feetupfun

This is from the Yamaha TY250A parts book: Pilot jet #50 Main jet #114 Slide cutaway #3.0 Slide needle 5C92-4 Needle jet is called "nozzle-main" Yamaha part number 434-14341-00 This is from a tune-up book: TY250A 434-000101 onwards Carby model Teikei Y26P Float level 21mm Starter jet No 90 Air jet 2.5 Air screw 2.5 turns Pilot jet No 50 Main jet No 112 Jet needle/clip position 5C9Z-3 Cut-away No 3.0 Needle jet S-85

I'll have a look this afternoon and post them up but you should be aware that the jetting numbers for that TK carby do not necessarily relate to Mikuni numbers.

Spot weld?????? If you electric weld (induce a strong, fluctuating magnetic field) near the magnets, they might not be magnets when you are done. If you flame weld near (heat up) the magnets they might not be magnets afterwards. I suggest two alternatives: Take the existing ring off, add your extra ring by welding and then refit it to the flywheel Take the existing ring off and fit a new ring the size you want to the flywheel

Use a Wiseco piston kit made for 1974/75 Honda CR250/MT250 Elsinore - it works with no mods required. Another alternative is to use a TS250/RL250 piston, but this will require a spacer fitted under the barrel.

Welding will damage the magnets. Additional weight is usually added as a band (shrink fit and fasteners) or as a disc (fasteners). If the previous owner has had machining done to a piece that is riveted or bolted on, you can take that off, weld on a ring, and then reattach the piece.

Step 1 is to work out if the problem is spark or fuel. Was the crankcase full of fuel? When you looked at the magneto, did the points have the right gap? Were the mating surfaces clean? Was the timing set right? Is the killswitch wire shorting to earth somewhere? Yes you can use any condenser made for points/coil ignition if you are fitting it under the tank. If you want to fit it inside the magneto, you will need to get the right one. Replacing the condenser will not clean up or reset dirty points. You need to start your problem solving at step 1 not step 15. You will need to provide much more info about the bike if you want it valued. From your description and location I would say it would be somewhere between $5 and $500 from what I have read so far. Maybe it is worth more, but you are not getting your information across. Can you post a decent picture of it somewhere - maybe on www.trials.com.au ?

I'm pretty sure it did not say TY175 on the Pro-X box but the box is gone now so I can't check. I suspect it said either DT175 or IT175. Some people have made out that there are differences between TY175, IT175, MX175 and DT175 Yamaha pistons and that these make a difference to the way the TY175 motor runs, but I have used TY, IT, DT Yamaha pistons over the years and have never noticed any difference to the way they run, and not noticed any differences to rear skirt length or crown shape or height. The holes in the back may have been different shape or size, but because of the reed valve, are not critical to the functioning of the TY175 motor. I have even used a CT3 piston in a TY175 back in the late 1970s and just cut the holes in the rear bigger to match the TY piston that came out, and it went fine too. Pro-X pistons are made in Europe somewhere (I forget where) using the same technology (metal and manufacturing techniques) as the pistons that were fitted to new Japanese bikes in the 1970s. Have a look at their website for details.

No I can't recommend any source for pre-jetted Mikunis. I bought a new "pre-jetted" Mikuni for a TY250 and spent many hours trying to get to run right and ended up giving up on it and rebuilding the standard carby. For the 348, I do want to try a KT250 Mikuni because they work well on both my KT and my 250 OSSA trials bikes, and being a piston port trials motor, I suspect the Cota 348 might also work well with the KT carby, but I haven't tried it yet. I suspect the reason the Mikuni you are trying on your 348 is not working well might be that it is jetted for a reed - valve motor.

What it is worth depends on the bikes condition and you haven't said much about that (except what the OD reads) or where you live. About the starting problem, how does anyone alse know what you have tried if all you say is that you have done everything you know? If the problem is poor spark, and the bike went well in the past, you should probably first check the condition/setting of the points.

Difficult to diagnose over the internet but the first thing I thought of was that maybe for some reason perhaps associated with the work you had done on the carby, the fuel level may be too high in the float bowl. Possibilities are sticking float/float needle, bent/broken/cracked float arm, leaking float (float doesn't float as high). High fuel level can cause fuel to be lost out the float bowl overflow and/or into the motor as you ride, and will cause the motor to run rich.

There has been lots of discussion on these forums already on this subject. Have you done a search on the topic? I use Pro-X pistons for 66mm - 68mm TY175 rebores

I'm pleased to report that I rode an event two weeks ago that has a tradition of encouraging the riding of older twinshock trials bikes. In previous years at this event there had been a ruling that bikes had to be made before 1980, but for this year the twinshock bike age rule was relaxed to align with the standard rules of the local licencing body, which has a cut-off date of 1987 (to intentionally allow TLR250s to compete). The pleasing thing for me was that out of thirty-something riders, all but one rode on pre-1980 bikes, despite many riders also owning post-1980 twinshock bikes. This is a nostalgia event that is run to maximise socialisation, and is seeing increased participation every year. At the other end of the spectrum, at the state trials titles event a few weeks before the above mentioned trial, every twinshock trials bike was a post-1980 model and there were only seven entries in the class.

The TLM 50 has 21"and 18"wheels. I've not heard of a TLM 80.

Hello back from 550km away. I hope you know about the Aussie trials website. You will find a strong following for TY175s amongst the forum contributors there as well as on these forums. www.trials.com.au Regards David

Hey Steve there are plenty of postings already on the Beta forum about your problem. Heres a search on stator http://www.trialscentral.com/forums/index....hlite=%2Bstator

I live in Queensland, Australia and the local Beta dealer has an exchange service, with the stators being rewound locally. The rewound stators don't fail. The only way I know of for testing them is to borrow one off a mate and see if it fixes the problem. Beware not all Rev 3 models have the same connections - I think yours will have a different number of wires to later model stators so you will probably need to find someone with a 2000 model if you want to test it out.

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).