feetupfun

Tubeless Dunlops and 1970s Akront rims are not a happy combination. Wider (2.15) tube type rims do work better with tubeless tyres but the fundamental problem is that the bead seats in those Akront rims is too narrow. It's very likely that you will be able to reuse the spokes so give the wider rim a go and if the Dunlop still won't stay on, then use a tubliss. I did an experiment that probably not many people would want to do, but it has worked for me. I wanted to see if I could get a tubeless tyre to stay on a narrow tube-type rim (TY250D rear rim) by cutting a groove in the bead seat for the tubeless tyre bead to key into. I did the experiment about 3 years ago and it has worked a treat. The new X11 Michelin tubeless tyre I fitted (with no tyre clamps) to the TY250D rim has never popped off the rim or slipped and is now almost worn out. I also bought a tubliss at the same time, expecting to need it, but it is still on my shelf

First thing I noticed when I found your KT, still trying, was that it only has one shock!! Hard to be a twinshock without two shocks, or maybe it's just an optical illusion there is another one on the other side of the muffler (out of view) Very interesting design and yes it sure makes the motor look big

I love experimenting with twinshocks too so know where you are coming from. I'm currently making (probably less drastic) changes to a KT and would love to see photos of your "KT". I'll go looking in the "projects" section About your specifying non-progressive rear suspension, if that was an actual rule then the early 1980s OSSA gripper would be excluded, because it has positive rate rear suspension geometry. Also the Godden Majesty 250/320 has negative rate rear suspension geometry so not having progressive geometry is probably not something that could be used in any rules without excluding some completely standard twinshocks. With the brakes there are lots of standard twinshocks including the KT that have a rod actuation for the rear brake so probably shouldn't make cables compulsory for brakes.

A small amount of thin anti-seize compound on both the thread that goes into the cylinder and the thread that goes through the head. When you tension the head nuts to the correct torque, the force on the threads prevents either of them from undoing. You should be able to work out which end is which by measuring the lengths of the holes through the head. Usually the end of a stud that is threaded into aluminium is longer than the end that has a steel nut, because aluminium is softer than steel.

You can also buy zinc-plated spoke kits made in Thailand. That's what I've used on my KT

Having seen what goes into re-sleeving a two-stroke cylinder and doing some of the process myself, I consider that $500 is good value for that job. Buy the material Machine out the old sleeve Machine the OD and flange of the new sleeve and rough out the bore Mark out the holes for the ports Cut the ports Fit the sleeve (shrink fit) Finish machining the top and bottom ends of the sleeve. Finish the ports to size (porting tool) Bore the cylinder to suit the piston Chamfer the port edges In my case it was done to make a big-bore cylinder. It would have been far cheaper for me to buy a second hand standard cylinder but that was not the goal

Nice stand

It's important what "on" means when you are doing the sag. For a trials bike you need to have all your weight on the footpegs. That means no weight on the seat or the handlebars. You can touch the handlebars to stop yourself wobbling, but don't put any up or down force on the grips. If you did that already and got the 1.5 inches of sag shown in the photos, then you have done very well, nothing more to do. The likely reason why you bottomed out on a speed bump is that you were sitting down, well I hope you were sitting down anyway. Trials suspension is tuned for the rider standing on the pegs. When you sit, the sprung weight of the bike is you plus the bike. When you stand on the pegs, the sprung weight is somewhere between being just the bike and the bike plus you, depending on what you legs and body are doing at the time the rear tyre hits the speed bump. If you set a bike up to resist bottoming on things like speed bumps with rider sitting down, the rear suspension will be way too stiff to work properly when you want to use it for trials-type riding.

5mm sag without you on the bike is fine. The sag with you on it is much more important

Original (NOS) replacement sleeves (made by Bultaco) for the popular models have been used up. There are businesses that can make new sleeves. Where I live a new custom made 2 stroke sleeve would be about $500 fitted in your cylinder. There are so many second hand cylinders out there from people parting-out bikes that you can usually buy a replacement cylinder that still has some rebores left in it.

Poor bloke just wants to know what they weigh. I haven't weighed one yet but would put money on it being substantially lighter than a TY175

There is always leakage from high voltage systems. Have a listen to the insulators at a HV transmission cable tower. That crackling and hissing noise is air being ionised (like lightning but on a smaller scale). These get washed with demineralised water to minimise the losses. You can minimise the power losses from your bike's ignition by keeping the HT coil, lead and cap clean and free of any conductive residue. Also check that your plug gap is not too wide and that the conductors inside the cap are in good condition. If you see carbon anywhere in there, it means there has been sparking happening which will reduce the voltage across the plug gap. The HV circuit on a motorbike runs at something like 50,000 volts so even the tiniest bit of leakage can flow through your salty body with great ease and cause damage and discomfort, so don't touch it with the motor running. Some ignitions need the flywheel to rotate at a higher minimum RPM than others to make a decent spark. This means that starting technique can be important.

After I get home from a wet trial, I pump the (tube type) tyres up to about 30 psi with the valve holes at the bottom. This squishes most of the water out of the rim. Then I put the bike on a stand and let the tyres down to flat (remove valve cores) and push the tyre beads off their seats in a few places. In our warm dry climate, the rest of the water inside dries out quite quickly. I also loosen off the magneto cover to let that dry out too.

Whether you should degrease it properly or not before lining it depends on your appetite for risk

Maybe DC's bike was run with a tube in the rear tyre for a while (which would let water in and would be slow to dry out)

Being on the opposite side of the earth, it's the perfect time for me to go to bed

There's no doubt that there are problems with static charge build-up in cars and yes you can buy conductive straps to help discharge the static from a car, but where I live it is thought that car sickness is caused by a conflict between our three bodily balance mechanisms

Yes it's very easy to break a cover like that one. If it does have some sort of sealant sticking it on, then you can try heating the cover where the gasket sits before trying to move it. This could end up very messy, but you could try using a TINY whiff of compressed air via the vent hose. Be ready for flying pieces of clutch cover if you over-do it with the compressed air. A safer but even messier version of this would be to stand the bike back up, completely fill the gearbox with oil and then use a (hand-powered) oil transfer pump to generate a bit of pressure.

I'm starting to get the idea that you are not being entirely serious. First you reckon static electricity causes car sickness and rim corrosion and now you are saying that you have to waterproof your spoke nipples . Mind you it is a fairly entertaining discussion

Yes the WD40 eventually dries and I find it continues to protect the rim from corrosion. As well as for seating tubeless tyres, it's good for protecting tube type rims that fill up with water when you ride a wet trial. I suspect that it wouldn't go well with a natural rubber tube, but I haven't seen one of those for about 40 years

Remove all the screws. Remove the kickstart lever and whatever else might be in the way. Lay the bike over on its right hand side with the cover you are about to take off being parallel with the floor. Carefully ease the cover up a tiny bit and make sure that the gasket stays on one surface or the other, to avoid ripping it. That way you might be able to resuse the gasket. Once the gasket is sorted, remove the cover fully. Oil will drip off it.

You can use WD40 to mount the tyre instead of a water-based lube

Another way for water to get into the gearbox oil is by riding through water

The symptom is water in the gearbox oil. A head gasket leak cannot cause this