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Need help - rattling noise when throttling

  • Thread starter Thread starter Archania
  • Start date Start date
A

Archania

Guest
I check my bike before i took off to my friends house. there is an oil leak from one of the screws on the top of the crankcase by the oil plug. There was oil in it according to the site glass.
I left for the 57 mile one way trip.
On my way home, the oil light came on and it died.
Tried to restart it but got dim lights. Had a jump from a guy passing by. worked.. on my way again...
Starting hearing a rattling/nocking noise. Not sure if its from the crankcase or the cylinder head.
Any ideas at all... please help.
I love this bike and very upset over it.. considering i was pushing it for about a mile.
I ride it just about everyday to work.. and going on a trip in the beginning of august.
 
I'm not sure what bike you have, but it doesn't sound promising. what was the oil lever when you finally got it home? My first guess is that it's time to source another engine. As to weather it is top end or bottom end... the 4 valve heads are prone to excessive wear and deterioration from low over heated or lack of oil pressure. however if it is knocking I would guess rods. the only way to know is to start tearing it down and seeing what you find.
 
Archania said:
I check my bike before i took off to my friends house. there is an oil leak from one of the screws on the top of the crankcase by the oil plug. There was oil in it according to the site glass.
Click to expand...

Definetly check the oil level. You could have filled the crankcase with gas via a bad petcock hence the oil leak.
 
Hi Mr. Archania,

This doesn't sound good. When the oil light comes on, that means there is no oil pressure, which means there is no oil. Running your engine with no oil is very, very bad.

Fill up the oil to the proper level and test. Hope for the best. Keep us informed.

Thank you for your indulgence,

BassCliff
 
you may have several unrelated issues
check your charging system
make sure the oil level in the sight glass is correct and record the use of oil
pay attention to the noise from the engine and record the details of when it happens and what does it sound like (knocking, rattle, buzz, when warm or cold, when under load, at idle, at high/low rpm, etc etc)
 
well it was out of oil when it stopped.
I put more oil in and it was filled 1/2 way.
It sounds like a knocking noise. It idles fine, just when i apply the throttle, it starts.
Shifts fine also.
i'm still confused on why it would leak oil from under the screw.
I'll be taking it apart this week and see.
Any ideas what to look for? or just take it down and see if something is bent/twisted/ broken?

I do have the clymer book also. But it doesn't really specify what to check.. just what might have caused it.
 
Last edited:
Just so that I am on the correct page here.
When I do start taking things apart.. besides taking pics of everything.. I need to also get NEW gaskets/seals etc. to put it all back together.
Correct?
And of course before I take anything apart.. drain gas/ oil.
 
This sounds like an oil leak from the base gasket for the cylinder jug. Also sounds like you've most likely got a blown head gasket which would cause that excessive oil consumption.
My Rx? Buy an engine overhaul gasket set, pull the valve cover, head and cylinders, follow the disassembly/assembly instructions in one of the available manuals, hope you didn't hurt the con-rods and mains, put it back together, it'll work. Mine suffered the same way 15 miles from home, I rode it home with it soaking my right leg in oil.....no major damage, still riding, and I have put 9k mi. on it since. These engines are tough, but if you run them out oil, like any other engine, you're SOL when that happens.
Archania said:
I check my bike before i took off to my friends house. there is an oil leak from one of the screws on the top of the crankcase by the oil plug. There was oil in it according to the site glass.
I left for the 57 mile one way trip.
On my way home, the oil light came on and it died.
Tried to restart it but got dim lights. Had a jump from a guy passing by. worked.. on my way again...
Starting hearing a rattling/nocking noise. Not sure if its from the crankcase or the cylinder head.
Any ideas at all... please help.
I love this bike and very upset over it.. considering i was pushing it for about a mile.
I ride it just about everyday to work.. and going on a trip in the beginning of august.
Click to expand...
 
Don't need to drain gas if your fuel petcock operates correctly (you do need to remove the gas tank). Drain the oil when the job is done, the old oil will catch any particles that fall into the pan and will drain out with it. If you're going to pull the pan to check the con-rods and mains, then yes, drain the oil.
Archania said:
Just so that I am on the correct page here.
When I do start taking things apart.. besides taking pics of everything.. I need to also get NEW gaskets/seals etc. to put it all back together.
Correct?
And of course before I take anything apart.. drain gas/ oil.
Click to expand...
 
I took off the carbs and air box last night.
The air box has a film of oil all in it. I don't think thats a good thing.
Tonight will attempt to look at taking the heads off.
 
a "knocking" at high revs is usually related to crankshaft probs, no good
make sure to inspect for any play at the connecting rods

however, what you're hearing may not be that kind of knocking... you'd need an experienced EAR to be able to tell you more about your prob, going by the sound only
 
Last edited:
i hope its not.. cause from what i understand.. if thats the issue.. then it is too costly to repair - thus bike shopping anew.
Hopefully tonight i will have a better understanding of what is going on...
 
Update:
With the help of 83Gsrider, we found out that the #4 piston is cracked and the ring is busted.
The housing seems to be alright.. no big gashes in it nor lips. So hone(sp?) it out slightly. If need be. order all 4 new pistons and rebore. Cost is a factor here... but will do it if need be. Really don't want to invest in a new bike if i can get her running again for a 1/3 the cost. meaning 500 for repair instead of 1500 for a new bike with possible issues since not knowing the po take of the bike.
Going to order new piston, gasket set, and put her back together and see.
And of course clean the crap out of it before.. no reason not to now since everything is basically apart enough to clean the engine properly.

pics coming tonight that is if verizon decides to work at my place.
 
Just FYI, I've seen used piston sets on ebay go unsold for $10-20 plus shipping. Might as well look into it. :-)
 
psyguy said:
so, what about the connecting rods?
Click to expand...
Are you asking me? If you are, I don't know what kind of bike he's got and I'm not inclined to do someone else's work for them when they can easily do it themselves. I picked up a crankshaft and connecting rods for $10 + shipping. It took a whopping 15 seconds to find a bunch of stuff like this: link. Pistons and rods for $35 shipped.
 
what condition are your connecting rods in

what condition are your connecting rods in

was asking "archania"
a cracked piston, i doubt, would give the sound he explained
 
everything else looks good.
Just that cracked piston and split ring.
the pistons did move very smoothly when turning them by hand.
Just ordered the parts and the gasket set.
I did look on ebay but nothing for a 81 GS650G.
And the gasket set was a pita to find.. just hope the one i "won" from ebay comes and is the correct one...
 
Archania said:
everything else looks good.
Just that cracked piston and split ring.
the pistons did move very smoothly when turning them by hand.
Just ordered the parts and the gasket set.
I did look on ebay but nothing for a 81 GS650G.
And the gasket set was a pita to find.. just hope the one i "won" from ebay comes and is the correct one...
Click to expand...

If you are going to bore anyway, why not use 750 pistons?
Little more displacement can't hurt.
 
you may want to look into WHY you piston cracked.. just an observation.
also, you may want to check your valves, at least the ones servicing the damaged piston, to see if they have been smacked or not. any marks on the old piston head is a dead give away, but if the damaged piston hit the valves then the stems could be bent, and may not seal properly.

Suzuki is a pita for piston rings (Rather expensive), but if you are going to be taking the cylinders off, then honing all 4 and putting in all new rings is most advisable, although if an experianced mechanic takes a look and thinks they are ok, you may not need to hone all 4.
also, while the head is off, you could perform a leak test on the valves. clean the head up best you can (head being fully assembled) and place it upside down over paper towel. fill the cylinder heads with varsol or laqure thinner and let sit for 10 minutes. if you find any varsol on the paper towel, you need to have your valves and ports ground.

you could also take a disassembled head, valves and 3 pistons to a garage or rad shop and have them hot tank the parts to get all the carbon off..

I could go on if you like, but one last thing. when you knock out the wrist pins, inspect them too. make sure they are not tight coming out and don't forget to remove the circlips.
 
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