feetupfun

I know these sounds too simple but I have seen both happen a few times so here we go. Step 1 Pilot jet blocks somehow. Step 2 Owner takes off carby including fuel supply hose with filter attached and cleans out pilot jet. Step 3 Owner refits carby and fuel line, this time the filter is installed opposite direction to previous. Step 4 Pilot jet blocks soon after from junk washed out of filter. Optional Step 2 Owner takes off carby leaving fuel hose and filter attached to fuel tap. Junk enters fuel hose while carby is disconnected. Step 3 Fuel washes junk into float bowl after reassembly. Step 4 Pilot jet blocks again. Another mode of pilot jet blockage: Junk gets into the pilot jet via the pilot air hole in the carby bellmouth (usually when the carby is being reinstalled)

I'm still not convinced from what you have written that there is something wrong with the jetting and I don't want you to go on a wild goose chase. The four local completely standard 348 Cotas in my area all perform very similarly and all have lots more low and midrange torque than a TY250 twinshock (434 and 493). If your 348 is actually capable of being ridden and continuous running yet won't even lift the front wheel, there is probably something else wrong other than the carby jetting. Because you have told us that you have the ignition set right, replaced the crank seals and the compression sounds OK, I'm assuming you have not checked the following other possibilities for problem sources: Blocked or otherwise restricted exhaust pipe/exhaust port Restrictive air inlet/non-standard airbox/incorrect air filter medium Leaking air hose between carby and barrel Incorrect port timing ie a ported barrel or a barrel from an MX or enduro Montesa or the piston skirt shortened at the back. PS Are you sure you have not set the timing 1.8mm after TDC rather than before TDC? PPS 80:1 synthetic oil ratio is quite extreme for an air cooled bike. I would suggest somewhere between 30:1 and 45:1 David

If the 348 runs reasonably smoothly at most throttle positions and RPMs with your new VM26 carby, the problem you have with your rice pudding is probably something other than the carby jetting. If the jetting is wrong, it will run either rich (4 stroking and lots of exhaust smoke) or lean (flat spots and pinging) or won't run at all. The rice pudding description is not enough info to go on. Is it a standard modern off the shelf VM26 carby bought from Mikuni? Is it an OEM Mikuni VM26 ie made for a 1970s Yamaha, Suzuki, Kawasaki? Is it a modern carby jetted for a Beta reed valve trials bike? They are all VM26 Mikunis. You can look up the standard jetting for a VM26 from the Mikuni website. If you want more help, please give more info about the symptoms and the type of VM26.

Johnnyboxer Those pegs on the bike in your post look exactly like the ones I bought from Sammy Millers and mounted on my TY250B. I think they were called "universal folding footpeg kit". They are quite good to ride with but the plating is a bit thin in places. David

Your symptoms are typical of a clutch that drags slightly. Question 1 Has the problem developed over time, or did it happen suddenly, or did you just buy the bike and have no history of the bike's clutch action? Question 2 Do you have wide experience of different bikes clutches to judge if yours is abnormal? I only ask this because there are not many trials bikes that can easily select neutral with back wheel stationary and the motor running. If there really is a problem with your clutch, you will need to take the clutch cover off and do some visual checking of the clutch. Check 1 Watch the pressure plate as you pull in the clutch lever. To avoid clutch drag, the pressure plate must move evenly ie stay parallel with the plates. If it moves away from parallel, you may have a problem with the springs. Check 2 Find out how much the pressure plate should move with the full travel of the clutch lever and check how much yours moves. If it not moving far enough, the bike may have the wrong clutch lever and/or mount assembly giving not enough travel of the cable. Another possibility is a problem with the mechanism that converts cable movement to clutch pressure plate movement. Check 3 If all this is OK, make another posting saying what you did find and I will suggest what to do next.

Competent auto electrical workshops are usually able to rewind Rev 3 stators successfully and where I live it costs about half the price of a new stator from Beta. Rewind cost is approx $150AU ($110US). David Lahey

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.