More Bull?

In October of 2008 I traded my '01 Gas Gas XC300 for this M206 Mk11 Pursang.

Despite the ongoing saga with the Sherpina I was somehow drawn to add a second Bultaco to my stable. My background has been in racing enduros and while I believe trials can help anyone become a better rider it certainly didn't fulfill my need for speed. So I had the bright idea to get into vintage motocross. In a round about way I ended up trading my 2001 Gas Gas XC300 to my friend Mark B. for his M206 Mk11 250 Pursang. The Pursang, with it's long travel, relatively speaking, suspension is actually a post-vintage motocross bike. It also had the standard left-side shift/right-side rear brake which would save me from possible disaster in a panic situation.

Mark rode the Pursang at the 2007 SMOG East Trail Ride.

I was quite familiar with this bike and knew most of its recent history. Mark had campaigned it in the AHRMA Northeast Post-Vintage class, but had a number of problems with the bike. For 2008 he switched to a Maico 400 to campaign in the Vintage class. I spoke with SMOG Grand Poobah, Ken Mcguire, who actually built the motor in the Pursang. His comments led me to believe the motor was solid and it just needed some minor tweaking to get running reliably. More than one person warned me that Mark's mechanical skills are somewhat questionable. Still my Gas Gas needed some work as well and resale on a seven-year-old Gas Gas is pretty poor. I actually considered it a fair trade, as did Mark.

Mark racing the Pursang at Broome-Tioga in 2007. He's a bit big for a 250.

I test rode the Pursang at the '08 SMOG ride and right off the bat I could tell the jetting was way off. The motor would barely idle and would die once you let off the gas unless the choke was on. It also would stumble just off idle, but ran very lean in the top of the RPM range. The Pursang had a Mikuni carburetor installed by Mark with a K&N air filter. Additionally the fuel lines from the tank to the carburetor resembled a spaghetti factory with an inline Fram automotive fuel filter. The Mk11 was the first Pursang to use a "high-pipe" expansion chamber. On previous Pursang models the expansion chamber ran underneath the frame where it was more prone to damage. To facilitate using a "high-pipe" the fuel outlet on the left side of the tank is angled away from the pipe and an inline fuel tap was used. Mark obviously did not give much thought to plumbing the fuel lines.

The Pursang looks right at home in the garage, sandwiched between my '03 Gas Gas EC300 and Sherpina.

It took me a week and about $15 for some 1/4" fuel line and an inline filter, but I got the fuel lines plumbed correctly. Next I spoke with Tim Weaver at Bultaco Motorcycles, who gave me some approximate jetting specifications. Since Mark had left the stock jets in the Mikuni I went ahead and ordered the correct ones from Tim as well as a few larger main jets to compensate for the free-flowing K&N air filter. I also went ahead and cleaned/re-oiled the air filter as it appeared to have been a while since this was last done. Along the way I noticed the spark plug was an NGK B7ES, one step hotter than the recommended NGK B8ES, so I swapped it out for the correct (heat range) spark plug. In addition to this I also changed the primary oil, transmission oil, fork oil and dumped the leftover premix in the tank. I mixed up a fresh batch of premix using 92 octane pump fuel and Castrol 2T two-stroke oil at a ratio of 32:1. It took me a few runs, but I got the jetting dialed in fairly spot-on. As suspected I had to go up two sizes on the main jet, but the motor pulled clean from idle all the way up to the top of the RPM range.

Testing & Repairs

Riding the Sherpina at the 2007 CATRA Vintage Trial.

Following the Stage Two modifications I decided to test out the changes by riding a few trials events. That doesn't mean I didn't have to put any wrenches to the Bultaco, quite the opposite. Riding a 35 year-old competition motorcycle, no matter what discipline you're riding it in, is going to require routine maintenance and repairs.

One of the problems I had was with the kick start lever, which I mentioned back here. The problem stemmed from the fact that I had the older style kick start that had the swivel piece held on by an external snap ring. Over time the lever wears and the snap ring no longer sits in the groove. The later model kick start lever is tapped and uses a screw to hold the swivel piece onto the lever. Of course my first repair was to use a new snap ring, but when that failed as well I gave the kick start lever to my machinist friend Phil Steel (no relation) who drilled and tapped the end of the lever and installed a bolt. Problem solved!

Pushing my kids on the Sherpina at the 2007 SMOG East Trail Ride.

Another issue, that has been and ongoing problem, is the fuel tap. Years of built-up varnish plugged it up so bad that during one trial the bike kept running lean going up hills or on long transfer sections. My solution that day was to stop half-way up the hill and breath into the tank overflow hose while tickling the Amal carburetor. I would also do the same before each observed section, just to make sure I didn't run out of fuel and take a five. By the end of the trial I was pretty light-headed from all the fumes and my last loop was actually my worst loop. When I got home I drained the tank, pulled off the tap and cleaned it out. I'm fairly anal when it comes to draining the tank and carb float bowl after use. One I don't want the tank to go soft and leak from the ethanol-blend pump fuel. I also don't want the carb jets to foul up from, once again, the ethanol-blend pump fuel. Unfortunately the gasket in the fuel tap is slowly starting to disintegrate. Even though I'm sure this is normal for a motorcycle of this age, I'll go ahead and blame the damn ethanol-blend pump fuel for this too. I'll probably have to splurge for a new fuel tap or find the correct fitting and install an inline fuel tap (remember, I'm cheap... errr... thrifty). I've never been too concerned about having a reserve. I've always ran my enduro bikes on reserve because if I do run out of fuel, oh well. Then there's the people who say running on reserves lets all the crap in the bottom of the tank into the carburetor. That is true, but if you run on reserve all the time little, if any, crap settles in the bottom of the tank.

At one vintage trial a friend of mine, Bob, was riding a Model 92 Sherpa-T 350. The bike lost spark and quit running after the first loop. After sitting a while it restarted, but again ran for only a short period before losing spark. This is actually a common problem with Bultacos that use the Femsa breaker-point ignition. The capacitor is located behind the flywheel and, when it gets hot, shorts out internally causing the ignition to lose spark. The solution is simple, add a condensor up to the frame near the wiring junction block. Almost any automotive or small-engine condensor will work, but I went the cheap (Scottish) route and just moved the stock condensor. While I never had any problems, at least now I have peace-of-mind that the condensor won't fail.

Condensor relocated up to the frame next to the junction block.

Another item I wanted to address was the clutch pull. Now I realize the Sherpina will never have the light pull of a modern bike with a hydraulic clutch, but it took the strength of all four fingers to pull the lever back. Even though vintage trials is supposed to be no-stop, there comes a time when you need to pull in the clutch, rev the engine and fan the clutch to keep from stalling. Also, if you check out any photos of vintage trials, you always see the riders with one-finger on the clutch lever. Well my clutch was, at best, a two-finger pull. Several factors contributed to this. One being it had a short actuation lever. The lever was also angled on the splines requiring more effort to actuate. There was a return spring that would bind during travel of the actuation lever. Finally the cable was cut too short, by me, to re-angle the actuation lever on the splines. To correct this I scrounged a longer actuation lever off another Bultaco. It was actually the actuation lever off the front brake. The splines for the clutch, brakes and probably the shifter are the same size. Next I purchased a longer cable to allow me to re-angle the actuation lever. Finally I pitched the return spring. This lightened the pull dramatically allowing the clutch lever to be easily pulled by two fingers or even one.

Finally I added some Bultaco decals to the tank just like to replicate the look of the original Sherpa-T. While this addition did nothing to improve performance, it does make the Sherpina look quite spiffy from a distance. While it's definitely not museum-quality, it at least looks good particularly from a distance.

Left side of the Sherpina.

After all this work you have to wondering why I would want another bull.

Stage Two

To say that my first experience riding the Sherpina, in an observed trail, was a complete flop is an understatement. Most of this can be contributed to my lack of experience riding trials. Oh sure I'd farted around on other peoples modern trials bikes and I've even done some time as a section observer. I knew the rules from that point, but I knew nothing about the technique. Additionally I knew squat about how a trials bike should feel. Now throw in the fact this was a modern observed trial, thus even the novice sections are a challenge for a vintage bike. Sure, there are guys who ride vintage bikes in modern trials, but these guys have been riding the same bike for 30+ years. Anyway you know what they say about excuses. They're like assholes, and they all stink. One thing this humbling experience did teach me was that the Sherpina needed a lot more work.

Having both German and Scottish heritage can be very perplexing when it comes to mechanical objects. The German in me wants it to look and run perfect. The Scotsman in me doesn't want to spend a dime. However there's nothing like getting your ass handed to you by some 60+ year-old geezer riding an old Yamaha TY250 held together with duct tape and bailing wire, to shut the Scotsman up. The next day I ordered more parts.

Most important, at this point, was getting some Renthal Vintage Trials bars. These bars have a taller bend than the freebies I had scored earlier. The may have been free, but my lower back was killing me from riding like the hunchback of Notre Dame.

I also splurged for a set of Sammy Miller front fender mounts and used the plastic front fender I had bought a few years earlier from Maier. This fender was actually made for the Sherpa-T and looked pretty decent when mounted up.

Finally I spluged for new sprockets. There was very little wear on the, most likely, stock sprockets due to the sub-20 horsepower of the Alpina. Unfortunately even first gear was too high for the slow-going needed for observed trials. I stuck with the standard 11-tooth front sprocket, but added a 50-tooth rear aluminum sprocket. Also a new 520 non o-ring chain was added as the previous chain was now too short. This dropped the overall gear ratio allowing for crawling around in first gear through most sections.

Right side of the Sherpina following Stage Two.

Left side of the Sherpina following Stage Two.

After all this work it was time to start riding some trials and do some testing and repairs.

Stage One

One of the most critical items on any off-road bike is the tires. A good set of tires makes and average rider like me ride somewhat better. Of course I don't mount a brand new set of tires every time I go riding. In fact some semi-worn tires will outperform brand new tires in the right conditions. Since knobby tires don't grip rocks and roots as well as a trials tire, off came the knobbys and on went a set of trials tires. The front is a Mitas 2.75x21 and the rear is a Michelin X1 (tube type) 4.00x18.

Next came moving the front fender down to just above the tire. This may not seem like such a big deal, but the low-mount fender actually makes it easier to aim the front tire. At first I fabricated a set of mounting brackets from 1/2x1/8 aluminum stock and mounted an aluminum front fender that I scrounged out of a pile of Bultaco parts a friend had in his garage. This looked okay, but I knew that the aluminum fender could easily get mangled and really wanted to use the plastic front fender that I had use during the initial restoration. Unfortunately I couldn't get the correct bend on my homemade brackets.

After getting the front fender sorted I scrounged a used pair of Hebo aluminum trials bars. These bars worked better for the stand-up riding position, but they were quite low and I'm fairly tall. Renthal made a pair of Vintage Trials bars, but I decided to hold off spending the cash and went with the Hebo's.

At this point I figured things were good enough to at least try my first trials event, but along the way I came across a used Sherpa-T slimline tank and seat pan. The tank needed some fiberglass work as did the seat pan, which was broken off and needed new foam and a cover. This tank was actually in better shape than the e-Bay Alpina tank the bike currently sported. So I repaired the fiberglass, sanded the tank and painted it with some red and silver spray paint I had laying around. I also added a black pinstripe between the red and silver. Too bad I didn't look closer at the tank. Once I mounted it on the bike, which required cutting off two ears on the frame, I filled it with gas and watched as gas poured out the bottom all over my garage floor. Over the years gasoline left sitting in the tank had eaten through the tank bottom. Always, and I do mean always, drain fiberglass fuel tanks after you're done riding. Particularly if you're using pump (ethanol) blend fuel. So off came the tank while I did more fiberglass work and sealed the tank using Caswell Sealer (same stuff I used on the e-Bay Aplina tank). Once that was done the tank went back on and I crossed my fingers as I poured more pre-mix inside. It held!

Next I turned my attention to the seat pan. Actually I used my friend Bob Young, who owns Burnt Hills Upholstery in Burnt Hills, NY, for help with that. At the time Bob just happened to have a Model 92 Sherpa-T in his shop and he used the seat pan from that bike to repair the half a seat pan I had in fiberglass. Bob also cut some foam and fitted a new cover onto the seat. It actually looks pretty darn good, especially considering he did all that work for nothing... Well maybe a few beers here and there.

Left side of the Sherpina following Stage One.

Right side of the Sherpina Following Stage One. Note the stock Alpina tank and seat in the background.

At this point the Sherpina was ready for her shakedown trial, or so I thought. Let's just say that riding a vintage bike in a modern trial is exercise in futility. On top of that the bike was geared way to high, the clutch was way to stiff and I had no clue what I was doing. It was a good thing the kick-start lever popped off, a common problem with Bultacos that use a clip to retain the kick lever. This led me to Stage Two.

The Transformation

Me on the Sherpina at the 2007 3D Picnic Trail in Oneonta, NY

At first, turning an Alpina into a Sherpa-T (aka Sherpina) seemed fairly easy. The Alpina is actually based on the Sherpa-T with a larger fuel tank and seat, high front fender and motocross/enduro style handlebars... Oh, and of course, knobby tires. In fact there are quite a few riders out there using Alpinas for vintage trials. However these are only outward appearances. In reality there are a number of differences between the two that go well beyond what you can see.

While I've never been able to compare the two, I'm told the transfer ports in the cylinder are larger on the Sherpa-T, which often results in a cracked cylinder. I'd certainly like to know if there's some truth to that rumor. Other things I've discovered is the Sherpa-T has a larger flywheel on the primary drive side. At least that was the case when I compared a basket-case Model 91 Sherpa-T (250) with my Model 98 Alpina (175 with a 250 cylinder). Another difference is the primary drive on the Model 91 is a single-row roller chain while my Model 98 came with a double-row roller chain. Another item I found, courtesy of (Hugh's) Bultaco Motorcycles was that first, second and third gears are a lower ratio in the Sherpa-T, but fourth and fifth are the same ratio as the Alpina. Finally, the rear shocks are a smaller diameter on the Sherpa-T. There are also differences in the lower triple clamp and the front brake is a full-width hub on the Model 98. However I've seen pictures of a Model 80 Sherpa which has the same lower triple clamp and front brake hub as my Model 98. This leads me to believe that the Alpina was assembled from leftover Sherpa-T parts.

Most of this information I discovered long after I started converting my Alpina into a Sherpina and the bike you see me riding above was actually part-way through the conversion stage. Essentially this has been an ongoing project for the last 3+ years. So I'll break it down into the various stages. Stage One.

Time for an Update?

Okay, so last we left our hero, his ego was shattered. Wait, no... It was his right pinky, and it was broken, not shattered! Besides, nobody really cares about that. The real hero of this story only had three gears. Sounds bad, no? Well maybe not that bad since third gear was about as fast as I wanted to go on a 30+ year-old dirt bike with all its frame flex, spindly front forks and two things in back that resemble shocks. However, the German in me couldn't have something half-assed in the garage. Actually it could, as the bike pretty much sat in the garage collecting dust for a year.

In the fall of 2005 I dragged it out and attempted to find the two missing gears. Now I was certain I had assembled everything back correctly when I put the motor together. Several inquiries on the internet with so-called "Bultaco experts" all said that if I put something in wrong, none of the gears would work. So, once again, I borrowed a manual and tried to find the culprit. I checked the entire gear-selector mechanism and found nothing wrong. Eventually I decided to split the cases a second time to go through the transmission. As it turned out there was one gear that, when put in backwards, would not allow 4th and 5th gears to engage. Imagine that!

Unfortunately I don't have any photos of the Alpina in these semi-finished stages. I rode it at the 2005 and 2006 SMOG East Trail Ride, so I'm sure there's at least one or two photos floating around somewhere.

At this point I felt bad about letting this bike sit around. I often thought about using it to teach my wife to ride, but she has no interest in riding motorcycles let alone a 30+ year-old Bultaco. I contemplated selling it, but I had already dumped a small fortune into it and the tank needed some serious labor to make it look semi decent. Then it struck me, why not use the Alpina for trials. After all the Alpina was based on the Sherpa T and it definitely had a stand-up riding position. That's it! I'll turn it into a trials bike.

Thus began the transformation.