feetupfun

never heard of a slide with zero cutaway. Is it fitted the right way around?

what part is tarnished?

Did the plates move out parallel? Even with very flat plates, if the springs are not preloaded evenly, the release travel will be long because the pressure plate tilts

The release travel required depends on the sum of the out-of-flatness of all the plates. The fibre plates (outer plates) I've put in one of my Bultacos (Barnett) were very flat and did not increase the travel required. The production method of the original Bultaco plates is stamping, which is a method that by its nature introduces some degree of out-of-flatness (depending on the condition of the shearing edges) It is very common to see high and low spots on used OEM Bultaco plates, which is evidence of their lack of flatness

It is much easier to set the clutch up with the perfect amount of preload on the springs if you replace the clutch inner with one that has threaded rods and nuts for the clutch springs instead of the clutch inner that has the pins-through-holes spring retainers.

Sprocket: The sprocket is on a taper. If you use heat to help it break free it will probably melt the oil seal but if you are rebuilding the motor it probably doesn't matter. I usually cut old sprockets off my 348 with a 100mm angle grinder. Works a treat Crankshaft: Remove the seal holder Warm the casing to free up the bearing outer

A friend in the 1970s ran his almost-new Suzuki Waterbottle (GT750) on straight petrol (with the oil injection system not functioning) for a few weeks of riding to work. He pulled the cylinders off expecting carnage but the top ends were still perfect

A router is flash. I use a hacksaw

Kind-of-porky OSSA MARs and every other twinshock I have ridden go much better with modern tyres than they did with old style tyres

MT13 Pirelli was certainly the hot ticket when I was a kid (late 1970s). My memory tells me that the other proper trials tyres at the time were either Avon or Dunlop

There is no law against using a roller. I've seen plenty of twinshocks with a roller on the tensioner arm instead of a slider. Whatever rocks your boat.

Wet trial = heat up brakes after trial before loading bike into transporter to get drum surfaces as dry as possible. When I get home, clean external mud off bike then take wheels out and dry brake parts fully. Then some time before the next ride, service the brakes

Wossner make 2.0mm oversize for TY175 and are good quality

still trying, you have ignored the friction at the interface between the cam and the rubbing plate and this friction causes loss of feel that gets progressively worse as the angle increases, and as guys says, jamming on of the brakes at higher angles. The best feel and strong braking is achieved by matching the shoes to the drum and minimising the cam angle. Depending on the cam width, 3 to 5 degrees cam angle is usually enough to provide a suitable working clearance for the shoes

Yes I'm 57 and same problem here. To see well when riding trials I have had a set of single focus (distance) lens glasses made and they are really great for riding trials. Only problem is I cant see clearly up close so using a smart phone or fiddling with carby jets is not on. I also had bifocals made with only a tiny bottom lens but I didn't like them anywhere near as much as the single focus pair for trials riding

Discs can be severely heated and not affect the hub, but if you heated up a drum to the temperature that people heat discs to to water-quench-clean them, the bearings would fall out and the grease would catch fire, and if you have a Bultaco hub with the replacement steel or cast iron liner fitted, the liner would probably fall out

It should clean out of the engine pretty fast without doing any special washing out. I had a two stroke lawnmower that had the tank accidentally filled with diesel and the person borrowing it attempted to start it (until they broke the starter mechanism). I fixed the starter, drained the tank and carby and put premix in the tank. It started up fine but the exhaust fumes smelled terrible for the first few minutes

I think that is the one Tim has seen but he might not have noticed that every second page is in English

5kg sounds fairly optimistic for an engine

as bigshiney bike says, but the crankshaft drive gear is on a taper, not a press fit

Pretty sure there is a Haynes workshop manual for TY175

I reckon that Yamaha just want to have their livery on show wherever possible. Back when they were selling motors to Scorpa for use in Scorpa trials bikes, the bikes that the Yamaha sponsored riders rode in Japan were Scorpas but decorated as Yamahas. Now that Scorpa trials bikes no longer have Yamaha motors, Yamaha can make a semi-works trials bike any way they want and decorate it as a Yamaha and vive la difference. It's not as if they are going to redecorate a Honda 4RT in Yamaha livery. I just wish that Yamaha would (once again) make a decent production trials bike and sell it internationally.

Yes the replica KT bars are about an inch higher than modern 6" Renthals. The bars on my M49 in this photo are a bit higher again than the replica KT bars and were custom made from thick-walled 7/8" structural aluminium tube to replicate the shape of the bars that people rode with on these bikes when they were new. The bars provide very nice ergonomics on this bike for me (5' 10") with the footpegs in the original location

I've just noticed that your bike appears to have shockies that are quite a bit longer than most people use on that bike, which would be contributing to your neck discomfort because the rear of the bike (including the footpegs) will be higher than normal

Because the bar clamps are now so much higher than standard, you have created a severe limitation for how far you can get your upper body forwards. This is one of the reasons Fat bars (that have no cross-brace) are popular. I see you have bars with no brace already, but you could improve your chest clearance and still have the extremely high bar-end position by having custom bars made that have a higher rise. You look quite tall, so could probably benefit from lowering the footpegs which would allow a less extreme bar end height and still have a comfortable neck angle.