feetupfun

Is this a wind-up?

about 25mm on a TY175 frame, if you make the bend at the front engine mount. If you are not confident, just draw a scale diagram

What was the issue that stopped you using a 69mm KDX220 piston?

have a look at the bike that the front end came off and you need to have less rake than it has

It needs a lot more than an inch extra fork tube protruding through the top clamp to get the rake right for those triple clamps and axle offset

Too much steering trail and you have made the steering rake too great by making the front of the bike too high. The trail might come down enough to make it feel OK with that front end if you can get the rake back to being a bit steeper than standard TY175 (slide the fork tubes up higher through the clamps) Rake is measured at the steering head not the fork tubes

The IRC tube type stays on nicely on the standard rim on my Cota 348 (1976 shoulderless Akront) and the standard rear rim on my M49 (1968 shouldered Akront)

Does anyone know why the early airbox was made so narrow?

The later front brake arm has always seemed to me to be a retrograde step

I just had a look through "Ride It" and every bike that Don is riding has the shifter on the right. I'm thinking that at the time Kawasaki was developing the bikes, the big selling bike was the Sherpa T (which was RH only shift at the time), and they would have wanted to make the KT as acceptable as possible to the trials riding market. By the time the KT went into mass production, the US laws requiring RH side braking were coming into effect so naturally they made the production bikes LH shifters, like everybody did. Another factor about which side the shifting was on would have been that Don wanted left foot braking because that is what he was most familiar with Something else I noticed is that the bike that is captioned as the "production" KT250 in the book has the "K" engine covers, the air box with only two fasteners for the lid and the less curvy version of the front brake arm

It is difficult to tell if the engine covers with the "K" instead of the later "KAWASAKI" are hand made or not in those photos. Please photograph the insides to reveal if they are die cast or sand cast It is possible that the "K" magneto cover was made to enclose a different shape/size flywheel than the production flywheel

I'm interested in the story behind any prototypes of production trials bikes. I'm a bit confused though. Are you saying there were 499 prototypes made before they made the production bikes? I know the early production KT250s had a different magneto cover insignia, being a big "K" while the later ones had a smaller "KAWASAKI" and I have no idea why they changed it There are many good photos showing KT prototypes in Don Smith's book "Ride It". Some of Don's bikes in that book show a bike very similar to the production KT but with different front wheel hub, or backing plate to the production KT. There are probably other differences and I will enjoy having a look for them later on tonight

yes it would be a benefit with some of those motors, especially when they are running larger bore and stroke that original, but there is usually very little room to add weight

Those cracks in your photos are only in the gel coat (not structural) so you can either redo the gel coat (lots of work) or just fill the cracks and paint the tank. Painting is the most popular approach and if done properly can give a finish that looks very much like the original, if that is what you want. I would recommend coating the inside surfaces with low viscosity epoxy resin (available from boat shops) to reseal it. Fibreglass tanks that old are usually suffering from surface breakdown inside and outside, and modern fuels are not kind to polyester resin (which is what it is made from). If it looks a bit hairy inside that is from the glass fibres becoming exposed as the resin breaks down If you want the gel coat (the outside of the tank) repaired, a fibreglass boat builder or a surfboard builder would have the skills to do it. As for the fuel cap, that cap is a good talking point for people looking at the bike, but if you want it to look original, the fuel cap is a very important visual element. Original caps are available second hand but are quite expensive. The aluminium part that the cap screws into could be easily made on a lathe or donated from another old Bultaco tank. There may be a bit of intricate fibreglassing required to restore the tank where that flip-top cap has been fitted

I have had that problem on a couple of bikes and it only happens after fitting a new tube or new tyre, then after a while, stops happening. When it happens, I just do what pshrauber says and then continue riding. One thing I have noticed it that the tube always moves in the same direction. I have experimented with using talcum powder or not using talcum powder and could not detect any difference

Yes it seems that they can do some fairly serious servicing on most of the overnights. I would like to know what is being done to keep that little 2 stroke Husqvarna going for so long. I hope everyone has a great time there, but being an Aussie I'm especially hoping that Toby Price makes it to the end in one piece

The alloy tank is more expensive to produce and will not change colour over time, can be painted any colour you want, stick-on graphics will stay on and the material will not be damaged by UV light

No, No, Yes

I did some in a Whitehawk swingarm recently which is probably a very similar (Whitlock) design to the Beamish. I carefully burned the rubber parts away which freed up the inner spacer. To remove the remaining steel sections of the bushes I used a standard hacksaw blade held in a cloth and cut through almost all the way through the steel of the bush. This weakened it enough to slide a tiny drift in, causing the outer to come loose. I found that the new bushes for my swingarm were a standard industrial item. As far as the burning of the rubber goes, there is a risk of discolouring the plating on the swingarm, but I was getting the frame re-plated anyway (which is why I had to take the bushes out)

you said past 20 years, so that is since the Beta Techno and Yamaha TY250Z era Since those bikes Bike mass progressively reduced (approx 15 kg difference to 1995) I think that four pot front brakes in about 2000 was the biggest "step change" in performance. Suspension technology progressively improved - a big difference from 1995, but not a step change Engine response has become progressively faster, not a step change Step change in ease of significantly changing the motor performance characteristics by the owner with introduction of programmable fuel injection with 4RT in 2005 Same for engine ignition map change via handlebar switch being a step change, but probably not important for 99% of riders

Around that time some Montesas had air valves and very light coil springs in the forks. Springing was air+coil. Mine was like that and I found it was an improvement to get some springs that were the right stiffness so I could run without air pressure in the forks. I can't remember for certain what springs I put in but think they were either Sherpa T fork springs or OSSA MAR fork springs. A weakness in those forks is the plastic material that the anti-bottoming cones are made from. It spreads/swells over time and can cause the forks to be sticky on full compression. Replacing the parts with aluminium replicas fixes that forever, or if you just want to try to see if it makes a difference, they can be machined back to size. I find that the damping action of the 348/349 forks is fine with them completely standard, and would not recommend changing the damping action. 15 or 20 WT fork oil works well for me Magical springs and adjusters is one way to get the spring rate and preload right, but do cost $$$

Yes a TK carby was standard on the first model TY250. If it still in good condition, you will find it works very well. You can buy some parts through Yamaha dealers but they are usually very expensive. There are new carbies available if you need to replace it. Keihin, Mikuni, Dell Orto and OKO are popular choices

just turn the sound off

other things that might be related are: People have been known to add extra fork spring preload, which will increase the likelihood of topping out There should be anti-topping springs on the damper rods, which may have been removed

It's not the angle that counts. It is the leverage ratio You need to measure two distances and divide one by the other to get the leverage ratio distance one: distance between swingarm pivot and wheel axle centres distance two: distance from swingarm pivot centre to centre-line of shockie (measured at 90 degrees) If you divide distance one by distance two on a twinshock bike, you will usually get a number between 1 and 1.5 A standard 1960s Bultaco trials bike will have a number close to 1, and a 1980s trials bike will usually have a number near to 1.4 I weigh 95 kg and on my bikes that are near 1, I use 40 pound springs. On my bikes that are around 1.2, I use 50 pound springs and on my 1.4 bike, I use 60 pound springs.