feetupfun

You have perfectly described the symptoms for the same mode of ignition stator failure that occurred on my 2003 Rev 3 Beta. Unfortunately, stator failure on Betas of that era are relatively common.

A less traumatic way to do that job is to use a stick welder to run a weld bead around the inside of the bearing outer. When this cools the weld shrinks the bearing outer and it will usually just fall out.

The closest thing I have found overall to the original TY levers in quality, shape and lever ratio are clutch lever assemblies from the Suzuki RM80X. They are not cheap. Some aftermarket levers have a similar lever ratio but I don't know how to specify them by brand as there are so many similar lever types, all unbranded and made in China and with quite a range of lever ratios. What you are looking for is a lever with a measurement from the centre of the pivot to the line of action of the cable of about 20mm. To answer your other question, yes plenty of people have lengthened the arm on the cam on TY175s, but it makes little difference to the leverage ratio because they don't also move the cable holder to match. Levers called (three-way adjustable) are available that have an extremely high leverage ratio, providing a similar effect to a properly modified cam lever arrangement. I think John Cane sells them. I still reckon though that a well set up standard clutch on a TY175 is very light to use.

It probably sounds a bit silly but I had that problem on my TY250A in a trial that had cold water deep enough to cover the cases, and the problem was simply that it cooled the motor so much, it needed to be warmed up again each time before it ran right. After it stopped the first time I kicked and kicked - nothing, then before I started pulling things apart to remove water, I tried kicking it with the choke on, and it started straight up and didn't miss a beat from then on.

I have bought three sets of Falcons over the last few years and never had a problem getting them, or parts for them, and their action is better than the other trials twinshocks I have tried - but I haven't tried Rockshocks. I did have a problem with the Falcon bump rubbers disintegrating on the first set I bought (in about 2003). The later Falcons and the replacement bump rubbers have been fine. If Rockshocks are the ones with the ball ends, then that is a good feature that Falcons don't have.

If a TY175 clutch feels heavy, then there is something wrong. They are light as a feather when standard with standard lever and high quality cable. Yes the takeup is sudden if you are used to bikes with a wide engagement. You didn't mention the type of lever you are using. There is quite a variation between different lever designs as far as lever ratio goes. Are you sure the right springs are in it? You didn't mention the condition of the cam. They do tend to pit which increases friction, and the case lever arm position moves away from the ideal.

Good to hear you liked your travels over here. I too had a great time travelling around, living in a 4WD wagon with rooftop tent for 13 months back in 1993/4. About your bike, it is very common to need to remove the pilot jet to clean the hole in it, as it has a very tiny hole which sometimes blocks solid. Even a partial blockage will give symptoms as you describe. If you put it up to a light, you will see if it is clear or not. The pilot stream path is a passsage for air and air/fuel mixture to flow through and goes from the inlet end of the carby and comes out two tiny holes where the slide touches the venturi floor, and there is a passage for fuel from the float bowl, that incorporates the pilot jet. The air screw also forms part of this passage and controls how much air flows through the passage. To clean out the passage, remove the air screw and spring, remove the pilot jet and blow with high pressure air through all the passages.

It sounds like the pilot jet or pilot stream path is blocked. You are probably getting overrun because it is going extreme lean when you close the throttle coming off load. Most people would not get to that point because of how annoying it is to ride a bike with a huge flat spot.

I'm not sure there ever was an owners handbook as such for the 348. The Montesa book I have for the 348 is a sort of combined parts book and specifications listing and the carby specs page in mine is an add-in for the 348T. If you don't find one that can be viewed on the internet, I can get a copy done but you will need to pay for the copying and postage (from Australia).

Note the TY239 is actually 206cc and they have used the same idea to achieve the 206cc as on my TY175/205 (ie a 72.5mm ID sleeve) except they have started with a late model DT175 barrell - probably to allow the larger reed cage to be used. There is more machining work required to use the later model DT175 barrell due to having to modify the TY175 bottom end to fit the different pattern barrel retaining studs. The exhaust pipe has been rerouted to clear the head finning too. A carby bigger than the standard 22mm does help the top end, even on a 175cc motor, but will not help the bottom and mid range, and from my experiments, it is hard to get a 26mm round slide Mikuni to work as well as the 22mm carby in trials use. Trail riding is fine, but for precise control, the 22mm carby is better. I still use the standard carby on my 206cc motor and it goes great. As far as the 26mm carbies on modern 125 trials bikes, it is a bit hard to compare because 125s are not ridden much at low RPM, but their high RPM performance is important. I notice that the Rayer bike pictured appears to have had the swingarm lengthened.

Yes you will find out eventually what springs are best for you and your bike. Betor shocks do have a noticable compression damping effect compared with other trials shockies so that might tend to compensate for the soft springs. I found that I needed to use max preload circlip groove setting on Falcons with 40lb springs to achieve 50% sag and they topped out with no rider. I prefer to have ~5mm sag with no rider aboard hence the 50lb springs recommendation. If you weighed 65kg I would have recommended the 40lb springs. I use 340mm Betors on my 348 Cota and with the increased leverage ratio on that bike compared with the TY250, the action of the Betors fitted with 60lb Falcon springs works out nicely.

This should help http://www.pro-x.com/eng/default.htm?products.htm~ProxMain

The TY250 is a different kettle of fish to the TY175 re pistons. The Wiseco TY250 piston is nice and quiet and well priced so i've never bothered trying others. PRO-X piston are made usnig the same machines that made the OEM pistons for jap bikes like the TY175. I bought mine through a relative of mine who is an engine builder but will find out who is importing them. I think it is someone in Western OZ.

Here is the how-to guide for photos http://www.trialscentral.com/forums/index....p;f=13&id=3 If it all goes pearshaped, post you photos on the www.trials.com.au twinshock forum

For running in you can use TTS or a good mineral-based or semi-synthetic 2 stroke oil. Run a stronger brew than what you would use for normal running. I use 25:1 for running in. If you use castor based oil to run in, or in normal use, you run an increased risk of forming gummy deposits in the ring grooves, and carbon deposits on the piston crown and in the head. Most importantly when running in the rings to the bore is to start with very short gentle runs, stopping the motor before it gets hot and letting it cool down before starting it again. This process is to let the rings bed into the bore without cooking things. The runs will gradually get longer until you can ride it gently continuously without getting the motor too hot. A good guide for the initial runs is to stop riding when the cylinder fins get too hot to put the palm of your hand on them (approx 60 degrees if you have a suitable thermometer) If you have been a bit fanatical with the clearance, it might be a good idea to whip the barrell off after the initial running-in, and remove the high spots from the piston. I would regard TTS as being just as good at resisting piston/bore and ring/bore seizures as castor based oil, and much less likely to cause other problems. It may be too late for your rebore, but some brands of TY175 piston are noiser than others. The quietest TY175 piston I have tried is the PRO-X and the noisiest was Wiseco, both bored to the piston manufacturers recommended clearance.

Sag 40%-50% with you on board and balanced fore/aft ie all weight on footpegs Set the fork tube ends level with the top of the top clamp and use 340mm shocks (also with 40% to 50% sag). TY250 steering is perfect when set up like this. You will lose precious ground clearance if you slide the tubes up in the clamps. 40lb springs will be too light if you weigh more than about 65kg

Some people take off the flywheel on the primary drive side of the 348s to make the motor a bit more snappy - I haven't Some people fit lower footpegs to 348s and 349s - I haven't Some people fit a better carby - I haven't - yet You might like stiffer fork springs unless you are light Electronic pointless ignition has recently become available, but the standard ignition works fine. Using very heavy oil in the clutch makes it smoother on engagement. I've heard that Honda 125 (CB,TL,MT,CR) clutch plates improve the clutch action. I have bought some of these plates but haven't tried them yet. If it has frames tubes under the motor, it is a 348

If you using both a 25mm nylon spacer and the standard yamaha spacer and are using standard yamaha springs, you will definitely be suffering coil-bind before the hydraulic anti-bottoming starts working. This means the forks will bottom with a bang and will have reduced stroke compared with standard forks. The oil level sounds fine.

The originals are alloy

Hi Newtotrials I'm also 50 and am 208lbs and 5'10" and have been riding my TY175 since 1976. I see you have already worked out that the forks are a bit soft. I tried many things over the years and was not happy with the forks till 5 years ago when I fitted TY250 twinshock forks. The slightly stiffer rate springs and reduced fork flex are a good improvement. If you want to try stiffer springs in the TY175 forks, those from a TM125 Suzuki will give you just that and there are probably other Jap dirt bikes of that same era that will have springs that will fit in the TY forks and be stiffer. The swingarm lengthening as previously mentioned is a good thing. The standard wheelbase is so short that stability is quite poor and riding up steep stuff takes quite a bit of concentration - especially turning up a steep bit from a cross-camber. The decision of what length shockies to get is really a personal one because it depends on if you are a stationary balance/hopping person, or a no-stop type rider. The extra clearance with the longer shocks helps with no-stop riding but stationary balance is worse. The Betors come standard with damping that is a bit stiff for best performance on things like loose rocks. They are good value though if you are not after the best at any cost. Theres nothing wrong with riding the bike with SM footpeg kits. They are a tiny bit lower and further back than standard. The overall width of the bike is increased and they are way more comfortable. The RH peg will need to be held up to use the standard kickstart lever. Theres no performance benefit with a SM tank - they don't give a weight saving over the standard setup and may even be heavier. They are useful though because many standard steel tanks have been lost to rust. Lightweight aluminium tanks are available for lots of $$$. Yes 50lb springs will be perfect you and yes it will upset the suspension balance a bit with the standard forks, but most people I ride with use this combination and love it all the same. David

Being the lightest available full-sized trials bike probably means that it isn't the strongest full-sized trials bike and maybe the suspension bottomed out more heavily that it was designed for?

Yes OEM Yamaha rears are no longer available from Yamaha. Yes you can get aftermarket 428 chain rears and fronts. What makes you think they will be cheaper than 520 sprockets? 428 and 520 sprockets from: www.bjracing.com www.tytrials.co.uk

I don't know but it is probably the same reason why wavy edge brake discs work well too. Don't complain, those clutches work fantastically. Note that the "nipples" are meant to line up with the arrows on the pressure plate and each successive plate goes in at 120 degrees from the previous one. The later model TY250 twinshocks have a slightly different clutch - on them all the steel plates are the same and the pressure plate works as the last inner plate.

If it is a MITAS 4.10 competition trials tyre, it will be slightly (~10mm) wider than a normal competition trials tyre and may rub on the chain guard on an M198/199. It will also have a non-ideal aspect ratio ie it will not have as much depth as a normal competition tyre. If it is a tubeless type (which the MITAS is), the bead may not stay on the seat when you let the pressure down for trials riding. For more info about the tyre you have been offered you will need to say what tyre it is (and don't expect a sane answer if you say you are thinking of putting a 4.10 knobby rear tyre on it). Any competition trials tyre that will fit your rim would be good for trail riding. The most likely ones to fit your bike are the Michelin tube type and the IRC tube type. The IRC is usually cheaper. For info on pressures you will need to say what sort of fun riding you do.

I use B6ES in my TY250A, B and D for trials competition If I was using it on the road I would use a B7ES