still trying

I'm pretty sure that you only have to cover the case hole, but it would be wise to check. The drive end of the oil pump is a couple of flats, which suggests that the drive side is retained and self contained. It would not be good engineering practice to expect the shaft flat shoulders to keep the gear on the shaft. I'm sure you have it covered(excuse the pun), but you haven't mentioned it, don't forget to block the carb access hole.

If you weld it, measure it very carefully before. multiple diameter readings all round, ring grooves, skirt dia etc. Pre heat it to help reduce distortion, also make a plug that is a tight fit and weld it in. (less shrinkage/ distortion). Use TIG and do little bits at a time, allowing the weld to cool to preheat temp, patience is key.

Dam right b40rt! As for twinshock Official rules, I would expect my KT250r (r for Roger'ed) to be excluded. I did it to see if I could, and to put my money where my mouth is. A lot of the ideas came from when I first started, and people told me high ground clearance, low seat height and narrow were good attributes for a bike to have. Riding in the bush back then and constantly drowning my TY175 made me want to swap the tank and air box locations. Partially done on this KT (air filters and intake is under the tank and runs down to the plenum chamber behind the carb. Did get my calcs wrong and had to add a second filter and intake vent above the plenum chamber,..... bugger). the shock location came from the first Yamaha monoshock enduro bikes with the triangular framed swing arm. So at least the ideas are old enough, just took a long time to upskill and get on with it. If the intent is to "Recreate" trials as per the twinshock era, then all bikes and parts should be as per period. Can be new bike, parts, but must be as per parts of the period, in look and function. So much trawling of the old photo's and talking to riders who remember what went on. get proof of mod etc. This is how classic car racing is run, heavily focused on how things were, with very few mods allowed. Basically for safety and reliability (ignition) reasons. At lest that's how I understand it. At the end of the day, you pay your money to ride for several hours. Winning lasts for several minutes, Get value for money, enjoy the ride, ignore what others are doing,and focus on you ride, try to make each lap an improvement.and thus it no longer matters how good the bike is. Top mod for any bike is, get fitter (it'll even help you health wise) and it can be done for bugger all! Oh and throw in a bit of practice as well... just for fun.

Sorry this is so late. Get a stick (clean) and mark the stick with the bottom of the thread and the full line. Put it in the sump up to the thread line, pull out and presto easy oil level indication. Second time will be a little less clear. Or you could use any similar thing as long as it is clean and not likely to leave bits behind.

If it keeps slipping off the rim try removing the lip seal on the inside of the bead. This worked for me ('76 kt250 DID rims). I used an angle grinder and sanded them off.

After all your testing of the electrics along with replacing most of it, The only thing electrical I can think of is a break in a wire. These are often very hard to find as they intermittently work don't work, (work when testing and not.when operating) is my experience I have had vapor lock on my bike. Took a bit to find, as it stopped revving out, and went all boggy at top end,. motor ran very hot (running lean). got stuck, got out of trouble and restarted it, ran ok, but trouble came back quite quickly, wouldn't rev out. Back home found the fuel line was only 2mm off the exhaust.and went up and down before going into carb. This "hump" allowed a vapor bubble to sit and restrict the fuel flow. Re routed it down under and up to carb inlet so any vapor will either go up through the carb, or back up into tank, also its away from exhaust. How is your air filter, I've had one get eaten by the bike, never found it. Bike coughed a few times then came right. That filter was old and must have been crumbly. Which makes me think of an air leak somewhere.that leans out your bike, but maybe only in certain conditions. check the inlet manifold seal, carb to manifold, base gasket, etc, ( pour heavy oil around it when not going well and see if there is any change. Good luck and let us know how you get on Cheers.

Things that could stop it revving out; All the usual things, like; timing not right, Blocked exhaust, restricted inlet, (blocked air filter etc) Blocked jet Not enough fuel getting to the carb Weak spark colappsing under load or something that I've forgotten, good luck, bike looks cool.

Very cool, Always had a soft spot for the cota 200.

Had this problem, and its the motor that has lost a winding. get a new motor time.

Yes you have it correct I can see the confusion in the drawing. The drawing is actually three separate drawings, hence the border around top and bottom drawings Usually if they are connected there is a segmented line from one group of parts leading to where they connect to other parts.

Just a thought, If the parts from the 280 when in the 125 are as poor, maybe its the return (earth side) half of the circut that is the probleme

high foot peg positions were (if I remember right) to help clear rocks and such. It also meant there was less bike between the riders legs allowing for more movement on the bike. These days the low seat height, suspension and narrowness of the bike takes care of this. If the pegs are lowered balance becomes a lot easier. It will also suit taller riders as they will be less cramped. Moving the pegs forward or back moves the riders nominal position and as stated can affect steering or rear grip adversely. An inch either way probably wont cause handling issues, but will help with tuning the bike to your riding stance, physical size, e.t.c.

Was going to say, The slide is chromed brass and the body ali. Heat it up, the ali will expand more, but you beat me to it. Fantastic looking KT. Good luck with it.

If the tube is "walking inside of the tyre, I must be the flexing Vs direction of travel. Easy fix. half way through the trial start the motor backwards and ride the rest in reverse! Bad luck for the fourstrokers, they will just have to put up with it.

That is one smart KT Front spokes; Drum side 230mm to rim from center of head Throttle side 240mm from rim to center of head Rear all 172mm from rim to center of head This is as best as I could measure on my KT (original hubs, rims spokes).

Oops, forgot about rod actuators, Cables and rods, maybe it should be equipment that was available at the time. So you could use a disc system off a period road bike, That would be heavy, huge, and in the way Yes my KT is a twin shock. If there was only one shock it would be way too soft (couldn't fit a big enough one in), and the top shock mounting bolts also connect the bottom / back frame (the box section bit) to the backbone. The twinshock guys said you could build your own frame (I think they envisaged a replica), so I sketched and doodled at work during breaks, (didn't intend to actually build it) until I thought, "I've got to build this". I learnt a lot, picked up a new skill (beating panels into petrol tanks), and gained a lot of respect for the guys back then who developed bikes.

I have had success with tubeless tyres on a '70's Akront rim (KT 250 rims). Here's how and why; Stuck the tyre on and yes it kept dropping off when pressure was lowered. I looked at the rim of my gas gas, it has a much more horizontal bead area and a very small rise at the inner edge before dropping into the centre well. The Akront rim is not that flat. I also suspect that it is slightly larger in seat diameter, although I didn't check. The tyre has a sealing lip on the inner edge of the bead. I got the angle grinder and a sanding disc, and removed the sealing lip, and a small amount of the bead surface. The result has been very succesfull. I've run as low as 3 psi in rocky sections and no problems. Of coarse I'm running a tube and rim locks. I've also done this for the front wheel, also succesfull. My Gas Gas is a 95 contact and I've had to do the same to its front wheel. every time it has worked a treat.

I'm not directly affected by this discussion as I'm not in the UK. However we also have "Twinshock trials". As a bucket list project I designed and built a bike, using the motor, wheels(drum breaks) and front forks/ triple clamps from a KT250. It is a very modified / modern looking bike. (this causes much debate at trials, but as I don't take points, no hassels,... sofar). I laid the shocks over and moved them up and in. (Mass nearer the C of G and narrowed the swing arm 40mm, frame 50mm at bottom and 80mm at seat (motor is still fat as ever) . Saved 15kg from original bike The shock position has no progression and the travel is10mm more than a stock honda tlr250 My interpretation of Twinshock is; The technology must be of the period, (exception being motor spark system). Air cooled motor Drum breaks Cable operated breaks & clutch unless proof of use in period Rear shocks MUST bolt directly to both frame and swing arm, with little or no progression from the mounting points / layout. Anyway these are my thoughts on the subject You can see my bike in the projects section on this site. The end result really only gave me a bike that rides like a well sorted twin shock. Funny that!!

With a bike standing on a flat surface the steering angle is the angle from the surface, to the Pivot axis in the head tube. No amount of changing the triple clamps, forks, axle offset, etc will alter this. It can be changed by altering the rear height, or the front height (sliding the forks up or down in the clamps). Basically "tilting the frame relative to the ground".. Or chopping the frame, (last resort please). Thus rear shock preload will have a big effect on steering. Also the way the power comes on can effect steering. As noted above riding position has a big effect, moving the handle bar clamps, and foot pegs to get the rider; a, comfortable, and b, in the right position is one of the most important things to get right. After all the rider is a major weight component. The factory settings are generally about the "middle" of the usable range. All aspects affect each other on the bike, so change one affect others, eg, raise the rear for ground clearance, and steering head angle is steepened (front forks now have more sliding friction, (impacts from bumps are more "side" impacts), C of G is higher thus balancing is now harder, and so on. Best to do a lot of work with shock heights/stiffness, and rider position, before changing the frame, at least in my opinion. Choose carefully, and good luck

Sorry no idea. but carefully remove dipstick and lay it on some newspaper or bog roll and the oil will show up. Worth a try at least.

I would think 10/40 would be the right grade, and mineral or synthetic wont matter too much, Synthetic might not emulsify with water that gets in as much as mineral will, if that's of any concern. Two sides to that; 1 if the oil stays separated then lubrication isn't compromised, 2 Water will be harder to remove at oil change time, ( a concern because of corrosion ). Fork oil is a matter of experimentation to find what works for you. My preference is 5W in both my Gas Gas 320 contact, and my KT250. I like shocks on the softer side to stop small things bumping me off line, so I can worry about the "big stuff" (NB Big Stuff varies with rider, mine, ...not so big). Also at trials speeds (generally) soft will help keep the wheel in contact with the ground, which = grip. Fuel, high octane = slow burning, Good if knocking (Detonation, or Pinking) is a problem. High compression will need high octane. Typical engines will get more power from 91 than 98. Make sure timing and sparkplug are spot on, rings, bore and valves are in good nick (compression check a good guide to this) and try 91. If it knocks when hot under load, change to 98. As for valve seats and guides, I have no idea if Honda used hard seats and guides back then or not, sorry.

My understanding is that a condensor is a capaciter by a different name The important thing is to get the same rating. (Measured in micro farads). You will need to use a Megga meter to test it. Industrial sparkies usually have one of these, (at lest they do over here)

My choice would be the Fantic 240 assuming all are stock standard as new. But a huge amount can be done to stuff up the handling or improve it with ride height, shock/ springs etc, as we all know. You can make a pig into something that goes really well, with a bit of knowledge. The pigger it is, the more you will have to do. I made a KT250 go quite well. Took a lot of work. Still got to work on the front forks, (still standard). If I didn't have to work on it, It would take half the fun away

And that folks is how you suck eggs!!

That is really good info you have. I have to say that I haven't gone into it as much after trying four springs. A thought did come to mind. A lot of the effort could be in the cable because of the load times friction. reduce the load through a lever, and the spring load can remain. Fitting a lever into the system on a KT is not easy. I'm toying with a rod from the cable connector on the arm up through the cable mount hole (nearest to the cylinder) onto an arm, with the hinge at one end, which would connect to a bracket bolted to the outer hole. Then make the cable holding bracket attach using the cylinder mounting bolt. Make the distance from pivot to clutch rod half the distance to the cable, half the load , twice the feel, and half the movement. It will be quite fiddly making the brackets etc, and getting them strong enough. This will most likely still comply with the rules. The other way is to go hydraulic, (frowned upon I suspect). To do this the easy way is to cut face off the side cover and weld thicker flat one on with bolt holes for slave cylinder from a Late model gas gas (I think), (get the oil type not break fluid type system). Or option two; Machine out the rack system and weld a block in and bore your own cylinder into it with porting where the arm was. This option lets you choose your cylinder size and thus mechanical advantage ratio. It will also look more standard. again go oil not break fluid system, and bore from the inside, so the outside once polished will look stock. Best to have a second cover so you can go back to standard if you choose to do this.