feetupfun

My M198 came with a copper head gasket. It was the first time I had ever seen a head gasket on a Bultaco and assumed it was standard. What's the go? Is it meant to have it?

Its a pretty common mod on late model Bultacos where I live. Yes it improves the even-ness of the firing.

It should be possible to machine off the existing mounts, leaving flat areas for new upper and lower clamp halves (and spacer blocks) with bolts going right through and nuts underneath. Ive seen this done on a few twinshocks other than TL250s Alternatively you can get bars custom made with a higher rise than 6" Renthals.

I have a DT175E bottom end that has a TY175 flywheel and ignition stator fitted so I guess that is one of the DT175 motors that has the same taper on the LH end. Are you really asking if they are the same crankshaft or if their crankshafts are interchangeable?

Oxy-LPG is used for oxy-cutting, not welding, and welding is what most home welders want to do.

Mmmmmm...you are probably right to share it

Might not work that well once someone from BOC reads your post

Easy fix - tighten the bolt Slightly less easy fix - weld up worn part of hole and file back to size/position

Mark if you pull the flywheel off we should be able to see if it is the same ignition as something else contemporaneous for which there are modern ignitions available And yes, fitting an electronic ignition does away with the need for a condensor Regards David

sorry to disagree but standard Falcon trials shocks don't have a membrane separating the oil and the gas. Oil can be replaced by releasing the gas pressure with the valve as high as possible (to minimise the amount of oil that comes out with the air). The valve body can then be unscrewed from the shock body and the remaining oil drained out the hole that the valve body came out of - no need to disassemble further. When all oil is drained/pumped out, put 100ml of new oil of your choice in each Falcon. I use 5WT fork oil and I use a syringe to add the oil. Screw the valve body back in and pump them up ideally with nitrogen or argon, to somewhere between 70 and 100psi. Dry compressed air will also work fine, but may cause the oil to degrade quicker than if an inert gas was used.

Yes I get M16 x 1.5

Is this for a 4RT mate?

Some of that model have been imported to here second hand since then. There has been a healthy trade in second-hand trials bike imports from Japan for at least 25 years by my reckoning. Most commonly seen are TLM220 and TLR200 but all 1980s and 1990s Japanese market trials bikes are represented in that trade including the Yamaha TY250Z. Recent developments in the worldwide economy have seen imports of second hand bikes from the USA increase greatly, but in that case it is mainly MX bikes.

black connects to black and is the LT wire for the ignition. The other two are for the lighting circuits and so don't have to be connected to anything unless you are fitting lights.

There should be piston clearance info on notes that came with the Wiseco piston. Wiseco need different piston clearance to what is in the Yamaha book due to the composition of the piston metal having a different thermal expansion rate compared to pistons like Yamaha and Pro-X. The Wiseco is not the best piston for the TY175 for trials use because they are made for race applications rather than trials so will rattle a lot more than others as has already been mentioned.

Is this a joke posting? All I could see is someone stationary balancing on a trials bike. How on earth can anyone suggest what to practice based on seeing that?

Do you mean the twistgrip is returning or the slide is returning? If slide is returning you may have an air leak on the engine side of the carby (probably the connector to the reed cage)

What is wrong with just painting TY hubs and backing plates with silver paint? It has worked fine for me for the last 35 years.

What is it you are asking about?

Jon have another read of the article. It says "steering head angle was tweaked" and "rear shocks angled". The steering head angle change claimed was most likely due to the rear end being slightly higher.

Total agreement - I love the patina of old bikes. I have a M198 with a discoloured but otherwise undamaged original red polyethelene tank and love the look.

I've had two electrical failures on our 24V OSET. One was the keyswitch relay had failed. The relay is a commonly available item at auto electrical shops. If you are not hearing the relay click when you turn the key, it could be the keyswitch failed or the keyswitch relay failed. The other failure was when the speed-limiting potentiometer failed. It can be disconnected if your kid is OK with using full power, which is how I got around the problem.

Andrew are you talking about a front Dunlop or a rear Dunlop that won't sit straight?