clutch plates won't completely seperate after bike sitting

[Ramjam]

Hi
My GT380 has been sitting for 9 months and i just fired her up again after putting some 40 SAE standard oil in the gearbox. I KNOW everyone will jump on me for that, but honestly guv, that was all they had in the local garage.

My question is why can i not engage first gear without the bike lurching forward and stalling - when it didn't do that before?

Is it all about the oil? I also adjusted the lever so that there is no slack now, but surely that can't be a remedy.

thanks in advance

Ramjam

[Vintageman]

If it only did it one or two times after it sat 9 months I would not worry. The plates were stuck. If it happens all the time now, or when cold, but not when warm the 40W is too thick. I think in general it is the wrong oil to use.

If it does stick even when warm then maybe something else, but change oil first. If not oil then take off clutch side cover remove clutch disk one at a time clean and re oil. I assume your clutch is adjusted as stated

Suz recomended 20/40W so oil a little thinner when cold than staight 40W.

[Ramjam]

If it only did it one or two times after it sat 9 months I would not worry. The plates were stuck. If it happens all the time now, or when cold, but not when warm the 40W is too thick. I think in general it is the wrong oil to use.

If it does stick even when warm then maybe something else, but change oil first. If not oil then take off clutch side cover remove clutch disk one at a time clean and re oil. I assume your clutch is adjusted as stated

Suz recomended 20/40W so oil a little thinner when cold than staight 40W.

thanks for that. but what about all these posts here from experts (!) who claim that a gt380 gearbox/clutch should run with a 'conventional' gearbox oil, say a 75/90? I'm a bit confused. And i know oil is an explosive subject. just asking.

RJ

[Alan H]

thanks for that. but what about all these posts here from experts (!) who claim that a gt380 gearbox/clutch should run with a 'conventional' gearbox oil, say a 75/90? I'm a bit confused. And i know oil is an explosive subject. just asking.

RJ

Suzuki recommend 'a good quality 20w40 oil' in the gearbox. If you can't get 20w40, then 20w50 or even 10w40 will do. It should be mineral oil not synthetic or the clutch will slip.
Personally I will be using Duckhams 20w50 as I used to when I bought my first GT550J in 1972

75/90? That's for a tractor. I thought you wanted gearbox oil for a motor bike.
I wouldn't leave the bike standing for 9 months without at least a start occasionally and warm to running temperature, other stuff will be bunged up too. Carbs, fuel lines etc. etc.

[Ramjam]

thanks for that. but what about all these posts here from experts (!) who claim that a gt380 gearbox/clutch should run with a 'conventional' gearbox oil, say a 75/90? I'm a bit confused. And i know oil is an explosive subject. just asking.

RJ

Suzuki recommend 'a good quality 20w40 oil' in the gearbox. If you can't get 20w40, then 20w50 or even 10w40 will do. It should be mineral oil not synthetic or the clutch will slip.
Personally I will be using Duckhams 20w50 as I used to when I bought my first GT550J in 1972

75/90? That's for a tractor. I thought you wanted gearbox oil for a motor bike.
I wouldn't leave the bike standing for 9 months without at least a start occasionally and warm to running temperature, other stuff will be bunged up too. Carbs, fuel lines etc. etc.

ok, cheers for that. Can easily get old-fashioned castrol 20/50 here. Tractor? Yeah, sometimes it feels like that when i try and pull away from the lights and she hasn't warmed up

[ConnerVT]

thanks for that. but what about all these posts here from experts (!) who claim that a gt380 gearbox/clutch should run with a 'conventional' gearbox oil, say a 75/90? I'm a bit confused. And i know oil is an explosive subject. just asking.

Gear oil and motor oil viscosity are not measured in the same manner. 75W90 gear oil is roughly equivalent to 10W40 motor oil.

http://en.wikipedia.org/wiki/Gear_oil

http://www.bestlubeusa.com/gearlube.pdf

[Vintageman]

Ramjam

You did not say if the issue still occurs and if so only when cold: If both are true then oil too thick IMO
However, a bike that set a while, plates will stick too (was this your case only?... you did not say). Every bike I have, that set for a long time needed the clutch apart, cleaned and re-oil.

(I a no oil expert) and if gear oil has similar viscosity (e.g 75W to 40W), it is till still much “thicker” especially when at ambient temp ... harder for all plates to separate

A Yamaha R5 and RD? has those rubber cushions between clutch dics to help separate evenly for one reason (as I learned). I took them out of my R5 for people said they are useless cause slip...., someday I'll put them back. Now, If the R5 sets for several days, you start it in neutral, pull in the clutch and kick down to first you better not be pointing at anything important for it leaps forwards first time. IF clucth slips and you tuned bike to have a bit more power need more plates or stiffer springs

Also if oil too thick marginal sized clutch can slip until oil warms up I use to run 20/50 and on cool days it would occur until warm on some of my old bikes

I like 10/40

[Ramjam]

Ramjam

You did not say if the issue still occurs and if so only when cold: If both are true then oil too thick IMO
However, a bike that set a while, plates will stick too (was this your case only?... you did not say). Every bike I have, that set for a long time needed the clutch apart, cleaned and re-oil.

(I a no oil expert) and if gear oil has similar viscosity (e.g 75W to 40W), it is till still much “thicker” especially when at ambient temp ... harder for all plates to separate

A Yamaha R5 and RD? has those rubber cushions between clutch dics to help separate evenly for one reason (as I learned). I took them out of my R5 for people said they are useless cause slip...., someday I'll put them back. Now, If the R5 sets for several days, you start it in neutral, pull in the clutch and kick down to first you better not be pointing at anything important for it leaps forwards first time. IF clucth slips and you tuned bike to have a bit more power need more plates or stiffer springs

Also if oil too thick marginal sized clutch can slip until oil warms up I use to run 20/50 and on cool days it would occur until warm on some of my old bikes

I like 10/40

Hi
Let me clarify. I WAS talking about when cold, yes as i didn't get the chance to wait 20 minutes and rise it around (as i was really worried that i hadn't put back the oil pump properly and it wasn;t pumping through the veins - as i dont remember putting the tiny 13mm pin in place ggrrrr!!)

But also please remember that i live in a hot country. Maybe this effects it and thats why i opted for the straight 40 SAE

But if you think it will make a differnece to bung in come 20-40 or 20-50 which is easy to come by, then i willl probably sunday morning and try it again. THIS time i will let it run until hot to see if this seperates the plates
thanks
RJ

[Alan H]

Gear oil and motor oil viscosity are not measured in the same manner. 75W90 gear oil is roughly equivalent to 10W40 motor oil.

http://en.wikipedia.org/wiki/Gear_oil

http://www.bestlubeusa.com/gearlube.pdf

ditives is needed.

Correct, but don't run gear oil in a bike gearbox as the sulphur will cause problens with the clutch amongst other stuff. Gear oil tends to be for heavier use than engine oil, and as a bike engine and transmission tend to run fast and relatively lightly loaded (compared to cars/trucks - and tractors! - etc) a lighter oil with different additives is the way to go. Suzuki recommend 10w40 so I reckon they know what their gearboxes need. That oil used to be very uncommon in the UK 'back in the day' so we used 20w50 which is slightly 'thicker' but works fine in cold or heat. Modern oils of 10w40 tend to be semi synthetic (not all) and is a bit more 'slippy' than mineral oil and can cause clutch slip. Remember that these bikes were designed over 40 years ago and oil technology - as well as most other technologies - has moved on a helluvalot. I'll stick to old style oils in my old style bikes and they seem to be quite happy.

[tz375]

There are several good quality oils specifically blended to work in the gearbox of a 2 stroke. Why use anything else. The price is not that much different considering how much/little you need. Why mess with anything else? My personal choice is Motul or Silkolene in a race motor and Honda brans trans oil designed for CR motocross bikes in street bikes.