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mineolaman

Bultaco start up

11 posts in this topic

Hi, just found a 1975 Alpina 350. One owner scooter that has been sitting in shed for 15 years. I'm going to drain gas for sure, and probably clean carb with some B-12. What,if any, should I run down the cylinder to coat it before kicking? I want to drain and replace oil as well. If someone could tell me where the drain plug and refill locations are, it would be appreciated. Also, what type oil should I put back in gears? Thanks for the help

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Its a two stroke, any normal brands would apply. The premix lubes the cylinder, nothing else is needed. Nothing mysterious about that bike, its just old.

Edited by YHGEORGE

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since the machine has been sitting for such a long time it may be prudent to lift the cylinder and check the top end and crank/brgs for rust damage.

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You need to get a manual, aftermarket service manuals are available. You are getting some bad information here.

I would avoid putting ethanol laced fuel in the fibreglass tank.

Edited by moto vita

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no ethanol in tank. if you do, make sure you drain completely after use, and leave the cap off so it can evaporate.

2 different fluids in bottom end - trans filler is center top, clutch is right top. drains are pretty obvious

i would expect at least the left side seal to be bad. maybe not. both seals are pretty easy to replace, the left one is easier.

clean carb, inspect/clean points.

fluids listed below.

Tech%20Tips.JPG

Edited by nyabinghi

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nsman post is very true, I just rebuilded a Bultaco that sat also around 15 - 20 years forgotten in a garage, I would too check the bearings, beside this the oil expecially in the gearbox and cluth should be replaced if you will get it out very well.

Second check the carb expecially the bowl the Bing of the Bul looked like this when I opened it:

DSC07811.JPG

The left oil gas mixture had devided in a clear liquid smelling very bad and a honey colored residue that was impossible

to get rid beside mechanical. I ended up buying a new one, (not easy to find this type btw.).

Here some of the jets:

DSC07817.JPG

Main bearings and con-rod where rough going too, (so they were corroded) :

DSC08027.JPG

At the end I had to do a complete rebuild, anyway maybe I just an unlucky person but before you spend endless time

to get the bike running I would advise, to check the bearings, the carb, airfilter too, (the foam of my bike had disintegrated),

and replace the fluids.

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No need to use different fluids in the bottom end and a general cleaning of the carb, forks, etc should be understood by anyone. Other than the possibility of an ethanol /gas tank problem there is nothing different than any modern two stroke. Anything that works in a new KTM will be just fine in that old Bul. I used the recommended Bardahl premix in my Alpina and Matador but I'll bet that will be hard to find today.

Edited by YHGEORGE

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Have you ever maintained a Bultaco? Maybe it's was just too many years ago?

You can use the same fluid for both sections, when using gear oil in both boxes the clutch is a pain, (the clutch has only metal plates!), instead using in both boxes thin ATF then changing gears will not work smooth and as the engine uses still felt seals and has a tiny little open vent hole above the front sprocket the bike will loose oil from the gear box too.

My recommention gearbox oil for the gearbox W75 - 90 and ATF for the clutch, this combination works best.

Gasoline with up to 5% ethanol is no problem for the engine, carb or the gas tank (in own experience).

Edited by P-Schrauber

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No need to use different fluids in the bottom end and a general cleaning of the carb, forks, etc should be understood by anyone. Other than the possibility of an ethanol /gas tank problem there is nothing different than any modern two stroke. Anything that works in a new KTM will be just fine in that old Bul. I used the recommended Bardahl premix in my Alpina and Matador but I'll bet that will be hard to find today.

it is a bit different than modern 2 stroke. all metal clutch plates, primary chain, felt seals, etc.. atf leaks out of gear box for sure, and would need changed frequently. best to use heavier oil i.e. (75w+) for gearbox. clutch can use atf, i've had no problem with it, but the primary chain wears the atf pretty quickly. i run 0w-40 in clutch, lasts a lot longer...

. .

10% ethanol can and will melt the tank. maybe 5% won't. either way, draining gas out of fiberglass tanks is pretty much the only way to ensure it's not going to melt.

Edited by nyabinghi

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If you can find NON-ethanol gas in your area, use it. Ethanol is such garbage if you let it sit for any length of time. I can't believe there are states that have no, or almost no non-ethanol stations.

This may help for U.S. residents -

http://pure-gas.org/

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Use these at you own risk as they dont match the stats from Bultaco very closely, just an estimate of fluid amounts.

"Fill the Primary side with 300cc of 10SAE oil And fill the Gearbox with 600cc of 90SAE oil."

Re: Bultaco Overhaul by John Larsen, Cycle Guide Sept 69.

Recomended Fuel Super Unleaded.

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