef1366]

Nice! Way to document your progress.

[jwhelan65]

Again, cool seeing someone else tear down your same engine.....

Click save!

[kirkn]

So, chugging along slowly.

I've put all the bottom end "accessories" on - stator, starter, clutch, ignition, sprocket & chain, etc. including cleaning and semi-polishing the covers and I've started putting bike bits back on - shifter and brake lever, air box back in, etc. I've done about all that stuff I can for now. Next up is all the head work.

[Kcwiro]

Sexy!

Good Job and Good progress very fun to read through your thread on this... Wish I had a workshop but all I have is a condo =|

[jetta90]

kirkn.........thanks for the rebuild detail and pics. Great job!