TWO Broken Rocker Arms. GS700E.

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....

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

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.....

Well, out of the handful of parts and gaskets I need so far, the fiches show that all are the same except the base gasket and the O-rings around the cylinder studs. The 700 has 'em and the 750 doesn't.

So, that opens up my searches a little.

Chugging right along...

[rapidray]

Dan, you can drop them in but you will get more power if you take the time to degree them. Ray.

[salty_monk]

Wonder how much oomph you got from that tweak... Anyone here tried it? Do you have to degree them or is it a straight drop in?

'83 and up GS750E and ES will be the same as the 700. There are only three parts I know of that are different between the two engines; rods, crank, and exhaust cam. The rods are actually longer on the 700 because the crank has a shorter throw. The exhaust cam was changed to add a little umph to the shorter stroked engine. Using a 700 cam in the 750 was a popular tweak back in the day.

Oh, yes, I WILL be taking someone up on the offer of rocker arms.

But I didn't see much on ebay for the 700. Somehow I must've missed 'em. I'll keep an eye on ebay.

Are any of these bits interchangeable with the 750?

To be sure check the part numbers at the fiche site of your choice, I like alpha-sports.com. I'm pretty sure the cam chain and cam chain guides are the same as the '83 GS750. When I looked an hour or so ago there were two sets of guides listed for the 700. I searched "gs700 cam"

/\/\ac

Oh, yes, I WILL be taking someone up on the offer of rocker arms.

But I didn't see much on ebay for the 700. Somehow I must've missed 'em. I'll keep an eye on ebay.

Are any of these bits interchangeable with the 750?

I don't see them right now but I've seen DID cam chains on ebay for about $25 in the past. You could also buy up all the tensioner guide sets on there for about the cost of one new guide and at least two people in this thread have spoken up about rocker arms... don't spend more than ya have to unless you've got cash to burn.

/\/\ac

OUCH! Just running some preliminary parts pricing:

cam chain, 3 tensioner guides, 2 rocker arms, piston rings, complete engine gasket kit: $528.88, plus shipping from an online house. A bit more at another online house.

I'm hoping that gasket kit contains (at least) valve cover gasket, head gasket, base gasket, cylinder O-rings, base stud O-rings, 16 valve guide seals, clutch cover gasket, stator cover gasket.

Ouch!

[rapidray]

Yes, it does. Ray.

The engine may of hydro-locked from gas in the oil.

Does the term hydro-lock refer to the cylinder being filled with fluid?

Forged cranks are VERY hard to twist in that engine, unlike an unwelded 80/81 GS1100 crank. Worst case scenario, a bent rod but EXTREMELY rare to happen with that engine. If that is all the valves leak, just lap the valves because they AREN'T bent. Ray.

Out of curiosity Ray (or Terry or Ed for that matter) I haven't done alot of work on the insert bearing stuff, but I have a couple of broken rocker arms i found in a pile of insert bearing motors/parts and was wondering how something like that could happen. I cannot recall if this was off of some 550 16v stuff I had laying around or 750/700 stuff. But what are other causes of this? Is it possible for the rockers to bind in the head at all? (again just wondering) and also, if hydrolock was indeed the culprit in this particular case, what sort of damage could be done to the shell bearings if any? I know you said the crank would be hard to twist but would that added load and pressure against the bearing warrant being checked at all? Just asking to learn.

[rapidray]

Forged cranks are VERY hard to twist in that engine, unlike an unwelded 80/81 GS1100 crank. Worst case scenario, a bent rod but EXTREMELY rare to happen with that engine. If that is all the valves leak, just lap the valves because they AREN'T bent. Ray.