TMofCumbria

Lead was put in petrol for 2 main reasons. To increase the octane rating and thereby prevent knock (pre ignition) and to prevent valve seat recession, that is why when converting a classic car engine to run on unleaded new valves and seats are fitted. I would expect any Japanese made or designed motorcycle engine since 1970s would have no problem running on unleaded. Follow topic Submit Reply

Exhaust paint is no good for engine casings, you can't get it hot enough to bake / cure it. you need engine lacquer for the casings.

I found halfords high temp black works fine but you have to let it dry overnight then bake it on with a propane torch until it turns slightly grey and stops smoking. then let cool before using or letting petrol get on it. Simoniz sperex vht is very good but like halfords it has to dry properly and be baked on.

Take the spark plug out and alternately push down on the front and back of the piston with a plastic or wooden rod. If you can make the piston rock / click its probably going to need a new piston and possibly bore work as well. Certainly strip to measure.

Yamalube 2R at 30:1 if your are going to ride it hard. For medium throttle use 40:1 and for pottering along trails with the old burst of speed 50:1. This advice only refers to Yamalube 2 R not other oil which can be much poorer / different lubricants due to being pre diluted

The mix ratio topic can cause a lot of controversy. Beta recommends 25:1 if you are using standard 2T mineral oil and 65:1 on Bardahl fully synthetic. As other posters have said you can run at 80:1 on modern synthetics. The problem is if your bile is jetted for 25:1 and you switch to 80:1 it will run rich, not burn the oil off and look as if there is too much oil as the plug will be black and oily. I do not know if your bike has a cast iron liner or a plated bore or if the piston is forged or cast. A high silicon cast piston in a plated bore can do with much less oil than a forged piston in a cast iron bore. If your engine is worn use a thicker / more viscous oil and put more in, but whatever you do get the jetting correct so plug is right colour. Fuel. An engine with a bit of wear and low compression will possibly run fine on E10 but some older bikes Like Yamaha monoshocks do not like E10 and run much better on E5 or even higher octane if you can get it. If your bike pinks (pings and rings) and sounds a bit odd use higher grade petrol. People refer to ATF as if its all the same, it is not and a Dexron 2 spec will probably damage your gearbox. Use at least Dexron 3 semi synthetic or preferably light gear oil or multigrade. 10w-40 works fine in most gearboxes.

I started trials in 1975 and MX in 1982 and have done a bit of grass track as well and had ridden off road (old road bike with knobbly tyres) a bit well before starting trials proper. Both sports complement each other. For quite a few years I did both, sometimes trialling till quite late on a Saturday evening and then getting up early on Sunday for MX, never had any problem adapting.

I think you are going to have to give a better description of exactly what you are doing if you are going to get a useful reply

Don't you mean 160:1 ?

Bit surprised at the question but will answer it anyway. A traditional clutch uses coil springs (usually 6 on a trials bike). These provide relatively low force when the clutch is fully engaged and the pressure increases the further you pull the lever back towards the bars. The spring in a diaphragm clutch is a large "domed washer" a bit like a saucer with a hole in the middle. It exerts maximum pressure on the clutch plates when they are fully engaged. The pressure to compress the diaphragm gets less the further it is compressed by moving lever towards the bars. In theory a diaphragm clutch should be better because is minimises the likelihood of clutch slip whilst reducing lever pressure and increasing sensitivity at the bite point. Diaphragm clutches have been used in industrial machinery for many years because when automated as in a cnc machine their energy consumption is lower than an equivalent coil spring clutch.

I am not familiar with the Vertigo but nearly all TPS are some form of potentiometer, On a car the usually operate from just over 0 volts to 5 volts with the voltage changing smoothly as the throttle is opened. I suggest you find a garage that has someone competent with an automotive oscilloscope to check your TPS operation. Give a vertigo motors uk a ring and ask them what voltage range should be.

Maybe cut sealing lip as you put shaft through then. Could be a groove i shaft due to previous seal wear or a bit of corrosion on shaft if new seal is contacting it in a slightly different place.

A 520 is about 25 % stronger than a 428 but comparing the tensile strengths of the chain is not that useful. You can look up minimum tensile strengths in engineering tables but this would not tell you everything. All decent chain is stronger than the minimum but some are much stronger and more hardwearing than others. All other things being equal a 428 chain will wear slightly faster than a 520 because there are more links to wear in a given length. A 428 chain is smoother running and lighter. A 428 chain will stand over 2 tonne which is far more than a TY 175 will put on it. Best thing you can do for a trials chain is an oiler dripping bio degradable gear oil onto it and spay it with WD 40 or similar after washing the bike.

on the lower photo you can see a fragment of metal at 4 O'clock, It only needs something of this size in somewhere like a bearing to jam it solid. Perhaps there are more fragemts in the shift drum bearings. rinse it out with two stroke mix over a clean container and look for more fragments falling out. try to rotate drum bearings whilst rinsing.

Check the reed petals are in good order and seating correctly. Check for exhaust leaks at cylinder joint. Many 125s are a bit gutless and lack pulling power at just over tick over, perhaps this plus a bit of wear. 4.5 turns out seems far too many