feetupfun

As for power you can take it to about 270cc with the standard sleeve. Some people fit reed valves. In my experience that particular motor is a dream to use in completely standard tune running well so maybe you just need to ride it some more and it might grow on you

That hub did not come with a chrome lining. Later Bultaco hubs did have a chrome lining Like every other drum brake, just because the pieces are all in place, it doesn't necessarily mean it will perform well Even if everything is perfectly set up perfectly in that particular hub, it will not work as well as many other twinshock trials bike front brakes, so don't get excited about it ever working strongly. As with all drum brakes, here are the things that need to be done right for it to work as well as it can: The drum surface needs to be smooth (shiny) The drum surface needs to be concentric with the axle The drum surface needs to be parallel with the axle The drum surface needs to be clean The curvature of the show friction material needs to perfectly match the curvature of the drum The outer surface of the friction material needs to be concentric with the drum surface The friction material needs to be of modern composition and designed for the purpose The friction material needs to be bedded in (smooth) and clean The wheel bearing races need to have minimal running clearance The bearings need to be solidly mounted in the hub The axle needs to be installed so that the friction material is centralised in the hub The camshaft needs to have minimal clearance in its bearing The cam needs to be almost flat against the shoe pads as the friction material touches the drum The camshaft arm needs to be at 90 degrees to the cable inner as the shoes touch the drum The cable outer needs to be kink-free and clean inside The cable inner needs to be kink-free and lubricated The camshaft lever needs to be the right length The handlebar lever needs to have the correct leverage ratio and be free-moving There are businesses that can do the relining and machining of the shoes and drum for you A common mod for Sherpa T front brakes is to fit the front hub or front wheel from an Alpina from M115 onwards or from a Frontera. They have bigger brakes that work well, but being bigger, do have a slight weight penalty. Alpina front wheels are commonly available on eBay. They look like the later model Sherpa T front hub. Most people would not tell the difference unless they were side-by-side. I can post a photo if you want

I just read again and see that you had the cases apart to swap the gearbox over, which introduces the possibility of air ingress via the centre gasket leaking

flywheel weight change is unlikely to be the cause. Pretty hard to diagnose from your description. It sounds like it might be lean at near-closed throttle position. This could be poor jetting, or a restriction in the pilot circuit, or air ingress downstream of the carby or a combination. Modern fuel is notorious for blocking the pilot jet if you let the fuel in the bowl evaporate The magneto side crank seal going hard is a common source of air ingress. If it is leaking, there will probably be a witness of oil near the seal behind the stator. There are also plenty of other possible air ingress sites Are you sure that there is enough fuel flow to the bowl, to keep the level up? Original Bultaco fuel taps are notorious for poor fuel flow rate Is it geared low enough in first? M97 Alpina?. The first Alpina 250 was M85 and the first 325 Alpina was M99

A Yamaha 3U5 carby is a bit small for a 325. Marginally OK on a trials 250. I run that size Yamaha-Mikuni on my 210cc TY175 and it goes great

Don't know that one, but do know that Honda CR125/MT125 friction plates fit into Montesa Cota 348 clutch baskets, if you remove every second tang

Maybe your AMAL Mk2 is different to this one? This shows one with the "choke" on (plunger out)

While it is possible to successfully degrease fibreglass tank internals in preparation for an epoxy coating, if you get it wrong, you may end up with a gooey mess on the floor instead of a fuel tank. I've successfully degreased and internally epoxy coated 3 or 4 old Spanish tanks that had contained premix and the results have been very good, but the degreasing process needs to be done with a full understanding of the risks and consequences before you start

Your description of the problem is not very clear, but if the piston is in backwards in a Sherpa T or any other bike with piston port induction timing and a piston with uneven length skirts, it greatly affects the inlet timing which can make a bike quite gutless and greatly affect the jetting requirements. If it hasn't been pulled apart since it last ran properly then it won't be this Please don't take offense but I hope you are using the "choke" lever the right way. I'm pretty sure with AMAL Mk2 the "choke" lever operates in the opposite direction to the "choke" lever on a Mikuni. AMAL Mk2 lever up = on, lever down = off. An easy way to check is "choke" plunger in = off, "choke" plunger out = on If it is not that, the consider that the "choke" on an AMAL Mk2 only has a significant effect when the throttle is in the closed position. It is not really a choke, but is an extra fuel circuit that only allows fuel to flow when the throttle slide is at the bottom. If the bike runs normally with the "choke" on, then the problem is in the pilot circuit of the carby. It is not unusual for the pilot circuit to be blocked in a used carby and it makes no difference what you do with the pilot jet if any of the pilot passages are blocked. I suggest if you can, to test the bike with the carby from a similar engine that is known to run properly.

Possibles: piston in backwards blocked exhaust worn rings pilot jet and starting circuit jet in each other's locations (they are the same type of jet but have different size holes)

The sale price sounds pretty normal to me

The other thing that would make it look a lot better would be to fit a replica of the original rear mudguard. You can get them in red or white and it would make the rear end look much better

They are rare indeed, mainly because the 349 sold alongside the 248 was seen to be a better bike (they were not desirable when new which is why they are rare now) However nowadays some oldies like me who still love riding twinshocks see things differently than we did when we were kids, and nowadays I would prefer to ride a 248 than a 349 of the same year As far as making it look nice, I've recently seen Montesas of that era that have modern build, shapely aluminium fuel tanks, and I prefer that look to the original Montesa seat/tank design. The TY tank doesn't look quite right in a single colour, but with some clever design input, it could be re-painted to make the bike look very attractive

Kickstart - yes Engine number - yes

People call lots of things Sammy Miller Replicas. You could buy lots of aftermarket parts for Sherpa Ts from Sammy Miller products that were developed by Sammy Miller and used on the bikes he rode, including distinctive-looking frames I've even seen a standard Honda TL125 advertised as a Sammy Miller replica

Looks like a Cota 248 with a Yamaha fuel tank

A change in the front sprocket of one tooth makes a noticeable difference. Two teeth on the front makes a large difference

Guy, Mikuni agents normally also have the pilot jets that fit TY yamahas. This is the web page for the Aussie Mikuni importer to show you the range they sell http://www.mikunioz.com/product-category/jets/pilot-jets/

Number 1 not certain but probably where the fuel goes in (looks too small but that might be from taking the photo so close) Number 2 is where the engine oil is injected Number 3 is the float bowl overflow Number 4 not certain but looks like float bowl vent

another thought for your weak spark is to check the strength of the flywheel magnets

not sure of this applies to your source coil, but I have fixed a couple of TY175 source coils by unwinding the last few turns, to remove a corroded section of the winding. There are other ways for the coil to fail though apart from corrosion at the outer end. The winding might have a break/crack or have corrosion that can't be seen. As for the electronic option, I have had a good run with ignitions from John Cane with TY175 and TY250 motors. Both ignitions are many years old now and had no issues. I do live in a dry climate though which might make a difference to reliability

Last one I had done was about $AU100 (by a local auto electrician)

for weak spark after changing the stator coil and points, check that: The coil laminations are not touching the magnets The coil laminations are well earthed The wire up to the HT coil has no broken or hard sections The HT coil has a good earth

while you are trying different points settings, set the clamping screw just tight enough to hold it in place. This makes it easier to make changes through the slot in the flywheel. When it is set right, you can then tighten the clamp screw fully

They are a quirky bike all right. If I had known you only had a ride with no trials usage involved I would have said the same as bisby In case you are doing it some other way, I recommend you drain the gearbox with the bike vertical