feetupfun

I just checked this and found that a genuine TY250 gasket was a bit too big in OD (56mm) to fit in the OSSA exhaust port (54mm)

New nuts are available. Yes never-seize is a good idea. Tie wire is the best way to stop it unscrewing. The nut comes loose because the header pipe moves relative to the barrel a tiny bit in use and takes the nut with it, so a springy o-ring will probably not help to stop it undoing. Yes a high temp silicone o-ring should seal off better than the copper gasket. Compressible composite exhaust gaskets as used on Japanese bike exhaust joints would also be an improvement compared with a flat copper gasket if you can get one the right size.

If the cause of the tightness is gummed exhaust residue in the thread, then heating it up will allow it to move Yes its a RH thread You will do a lot better with steady pressure rather than using a punch. A "C" spanner can be made from some flat steel, or bought from a tool supplier Not uncommon for the those threads to be crossed either. You should be able to see if the tube nut is crooked

very similar to Suzuki RM80X clutch lever

here is what mine looks like

as to why it shift hard, what do you mean by shift hard? more detail needed

The clutch arm shaft can stay in the cover when it comes off Can't tell what went wrong with the rear guard from your photo

348 parts also from the UK http://www.inmotiontrials.com/product-category/montesa/ and if you look around on the web you will also find parts suppliers in Spain

With any axial flow fan you can tell which way it is intended to run, by the curve of the blades. The concave side of the blade should always be on the downstream side. There have been trials bikes made with the radiator cooling air direction intentionally being towards the front of the bike. I don't remember which bike it was yet.

earlier (pre 2002 approx) tubeless with the rubber ring were 36 hole and are now hard to get new but of course are available S/H from wreckers. The flanged ones are available in 36 hole but I can't remember where from

A friend of mines 2001 Rev3 developed what seemed like too much sag on the forks and on investigation he found the spring was broken

may also be restricted tank vent

pretty confusing post there Steve. Head gasket goes at the top of the barrel not the base of the barrel. Or maybe you are talking about problems with both the head and base gaskets?

what year did they have come out?

To save a lot of unnecessary work, before you start pulling it apart you need to work out if it is a fuel or a spark issue. To help with diagnosis, crank seals will not cause a bike to cut out. It will make it run lean when the throttle is in the closed and almost-closed position. Even if the float bowl is clean, and fuel flows from the tank, that does not mean there is not a fuel problem. You should inspect the plug immediately after the failed start attempts to see if it is wet or dry. Sudden cut-outs sounds a lot more like ignition problems. If it starts and runs when cold but cuts out when hot, it is most likely the condenser. If you haven't serviced the points, that can also make the spark less energetic. Also just because you can see a spark when you kick it over with the plug out, does not mean there is a spark when the plug is back in the motor, because the increased pressure in the combustion chamber means that a higher voltage is required for the spark to jump the gap. The colour of the spark can say a lot about the health of the ignition. Pale blue spark is the most energetic and yellow/orange/red is least energetic

For next time, and when you want to tighten it, don't hold the magneto flywheel because you risk twisting the crank out of alignment. Ideal method to undo - use rattle gun Next best method - jam a thick wad of rag in the pinch point of the primary gears For doing it up again - use rag method and a torque wrench, and loctite on the thread

All bikes have play in the drive. They differ only in degree. In trials riding you will ride a lot better by gently using the rear brake against the throttle to provide the fine control you seek. If you are concerned from a mechanical damage viewpoint, I would check the gearbox output shaft spline fit, the swingarm pivot, rear wheel bearings, rear sprocket bolts, clutch inner nut and the primary drive gear nut. Many bikes have a cush drive in the clutch between the drive gear and the basket but the previous respondent says that the Reflex does not. The best way to find where the slop is, is with the bike on a stand and in gear with the motor stopped, rotating the rear wheel back and forwards. When I was a kid and had not been trained in how to ride trials, I went through my TY175 from end to end fixing things to reduce the slop in the drive, even going so far as to fit custom-made cush rubber segments in the clutch instead of the Yamaha items, to reduce the slop. It made absolutely no difference to the way it felt in sections. The first time someone showed me about using the rear brake to avoid the slop, it was a revelation.

yes both seals can be changed without splitting the cases. The primary drive side seal is easy because there is a removable sleeve on the shaft. Buy a new O ring that seals the sleeve to the shaft. For the magneto side I usually use a self tapping screw, or two screws on opposite sides, screwed into the seal and pull carefully on the screw.

Yes they work well. So well I only use one of them on the rear and have never had a problem with the tyre moving. A warning though - they are a bit blunt ended which creates recesses at the ends of the clamp plate that can cause a tube to fail if you use too much pressure seating the tyre.

Rims or rim? Modern fronts are tubed

All the bikes shown in this topic so far have their standard upper shock mounting (ie they are not modified). Yes it seems that there will be too much bending moment in those frame tubes, but it seems to work out just fine in real life

bestrcpilot, I'm interested in building a replica OW10. Are you willing/able to share the blueprints you generated?

There are different rules for twinshock trials bike eligibility in different parts of the world. TLS brakes lie in a grey area in our part of the world for trials, because the only common dirt bikes that had them back in 1982, were MX and enduro bikes that also had monoshock rear suspension, and some people consider that any parts from a bike that was originally a monoshock, should not be allowed in Twinshock Trials. Luckily we are a laid-back lot and don't really care much what forks or brakes are on a Twinshock trials bike, and the rules are suitably vague, so there has not been a protest that I know of. Nice looking bike by the way, especially the graphics and finish on the fuel tank. Also thanks for showing the brake pedal. My Whitlock TY175 frame came without a brake pedal and I am planning to make one that looks correct. What is that kickstart lever off? I'm guessing Yamaha WR200?

you can't get more original than this

Have a look in the topic about Mini Majesty seat/tank Units after your question there. I posted a photo of a full-size Majesty 175 for you