feetupfun

Just because Falcons have gas pressure doesn't mean they don't have oil. They have oil just like all other shocks which is what provides the damping as it travels through restrictive gaps and holes. All shockies have gas somewhere inside. There has to be a gas space somewhere inside or connected to the inside to allow for the change in internal volume of the shock body as the shaft moves in and out, otherwise they would not move (oil does not compress) Falcons and many others use a static gas pressure higher than atmospheric to reduce the formation of bubbles within the oil and to assist the shaft seals to seal. A side effect of the gas pressure is a small extending force due to the cross sectional area of the shaft. Dry air works perfectly well in Falcons but does reduce the life of the oil compared with using nitrogen due to the presence of oxygen in the air. If you use air it just means that the oil needs changing more frequently. I change oil annually but it seems fine when it comes out. Falcons are not sensitive to what pressure is used. I have found that anything between 60psi and 90psi works fine. I use a basic direct drive (cheap) air compressor at home to add the gas. It could be done using the tyre inflating gear at a car refuelling station but it is easiest if the shockie is being held firmly (fitted to the bike) so you can pull the air valve chuck off quickly to avoid loss of pressure as you remove it from the valve. There is no seperator between the oil and gas inside standard Falcons which is why they have to be fitted with the shaft at the bottom (gas at the top) Standard steel-bodied Trial Classic Falcons are relatively light because they have a single wall tube of a sensible thickness and the attachments and springs are well designed. Also the dust seal holder, the oil seal holder, the upper spring retainer and the piston are made of aluminium.

Portrait of Sigmund Freud by Pablo Picasso?

The 200 motor is a modified TY175 motor, so no, the TY250 motor won't fit the Majesty 200 frame

Depends on what you are calling "the cheap ones". The Talon ones work amazingly well at gripping the rear tyre on my bikes - so well I only use a single Talon on the rear and have not had problems with the tyre moving. When I first experimented with the single rear clamp thing, I put paint marks on the tyre and rim to check for movement, and there was none. There is a drawback though with TALON grips in that unless you use a rubber rim tape that goes over the outside of the gripper plate, it is easy to cause the tube to herniate at the ends of the gripper plate when inflating it to get the bead up onto the rim, due to the sharp change in contour. A rubber rim band helps stop the tube from expanding unevenly into those spaces. I have gone back to using rubber rim tapes (from adhesive tape) for that reason. The OEM clamps on Japanese and Spanish bikes from the 1970s have a gently tapered profile that prevents the herniation problem, and seem to grip the tyre OK, but I'm finding that all my old clamps are falling apart and soon will all have been replaced with the TALON type. I have not experimented with single rear 1970s-style clamps for slippage.

May also be explained as Advance - rotate stator opposite direction to crankshaft rotation Retard - rotate stator same direction as crankshaft rotation

Just found this - maybe what Glenn was talking about PJ1 TRACKBITE COMPOUND is a custom formulated resin that provides controlled traction for competition racing. PJ1 TRACKBITE is a liquid track and tire treatment, which improves traction on asphalt and concrete surfaces. It achieves added traction by means of adhesion and does not soften tires. It will not harm asphalt and concrete and is biodegradable when dry. PJ1 TRACKBITE can be applied with a roller, brush or can be sprayed directly on the tire or track. The chemical compounds used provide maximum adhesion in all types of weather, it is water-resistant and is not washed away by rain. PJ1 TRACKBITE was applied to the track during every race when world drag strip records were set over the past decade. NHRA & IHRA approved, sold worldwide to record setting drag strip tracks. IDEAL FOR USE IN ALL TYPES OF RACING ON HARD SURFACES, INCREASES TRACTION REGARDLESS OF WEATHER CONDITIONS, WEIGHT OF VEHICLE OR HORSEPOWER. Application: Apply a small amount of PJ1 TRACKBITE in front of drive wheels. Spin rear wheels with minimum engine power. Avoid hard burnouts whenever possible. Where liquid burnouts are prohibited, apply directly to tires with a brush, roller or sprayer.

The product HAM2 was talking about was "tyre grip" in an aerosol can that the advertising blurb reckoned was good for icy roads and was a resin coating that was applied with alcohol that evaporates. Are you sure that is the same stuff that the go-kart racers use? I'm asking because a resin coating will make no difference to the hardness of the rubber while others are talking about the karters measuring the hardness of the rubber to avoid going too soft. There is also the thing about it being in a WD40 pump pack or an aerosol can that is not clear at all. I think there might be two different products being talked about here. One is "tyre dope" that may well be relevant to us wanting to soften old trials tyres and the other is resin to use on your car tyres before driving where there might be ice on the road. Does anyone know what the "tyre dope" is and how it works?

If there is oil in the pump it will be OK to do that. If the pump is dry, it might eventually damage the pump depending on how long you ride for.

Because you don't know what is in the fuel tank, and the oil pump may have lost prime over time, or have been disconnected from the cable because of a problem with it, it is safest to mix up a batch of new premix fuel before you go riding and get rid of what was in the tank when you got it. If you want to reinstate the injection system, it should be primed by hand to get all the air out of the system. There is a bleed screw on the pump and once that has just oil coming out operating the pump by hand, then put the screw back, remove the line at the point it goes into the motor and keep pumping by hand until all the air has come out. You should also check the pump settings are right. There is a line on the cable pulley that should line up with a pin on the pump plunger when the throttle is closed. There are lots of things can go wrong with an injection system so there will always be a risk of lunching the motor.

Im intrigued with the chemistry going on here. Do you know why the karters are washing off their tyres? Also what is the process going on with the WD40? I'm guessing they don't use the tyres for a while after putting on the WD40? There may be something valuable in this washing and WD40 thing for trials tyres too

The oil pump resides underneath the oil pump cover and is attached to the Right hand side engine outer cover (I call that the clutch cover). You have to take the clutch cover off to get the shaft out because the gear on the inner end of the shaft will not fit out the hole the pump drive shaft goes through.

You need to take the clutch cover off, and fit a little cover to seal off the hole where the pump was

I agree with what Tony said and yes I know of two Yamaha single cylinder two-stroke motors that siezed because the oil pump stopping pumping

I suggest you first measure the voltage difference between the motor casings and the frame. If there is a voltage difference, then your motor is not grounded to the frame (and it needs to be grounded to the frame)

I like lots of things about Dr Who. One is the way they include self-mockery like when the Doctor's Daughter says "I like the running" Tim I have to agree - that "don't blink" episode is my all-time favourite Dr Who. It even scares my kids

To make the head angle steeper, I lengthened the frame backbone 25mm and made a bend in the front tubes at the motor mount To lengthen the swingarm, I extended the axle plates 45mm Mine actually looks quite standard unless you look closely, which was my intention If you send me your email via PM I will send you photos of a TY175-based bike that you would probably be interested in seeing for ideas for your "far as I can" bike

Its not the carb size or the air filter design that limits the performance

Its hard to tell from what you have written, but it sounds like you might be measuring voltages of open circuits. If the ground wire in the headlight circuit is 19V above the frame voltage, then the "ground" wire is not grounded. To find out what voltage the bulbs are seeing at different RPM, measure the voltage difference between supply and ground with the headlight and taillight both on. Some bikes do make too much voltage at high revs even with the correct bulbs in service and good earths. I used to use 12 and 24 volt bulbs in my (nominally 6 volt) 1970s Japanese trials bikes and trail bikes to avoid blowing bulbs. I have seen many other techniques successfully used too.

Yes you have described a sticking clutch. To free up clutch shift to top (5th) gear, pull clutch lever in and rock bike forwards and rearwards. The tyre will grip better in the rearwards direction so concentrate on maximising your effort when moving it rearwards As previous person said, clutch issue has nothing to do with motor not starting. If it ran, now it doesn't, ask yourself "what is different?" Usually that is engine flooded with petrol or no petrol getting to combustion zone.

I use automotive acrylic lacquer for frames but I'm sure there are many other suitable paints.

Gloss black is the right colour for the Cota 348 frame. The brace pieces that go from the swingarm pivot to the cylinder head are plated decorative chrome

Looks like the 4 stroke has a non-linear cable pull ratio. This is usually done to smooth out the action of the throttle when it is near closed. Trimming the ramp to make the action more linear will not help you with off-idle throttle sensitivity because the ramp is the bit that affects throttle opening at the other end of the throttle action You need a tube that has the cable end holder following a smaller diameter circle - like the other one in your photo

One TY175 I have came with a 26mm Mikuni from a DT175. It now has a standard TY175 carby on it because with the 26mm carby it did something that put me off a bit. It felt exactly like a normal TY175 below about 6000RPM. If you accellerated at full throttle through 6000RPM it would suddenly accellerate faster at that point, much like the way a two stroke MX bike does, but much milder. It was a bit disconcerting for me when riding obstacles that require full stick. Because of this, and because the bike is a loan bike for trials learners, the standard carby is probably better. For trail riding on that bike, the 26mm carby is definitely a hoot and helps with big (sustained) hill-climbs.

Earlier this year, I actually went through the process of modifying a TY250 frame to make a replica of a bike which was built in 1976 and which used very similar ideas to what was done years later with the Yam frame Majestys. It was quite a learning experience and as people say, a lot of work to do it right. It took me 4 full working days to make the jig and do the basic frame mods. It doesn't sound much but that is 32 hours work and that does not include the myriad of other work that is needed to be able to complete the bike. It is definitely not easy and I would agree quite impossible to do properly without making a jig first. In the case of the bike I did, the target was to raise the motor 1 inch, and from all I have seen and read about the Yam Frame majestys, I would say that was the case with them too. The claimed 2 inch increase in ground clearance and steepened steering head angle were achieved via the combination of raising the motor close to one inch and the increased rear end travel raising the rear end of the bike. Having studied photos of Yam framed majestys with tank removed, I know by comparing the locations of the sparkplug tips relative to the horizontal brace behind the toolbox, that they had the motor raised the same amount or very close to the one I did. I'm not keen to post up photos of how the work was done yet because that bike was built for a feature article in a magazine and it hasn't come out yet. I do plan on posting the photos up somewhere accessible later on.

It is an older Beta motor but does not look like a Zero motor to me. They had cylinder castings with flats. This one is round. Cylinder doesn't look right for the Beta Synt models either