feetupfun

Yes 4 pot front brakes were a huge advance in brake control compared to 2 pot. The EVO also feels substantially lighter to ride than the Techno. I remember riding my first Rev 3 in about 2001 and being amazed at how light it felt to ride compared with a Techno.

I've done it the other way around, fitting TY250 forks to a KT (wanting to increase the trail). I used a TY wheel. An axle spacer was needed for this. It was just an experiment and I went back to using KT forks on my KT. There were two problems with the TY forks on the KT. The amount of trail was too much which upset the steering and the front mudguard hit the exhaust header on full compression of the forks. I then modified some KT triple clamps to provide only about 5mm extra trail over standard and was very happy with the result. If you fit KT forks to a TY250, the KT wheel assembly will be a bit too wide because with KT triple clamps, the fork tubes are slightly (2-3mm) further apart than with TY250 triple clamps. I've not tried to fit a TY wheel to KT forks. KT forks are longer overall and have more travel than TY250 forks and would reduce the trail by about 20-25 mm due to the leading axle design. They are functionally very similar inside with the main difference being that the KT forks do not have anti-topping springs. They are so similar inside that you can use TY internals in KT fork tubes and vice versa. It sounds like a fun, interesting project.

A standard 250 1997 Techno has a lovely soft motor. Technos came out in 1994 and were highly responsive - probably too responsive for the average rider. The 1996 model was made much easier to ride for the average rider and it stayed like this for the rest of the years of the Techno (96, 97, 98, 99). By the way, is your Techno a 250 or a 270?

One way to judge piston ring seal without pulling much apart is to inspect the cylinder wall via the exhaust port or the plug hole, looking for dark areas (carbon). Carbon on the walls indicates piston ring blowby. Be aware that trials two strokes nowadays commonly suffer from having the rings stuck in their grooves by gum and carbon. This can happen quite quickly depending on how the bike is ridden, the type of premix oil and how well the bike is jetted.

TRS sells electric start 250 and 300 two strokes and they are very popular.

The ball and spring can be installed or removed with the engine assembled

You can use the TY175 head or the DT175 head. If you use a DT175 head, the compression ratio will be higher but you may need to trim the head fins for exhaust pipe clearance. You can mount a clutch cable holder on the engine casing or on the bottom cylinder fin. The DT175 cylinder fins will not interfere with anything physically. Trim them if retaining the original TY appearance is important to you.

DT175 1974,75,76,77 (DT175 ABCD models) cylinder will fit and function well but has different finning outline to TY175. I have not tried or measured up a CT1,2,3 cylinder.

Which brake plate is standard/correct depends on which hub is on your model 92. Also, they might both function OK. Can you do photos of the hub showing the brake drum and an external view showing the finning and both spoke flanges?

Here's the OSSA cush drive puller photo

Yes, quite impossible. "Fingers" on a puller made to fit in there are not strong enough for the job by a large margin. The puller needs to pull on the whole surface. The Montesa primary drive crankshaft gear of the same era as the OSSA cush drive is also on a taper and is also impossible to get off with a universal puller so it is not just OSSA who did this back in the day. I'll post a photo up later when my cloud storage is talking to me

200 Euros labour plus parts sounds quite reasonable to me and even cheap if they have to source or make a special puller. Do they know what's involved?

Yes it's not easy but are you saying you can't find where to buy the special puller from?

Triad, if the primary drive crankshaft sprocket has a cush drive, then it is an easy job to change the crankshaft seal, but you need to buy a special puller for the cush drive. These pullers are available from vintage OSSA parts suppliers in the UK and USA. Buy a primary drive cover gasket and crank seal holder gasket while you are at it.

Non-powerjet. If you want an OKO, the model is K-100 and people usually run a 26mm or 28mm

While it's probably OK to leave fuel in it, it would be kinder to the tank liner to store the tank dry over winter. Nowadays after a ride, I drain and dry out my lined fibreglass tanks if it will be more than a few weeks until the next ride. My oldest epoxy tank liner is about 20 years old now. For the first 15 years I left that one with fuel in between rides and it gradually changed from honey colour to dark brown over the 15 years. After I noticed this happening I started draining it between rides and now at 20 years it is still working fine. It may still have been OK if I had continued leaving fuel in it, but the colour change made me wonder if it was being gradually damaged structurally. For info, Caswell liner is epoxy resin

If you are using the Explorer exhaust system, there is no advantage in using anything bigger than the 27mm AMAL. The Pioneer uses a bigger carby because it sucks a lot of air when it is on the pipe. The Explorer exhaust will mean that the Pioneer motor will suck about the same amount of air as an Explorer motor at full power.

When you have finished riding, turn the tap off and run the fuel level down in the float bowl before you stop the motor. Otherwise the evaporating fuel can make the float needle sticky. You may even have a passing fuel tap which could exacerbate this effect by allowing lots of premix to evaporate between rides. As for the lanyard killswitch, it can be wired in parallel with the standard kill button/switch, so the standard kill button/switch can stay. Maybe post a photo showing the "actual" slide switch you are asking about

Mikuni or Keihin or OKO or Dell Orto are all a better option. Keihin most expensive. OKO least expensive.

If your rear drum is worn (bigger than standard), new shoes will not match the curvature of the drum, causing the friction material to have a reduced contact patch area. If you have your shoes relined and machined as Kurtas suggested, the friction material curvature can be matched to your drum curvature, giving full contact surface area. To determine if this is your problem, pull the rear wheel out and have a look at the friction material. It will be shiny where it is touching. The areas that are shiny are the only bits that are doing anything to slow your bike down. The other aspect of your brake performance is that the co-efficient of friction of your lining material may not be as high as what is available, so when the shoes get lined, choose a material that increases the co-efficient of friction.

Throttle pulley size is a personal preference thing, like bar position, lever position etc. I use the slow twistgrip on my 250 MAR and throttle control is exactly how I like it.

I saw some made from stainless steel last weekend. A friend had a few custom buckles for trials helmets made locally. While it sounds like a good idea, non-OEM helmet parts or modifications will render a helmet non-compliant in a legal sense.

I didn't see the post until tonight. You're probably right. I only ride IC trials bikes but the same applies about hearing the sounds of the motor being an important part of riding trials well. As far as electric trials bikes go, I have only ridden a clutchless EM and I could hear the groaning of the motor at low RPM quite well, but someone with poor hearing may have had difficulty. Do the modern EM bikes sound different to the original ones?

Good outcome. I suggest you re-torque the cylinder hold-down nuts after a couple of heat cycles. There's a good chance of generating another base gasket leak unless this is done.

Paint shops can usually match a colour by scanning what you are wanting to match