tomskiy

Hi benz19, I wouldn't get too obsessed with "relatively" small amounts of mass. I myself used to be and a mate of my put it into perfect perspective when he suggested that maybe I should just have a crap before a trial rather than after. Another thing he said, which at first sounds rediculous, was go on a diet. If you're carrying any extra weight, it's easier to get it off you, rather than the bike. And it's cheaper! Tom

I agree with TooFastTim, it's definitely a CZ bottom end. Sprockets on the right and concentric gear shift and kick start shafts. I had a late '70's CZ 250 motocrosser and as far as I can remember, the bottom end is exactly the same. Tom

Thanks for the advice Guys, It was just a thought, as all I seem to do is remove, clean, re-lube and re-fit my chain. As for the suitability of O-Ring chains for trials bikes, A. I'll never be good enough to notice any extra drag and B. doesn't the Montesa 4rt come with an O-Ring chain as standard? One more thing, what are the standard sprocket sizes for the 2003 TXT 280 Pro. Thanks again. Tom.

Hi everyone. The chain on my 2003 280 Pro is on it's last legs! When I replace it, I like the idea of running the bike with an O-Ring drive chain. Has anyone had any experiences, good, bad or indifferent with an O-Ring chain on a Pro. Thanks in advance for any help. Tom.

Interesting engine placement, although there's nothing really unusual about the engine itself! Tilt your head to one side, clockwise, and the engine looks, and is, completely normal!

Hi Jack_H, Kinell is correct! If the mixture screw is between the carburetor slide and the airbox, the screw controls the amount of air and should be turned outwards, anti-clockwise to lean the mixture. If the mixture screw is between the carburetor slide and the engine, the screw controls the amount or fuel and should be turned inwards, clockwise to lean the mixture.

Hi cman, my 2003 280 Pro had the exact same problem and had been worn through although beautifully repaired by the previous owner, but the tyre was still rubbing the silencer! My solution will give you up to about 8mm clearance between the tyre and the silencer at full suspension travel. You can, of course, adjust this so that the tyre is just missing the silencer, or to a point somewhere in between. Remove the seat/airbox. Remove the nut and washer on the middle box/shock top mount. Remove the middle box/rear brake master cylinder bolt and small spacer. Loosen very slightly the middle box top allen bolt, near the top of the carb, enough to allow it to move. Loosen the front pipe allen bolts, just enough so that the front pipe can twist in the barrel. Now place the washer that was between the nut and silencer bracket at the top shock mount, to the other side of the silencer bracket, so it is together with the small alloy spacer and replace the nut, but don't tighten it yet. Now replace the middle box/rear brake master cylinder bolt but with two small M6 washers in place of the original fibre spacer. Now, with your allen key at the ready, apply pressure towards the carb, at the point on the exhaust, where the front pipe enters the middle box. Whilst maitaining the pressure, tighten fully the allen bolt on the middle box front mount. Tighten the remaining mounts, not forgetting the front pipe. This proceedure should have gained you the above clearance by moving the front of the middle box inwards slightly and the rear of the middle box outwards but still leaving sufficient room to easily replace the seat/airbox.

Hi Steam, if your bike still has the Dellorto carb fitted, take the float bowl off the carb, place it upside down and as PeterB said the needle valve operating arms should be parallel to the face that the float bowl matches up to. When in this position, the measurement from the surface that the float bowl matches up to, to the top surface of the operating arms should be 18.5mm.

Hi Anth, the rear brake bleeding method I use will only work if you bleed the system from the "caliper" towards the "reservoir" as the fluid will be travelling upwards, the way that the bubbles will naturally want to travel. If you tried to bleed the rear brake from the reservoir towards the caliper with the bike's front raised, this will make it more difficult to expell the bubbles than if the bike was sitting on the ground.

Hi Anth, I've just sucessfully bled the rear brake on my 2003 280 Pro. The technique I used is a little unusual, but it helps to get any air bubbles heading in the right direction, out of the system! I ran the bike up the garage wall, literally, engine running, obviously, then roped the front wheel to a bracket I have on the wall. It will probably be easier to enrol an assistant to help with this manouever! I find having the bike at an angle of 45