Bultaco: part 2

It's Alive!

Well we got the Bultaco running. Turned out to be a little easier than I thought it would be. Sometimes you just have to get to know a bike in order to get it running and that might have the been the case with the Alpina Bultaco.

But first off, let me explain what steps we took and repairs we made before we buttoned it up and kicked it over. On the last post, we just finished putting the carburetor back together and mounting it back on the bike. The next item on our list was fixing a pinhole in the gas tank.

If you look closely to the image above you can see a pinhole in the center of the gas tank. That had to be repaired. We used Caswell epoxy gas tank sealer for fiberglass tanks to get the job done. The goop comes in two small cans which are mixed together and has the consistency that makes molasses look runny. We only have about a 1-1/2 gallon tank so twelve ounces is all we needed. After plugging the balance tube fittings for the fuel lines with modeling clay, we swirled the epoxy around inside the tank for about 20 minutes (mostly focusing our attention on the area where the pinhole resided).

Once the epoxy dried, we bored out the balance tube fittings with a small piece of wire and reattached the tank to the bike. With the carburetor back in it's proper place and the fuel tank filled up with a gasoline and two stroke mixture, we were in position to try the bike again.

Kick, kick, kick... it still wouldn't run. It chugged a little but nothing more than that. Then Chris came up with a good idea. He depresses the valve allowing the float bowl to fill with gas, opened the throttle and instead of giving the kick short quick jabs, he instead gives the kick a nice sweeping smooth stroke and VAROOOM! the engine is running. While it is running, we closed the idle stop screw on the carburetor all the way and then adjusted the idle mixture until the bike maintained a nice hum and then opened the idle stop a little until the bike was able to idle on it's own without holding open the throttle.

Now comes the fun part. Riding!

Me starting the Bultaco

Me riding the bike out of our garage.

Viva el Bultaco!

California May Require Smog Checks For Motorcycles

Which is another reason to pull out your old bikes. All models as old as, or I should say as new as 2000 and later would be targeted if the smog check requirement passes.
Read the article here.

Thanks to the Baron for showing me this link.

Bultaco

My first job as apprentice to Chris Sidah was the '74 Alpina Bultaco. Bul what? Exactly. Motorcycle enthusiasts know this Spanish bike well, especially trials and motocross enthusiasts, but for the layman, the name will catch em off their guard.

The Bultaco is a pioneer in trials and motocross and with all the dual-sport bikes on the road these days, a good Bultaco will fit right in while maintaining the classic motorcycle look. Plus, this 250cc engine is small and simple to work on.
Armed with this knowledge, I was eager to dive in with the first assignment.

The first question every mechanic must answer when they are about to work on a bike is: Does it run?

And so we tried to turn it over. We checked for spark and then tried the kick, but that didn't work at all. The compression seemed low and the kick felt sloppy and the motor gave a pathetic weeeez for every kick. So on to the push start.

This, my friends, was a sight to behold. Let me tell you a bit about Chris. This ex-motorcycle racing/Honda expert/BMW Certified/Ducati and Moto Guzzi and anything vintage mechanic took his late 50 year old body and used it like a spry 20 year old. With a little push by me and a thrust by him we were off down the driveway and then BAM! he hops onto the seat of the bike giving the back tire traction while releasing the clutch and then back up on his feet again running and pushing and pushing and running while the bike starts to spit a sputter.

Doesn't run, but I sure wish I had all that on video, because it was a grade "A" lesson on how to jump start a Motorcycle.

On to question 2: Does it have good compression? Chris' motto "if it has spark and good compression, he can make it run" That simple.

And we check the compression with one of his many compression gauges: Also good.

Great! We can now fix this sucker.


By first dismantling the carburetor. Like with everything on a Bultaco, parts are open and easily removed. With a little disconnect of the two bolts on the slide, two nuts off the manifold and loosen the boot... voila! Off.

Now dismantle.
WARNING! Parts to this carburetor are hard to come by and so be careful when you work. Keep in mind, the needle attached to the float is made of plastic. In fact there are no metal parts attached to the float whatsoever except for the tiny rod that keeps it in place. This is very important to remember so that you don't mistakenly dunk all those parts into Carb Dip and fry your float.

After removing the gasket from the float bowl mating surface (use a small blade. These gaskets are also hard to come by and you want to keep it in tact without tearing it) low speed jet, main jet (two parts), idle stop and low speed needle, dunk all the metal pieces into Carb Dip for at least an hour. Again DO NOT dunk the float, the needle or the plastic filter!

Once the parts are removed, clean each one thoroughly. We have luxury of using an air hose, which made short work of the cleaning. All those tiny holes must be blasted clean. If there is any gasket residue, make sure it totally removed. We used a granite plate and a piece of #220 emery paper to scrub the float mating surface clean. Once all parts are shiny, reassemble and put back onto the bike.

Stay tuned for our next job: using a two part epoxy sealer on the fiberglass gas tank, fueling it up and seeing if this time it will run...

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