If you haven't pulled a Montesa cylinder off before, you may not know that you will need an (uncommon size) 7mm hex drive tool for the (recessed) cylinder nuts.
If the rings are stuck, they may still be fine after cleaning out the ring grooves and the rings.
The D slide OKO provides faster response in both directions than any round slide carby.
Venhill and others make suitable throttle cable kits.
Yes different carbies require different length inner cables, unless you are very lucky.
The important Teikei carby parts for the carby that came on the TY250A have been unobtainable for many years.
The Domino twistgrip is a good thing. I have broken many AMAL T200 twistgrip cable attachments in crashes. The Domino is more crash-resistant and is lighter and you have a choice of pulley sizes. The Yamaha TY250A and the later TY250 twistgrips are also easily broken and the cable loop catches on things.
Restoring my Whitehawk TY175 for the second time in 25 years, but this time i want to smarten it up with new stickers. Does anyone out there know where i can get a set please?
I stripped my bike down to inspect the cylinder, had planned to just do a top end rebuild but the cylinder looks quite damaged on the inlet side. Would you leave it or what are my options? Does it need replating?
My nail does catch on the marks.
Additionally - the crank has some minor pitting. I’ve not done this before so unsure if it’s anything to be concerned about. A more experienced set of eyes would be appreciated!
When geared for trials riding, they are fine for trials riding. Steering and geometry are excellent. They can be made lighter and handle even better than standard with lighter exhaust, fuel tank and lighter wheel rims. WES exhausts are quite quiet. It would be the first thing I would do to prepare a Reflex or a TLR200 for competition (because of the weight).
You may be a bit light for 50 pound shock springs.
At 5"9" you may feel a bit uncomfortable with the standard bar mount/bar rise/footpeg location setup. Yes lowering the pegs is better for balance than raising the bars to achieve a comfortable riding position.
No you don't need to alter the brakes.
Pirelli MT43 are good for the road and trail riding but terrible in trials sections (due to extreme carcass stiffness). MITAS make a road legal rear trials tyre that is better than the MT43 for trials but not as good as a proper competition trials tyre (due to the lower carcass flexibility). Note these are both tubeless tyres so you may have issues getting them to fit properly on a standard Reflex rim (which are made for tubed tyres).
You didn't mention tyre pressures but your comments about gearing make me think you will want to go faster than tyres with 3-4 psi will cope with (overheating tyres and weird handling on the road).
It's very rare to touch the bashplate on anything nowadays using proper technique but if you ride amongst rocks and are not confident, it's probably a good idea financially to have a bashplate that is effective because engine cover repairs or replacements are expensive.
Back in the 1970s it was a fairly normal thing to ride on the road with road gearing and change to a smaller front sprocket when you got to the riding area. It's not clear why you need to go fast on the road anyway. Can't you do the 2-3 miles on the road at a sensible speed?
thanks, I can find some but I need to know the lengths of these alternative shafts. Need one about 9mm longer.
Based on previous postings on this subject, if you buy the shaft for the motor that the clutch cover you have is from, it will protrude the right amount.
There is a search facility for these forums where you can find previous postings on this subject.
Yes, mine is a 250A. The kick stand mounts to the main frame and there is not a lot of space to move the peg. Thanks. Did you use weld on peg mounts or make your own?
I'm not sure a response to an old post will show up. I like this simple style of mount and want to do something similar. What did you do to accept the lower bolt in the frame? The tube is quite thin. Did you weld in a threaded plug? Was it tricky to avoid interference with the kickstand?
This is an old photo of one of my TY250s. The lower cross tube on some models of the TY250 has a threaded hole, as this one has, which I think has a TY250B frame. People who have a TY250 without the threaded hole fit a threaded steel plug into the tube. Some are welded, some with an interference fit.
The stand is not an issue on this bike. It is mounted to the right hand side of the swingarm and does not interfere with the footpeg. It sounds like your TY250 might be an A model with the stand mounted to the main frame under the left side footpeg.
This is an old photo. It now has countersunk internal hex titanium screws instead of those external hex head screws.
many thanks for your response. This came with the bike & there is a slight gap where exhaust flange isn’t sealing against barrel, not great photos but looks like due to exhaust flange not being able to rotate it doesn’t seal properly. Next question is what would be the best solution for this?
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Maybe the header pipe is bent. There is meant to be a metal crush sealing ring in there to seal against the flange. The flange needs to be quite close to being parallel with the mating surface for this sealing ring to work. When these header pipes are being fitted new, the first thing to do is fit the header pipe up fully to the cylinder then make whatever changes are needed to get things to fit. I remember fitting a header pipe that looks a lot like yours and had to reshape the header pipe (heating it with an oxy torch) to get the rear end of the header pipe in the right spot to fit to the front end of a WES mid box.
new to forum & looking for guidance on install of stainless front/down pipe ( unsure if I can mention manufacturer on here)? for 78 Yamaha TY250 T/S. Website I was looking at mentions a flange & using bolts instead of studs? Any help appreciated, many thanks.
Depending on the shape of the pipe and if it has a fixed flange or not, it may need to have bolts used where the pipe flange bolts to the cylinder, instead of studs and nuts, to allow the pipe to be fitted.
Some TY250 twinshock cylinders have exhaust flange mounting holes that are M6x1.0 threads and some have M8x1.25 threads.
The standard arrangement from new is studs and nuts.
The standard exhaust pipe flange can rotate on the standard pipe. Some aftermarket pipes have a fixed flange.
Thanks for that. I did find that manufacturers list an XT225 sprocket as having the same offset as a TY250 sprocket and happened to have one from an XT. The sprocket that came on the TY has about 5 mm too much offset. I did some measuring and my numbers are slightly different from yours but also found that different manufacturers (on Amazon) list minor differences in sprocket thickness. That seems odd.
If you had an OEM sprocket to measure, why did you not just compare it with the one causing the issue on the bike?
Were the original sprockets aluminium? This one is magnetic and all references I see to the brand on line are all old so it could be a 25 year old aftermarket sprocket. Is the OEM offset listed somewhere?
Everything looks straight as far as I can tell with a tape measure, eyeball and the bike together. One odd thing is that the paint is rubbed off the swingarm where it touches but I would expect to see it more torn up from the chain. If I mis align the snail axle adjusters by one step, I get about 2 mm clearance.
Were the original sprockets aluminium? This one is magnetic and all references I see to the brand on line are all old so it could be a 25 year old aftermarket sprocket. Is the OEM offset listed somewhere?
Everything looks straight as far as I can tell with a tape measure, eyeball and the bike together. One odd thing is that the paint is rubbed off the swingarm where it touches but I would expect to see it more torn up from the chain. If I mis align the snail axle adjusters by one step, I get about 2 mm clearance.
Yes original is aluminium. I'll measure the offset on an original sprocket
At the end of March I bought a TRS One RR 300 cc - 2023 new.
I got a very good deal and visually it looks very well finished compared to the Vertigo ( Finish close to the GasGas ).
I did not ride it yet as I am abroad fro business. Will be back this week and hopefully ride it in the week end.
What are your thoughts / experiences on this bike, please?
Thanks!
Kasty
I've ridden a 2022 300 TRS One RR recently while getting it running well for a friend. Yes they are very well-made. It had lots of mumbo on tap. The handling, brakes, suspension and steering are excellent. Initially the footpegs felt further forwards than what I am accustomed to but the feeling went away after a few minutes riding.
The couple of books I have at home say the first Sherpa T was based on the Millers modified Sherpa N. It's hard to find any information on the Sherpa N or the Matador, so it is difficult to work out what differences there are in those two models.
One thing I have noticed is that the standard Sherpa N has a very long horizontal rear frame loop (for a dual seat). The prototype Matador, Mk1 Matador and Mk2 Matador all look like a Sherpa S frame to me because of the steep short rear frame loop. On the Miller Sherpa T prototype, the rear frame loop and shock mount area doesn't look like any of them. It's rear loop is short and steep but the tubing looks smaller diameter and the gusseting at the shock mounts is very different.
The photos I'm looking at are in Bultaco Todo un mito and Don Morley Spanish trials bikes. I've also looked at two frames. A 5 speed Campera frame from 1966 which I think is an M21 and a 1963 M3 Sherpa S frame.
Hi I am looking for help/information about my 1980 Fantic 200 rear kick please.
I am in the process of sorting out my Fantic 200 and the distance between the shock mounting points is 203mm from inside frame mounting point to inside mounting point at the top on the frame and 220mm for the same points on the swinging arm this does'nt seem right to me and nothing seems to be bent, even with the wheel in and done up the bottom distance is still 215mm so the rear shocks are not parallel. I wonder if someone has replaced the swinging arm with one from a different Fantic.
Any views or help would be appreciated.
Thank you.
It's fairly common practice on multiple brands of twinshock trials bikes to have the top mounts closer to the mid-line of the bike than the bottom mounts are. It was done to make the bike slimmer where it counts
Hoping I can get some replies here! I’ve have a ‘74 TY250 for about a year. Took it out for a single ride other than up and down the road and around the property (moo), it was so much fun. Can’t wait for the upcoming season.
two questions:
1. i purchased it for $1300. It came with an entire other bike’s worth of parts. Wheels and tires, gas tank, etc. All except the engine that was destroyed when it got wrapped around a tree. What’re your thoughts on that price for the bike and parts? I thought it was a steal.
2. I get voltage spikes on throttle and keep blowing bulbs. I replaced the condenser, contact breaker, and spark plug today and the thing fires up like it’s brand new. But still experiencing the voltage spikes. Any ideas? Maybe I’m just dumb and incorrectly wiring the lights, but also fear it could be something more systemic. Would bad magneto coils lead to this or would the condenser catch that? Any tips for trouble shooting this would be greatly appreciated.
best from Montana,
Connor
Yes that is great value. They are a fabulous motorbike.
The ignition system is not connected to the lighting system. Each has its own stator coil in the magneto.
Blowing 6V bulbs was standard back in the day for TY250A. Fitting 12V bulbs was one way to avoid it, but the lights then became dimmer. They came with no voltage regulation on the lighting circuit so as the RPM rises, the voltage rises.
Nowadays there are a myriad of options for the lighting circuit on motorbikes.
My memory of riding the big-wheel Beta 80 is that it was OK for me at 5'10" but I would think it might be a bit cramped for someone tall. The motor was easy to use in sections.
Modern 125 two-strokes are excellent.
The modern mecatechno (electric) trials bike is extremely light.
I've just done a top end decoke on a friend's (low hours) 2022 TRS 300 and was astounded at how tenacious, dry and thick the carbon deposits were that completely covered both the piston crown and the inside of the head. It ranged from 0.25 to 0.5mm thick. The tenacity and hardness of the carbon in this TRS reminded me of the carbon that formed in my 1970s air-cooled two stroke enduro bikes running on 20:1 castor oil premix.
Sure enough, when I then asked the owner what premix oil they use, they told me it is castor oil based.
I'm accustomed to seeing soft, wet smudges of carbon that cover about 40 % of the piston crown on my 2 stroke trials bike pistons.
Is using castor oil premix in modern trials bikes common practice?
Rattling 248 Montesa, or just normal 248 Montesa?
in Twinshock
Posted
If you haven't pulled a Montesa cylinder off before, you may not know that you will need an (uncommon size) 7mm hex drive tool for the (recessed) cylinder nuts.
If the rings are stuck, they may still be fine after cleaning out the ring grooves and the rings.