dadof2

SAe 5w - 30 or SAE 10W - 30 mineral or semi synthetic. Castrolite SAE 10W - 30 used to work well. I would think ATF would also - Dexron 2 or 3. More modern grades such as the ELF HTX or dexron 6 may cause clutch slip on older bikes.

Generally a racing (as in max power / speed) 2t engine has a maximum piston speed of about 4,000 ft per minute. This would equate to a shade over 10,000 RPM on a 300 Sherco. As trials engines are tuned for low end torque and only deliver about 1/2 power of a MX engine I would think a Shercos max revs would be some way short of 10,000 especially as it has a restrictive exhaust and not an expansion chamber.

I had come across this some time ago on youtube. Not impressed then, not impressed now. totally pointless and could have deprived the sport of a good rider.

Anyone know if and which free to view channel motogp is on in UK? Could not find it on ITV 4 or channel 4 this week, it was on one of those last year

No need for yours or heffgms sarcasm, I spent many years in the oil / chemicals industry and several more where research into and manufacture of biofuels was carried out. What I posted is common knowledge in these places. I do not know the exact situation in the USA but in the UK the composition of pump fuels both petrol and diesel is varied between winter and summer, the adjustments to avgas to allow for low temperatures and pressures is far greater. Aero engines are designed for steady speed running and so is the fuel. No point in using higher octane race gas unless your compression ratio has been increased to benefit and appropriate adjustments made to ignition timing. Stick it in a standard engine and you will loose performance and waste money and possibly overheat the exhaust components. Lead fouling Insulator nose covered in places with brown/yellow glazing, which can have a greenish color. Cause: Lead additives in fuel. Glazing results from high engine loading after extended part-load operation. Effects: At high loads, the glazing becomes conductive and causes misfiring. Remedy: Fit new spark plugs since cleaning the old one is pointless. 1. 2. 3. 4. Pronounced lead fouling Insulator nose covered in places with thick brown/yellow glazing, which can have a greenish color. Cause: Lead additives in fuel. Glazing results from high engine loading after extended partload operation. Effects: At high loads the glazing becomes conductive and causes misfiring. Remedy: Fit new spark plug The above advise is from Bosch. Lead fouling resistance is no longer a criteria in spark plug manufacture and even less extreme results than the above greatly shorten plug life. Hence as others have posted the "no leaded fuel" stickers on their bikes.

There is no one correct answer to mix ratio, there are too many variables. My opinions are based on working with 2t engines for nearly 50 years.Most of my knowledge of oil performance was gained on MX and kart engines where the lubricant is worked much harder than in trials engines and lubricant deficiencies show up much faster. All the technical arguments (more power and less wear) favour putting more oil in the fuel. The environmental and oil cost arguments suggest putting less oil in the fuel. In my early days of trial most trials were a lot longer duration than today and involved a lot of roadwork and often a time element, this form of trials needs more oil than the present typical club trial of pottering round a couple of fields for less than 4 hours. What I did notice on MX engines was a very significant increase in wear rates when the ration was 40:1 compared to the wear rates at 20:1. On air cooled trial engines far more wear occurs at 50:1 than 25:1. On watercooled trial engines I have seen 125cc piston / bores well worn out in under 2 seasons when run at 80:1. Run at 40 or 50:1 and the same or a bit less wear takes about 5 seasons. Run a larger capacity watercooled trials engine at 32:1 and wear is virtually eliminated but you do have the extra oil costs. Modern watercooled engines with sealed mains, high silicon cast pistons and tough bore platings can get by on remarkably little oil, but a bit more oil is useful insurance against hard use, water ingress, a stuck open throttle, a carburation fault or running out o fuel.

Manufacturers of 2t EFI bikes recommend very lean mixtures to enhance fuel atomisation at the low pressures their EFI systems work at. Whether such mixtures promote engine longevity is questionable to say the least. If you get exhaust clogging it is because you are using crap oil, crap fuel or your carburation is incorrect. If the oil and fuel is good and carburation correct you do not get exhaust clogging even at 20:1

A bit of snow on the hills and a very plesant 17 degrees C here today. Brilliant sunshine all day and same forecast for tomorrow.

In general do not use avgas in a trials engine. It has additives an characteristics a trials engine does not need and in some cases may be detrimental to the running of a trials engine. For same reasons avoid high octane race gas. Unleaded 95 to 98 Octane should be fine even if it contains ethanol. Ethanol reduces power but so little you won.t notice. Ethanol does not affect running on the 4RT so long as its not left in the tank too long. The 4RT ECU can't "sort things out" because it has neither knock nor Lambda sensors. Leaded fuel should not be used because modern spark plugs are not designed to withstand lead.

American police Harley davidsons used to have a left hand throttle. This was so they could keep it open whilst using the right hand to shoot.

Change the spring, they weaken then crack.

There tends to be a % of polyester in most clothing, The lower the % the better for all off road motorcycle clothing. Polyester is hardwearing but it does not breathe well and there is a much higher burn risk compared to cotton and wool clothing. I think the british military abandoned polyester clothing due to their experience with it in the Falklands war.

2t it may be but in attempting to reduce emissions it has lost the fundamental 2t advantage of simplicity. Its a pity the sports governing bodies ever allowed disc valves, reed valves or power valves.

Maxima 0w 10 is virtually identical to Castrol synthetic ATF. Regular ATF (Rather than the most recent synthetic types) will not provide the same level of protection.

Do away with rim tape Fit a bolt in valve with O ring Seal spokes with sikaflex winsdscreen adhesive or dow corning lead and gutter seal. Do not use acetoxy silicone, it will rapidly corrode the rim.

I would think autotest is the safest form of motor sport (probably the most boring as well)

Have a read of the BTC summary, who really needs a new bike (old monts never die?)

I think you may find that there is more than one petition on this,

Which way was your bike facing on the trailer, if it was exhaust forward could water have blown into the engine through exhaust or airbox? Generally considered best to store or transport or wash a single cylinder 4t with the engine on the compression stroke. 2t should have the exhaust bunged.

MX jerseys / shirts tend to be thin and ventilated as they are intended to be worn along with body armour, elbow and back protectors etc. maybe not ideal for UK trials. Many mx jerseys are made of material with a high % of polyester which melts easily on hot engine / exhaust parts and then can stick to the skin with unpleasant results.

I signed and wrote to my MP. To sum up his reply "the government is looking at it"

HG stove glass cleaner does a brilliant job and removes the oil / coke well before it starts to damage the alloy. It takes several minutes to shift the coke but several hours to start to mark the alloy.

Breagh's second sentence is very important. On any engine with electronic ignition you must always let it fire through an earthed plug or earthed ignition tester. The ignition system produces a burst of high voltage electric. If that energy can't ground through an appropriate place it dissipates in the electronics damaging them, eventually to the point of destroying them completely.

2 stoke use on road is in decline due to emissions laws. The side valve engine is not used because it has poor volumetric and scavenging characteristics particularly as revs increase. A side valve engine has very good low speed torque and a linear power curve, Laws in UK restrict car maximum on road speed to 70mph yet nearly every car on the road can exceed this by a large amount. If a manufacturer produced a side valve engined car it could be cheap and have excellent driving characteristics at all legal speeds but it probably would not sell because of the way in which most people perceive vehicles with a low maximum speed. Very frequently people buy what the perceive they need, not necessarily what would be best for their purpose.

Pressurising the engine does not necessarily prove the seals are OK. The seals are designed to seal tighter with crankcase pressure. It is when the crankcase is at negative (relative to atmospheric) pressure that worn seals allow air in. You would have to create a vacuum of at least 22 inch mercury to assesses the seal effectiveness.