feetupfun

WES two box or good custom exhaust, ignition with a decent advance curve, free flowing airbox, lighten flywheel, non-offset carby-to-reed cage adaptor, light seat, light tank. Standard size carby is fine for 175cc

I've got a 348 (which is pretty much the same in that area). I usually fit the airbox last. Fit cylinder connector to cylinder, fit carby to cylinder connector, fit airbox connector to airbox, fit airbox

That was great to see. Thanks Dave

Here is I photo I have already showing the brake pedal. The bike in the photo is a very early M49 which shares many components with the M27, including the brake pedal. I will take more photos to show the pedal and mount better, maybe taking the footrest off I don't have any way to show the stand mount because I removed what was left of the broken-off mounting.

Q1 sounds like a restricted pilot jet or low speed circuit Q2 sounds like the fan motor bearings need some lube Q3 Yes make sure there is not too much transmission oil, then if it still does it, the gearbox may be getting pressurised

I can do close-up photos and take measurements if you want to make a replica

Have you tried using the bearing dimensions to find the bearing ID for the second bearing, using the same pattern as the other bearing. It is likely to be another Koyo bearing. The first bearing number 20NQ3212 comes from: 20mm ID, NQ = type of bearing, 32mm OD, 12mm wide

I remember someone posting their local rules up years ago and there was a rule that really got my imagination working: "The rear wheel exits the section before the front wheel" (scores a 5)

The in-line axle 35mm Pursang forks I inspected today have taper-top fork tubes which means they are from a Pursang that was made before they went to a clamp-type top triple clamp design which happened around 1972 from memory. The Pursang sliders are the same internally as leading-axle Alpina/Sherpa T/Matador fork sliders of the same era.

Sounds like something is wrong. I've fitted lots of tapered steer bearings to TYs and the nut has always screwed down to the same position on the stem as it did with the original bearings. A photo would be good

It depends on what you are seeking to be able to say if is the ultimate set-up or not. With the square barrel, it would no longer look like an M49. If that doesn't matter to you then it sounds like a fun experiment. If you haven't seen many Sherpa Ts with reed valves, maybe you are looking in the wrong place. In some parts of the world it is a popular mod on late model Sherpa Ts, but not on early models like the M49. I suspect that the reason for this is that if someone wants a competitive Sherpa T, they start with a late model rather than an M49 due to the superior chassis dynamics. If people want to enjoy the awesome look of an M49, they would probably not want to make it look unusual/hybrid/ambiguous which would happen with a square cylinder or a reed valve. It's fairly rare to see reed-valved Alpinas probably because the main benefit for the Sherpa T motor is improvement in smoothness and even running of the power, which is not an important issue with Alpinas.

Whistles can be helpful as long as the sections are far enough apart so that the riders can't accidentally hear a whistle from another section. Sign language can be helpful too - holding your hand open to indicate a 5 so if the rider is in any doubt, they can look at you

Have a close look at the hole in the needle jet. It should be round, but they wear oblong. That jet and the needle that rubs on it (the slide needle) wear very quickly and cause the symptoms you are describing, hence why people are telling you to buy a proper carburettor

I bought 35mm Pursang sliders for a similar reason but haven't got to doing it yet. I can assemble a leg to make sure in a few days time if it helps

What sort of info? It's a popular and well-regarded model Some people have the brake pedal on the left side to get a better feel

Well my memory was wrong about the M198 engine being apart. I found the motor re-assembled and mounted in the frame!!! I did however measure up some 250cc pistons that had come out of M85, M85 and M49 engines and they were all different rear skirt lengths, and the rear skirts had all been shortened. I measured from the crowns to the edges of the inlet skirts and got 56mm, 58mm and 59mm. One of the M85 cylinders had had the top edge of exhaust port raised in one window but not the other window, so I know what you mean about being ruined by someone with a grinder (and is why I bought a second M85)

I do have a M198 (a 238cc Sherpa T contemporary to the M212 Alpina) and it came with the original piston, so I will dig that out and take a photo

Only the M99 (325cc) Alpina model barrel is the same as the M92. After the M99 model Alpina, the stroke was made longer to make them 350cc, so the later Alpina "350" barrels are also longer, so are not the same as the (325cc) M92 barrel

Bultacos of that era used the same basic piston but the induction side skirt was shortened on the models that were designed for top end performance (Pursang, Astro) to increase inlet port duration. Not having a reed valve meant that shortening the skirt was a compromise and took away from the performance at low RPM. Alpinas and Sherpa Ts that I have worked on mostly have had the full length inlet skirt but some have had pistons with shortened inlet skirts (and other porting changes) that were previous owners work. People do fiddle around with engines. The important thing is that the inlet skirt provides the correct inlet timing. If you want to be certain of the inlet timing, you can confirm the inlet timing with a protractor or "degrees wheel" against standard timing. I rode a Bultaco with similar port timing to the M212 (M49) for a couple of years before I pulled it apart and discovered that it had a shortened inlet skirt (about 4mm). After the rebore and now with an original type MAHLE piston that had the full length inlet skirt, there was an improvement in low RPM power, but it would have also had improved ring sealing as well as the more conservative inlet timing.

US ebay usually has lots of those primary drive covers advertised. The original cover on a M92 is the most commonly available type of cover and sometimes called the boot heel shape. A good M92 cylinder will be much harder to find because it is a wearing part and unique to only a few models This is the first boot heel primary drive cover I saw when I searched on US eBay https://www.ebay.com.au/itm/BULTACO-RIGHT-SIDE-COVER-FROM-1971-ALPINA-125-DIRT-BIKE-TRIALS-BIKE-ENDURO/123068514902?hash=item1ca7748256:g:HNcAAOSwuIRamwb I'm sure there will be lots more listings

Replacement primary drive covers are readily available

https://www.ebay.com.au/itm/Ty175-Yamaha-Trials-bike-gearbox-gear-set/323173172248?hash=item4b3e9f4418:g:oMYAAOSwu4haukF4 TY175 gearbox in Australia. There was one in the US too just now when I looked

I see a lot of TY twinshock parts being advertised on eBay by wreckers in the US. There was a gearbox listed the other day, not sure if TY250 or TY175

Sorry, bikes are assembled

Maybe you accidentally did it as a preview