GS250T No power and rattling noises

[Spuds1234]

Hoped to lurk around here a little longer before I started posting but as the gods would have it...

I ride an old (but so far reasonably reliable) 1981 GS250T Suzuki. Its done 55000 miles, and had major engine repairs once.

I was riding home tonight, and got stuck behind a car going down Mairehau road with L plates doing 60 in a 80k area. That was ok, I was about 4 seconds behind them, and in 6th gear, and as I started going into a corner I slowly started to speed up to overtake down the next straight.

Things went swimmingly untill I clutched in when it changed from an 80k area into a 50k area. I clutched in, and coasted up to the round about (could hear a faint clicking when I was coasting but put that down to the chain doing something funky at the time), saw there was no traffic in either direction and clutched out and rolled on the throttle. Got nothing, the engine just reved. Thats ok I thought, just hit neutral by accident.

I tried to click it into first. Hmm seems things are already in first, let the clutch out again. Nope same as before.

Jumped off, and pushed it out of the middle of the round about, and so Im 3km from home sitting outside Burwood Hospital thinking hmm not cool.

Tried second gear. Same as first.

Started to push...

Not a good end to the day.

As I was pushing it along, I could hear a clicking noise from the engine. Kinda like a gear is loose somewhere in the engine, and its periodicly making contact with something thats making it turn and rattle. Its a pretty regular noise (I had to listen to it all the way home).

The engine starts and revs fine. The bike changes gears fine. The engine just isnt engaging the gear box. Which leads myself and my father to believe that its something between the final drive train, and the gearbox.

The clutch seems to be working, and not stuck.

And the clicking doesnt sound anything like when my bike shat a big end bearing.

Any suggestions would be appreciated, could this be something simple to fix, or something more along the lines of "get what you can for it" and get a new bike?

Im not afraid to go diving into the engine with a spanner, as I do most of the work on the bike by myself, or with my fathers guidence when I dont really know what Im doing.

[Ixion]

Hm. I have heard of the gearbos sprockets coming loose on Suzukis. Worth a check.

Does that model have a kickstart?

If it does , first see if the kickstart turns the engine over. And the put the bike in gear and try see if the kickstart tries to move the bike. That will help determine if it is n the primary or secondary side of the transmission. I take it you ahve checked the chain hasn't come off ? And that the chain doesnt go round when you engage the clutch with the bike in gear (eg broken cush drive?)

Beyond that, starts to get nasty with things like broken shafts. Unlikely to be the clutch main nut fallen iff, cos then the clutch wouldn't work

[Spuds1234]

Thanks for the reply.

Unfortunaly it has no kick start.

Heh yes the chain is still on (its a new chain that got put on less than a week ago. Just connected it to the old chain and pulled it around).

My dad says its definatly not a broken cush drive (im not sure what one is but he was pretty certain that its not broken on my bike).

Thinking about it, the sound seems to be comming from the left side of the engine (if this helps).

Other than that he just says "hmm yes I thought of most of that"

If you were to start taking apart the engine where would you start, and what would you be looking for?

Also would something like this (assuming a gear has come loose) cause a lot of wear and tear inside the engine? If it costs heaps (ie more than a few hundy) to repair, then I will just buy a new bike (albiet not with the budget I had first intened).

[Ixion]

Left side is gearbox sprocket side. So i'd definately have a gander at that sprocket. The ones with nuts, the nuts can come loose and the the sprocket falls off, ditto the bolts on the sort with little plates. And you'd have to pull that cover off anyway , to investigate any further . Did you check the front sprocket teeth condition when you replaced the chain. I have known a new chain on a tired old sprocket strip all the teeth off . Though that usually retains some intermittent drive on the tooth stubs.

Pull the gearbox sprocket cover, that's usually pretty simple.

Next thing would be to pull the primary drive cover , also usually not a very big deal.

Then you'll be able to see and get to grips with the drive. Anything you can't see from there is probably inside the gearbox, and expensive, cos the motor has to come out and be completely stripped.

[Spuds1234]

I havnt done anything as yet to the bike, because I was a little angry, hungry, and had a curry waiting for me at the dinner table.

I didnt check the front sprocket teeth when I replaced the chain, as the rear one looked ok (not shit hot though). But I doubt that it has stripped all the teeth off because I havnt put the bike under much stress since the new chain got put on as I kinda need it to last a while so I have been taking it real easy on the throttle. How ever I will check it out tomorrow morning or night after work.

Guess I will be diving in tomorrow and getting dirty and greasy. Good times. Turning up to work with dirt under the nails and stained skin on the hands, and serving 1000 or so people food.

[Ixion]

Once you get those two covers off you'll be pretty much able to see all the bits that go round, and turn them manually (except the bits inside the gearbox itself) . Its pretty obvious, just follow through and see what bit turns when it shouldnt. Assuming nothing obvious shows like broken bits falling out.

[Spuds1234]

Been meaning to post this for a day or two.

As it turned out, the locking tab on the drive shaft had broken, and the nut that held the sprocket on has slowly unwound itself.

I found the nut sitting in the bottom of the cover, and the sprocket was sitting on the threaded part of the shaft, so of course I would get no drive.

The thread on the nut was shagged, and the thread on the shaft was looking a bit dodgy, but a new nut and locking tab went on pretty well.

Cost $11 and half an hour of a mechanics time (he had to look though about 5 bins of nuts and bolts to find one that would fit), and I fitted it all myself. Good times.

Learn from my mistake people. No matter how hard it is to get to your front sprocket, or how lazy you are, when you change your chain, make sure you check your front sprocket. Its a bitch to have to push your bike any great (or small) distance.

[Ixion]

Snap. That's about the fourth I heard of. Glad it's all sorted without great expense

[Mr. Peanut]

:done: Hooray!