feetupfun

Jackman, B&J Racing in the US sell wider, lower and further back footpegs for the TY250 twinshock but not as low and not as far back as on the TY in this thread. Mine are similar in size and location to the B&J footpegs and for my size (5'10"), are perfect with the standard length swingarm and handlebar mount position. David Lahey

Be careful when adding additional preload to TY250 springs because they are close to coil binding when fully compressed with standard preload. Better springs than Yamaha springs are available for twinshock TY250s from B&J Racing in the US. They have a higher rate, decent coil spacing and work brilliantly together with 5WT and 10 WT fork oil for my 88kg. The 5" oil measurement technique works very well and when done properly is more accurate for keeping both sides the same than measuring the volume and assuming that both sides are equally "empty" to start with. It's a good idea to do a travel check after fiddling with oil levels and preload. To do this fit a cable tie on one fork tube above the dirt scraper and with the caps off, move the forks to full compression position ie metal to metal. Measure the position of the cable tie from the lower fork clamp. Then get the bike ready to ride and slide the cable tie down a bit and go for a ride where you can really load up the forks ie a decent drop off. If you aren't getting the cable tie back to the position it was with the caps off, there is something unnecessarily limiting your fork travel. The problem may be that the fork oil level is too high in one or both sides, or the springs are coil binding (coils are touching together).

I haven't seen the pawl on an Easy but most bikes I have worked on do have an adjustment that can change the resting position of the pawls. Please look for these things: Does the shift shaft (that the shift lever fits onto) move completely freely? Sometimes they get a bit bent and the action becomes too sticky for the spring to centralise the shaft position reliably. Is there an eccentric screw or bolt that the spring rests on? This is what some pawl centralising adjusters look like. Is the shift drum indexing plunger and spring working properly? If the shift drum isn't being held in the right place, the pawls will appear to be offset.

If you are asking about the SY250 Scorpa, look for bending and cracking of the clutch actuating lever arm on the gearbox. I've seen a couple of these bend beside where it is welded to the vertical shaft.

Yes Mark Fred Carter in New Zealand makes replica KT250 handlebars. They are chromed steel, well made and are just the thing if you want bars that have the rise as deep as they were in the mid 1970s. I have a set on my KT250 and am planning on also putting a set on my Sherpa M49 as they are the only trials bars I have seen with the correct rise for that era. http://kawasakikt.tripod.com/FREDKT.html David Lahey PS do you want a photo showing what they look like on the KT?

It's always hard to give jetting advice over the internet. If it is the idle mixture screw you are calling the fuel screw, it will not hurt your bike to ride it with it at non-ideal settings unless you are using the bike for high speed road riding. If you are using your Gasser for trials type riding, the worst you will do is cause your plug to foul if you leave it idle for ages with the idle mixture too rich. I suggest you set the idle mixture screw where the bike runs best for you and your fuel, oil to fuel ratio, altitude, temperature and humidity and if you like the motor to idle or die on closed throttle. A good guide if you like to ride with an idle is (with the bike in neutral) to slow the idle using the throttle slide lifting screw until it is running very slowly, then set the idle mixture screw setting to give the smoothest idle. Not the fastest idle, the smoothest idle. You should hear the motor run lumpy when it is too rich and run unevenly like it is running out of fuel when it is too lean. See if you can get it right in the middle of those effects with the idle mixture screw. When that is done, increase the idle speed using the throttle slide lifting screw until it idles at the speed you want with the bike in gear and clutch pulled in. Unless someone has fiddled with the pilot jetting or there are induction air leaks, the idle mixture screw setting you end up with should be close to the standard setting as recommended by the manufacturer ie if the standard setting is 2 1/2 turns, you should end up somewhere between 2 and 3 turns.

If "twinshock" class had a date cutoff of 1981, I suspect that there would be few SWMs and Fantics competing. In a pre-81 class I suspect that Bultaco (and Montesa) would be quite popular. We need to compare apples with apples.

I notice that there are lots of mentions of mid 1980s SWMs, Fantics and Hondas but no-one seems to say much about the Cota 242. I didn't ride between 1980 and 1988 and so have little first hand knowledge of what was popular in that era and why. Can someone tell me why these bikes are not popular in Twinshock Class nowadays? Did they have any redeeming features?

The top "overflows" are vents. Fuel will only come out them at extreme angles ie if the bike is lying down or upside down. If the float needle valve really is sealing properly, you may have a split in the overflow tube (the 3mm diameter brass tube that sticks up through the bottom of the float bowl and has a nipple under the float bowl) The split may be very hard to see. Depending how you are doing the blow test for the float needle, you may not have eliminated the possibility of the float level being set too low. If the overflow tube is not split, check the float needle a different way ie by connecting the carby up to a fuel source with the float bowl off and very gently lift the float arms to replicate what the floats do then turn the fuel on.

Just tried again. Worked again for me. David

Its working fine today Mike. I've just tried David

My Falcon Classic steel bodied shocks are 340mm eye to eye and 100ml of 10WT fork oil per shock works fine. I found that if I used 5WT fork oil there was not sufficient compression damping. If your bodies are shorter you may need a different oil volume (to provide the correct gas space). To work out how much oil to use I measured what came out the first time I changed the oil (none had leaked out). I don't know what the standard pressure is meant to be but I have found that anything between 40psi and 70psi works fine.

I assume you are referring to Falcon Classic steel bodied trials shocks. The aluminium cover you see that looks like a seal holder is a push fit in the body. It is actually a dust scraper holder. Tap it off carefully with a punch. Inside you will see the shock seal carrier held in with a snap ring. Depressurise the shock and then you will be safely able to remove this snap ring with internal contracting pointed nose snap ring pliers. From there it is obvious. PS if the shaft and seal is still OK and you just want to change the oil, you can do it through the hole that the gas valve screws into.

Grandma sucking eggs refers to the process of emptying chicken eggs via two small holes, one in each end, to preserve the shell in one piece. It is quite a skill to be able to empty the egg without breaking the shell....hence the saying.

Assuming you are making a heat shield to reduce the heat transfer from the pipe to the carburettor, you should use stainless steel as it is the worst conductor of heat of the materials you mentioned. Titanium and aluminium alloys are very good conductors of heat so when bare they make poor heat shields. If it was possible to fit insulation to the heat shield, these materials would also be OK. Steel has higher conductivity than stainless steel yet is no lighter so is not as good as stainless steel as a heat shield.

I'm assuming a few things here: You are turning the fuel off at the tap when you stop the engine. Your carby float bowl overflow hose is routed downwards. Your carby float bowl overflow line is not blocked or kinked. If you have a problem with the float needle not sealing off and the excess fuel can't get out the float bowl overflow line, it will flow into the crankcases, flooding the engine. I have seen the crankcase so full due to this problem on one of my bikes, it was dripping out the exhaust pipe joint. Note there is also the possibility of the fuel tap allowing fuel past even when it is shut (easy to test). If you are using fuel with ethanol or another alcohol in it, all sorts of corrosion problems can occur with metal components exposed to the fuel. David

Warm greetings from a warm part of Australia in midsummer (phew not much riding going on at present) If you want to continue to ride the Scorpa Easy in your warm Israeli rain, I suggest you try a different fuel. The worst fuel for you to use would be a petrol/ethanol blend because the ethanol part increases the refrigeration effect compared with straight petrol. Insulating the carby would make it worse because in high humidity conditions, carbies need a heat source to keep them above the dewpoint inside. In the case of your Scorpa the heat comes as radiation and convection from the exhaust system and the engine. If you insulate the carby, it will get even colder inside. Sorry I can't recommend a fuel for you because they vary so much around the world in their properties and composition. We generally use unleaded car fuel of about 94RON containing no ethanol in our trials bike premix. Some of the modern trials bikes which are a bit sensitive to poor fuel benefit from using ELF unleaded racing fuel because the petrol bought from car petrol stations is variable in quality.

The water you found on your throttle slide is probably condensed from the air. The slide can become cooler than the "dew-point" of the air in high humidity conditions due to the cooling effect of evaporating fuel from liquid to vapour as it enters the airstream at the throttle slide. It is the relative humidity of the air that is important, not the temperature. The humidity of the air you are riding through will be the determining factor for a given bike and fuel combination. You may have formed ice from the water which jammed the slide if it got cold enough but I doubt this happened. It is more likely that the water/fuel/oil mixture was gooey enough to stick the slide even without the water freezing. Petrol fuelled cars with carburettors usually have inlet heating systems using the engine coolant to prevent this effect causing problems in high humidity conditions.

If you bike runs well in sections but then pings and carries on when you make the motor work in a sustained manner like riding at speed or up a long hill, it is possible that the fuel supply route to the float bowl is restrictive, causing the fuel level in the bowl to go low during sustained strong fuel demand. If it is this case, the restriction is usually in the fuel filter, fuel tap or tank breather.

I think you should consider the broader motorcycling market before thinking that the Spanish makes folded because of Fantic. Sure enough the Fantic was a more modern design than the Bultacos of the same year but the seeds of what happened to the Spanish makes were planted 10 years before the Fantic 200 came out. As popular as trials was and still is in Europe, trials bikes were and still are only a small part of the motorcycle market worldwide. Think about the big sellers ie Road bikes, Trail bikes and Motocross bikes. During the 1970s the Japanese makers took over most of the world market in these fields which had been previously dominated by European brands. With reduced sales, product development was limited and so the Spanish bikes fell behind others in the race for technological improvement. There were also significant political changes happening in Spain at the time which led to increased labour disputation issues in the Spanish workforce.

To answer the question about riding it with oil leaking, if it goes bang (noise and jarring felt through the grips) on landing, you are doing damage to the fork internals. Also if it is low on oil it will probably also go bang as the front comes off the ground. If you don't get a bang, you have not lost enough oil to make a difference yet.

Hello Patrick Thanks for the great photos of you and your fine M49. I had a bit of trouble reading your web page (we Aussies only get a small amount of schooling in other languages). Did you say the restoration cost 4500 Swiss Francs? Mine is also an early M49(M4900100). You may weep if you saw how unusual mine looked when I bought it so I won't send you any photos until it looks more like a M49. It had been fitted with a road bike dual seat, huge front and rear road-bike type footpegs mounted on heavy steel frames, the rear frame loop had been bent down to allow the double seat to fit better and the tank and side covers had been painted pale blue with a white flash to resemble a 1978 Pursang. The good part is that the bike is generally in quite good undamaged condition and runs well. It still has an old chevron pattern trials front tyre and the original aluminium front mudguard and mounting stays. I was able to buy a correct seat with a good base and a spare tank and set of sidecovers and am still deciding which tank to use. It is very good to see such clear photos of a bike such as yours for when I paint the tank and sidecovers. Yours is the first I have seen with "BULTACO" on the sides of the fuel tank. Was that standard on yours? I can't quite see what footpegs you have used on yours. Where I ride the safety rules require folding pegs so I will probably make up a set to fit the standard mounting locations for Post Classic competition events. More news later Bye for now Regards David Lahey Australia

Thanks twinnshock, I hadn't seen the trialclasico.com site before. There was a good closeup photo of their replica muffler for the M49 so if I want to make one it will be easy to get it looking right. They certainly are expensive to buy. I agree that they are not the most practical type muffler to use but the old Bultacos look a bit strange with cylindrical mufflers. If you want a good practical cylindrical end muffler for old two stroke trials bikes, I suggest that a Suzuki RGV250 end muffler from a wrecker is a good starting point. They are light, cheap and look quite good. David

My Sherpa M49 came without the (top-in bottom-out) triangular box end muffler. I have not seen them for sale anywhere so am guessing will need to make one. I don't have any decent close-up photos of an original muffler to help with this. Maybe the replica triangular muffler (bottom-in top-out) as sold by Sammy Miller can be easily modified. Can anyone help me with this issue? Thanks David Lahey

Things to check: 1 The vertical rotating shaft tends to develop a rounded pit where the end of the pushrod bears on it. This increases the surface area in contact with the end of the rod which increases the friction. It can be restored by welding and refinishing or they are available from Yamaha. Make sure that the point where the pushrod bears on the flat surface of the vertical rotating shaft is well lubricated with a grease containing a high pressure additive such as molybdenum disulphide to resist galling. 2 The action of the TY175 clutch mechanism is affected when the flat face of the rotating shaft that pushes on the pushrod is not at 90 degrees to the pushrod in the middle of its movement. If yours is not at 90 degrees, you will need to make changes to the clutch components to get it there to optimise the action. Things that affect this angle are: Incorrect adjustment of the rotating shaft height, clutch plate wear, pitting of the flat surface of the rotating shaft, wear of the end of the pushrod and wear of the ball. If the angle is significantly less or more than 90 degrees, the end of the pushrod will be getting pushed sideways which will greatly increase friction and wear in the mechanism.