feetupfun

Not a production bike. I can see Yamaha and Honda parts and a lot of custom work. Frame started as a pressed steel backbone type Honda frame.

I'm quite interested in the development in the design of Bultaco frames, especially Alpinas and Sherpa Ts.

In Australia Yamaha fitted minimalist road rego equipment and gained approval for road registration. I rode my 1996 model until 2002 and absolutely loved it. It was a very capable bike for racing and exploring and was totally reliable. The power curve was amazing (no steps and plenty of go at all revs). With the standard exhaust it was so quiet I had many close up encounters with emus and kangaroos who had not heard me approaching.

I have marked the frame elements red in this photo

I just noticed that the frame in your photo is different to a 115 frame and a 116 frame I have here. Yours is missing some frame elements that connect the rear uprights to the central rear down-tube. Your model 115 frame looks like my model 138 frame in that section of the frame. Your headstock gusseting looks the same as these 115/116 frames which is different to the 137/138 frame. The 137/138 models followed the 115/116 models so I'm wondering if your frame may be near the end of the production of of the model 115. Here are photos of the model 115 and model 116 frames I am referring to

I've got both and they sure do look the same

Sometimes oil doesn't drain out because there is thick sludge in the bottom of the gearbox. Try poking something through the drain hole to see if that is why no oil came out. Another thing to consider is that your bike has two gearbox compartments that are separate. You should also change the oil in the second compartment.

Everything is possible, but if there is only one hole in the head, then the head will need to be removed and some finning machined away and a hole bored and threaded to create a second hole for the decompressor. They can't both go in the same hole.

Yes that's a helpful book. The OKO D slide is a copy of the Keihin and getting the jetting right on an OKO on a trials bike is very different to jetting a Mikuni VM

One interesting thing I've noticed is that some 199Bs had fork tubes and top triple clamps with the tapered top attachment that was phased out on Sherpa Ts in about 1972

Larry can you measure up the important dimensions of your Cota 200 piston to help with finding something suitable. Pin centre to edge of crown Pin diameter Width between pin bosses Length of rear skirt Nominal diameter Ring location pin locations

Will do. Thanks

It did take 48 years to do all that 😄 so I reckon I've actually done pretty well

I'm 62 going on 18 too and have been riding trials all my life. Here are the trials riding injuries I can remember: ACL torn due to jumping backwards off a bike at the top of a bank and landing on my feet awkwardly because of a stick that prevented my knee bending. Broken ribs from falling down a bank tangled up with the bike. Torn rotator cuff from falling onto shoulder. Torn calf muscle from landing from a jump without being warmed up. Bent nose and cut forehead from face-plant after brake cable hooked over fork top clamp. Leg burn after handlebars broke and landed on the exhaust header. Leg burn after crashing with leg trapped against exhaust header. Broken pinky finger from crash with my chest against on a rock with my hand between my ribs and the rock. Fingers squashed between levers and grips multiple times hitting trees and logs. Lots of lower leg injuries from impacts with kickstarts (when kicking), footpegs (when crashing) and sticks flung up. Ankle injury from a vine loop pulling the front of my foot down and under the peg. Knocked out from an upper cut to the jaw from the handlebar end when crashing. Head impact that knocked me off the bike when front of helmet hit an unseen tree branch (going up a bank looking into the sun). There is a longer list for enduro injuries but that was not the question

Has the motor been lifted? It may be a header pipe made for a different model. It may just be poorly fitted. What ID prefixes are your frame and motor? I think I see your motor prefix is 92 but what is the frame? The original finish on a model 92 header pipe is chrome plated. The tank looks right for a model 92.

How well did the multi-drill deal with the hardened bolt shank? I've got a similar problem but with a handlebar clamp bolt and am trying do decide how to deal with it

The visor came with my trials helmet and it is still there and I've never used it. If I'm going trail riding on a trials bike, I use a motocross helmet

The standard fuel tap thread in an Alpina tank is a metric thread M12 x 1.5

Viton rubber is the go for petrol o rings

Looks like it's been through hell. Has it been chewed up by an animal?

1 I can't understand your question. 2 There are usually anti-topping springs on the damper rod that have this effect. The intention is to avoid harsh metal to metal impact when the forks extend fully (like when you riding up a steep bumpy hill). It's also possible that the fork spring preload is too small to hold the forks at the top of their travel. 3 Some fork caps have vent valves that hiss when you compress the forks. Some caps don't have venting. Sometimes with vented caps, the valve sticks shut and doesn't let air out. If yours are the vented type, you should be able to find a small (1 mm) hole on the cap where the air comes out.

What's wrong with yours? There's not much to them. Anyway if you want a new one, In Motion has push-in type Bultaco caps list price 24 british pounds. If you can bear having the wrong logo on it, the Montesa Cota 348 push-in cap will fit your tank. A friend uses a rubber foot from a tubular framed bar stool as a cap for his tank.

Both Mont and Beta 4 strokes are very nice to ride but are quite different in power delivery and both are quite different to a 2 stroke. People changing from 2 stroke to 4 stroke in trials either persist long enough to eventually become as good as they were on a 2 stroke, or give it up as a bad joke and get another 2 stroke, or an electric, which is yet another learning curve. Probably the easiest thing to do would be to tame down your GasGas and then when you have got used to trials competition riding you can change it back to standard and have a ball.

What is the problem with lacquering over stickers?