feetupfun

If you can't find a decent second hand pipe and still want to use the Feked silencer, a new front pipe for your bike would be a fairly easy thing for a tradesman to make, especially if there is your old one to copy the shape from. As a for-instance, I've seen front pipes for Bultacos and Italjets made from pre-curved architectural tubing (thin wall stainless steel handrail material) that look excellent

If you post a photo maybe someone can help

Every ride here ends with a helmet soaked with sweat. I've not yet had a trials helmet that doesn't die of rust before something else stops me using it

I have had a few Airoh trials helmets and they all suffered from rapid rusting of the metal parts even when I took precautions

yes there are replica KT250 bars available that look just like TY175 bars. Search on Fred and Debs KT parts

Trials bikes are kickstart only and don't usually have a battery

Small job either way but expensive if it's a hole in the casing

If you haven't just been riding in deep water then you probably have a leaking water pump shaft seal or a corrosion hole in the water pump housing

Thanks majesty. I know there are at least 108 of them

If I had a decompressor on my 348 I would use it to ease the piston over TDC before giving the kickstart lever the starting stroke

Don't get hung up on the front hub. The IT range had speedo drive from the front wheel and a YZ hub

https://www.yamahaty.com/english/tyusineen/majestyen.html

Slide number is usually the height of the cutaway in mm

Here's a photo of the adaptor plate I was talking about

As for your other question, yes when you use a rubber connector for the carby, you no longer need the thermal insulator piece. To seal that joint, you can use a paper gasket or machine an O ring groove or use a sealant that stays soft

You could alternatively fit a flat adaptor plate that fits the existing studs and has 2 holes in a vertical plane for a connector that has the mounting holes further apart. I've seen those adaptors for sale but would be very easy to make. Connectors with wider spaced mounting holes are easy to source. Yet another option is to use the inlet connector piece from a later model Alpina or Sherpa T, which are made to suit spigot mount carbies. That's what I did on my M138 Alpina when I replaced the AMAL flanged carby with a Mikuni, then an OKO

Yours is an early A model TY250. It will probably have a engine number prefix 434 and frame number prefix 434. There is no reed spacer on your bike. The alloy plate you can see the edge of is part of the reed cage. That carby is an aftermarket Mikuni. Easy to tell by the large spigot that the fuel hose goes onto and the idle air screw is on the wrong side. The original carby on the A model TY250 is a TK brand. The TK carby is good until it wears then not worth keeping because the wearing parts are expensive/unobtainable. Later model TY250s came with a Yamaha-Mikuni carby that was unique to the TY250. The B model TY250 Yamaha-Mikuni is different to the C,D,E models TY250 Yamaha-Mikuni. The important parts are not interchangable between the off-the-shelf VM26 Mikuni and either of the VM26 Yamaha-Mikuni carbies. Your carby may well work well. If it does work well and is 26mm, please share the jetting specs because I've never been able to get the one I bought to work well on a TY250 motor.

I'm old and unfit but can still manage to start my 348 dozens of times during a trial without using a decompressor. Having said that, I find that starting it for a section often takes more effort than riding the section. If it wasn't so hot where I ride, I'd probably leave it running more than I do. They do make a cool noise if you use one for braking. The 348 kickstart mechanism is robust apart from the return stop so there is no need to fit one to protect the mechanism.

The open class Pursang cylinder that fits that bottom end is also 325cc. The later open class Pursangs (360 and 370) have a longer stroke, as does your model 213 Alpina

More HP? Have you ridden it yet? They are known for a few things but not for lacking power

Not me but I've seen some. Eligibility can be tricky here. OK for P65 motocross but not for P65 trials

I use NGK B6ES with 0.5mm gap with a standard ignition TY250 engine and B6ES with 1.0mm gap with an aftermarket electronic ignition TY250 engine. On both engines the spark plug gets looked at about once per year. They usually start to get rounded edges after about 5 years. I've been setting the plug gaps on my trials bikes with points ignition at 0.5mm for about 45 years now and have no recollection of where the 0.5 mm first came from. A B7ES is a conservative plug for a TY250 twinshock and was recommended by Yamaha because they wanted to minimise the risk of customers melting a hole in the piston crown when they went flying along the road on a TY250 (like commonly happened in the 1970s)

I use car manual gearbox oil in my 348 clutch and it works beautifully. I was using ATF in the clutch previously but it squealed during engagement.

Take the cable plugs off the thermostat and join them together electrically. Set a multimeter to measure resistance and measure the electrical resistance across the connections on the thermostat as the wet end of the thermostat heats up. A saucepan of water on a stove works for this. It should drop to zero ohms when the water gets hot enough - somewhere around 80-90 degrees celsius.