GS700ES funny noise

[lallyrh]

I'm 21 years old and just bought my second motorcycle, a sweet 1985 GS700ES with 16,XXX miles on it. The guy I bought it from owned it for about a year, and never titled it, just putted it around his neighborhood. I love the comfortable riding position and sporty appearance. I can't wait until I get it titled so I can ride it more! My first bike was a 1982 GS750T, which I sold beacuse I got a great offer on it. At any rate I'm having a few issues with the bike and was wondering if you guys could help me out.

There is a rattle that sounds like it's coming from the engine. The rattle starts at about 3,000 RPM and stops at about 3,250 RPM. The same sounding rattle starts up again at about 4,500 RPM and goes on until I let off the throttle. I haven't had the bike all the way up to its 10,000 RPM redline, but the rattle occurs at least up to 7,500 RPM. The rattle happens in every gear and when the bike is in neutral, so I'm pretty sure it's happening in the engine. The frequency of the rattle is also directly proportional to engine speed, and it happens regarless of throttle position.

If I heard the rattle when I bought the bike I probobly would have passed on it, but I had my helmet on and I didn't notice it. I first heard it when I was revving the bike up in the parking lot here at school. Now it sticks out like a sore thumb whenever I ride it around campus.

Anyway, I have the gas tank off right now because I was fixing an electrical problem, and I was thinkning that it is probobly a good time to check valve clearances and cam chain tension. Do any of you guys know the valve clearnace and cam chain tension specs for my particular bike? Have any of you guys experienced a similar problem or have any thoughts on what it could be?


Thank you so much for your help. I'm really happy to be riding a GS again!

Rob

[Steve]

A rattle at lower engine speeds (under 2500 or so) would likely be the cam chain tensioner.

A rattle in neutral that goes away when you squeeze the clutch handle would be the clutch basket.

Yours does not seem to fit either one of these, so I'm stumped there. I think the first thing I would do is to change the oil. No telling what is in there, unless you have already changed it. Sometimes older oil will be thin enough to allow strange noises to happen. If the noise persists, use a long screwdriver or a wooden dowel as a listening stick to see if you can isolate which part of the engine seems to be loudest.

I am not going to open a can of worms by suggesting which oil, just make sure the API 'donut' does NOT include the words "Energy Conserving". Those oils (usually 30w and thinner) have friction modifiers that are not friendly to a wet clutch.


.

[Billy Ricks]

Valve clearance is .09-.13mm or .004-.005". As for the cam chain 20 pin length limit is 157.8mm or 6.21". Your cam chain tensioner may need to be looked at. With only 16k miles on it the chain should be within limits.

Here's how to service the tensioner.

With the tensioner removed from the cylinder block loosen the lock nut on the left side of the tensioner and back the slotted bolt out ¼ turn. Turn the knob on the right side of the tensioner, which in the Suzuki service manual is called a lock shaft handle, counterclock-wise. As you are turning the knob counterclock-wise push the pushrod all the way back. Keep turning the knob until it refuses to turn any further.

With the pushrod still pushed in as far as it will go tighten the slotted bolt so that the pushrod will not plunge out.

Remount the tensioner to the cylinder block. If the tensioner is not going in turn the crankshaft clockwise slowly to get slack in the cam chain on the intake side of the block.

Loosen the slotted bolt ¼ turn allowing the pushrod to advance towards the cam chain. Tighten the lock nut but leave the slotted bolt loose by that ¼ turn.
While turning the knob counterclock-wise, slowly rotate the crankshaft in reverse direction, counterclock-wise. This causes the chain to push the pushrod back.

Release the knob and slowly turn the crankshaft in the normal direction, clockwise. You should see the knob rotate as the chain becomes progressively tighter. If it does the pushrod is obviously moving forward under spring pressure signifying the tensioner is in good operable condition. If it moves sluggishly or not at all that means the pushrod or the slotted bolt is sticking. If so remove the tensioner from the block again and inspect the pushrod. It could need cleaning or could be bent or galled. Further crank rotation will take the slack out of the cam chain.

[lallyrh]

Well, I went outside to go pull the tensioner, but it started raining so I put the cover back on the bike. It looks like the tensioner is going to be really tough to remove with the carbs in place. Do you reccomend removing the carbs so the tensioner will come out easily?

Thanks for all your help!

Rob

[fgh]

The tensioner on my '83 GS750ES can be gotten to with the carbs on. As I recall takes a 10mm socket (1/4" drive), a universal joint and a extension. You also have to be able to turn the lock screw and tighten the lock nut when installing. It's much easier with the carb's off, but its not worth taking them off unless you can't get the tensioner set with them on.

[lallyrh]

This may be a noob-type question, but well frankly, I am a noob.

In the instructions you guys gave me to servicing the cam chain tensioner it says to rotate the crank to vary the tension in the cam chain. I cannot find any way to turn the crank without removing a cover on the engine. What is the best way to rotate the crank?

Thanks again for all your help!
Rob

[Billy Ricks]

This may be a noob-type question, but well frankly, I am a noob.

In the instructions you guys gave me to servicing the cam chain tensioner it says to rotate the crank to vary the tension in the cam chain. I cannot find any way to turn the crank without removing a cover on the engine. What is the best way to rotate the crank?

Thanks again for all your help!
Rob

Remove the small round cover on the right side of the engine to turn the crank. Be careful not to hit the signal generators. If you do you can screw up the ignition timing.

[ruddy]

If the bike is on the centerstand, just put it in a high gear and rotate the rear wheel to turn the crank.

[lallyrh]

Well, I pulled the tensioner off the bike the other ngiht and found some minor galling. The tensioner probobly sticking in its housing. I disassembled the tensioner and cleaned all the galling i could get to with emory paper, greased everything and reassembled it.

Everything checked out according to Billy Rick's inspection recomnedation, but the rattle remained until the bike warmed up. I guess it just needed to melt away the grease a bit or something. I havent heard the rattle since. Thanks for the help guys!