Bultaco, oil for Model 190

[deek]

I am a newbie to twinshocks and have just got a Bultaco 190. It's a 1976  238cc. 

Can anyone advise me on which lubricants to use in the gearbox and clutch. Also fuel/oil mix,

Cheers 

[shakennstirred]

what a question lol

you will get 10 different answers at least lol

[model80]

Hi Deek,

Welcome to the forum. I hope that my answer will be of some use to you.

I have always used Automatic Transmission Fluid  commonly know as ATF for the Clutch. EP 90 for the Gearbox. I also use ATF for the Forks,springs removed and fill to 6 inches from the top. I switched to synthetic 2 stroke Putolene and mix at 50:1.

Cheers and enjoy your bike.

Edited January 4, 2017 by model80

[deek]

Thanks model80,

I've read that alot of folk use ATF, I'll give it a go along with the 90 which I assume is classed as light gear oil.

Cheers

 

[model80]

4 hours ago, deek said:

Thanks model80,

I've read that alot of folk use ATF, I'll give it a go along with the 90 which I assume is classed as light gear oil.

Cheers

 

I've attached a photo of a page from the original factory owners manual

Interestingly enough I see they recommended 140 gearbox oil. However I've always put EP90 in my Sherpa, as that is what we use to sell in the shop back in the day when I worked for the Irish Bultaco importer.

Edited January 5, 2017 by model80

[trialsrfun]

ATF is a good choice for the primary drive but I would not use an EP oil in the gearbox.

EP stands for extreme pressure additives these are intended for use in applications where all steel bearings are used and there are sliding gears as in a crown wheel and pinion. EP 90 is a GL5 category oil  and should not be used where yellow metal bearings are fitted, these are the brass, bronze or copper bushes and shims that are often found in motorcycle gearboxes where a GL4 spec oil should be used. The EP additives stain these bushes which is surface degredation this is then eroded away on the bearing surfaces.

I have done a lot of fact finding on this very subject for an industrial application, there is a lot of information about this on the web.

[shakennstirred]

personally, in the gearbox of my bike I just use what the manufacture said , in my case 20w/50

you cant go wrong then and use the wrong oil which could damage the old engine.

for the twostroke oil I use Putoline trial TT at 50:1

Edited January 5, 2017 by shakennstirred

[model80]

8 hours ago, trialsrfun said:

ATF is a good choice for the primary drive but I would not use an EP oil in the gearbox.

EP stands for extreme pressure additives these are intended for use in applications where all steel bearings are used and there are sliding gears as in a crown wheel and pinion. EP 90 is a GL5 category oil  and should not be used where yellow metal bearings are fitted, these are the brass, bronze or copper bushes and shims that are often found in motorcycle gearboxes where a GL4 spec oil should be used. The EP additives stain these bushes which is surface degredation this is then eroded away on the bearing surfaces.

I have done a lot of fact finding on this very subject for an industrial application, there is a lot of information about this on the web.

Cheers feetupfun, I've certainly learned something from your post, its clear that the recommendation I received back in the day was completely wrong. I definitely will not be using EP90 again, whenever I get to start my 199A rebuild this year ?

Edited January 5, 2017 by model80

[bodwheel]

Castrol MTX 2 stroke gear oil  80W - been using it for years.

Edited January 10, 2017 by bodwheel

[73tr6]

Re the GL4 / GL5 discussion. I have attached a screenshot of the API (American Petroleum Institute) specifications below (note: active in the spec In blue means the spec is still in force and doesn't refer to the additive levels).  After 35 years in the lubricants business, I still smile when I see postings about oils. It's sure to start a discussion.

EP90 is primarily an Industrial oil designation and has no relevance to automotive performance standards issued by API such as the GL1 through 6 specs. It's actual interpretation is that the product is an EP treated oil with a viscosity at 40C of between about 125 and 300 cSt (Centistokes). Yes the spec is wide enough to drive a bus through but that's why ISO viscosity grades were invented ;-)

GL5 is a higher additive level than GL4 and therefore a lower coefficient of friction.  They both contain sulphur phosphorous EP additives but at different levels. Compatibility with yellow metals (brass / bronze etc) is not a problem as these gear oils have not used active sulphur for decades and there is no compatibility issue. Discolouration of yellow metals was an issue many moons ago but not any more. There is a caveat here though, prolonged, very high temperatures will cause some discolouration of yellow metals due primarily to oxidation of the oil. This is not a likely scenario in a Bultaco gear box.

Providing the viscosity is high enough to provide a sufficient fluid film between the gear teeth, and we are talking simple spur gears on parallel axes here which rely on an EHD regime (elasto hydro dynamic) and not hypoid / spiral bevel, then automotive specs are a bit redundant as these are simple gearboxes with none of the high sliding velocities found in automotive applications. Industrial Gear Oil specs are probably more relevant.  If the higher viscosity would cause operational problems, ie like difficulty shifting gears when cold, then a lower viscosity EP lubricant will be called for and the EP additives will help.

Reference to Lubrizol's website will give the same info but in a bit more detail.

https://lubrizol.com/Lubricant-and-Fuel-Additives/Driveline-Additives/Axle-Oil/Specifications

Upshot.......... SAE 90 GL4 or 5, or SAE 90 or SAE 140 industrial gear oil, you could also use engine oil with a viscosity of > 150 cSt @ 40C (an SAE 40 or 50)......................... your choice.

 

(Puts tin hat on and awaits the onslaught........................)

GL-4	Active	The designation API GL-4 denotes lubricants intended for axles with spiral bevel gears operating under moderate to severe conditions of speed and load or axles with hypoid (see note)gears operating under moderate speeds and loads. These oils may be used in selected manual transmission and transaxle applications where MT-1 lubricants are unsuitable. The manufacturer's specific lubricant quality recommendations should be followed.
GL-5	Active	The designation API GL-5 denotes lubricants intended for gears, particularly hypoid (see note) gears, in axles operating under various combinations of high-speed/shock load and low-speed/high-torque conditions.

 

[trialsrfun]

The advisory team at two oil companies we deal with both said stay with the machinery manufacturers recommendation of a GL4 spec oil because there was a much lower level of EP additives present than in a GL5. The machines in question are both current, from different manufacturers, the handbook to one says use only a GL4 spec oil, the other use a GL4, in countries where GL4 is unavailable a GL5 may  then be used. Both manufacturers prefer a GL4 oil because of the lower level of EP additive present.

Edited January 10, 2017 by trialsrfun