b40rt

They don't look to bad to me, just clean up the front with a wire brush. As you said your not intending on competing, why not put a tube in the back ? You will have to drill the rim and fit a rim lock to stop the valve getting ripped out.

Not for removing the nut, but if you find you need to remove the flywheel, you will need a puller. The flywheel nut should be torqued up to the manufacturer's specification when you put if back on.

@archiel. If you remove the flywheel nut, you maybe able to see the end of the woodruff key / slot. This will eliminate / confirm if this is the issue.

Maybe, don't think either of us will be proven right soon ?

You will need a puller, do not be tempted to try hammers / leavers etc. It will end in tears. Another way to stop flywheel rotating is get an old belt, about 50mm wide, wynd the belt round the flywheel 2/3 turns, then clamp free end to footrest. The idea is that as you start to undo the nut, the belt tights onto itself, stopping the flywheel rotating. You can tighten the nut but reversing the direction of the belt.

It would be interesting if manufacturers started fielding teams in "real" trials, then it might have some relevance to 99.9% of riders.

Have you checked timing, not unknown for woodrough key to sheer allowing flywheel to spin on shaft, altering timing.

Oil smoke is blueish, not white ?

I must have had 10 pairs of boots over the years, and none of them have even been waterproof, even when new. Goretex socks are the closest to dry feet in my experience. This was before it really started raining.

Throttle cable pulled out twist grip or carb ?

Assuming its an amal ? Screw nearest engine is the mixture screw, in for richer. This screw is very sensitive, so make very small adjustments at a time, and only once engine is warm. Screw behind it is tickover, in faster.

NGK BP5ES

Normal unleaded is fine. Have you tried a new plug ? When you tickling it, don't go crazy, slightly flood it only. If the plugs wet, dry it, heat it and try again. To start it ease it over compression on the firing stroke, then give it a long push, rather than a kick.

If your seriously interested in these bikes the following book is probably the best http://www.ratiopublishing.co.uk

You said you had boyer ignition ? Sounds like a standard set up to me. Black things a rectifier, blue a condenser.

For the purposes of getting it started any petrol will do, for longer term running and piece of mind castrol do an octane boost / lead replacement . https://www.ebay.co.uk/itm/CASTROL-VALVEMASTER-LEAD-REPLACEMENT-PETROL-ADDITIVE-OCTANE-BOOST-DA6267/323238330293?ul_ref=http://rover.ebay.com/rover/1/710-53481-19255-0/1?ff3=2andpub=5575376664andtoolid=10001andcampid=5338268676andcustomid=9b232b89-2caa-430a-b189-660203316fd0andlgeo=1anditem=323238330293andsrcrot=710-53481-19255-0andrvr_id=1852669596561andrvr_ts=d672addd1680aad98dc1ebdcfff315a8andul_noapp=trueandpageci=cae57e3d-7ab6-4a3f-a927-e9aa0c38acb2andredirect=mobile

Petrol

@tshock250 Good things come to those that wait ?

Unless there is more than one fly wheel. M35 x 1.5 right is correct. https://www.ebay.co.uk/itm/FLYWHEEL-PULLER-M35-x-1-5-RH-HUSQVARNA-610-ROTAX-250-350-500/263017909599?hash=item3d3d16cd5f:g:LLcAAOSwQz1bGUQyandredirect=mobile

Steam clean.

You sure you need seals ? Does it run very weak / erratic, dry side seal. Burns gear oil which generally looks different to 2stroke smoke ? Other side. Not just the exhaust needing a good clean out ?

TXR engine is good, its the climber primary that's higher.

Hi G, here we have to agree to differ. I ride in second gear in many sections and agree its very usable, but I do like the option of a lower first gear. ( Are you going to Telford this year ? )