The sleeve in my bike is made from an early 1980s Suzuki GS1000 sleeve and yes it ends up thin when bored to 72mm but is suitable to be bored to 72.5mm if required.
The WR200/DT200 big bore pistons are no longer available here either. I would suggest checking out big-bore kits intended for the Yamaha Blaster Quad if you are serious about making your TY into a 205cc.
More powerful: source a later model cylinder and head. The TY250B (1975 model 434), C and D model (493 model) TY250s are noticably more powerful than the TY250 (1974 model 434) in standard trim.
More powerful: Big bore it to 320cc (DT360 piston, new sleeve, welding and machining). Not cheap but works
More powerful: fit an ignition that has an advance curve
One my mini Majesty 175cc, the flyweel have 5 mm less in diameter.
Do you know how you can go up to 205 cc on a TY175 cylinder ? Witch kind of piston is used ?
Regards
Mine uses a piston made to increase the capacity of a DT200 or WR200 to 230cc. I've heard but not tried out a big-bore kit piston made by Wiseco for the Yamaha Blaster Quad. It's not listed in the regular Wiseco catalogue but are made for someone selling the kit for the Blaster. I've also heard that a TY250 piston can be used but this must also require a different conrod because the TY250 piston has a larger gudgeon pin than the TY175. KDX220 pistons are the right diameter but I haven't checked ring locating pin locations or pin to crown height on them.
There is much more to it than finding a piston. The cylinder has to be resleeved with a larger diameter sleeve, machine the crankcases to suit the sleeve OD, weld the head and remachine to suit the new bore size and weld the cylinder stud holes up and redrill a smaller size. Shape the head to achieve the correct compression ratio. Find longer studs to reach through the head. Use plain nuts. Make a bigger head gasket. Lighten the piston as much as possible. Rebalance the crank, rod and piston to suit the inevitably heavier piston.
If you are running 428 chain on your TY175 then yes a 16 tooth front sprocket will fit. I used to run a 16 front 51 rear combo on mine when I rode it to work and it would do just under 100km/h on the freeway.
A big bore (205cc) also improves things over standard but if you are going that far with motor mods I wouldn't lighten the flywheel until you are finished.
In the last 10 years I have sourced many parts for Yamaha TY175, TY250, Kawasaki KT250, Montesa 348, OSSA MAR, Bultaco M49 and M198. I've had no experience with bikes that became popular after 1978 like SWM, Fantic and Italjet.
Bultaco parts are generally the most abundant but other popular 1970s trials bikes also have their parts suppliers in different parts of the world. There are good suppliers for Montesa parts in the UK and the USA and the same goes for OSSA. Very few genuine parts are available for the Japanese bikes but there are very good reproduction parts available. If you buy a bike that is complete, you can be sure to be able to get it up to competition standard. If it is a popular model, missing parts can usually be sourced from wreckers and on eBay.
My advice is to steer clear of buying any model that was rare in its prime, no matter how cheap it seems, unless you thrive on a challenge.
The steering stem is intended to shear before the forks or frame get bent. Instead of forking out big $$$ for new frame or new fork tubes, the steering stem is relatively cheap and easy to replace. Yes making a steel one would probably stop it shearing in a similar crash but if you want a trials bike to weigh 65kg, easily damaged chassis parts are part of the deal. Alternatively the same part could be made from titanium at huge expense but who would want to pay megabucks for a trials bike that was slightly more crashproof?
Yes it certainly is possible to fit the rear wheel from a M137/138 Alpina (or from a left shifting Frontera or Pursang) to achieve a brake drum on the right hand side. The penalty paid for this arrangement is a rear wheel that is heavier than the original M199A wheel because of the different hub design. You may find the rim is a bit wider than the Sherpa rim too depending on which donor bike it came from.
I apologise!! after 15 years in aus and undergoing a frontal labotomy to gain citizenship my ability to decifer double meanings has deminished!!!!!!!!!!!!!!!! I agree the SY is the best all round bike on the market but I still want to know if any other riders have suffered more problems with loose nuts on their SY's than previous machines.
I didn't need a lobotomy, being born here in OZ. I have found though that the heat does tend to gradually melt ones brain which is probably a bit similar to having a lobotomy, but slower.
Anyway, about the fasteners, I have seen two Beta Rev3s, one TY250Z and one Scorpa SY250 all suffer from the frame screws and brake disc screws coming loose in use. I don't think it is a problem confined to SY250s.
I suggest you might get more response if you post your 349 queries in the twinshock forum.
I would say it is very likely that the 248 front end would fit your 349 provided you use an axle length and wheel that matches the width of the fork tube spacing of whatever clamps you use.
Are you having a bit of a lend here? Do you really carry a handgun when out riding?
Where I ride we have snakes that leave anything in the "Wild West" of the USA far behind for danger to humans (Australian taipans, eastern browns, and tiger snakes in particular are quite deadly while death adders provide a similar risk of death from a bite to the US rattlesnake) yet all most people do is keep their eyes open. People who like to take precautions carry constricting bandages and some form of hand held communications.
Please tell me the snake shot gun thing is really a joke.
2001 Rev 3 270 should have come from Beta with a hydraulic clutch. Betas have had hydraulic clutches standard in all Rev 3 and also the preceeding series which came out first in 1994 (Beta Techno).
Are you able to post or email a photo of the bike you are looking to buy?
Mate those forks must be pretty confused with all that swapping around.
The forks with the Bultaco sliders should work well with 190ml per leg and so should the ones with the OSSA Betor sliders. If you are ever in doubt, just use the measurement method with the forks bottomed with springs removed. Add oil slowly until it is about 5" from the top of the tubes. As a check, extend the forks with the springs out and caps off and if they snore near the bottom, you need more oil.
Fork setup is such a personal thing that I am reluctant to suggest oil weight and spring preload for you but seeing I am also 14 stone of rippling flab you may find my numbers are a suitable starting spot.
75mm of preload with straight wound trials rate springs and 7.5WT oil works pretty well for me in my M49 Sherpa T and MAR OSSA. 10WT is a bit heavy unless you like a slow fork action.
I suggest you ride a few other 349s and compare. The clutch on the 349 and 348 is probably the worst aspect of those bikes for modern trials riding techniques. The drag should be livable but it should not slip.
Sometimes slip combined with drag can mean plates that are not flat.
Slip combined with drag can also be caused by the springs exerting uneven pressure on the pressure plate.
After lots of work, my 348 clutch disengages nicely and doesn't slip, but engagement is still difficult to control in tight turns. It really is a good bike for non-stop events!
With Rev 3s, the riding duration is highly variable depending on how much fuel goes out the float bowl overflow. If you have yours sorted, and have a clean air filter and good jetting, it should do more than 20 miles of steady gentle trail riding on a tankful. That 20 miles would take about 3 hours to cover in the sort of terrain I'm talking about.
The aluminium tanks fitted to the TY250 models after the A model are pretty much the same capacity as the steel A model tank. If it's important that the volume be known, I could accurately measure the capacity of an aluminium TY250 tank.
The aluminium tanks are definitely lighter than the steel.
If you don't have enough oil in your fuel, the friction from the rings and piston rubbing against the bore greatly increases. This friction can get the rings and bore and piston very hot. Aluminium expands more with temperature rise than steel and cast iron so as your bits get very hot, the clearance between the piston and the bore becomes too small. If this process goes far enough the parts may stick (sieze) together. Even if they don't get to the point of seizing, running an engine with insufficient oil will make the rubbing bits wear out faster than otherwise.
The heating due to rubbing friction has nothing to do with the heat produced when fuel is burned in the engine. The amount of oil in your fuel has only a tiny effect on the amount of heat produced by combustion.
I put lightweight all plastic acerbis hand guards on a trials bike but took them off after one ride because they made the steering feel noticably heavier in the tight bits.
I was trying them out after having problems on an exploration ride with the lever knobs catching on vines and branches.
Hello All From Australia
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Hello Cactus Jack. Where in the wide brown land are you?