feetupfun

Whichever engine you use, the crankcase will need to be machined out to suit the bigger sleeve.

To fix only the immediate problem: Clean out tank with acetone Mask tap thread with plasticene Mix up brushing grade epoxy resin Tip in enough to seal the area around the tap hole Move tank around enough to make sure the problem area gets a coating Allow to cure To protect the tank from modern petrol and fix the crack: Clean out tank with acetone Mask vent hole and tap hole to prevent blockage Mix up 300-500ml brushing grade epoxy resin Tip in and rotate tank until whole inside surface is coated Allow excess to drain out the filler hole as it cures

Early DT175 motor is the same cylinder stud arrangement as TY175 motor. Late model DT175 has different cylinder stud arrangement but I have not yet measured up how big a sleeve can be fitted. Rayer big bore cylinder photos I have seen look like a late model DT175 cylinder but modified to suit the TY175/early DT175 stud pattern.

and the other wire from the kill switch goes to earth (usually at the coil mount)

I've had success using contact cement to attach those plastic badges.

The 72mm and 72.5mm piston kits for the Blaster look very much like what went into my engine but I can't be sure they are the same. My piston uses Wiseco rings also. The pin size looks right in the photos, but if you have a doubt, why not just ask the seller what size the pin is? - and check the other important aspects of a piston swap like ring location pin positions, height from gudgeon pin to top edge and gudgeon pin to rear edge of skirt. Beware while those piston kits and the sleeve look well priced, the main cost components in the job will be the welding and machining. Cylinder head - weld up head nut holes and redrill to 8mm - machine head surface flat - machine combustion chamber to suit bore diameter - machine combustion chamber to provide correct squish and correct compression ratio. Make custom head gasket to suit bigger diameter bore. Make or find longer cylinder studs to enable use of plain hex cylinder head nuts. My studs and nuts are from a Maico MX engine. Machine throat of crankcases to suit OD of bigger sleeve (requires complete disassembly of motor) Machine out old sleeve and prepare cylinder for new sleeve Cut port holes (undersize)in GS1000 sleeve Machine GS1000 sleeve OD to provide interference fit in cylinder Fit sleeve to cylinder Take ports out to match cylinder with porting tools Bore sleeve to suit piston Make custom cylinder base gasket Other possible pistons to consider are KDX220 and TY250 twinshock. Don't know much about the KDX220 but the TY250 piston requires the gudgeon pin holes to be bushed smaller but being only 70mm will have a far less risky sleeve thickness than mine.

Hi Steve The steering on that TY175 with the frame mods is as good as I have ever felt on a twinshock, so I have no desire to change the steering angle. I suspect that the fore-aft weight balance of the bike+rider also has a lot to do with the steering as well as the steering geometry. Yes I do ride (other people's) moderns now and then and find that there are so many differences to a twinshock in how they are to ride, that I have trouble riding anywhere near the same standard as I can on a twinshock, so can't really comment on differences in the steering. I think that the TY175 with the frame mods has better ergonomics than the standard TY175 because the handlebars are now higher and further forwards, which gives more room to move around on the bike, and the stance is slightly more upright. I am only average size but feel a bit cramped on the standard frame bike. A smaller rider may not find those changes to be a benefit. The TY175 with the YZ125 clutch cover has a motor which has the bottom end from a 3H8 prefix motor (DT175E I think). The motor came with that YZ125 clutch cover. I haven't tried to fit the YZ125 cover to a TY175 motor. I'm only thinking it is a cover from a YZ125 because it looks the same to me as covers on late 1970s YZ125 (DEF) and IT175 (DEF), which lines up age-wise with the DT175E. Maybe the earlier YZ125 motors (ABCX models) had slightly different clutch covers that will fit the TY175. An easy way to check these things is to look up the part numbers for the clutch cover gaskets for the different models. I will take a photo of the longer TY175 brake link and to avoid external photo hosting, will probably post it on the Aussie trials website.

Yes as Andy.T said, I replaced the rubber elements in my TY175B cush drive in the late 1970s when I noticed there was a bit of slack there and thought it might affect the way the power was delivered. It took quite a bit of work, having to make new rivets and cush elements. I didn't notice any change in the way the motor felt and reckon I just wasted my time by working on it. I still ride that same bike and the clutch basket cush drive is still going fine. Of course if for some reason the rubber elements were allowing metal-to-metal contact they should be replaced.

The sleeve was made from a GS1000 sleeve The piston was from a kit that converted the DT200/WR200 to 230cc

corrosion in the cooling circuit

Australian design regulations for road-registerable motor bikes require the side stand to be self-retracting. I assume it is the same in many other countries. Aparrently there were a significant number of deaths and injuries around the world attributable to people riding (road bikes) with the side stand still down so all road-registerable bikes require it. Until now I didn't realise it was a "feature" on new trials bikes. It is very unusual to road-register trials bikes here so the trials bike importers probably nobble this "feature" before we see them.

On the same issue, I suspect that fitting a wider rim will make a competition trials tyre work less well on trials terrain than it would on the standard width rim If it was being used on a Dirt Track racing bike (a slider) there might be an improvement by fitting a wider rim.

The increased width of the bigger rim will be no problem as far as clearance goes. I know this because I fitted my M138 Alpina with a Pursang rear wheel (which have a much wider rim than Alpinas and Sherpa Ts come with)and it made no difference to the clearance to the swingarm, exhaust and chain. The width of the tyre is the critical dimension - not the rim.

I think that for such a big 428 sprocket you will not find one ready-made for an early Alpina hub available on-line. The Aussie Talon importer sells 428 and 520 rear blanks made from aluminium alloy for reasonable prices so I imagine you should be able to get a blank from Talon direct or from someone nearer you who sells them.

I bought new Alpine Stars just before christmas and have not had any problems getting used to them. I had SIDIs previously. The sole is more grippy on the footpegs than the SIDIs but they feel very similar otherwise to me when riding. The SIDIs were easier to walk in but I have no problems walking in the new ones and it is probably only different because the SIDIs were at the end of their life.

The reproduction type looks good but is more prone to breaking. The genuine is more expensive but has the same (good) bending properties as what came new on the bike. Don Newell in Brisbane sells the genuine type as do many other suppliers.

I usually ask the seller to email some more photos in that situation

Someone in the UK was chasing TY250 engine covers on this forum a few months ago. Here is a magneto cover on eBay in Australia. Same seller has also listed an oil pump cover. http://cgi.ebay.com.au/Yamaha-TY-250-Ignition-Cover-/270732172495?pt=AU_Motorcycle_Parts_Accessories&hash=item3f08e51ccf

Photos of TY175, TY250 and KT250 illustrating fork tube angular offset http://www.trials.com.au/content/index.php?option=com_wrapper&view=wrapper&Itemid=42 In case that link does not work for you, the posting is in the Technical Help forum of trials.com.au

It is bedtime now but I will endeavour to take some photos tomorrow evening

Gav the ideal upper shockie mount location will depend on what the extended and compressed lengths are for the shockies you are planning to fit, and the leverage ratio you are intending to achieve - so there no one correct location that is ideal for every rider and every shockie. There are limitations for rear axle travel with standard TY250 frames/swingarms, but these can be overcome if the brake pedal pivot mount is moved or if the rear subframe is bent upwards or cut off, or the swingarm length increased. As far as the shock mount design goes, I will take a close up photo tonight to illustrate the way I did one bike. I can't seem to upload photos to this forum tonight so will send you the photos via the email address you posted at the top email sent

maybe you are measuring something different to what we are talking about? I can take a photo and post it up if required to remove any confusion. It is the fork tubes that are set non-parallel to the steering axis

I think you will find the OD of the standard sleeve prevents going above 70mm bore (it sounded to me like you were asking about boring the standard sleeve bigger). Bigger bores than 70mm are possible but only with a bigger OD resleeve and the maximum OD of the sleeve is limited by the location of the cylinder studs. My TY175 is 72.5mm (bigger sleeve fitted) and the sleeve is very thin. If money is no object then 72.5mm bore is possible but a 70mm bore would be much less labour cost.

The rear Bridgestone trials tyres I have seen are not competition trials tyres but do have a block pattern like a real trials tyre. They have a rounded profile, cross plies and have stiff sidewalls. Conpetition trials tyres have a square profile, radial plies and flexible sidewalls. Bridgestone trials tyres would probably be good on a bike that was never going to leave the bitumen. Bridgestone trials tyres are very much like the rear tyre that would have come standard on the TY250. Since then there has been 35 years of competition trials tyre development.