feetupfun

It's fairly common to need to open the fork tube clamps a bit. If you've had the tubes re-chromed sometimes they end up slightly bigger in OD than original, but even standard tubes sometimes need it too. If it is only the second (upper) clamp that is causing problems, it might pay to check if either of the clamps is not quite straight. Another option is to fit the tubes through the bottom clamps without the top clamp, then fit the top clamp, rather than try and slide them through both clamps at the same time.

Common failure on that type of hub. It is a Honda hub and good ones are rare, not just because it is a rare model bike, but also because they break). Cota 242s also had that front hub. The earlier Cota 247/348 type front hub can be used and are far easier to find. I've also seen Yamaha drum-brake wheels fitted to 348s and 349s. Some 349s have narrow spacing between the fork tubes which limits the type of hub that can be fitted (unless you also get a set of wide triple clamps)

The rim and tyre should be in the centre between the forks. The rim can usually be moved left or right by adjusting the spokes. It's possible that it has a non-standard wheel so if you post up photos, you will get help with that.

How the air screw is set makes a big difference to the off-idle response

On the SWM in the photo there is still cable between the clutch and the device which would operate at full cable loading. Your suggestion to have an intermediate lever just above the clutch cover with a rod to the clutch arm would have less friction overall than the setup on the SWM because the whole cable run would be operating at reduced loading.

Have you tried Hell Team (GasGas importer and a wealth of GasGas knowledge) in Sydney, Australia? I think they helped my friend out who bought either rings or a piston kit for their GG70

The green is the 212 (250) and the red is the 213 (350)

Sammy Miller Products made some a couple of years ago

Here is the page from the parts book for a TY250C which lists that (output) shaft as the same part number as a TY250A. I notice that the clutch (input) shafts have different part numbers.

OK I have tried a few things out on my KT clutch in attempt to reduce the lever pull by reducing the pressure plate clamping force. First I inspected the clutch and read my log book. The friction plates are genuine Kawasaki KT and about 10 years old and low hours. New genuine Kawasaki KT springs were fitted at the same time. The drive edges on the friction plate tabs were smooth. The basket fingers are steel and were smooth. The rack and pinion had a smooth action and was well lubricated. The cable is a 10 year old Venhill and was well lubed. I think I could improve on the cable by making it a bit shorter, to improve the routing. The gearbox oil is Dexron II ATF. After that, the first thing I tried was to reduce the clamping force on the pressure plate by reducing the clutch spring preload by spacing out the spring retainer plate. I found that reducing the preload by 2mm made barely any difference to the lever pull. I also found that 2mm is about all you can add there before having to use extra clutch cover gaskets or machine something. Next I went looking for alternative springs and found that some springs that came out of a TY175 motor were very similar to the KT springs, but a bit higher spring rate. The KT springs were 165 lb/in and the TY175 springs were 186 lb/in. This meant that six KT springs would theoretically have a clamping force of 779 lb and four TY175 springs would have a clamping force of 585 lb, or 75% of the force it had with the six KT springs. Four KT250 springs would have 66% of the clamping force of six KT springs. I fitted four of the TY175 springs and tried it out and found it worked fine in all gears and the lever pull was noticeably less, but still not as light as my TY250 motors with their three springs. I am running very low gearing on this KT and suspect that if it had standard gearing it might have clutch slip in the upper gears. KT 250 springs 15mm OD, 7 coils, 2mm wire, 31.5mm free length TY175 springs 14.4mm OD, 7 coils, 2mm wire, 31.1mm free length By the way, those springs that came out of the TY175 motor might not be standard TY175 springs

maybe post suitable photos so people can tell which carby you have there and is it really called a TOKO or is it an OKO and is it really a flat slide or is it a crescent slide? There are lots of different carbies out there

Has anyone tried riding trials on a KT250 using only three of the six clutch springs? I've done this with a couple of TY250 twinshocks and it works out very nicely. Before I try it on my KT, has anyone already tried it?

The crankshaft on the A drives the primary gear with a spline. Later models use a key drive there. The cylinder is different but is interchangeable. The flywheel has a different size external ring but is interchangeable. The ignition stator is the same. The reed cage is the same. I do have the parts books for all the TY250 twinshock models so can look and compare them if there is something particular you want checked

Not a good idea to ride with something attached to the throttle cable

I know you can splice on a new lead because that's what I did with my 348. I didn't try and take the old lead out of the coil though. I spliced at about 25mm from the coil casing. There's nothing wrong with fitting a new aftermarket coil either, but getting one that fits in the available space might be tricky.

Those things will climb anything in 4th gear if you are strong enough to hold on and are a good enough rider

A reasonable guide to judge if a motor is overheating is to wet your fingertip with saliva and touch the flat surface of a head fin. If the saliva sticks before it evaporates, then it is not overheated but if you can't get it to stick it is possibly too hot. A happy temperature for the heat transfer surfaces of an air-cooled engine is around 100 to 110 degrees C. They do get hotter than that when you ride with sustained open throttle or leave them idling in hot weather.

Has it just been rebored, or had new rings fitted?

I don't know the reasons the UK ACU based their decision on, but it is fairly logical that having something like a gopro attached to you helmet will increase the risk of you getting a broken neck

So after the steering head angle mod moves the front wheel back, do you do anything to get the wheelbase back to standard again?

Doesn't titanium have some unusual frictional properties? I don't remember the details but do remember there is a friction problem when it is in contact with some other metals (ie they stick together)

On some old trials bikes, anything but the plain standard type of chain can be too wide to fit at the front near the front sprocket. Another thing is that O-ring chains have more parasitic drag than a lubricated non-O-ring chains, and weigh more. Standard chains used for trials riding last many years here where it doesn't rain much so there is little reason to use anything else. O ring chains last a lot longer (in distance ridden, not necessarily age in years) than non-oring chains especially in wet, muddy or dry sand riding.

you shouldn't have to take the brake caliper off to take the wheel out

First off does it have USD forks or slider-at bottom forks? My memory is telling me that on slider-at-bottom forks, you loosen the clamp bolts at the head end of the axle and unscrew the axle. The axle has a socket hex head (maybe 12mm hex) at one end and the other end has a male thread that screws into the fork slider

There are two different standard TY175 carbies. One has a stamping 525 - ***** and the other is 1N4-*****. They have different jetting and are that way because there are two different TY175 end muffler designs and the 1N4 carby bike comes with a rubber snorkel on the airbox lid. Have a look at your carby and see which one it is. If you want the alternate jets on hand for when you test ride the bike, you can take the pilot jet and main jet out of the carby and read the sizes that are stamped on them and maybe buy jets one size bigger and smaller. You can buy genuine Mikuni jets from a Mikuni agent or aftermarket jets from multiple sources. The non-genuine jets are sometimes not size stamped. Pilot jets for those carbies go up in intervals of 2.5. For example 22.5, 25, 27.5, 30, 32.5, 35 etc Main jets for those carbies go up in size in intervals of 5. For example 130, 135, 140, 145, 150, 155, 160, 165 etc Both jets are commonly available types. You can look at Mikuni parts listings on the internet. Look for Mikuni VM type carby parts. You can probably also buy them as Yamaha TY175 parts from a Yamaha shop but that would be quite expensive. You may not need to make any changes to the jetting