diggin4s

I had re sleeved my cylinder to an original OEM piston, machine shop indicated that this being a trials bike was a saving grace. Very little material to work with in original cylindar as that this basically started at about 185 cc then 200cc up to 250. IF you have the rare large finned Australian cylinder going to sleeve and original piston would be my suggestion. Someone on ebay or this forum has re-pro 250 pistons. I had bought 2 sets a dozen or so years ago, but never found a 2nd TLR . I may be open to offers. 95% of my issues were resolved through info on this site, hope yours works out.

Typically a lot of oil has condensated on the bottom of the crankcase(more fuel), waiting to get heated & vapoured during this diesel effect, may of minimized damage, as suggested a glove or boot on the exhaust will shut it down the best, unless your system is very leaky. Thinking about covering the exhaust when its reving & realizing killing the spark is not the answer often comes from a bystander with no vested interest in the bike. Little chance of this happening on a 4 stroke, no residual oil etc. in mixing/combustion chamber.

Often the carb vent tubes get water trapped inside, a common fix mentioned on the forum is to slice the ends at a diagonal, water and crud has tougher time plugging ends

Make sure your carb tube vents are clear, especially the one's that run towards the skid plate, an old tip was to slice the ends diagonally to prevent fluid stops. The old TY's had some routed towards the skid plate, where any bit of bog could plug it

As everyone said, fork leakage issues, one fix was to combine 3 single lip seals in place of one single seal, rough the slides with 600+ emery cloth/crocus pape, seems like a bit better for oil to stick to fork and seal rather then pass by, note the forks are different, one compression, other rebound. Electrics can fail, found that cheapest & most reliable was to have motor rewind shop replace, bud with 1 yr newer model had received from dealer a faulty unit, found this out by resistance measurements & replacing his with my unit. Watch out for the mystery oil drain plug, mistaking the shift retainer/whatever bolt may result in teardown exercise of Rotax motor. Purple 1989's? where milder than the green 1990? "hot rod", something to do with the rotary valve slot size I/P. If ever submerged hot/running the valve would warp & seals could displace, this problem was rectified in our area as that we no longer allowed in streams were fish ran, and typically any water over the rim disappeared in sections once bikes became pricey. Rest of the bike can be repaired with some resourcefulness, enjoy the power & the sound of the straight cut gearbox(never tired of this). To bad Aprilia dropped the trials line after the world win, but was more likely heavily biased by Rotax(Bombardiar) not allowing changes to there tried & true design. Many various parts are likely about with ex-dealers, plastics could be rarest, if price was cheap & you have basic maintenace knowledge great entry bike.

On my TLR250F I had welded a plate & installed the larger universal foot/peg kit, went down approx "1 & back same, agree with previous post, setting pegs back will lighten up the front a bit much, brake pedal isn't an issue unless you have very short feet. The downhill engine braking with the 9tooth front sprocket & angle of foot to pedal seems to compensate well for this bike. I also noted these mid eighties bikes(TY250 Yam mono) pegs where very high and as you age this riding position reeks havoc on baby boomer backs.

IF? your carb vent tubes are long and/or kinked/plugged puff some air thru them and then diagaonal cut the tips(less chance of water/crud plugging end), your carb may not be having the the venting its required