Trouble with my GN250, possibly the clutch plates?

[Bad Biker]

Having some trouble with my GN250 and what I think is the clutch plates.

With some unexpected medical bills looming for my loving wife I am looking to get this repaired as cheap as possible so I don’t need to spend this summer without a bike.

Symptoms

I am finding that from time to time the bike will not accept a gear change and I need to release the clutch a couple of times to accept the gear change.

Other times I could be riding a long and the bike suddenly changes and feels and sounds like I am riding the clutch and I start to lose forward power and shoot up to 8-9000 rpm and then it will pick up again and start running fine.

Trying not to spend to much on the bike as will be looking to change it soon after getting a full licence – target for a new bike mid 2012.

Question


Has anyone got any ideas that do not include me using the bike as an anchor and won’t cost me a fortune?

Is it easy to do a self fix by someone that knows a little about mechanics but mostly on cars and knows very little about mechanic on a bike apart from oil, filters and basic maintenance?

Approx what cost would I be looking at?


HELP!!!!!!

[sleemanj]

Easy things first.

1. Check clutch cable isn't binding up, etc.
2. When did you last change the oil. Remember - MOTORCYCLE OIL ONLY because like most bikes the GN250 is a wet clutch (runs in the oil).

[Bad Biker]

Easy things first.

1. Check clutch cable isn't binding up, etc.
2. When did you last change the oil. Remember - MOTORCYCLE OIL ONLY because like most bikes the GN250 is a wet clutch (runs in the oil).

Checked my clutch cable which is at the full adjustment and I probably do require a new one, but I wouldn’t expect that to alter the gears once a gear is engaged and riding normally.

Changed my oil and filters about 800km ago.

Maybe a change in the gearbox oil???

Does the clutch plate run through the engine or gearbox oil?

Probably stupid question, but don’t ask don’t know

[nadroj]

Checked my clutch cable which is at the full adjustment and I probably do require a new one, but I wouldn’t expect that to alter the gears once a gear is engaged and riding normally.

Changed my oil and filters about 800km ago.

Maybe a change in the gearbox oil???

Does the clutch plate run through the engine or gearbox oil?

Has it been doing it since the oil was changed?
If you have changed to synthetic oil that is the likely cause as clutch runs in motor oil which is also gearbox oil.

Not a hard job to replace clutch plates yourself.

[Bad Biker]

Has it been doing it since the oil was changed?
If you have changed to synthetic oil that is the likely cause as clutch runs in motor oil which is also gearbox oil.

Not a hard job to replace clutch plates yourself.

Started about 600km after oil change.

When I replaced the oil I used Castrol Activ 4T 15w-50.

Recommended by a Suzuki dealer to use.

[nzspokes]

How many Ks has the bike done?

[Bad Biker]

Approx 18,000km

[FJRider]

How many Ks has the bike done?

It doesn't really matter ... as the clutch on a "learner" bike get a hard life ...

Owners ride the clutch a lot learning starts ... and unless corrected ... continue to do so.

Not to mention badly adjusted cables ... and some that dont know better, put car oil in the engine ...

[F5 Dave]

Symptoms
. . .
Other times I could be riding a long and the bike suddenly changes and feels and sounds like I am riding the clutch and I start to lose forward power and shoot up to 8-9000 rpm and then it will pick up again and start running fine.

Hard to say from your description, it isn't very clear.


At 18,000 there should be negligible wear anywhere, however these were made in China so all bets are off, but that’s just cynicism creeping in.

3 real options I can see;

One the clutch is slipping which could cause symptom 2, but unlikely symptom 1 which clutch dragging may do. Maybe.

If it is slipping then an easy test it to wind on the power hard in a medium high gear up a hill. If it starts slipping you will know then. It will only smoothly come down in revs & grip again likely when you’ve powered off.

If it clunks in & out of power then it’s most likely a gearbox issue.

The alternative is that one or more of the clutch plates are broken or maybe the basket is loose or damaged.

They are a pretty basic engine, you could drop the oil & pull the RH cover off & see if you can find anything amiss with the clutch. It’s grasping at straws a bit, but at least the free option.

Aside from that it’s engine strip time & maybe a blown Japanese GN motor will yield a gearbox that is fit for use.

[Bad Biker]

.....One the clutch is slipping which could cause symptom 2, but unlikely symptom 1 which clutch dragging may do. Maybe.

If it is slipping then an easy test it to wind on the power hard in a medium high gear up a hill. If it starts slipping you will know then. It will only smoothly come down in revs & grip again likely when you’ve powered off.

Thanks for your input.

You appear to be able to describe the symptoms a hell of a lot better than I can.

I know the clutch cable is at its full stretch so I will replace that.

As you said it could be a slipping clutch so I will pull the bike apart and see what I can find.

Any idea what I would be looking for if it is just a slipping clutch?

All the gears appear to be working fine with no clunks which make me think the clutch.

Thanks for your help

[Pedrostt500]

Another possibility is if the clutch cable is at full streatch then the cluch has been given a hard time, it would also be worth changing the clutch springs, particurly if you are going to change the clutch plates, suggest you get a copy of a work shop manual for your bike, or phto copy the relavant pages of one from the library, worth owning one, its the best tool in your tool box.

[FROSTY:Me]

2 things come to mind here. First that the oil is knackered or underfilled. Second that the clutch cable is OVER tight and/or the lever pivot and cable need lubing--ie are binding preventing the clutch from engaging. On the same front a frayed cable may cause the same symptoms.
Given the OP feels the cable needs replacing anyways I would start with a new cable and work from there

[kneescraper]

Your clutch lever being cable operated should have play in it before the clutch is engaged...if the cable is to tight you will have no play and if it is to lose you will have far to much play...depends on the rider but I think around 7mm - ish play would be OK.

You can "break" the clutch plates which basically frees them up, over time the clutch plates can become seized or the surface of the friction plates can bind to the clutch plates. Apply both front and back brakes and in first gear hold the revs up and just let the clutch out and then back in, your want to force the plates to break free...be careful not to give it to many revs. It can be done while riding to, be careful.

To me it also sounds like the selector in the gearbox is bent, its a star shape that when you select a gear moves and in turn moves the tumbler. Its a common problem if the rider has a heavy foot and really jumps on the gear lever.

Worn baskets can be a problem, some times where the clutch plates sit in the basket the edging can become sharp or worn and this can be fixed by using a fine file and file the edging of the basket smooth.

If you do remove the basket and plates you can use emery tape to cross hatch the fiction plates and use plenty or cleaner to clean the parts, once you have the basket all set ready to put back into the motor soak it in new engine oil making sure it has oil right through it.