dpyam

Another thought - I don't know what the 125 is geared like but my 175 is basically 1,2,3 and 4 are "crawler" gears for off-road, with a jump to 5 and 6 for road use (max cruising around 40mph). Maybe someone thought that with a 17T front you would end up with 4 "road" gears, and 5 and 6 are only usable down steep hills?

If it has still got all the "road" bits fitted it sounds like a rarity to treasure - enjoy ownership! My TY175 is road legal but realistically a TY is designed for slow, low-revving off-road riding, but with some lights fitted, allows use on-road. I wouldn't use my TY for commuting or anything - it would kill it - a trail bike (like a Yam DT) would be a better bet for that - a good excuse to own 2 bikes! The steep fork angle on a TY, plus off-road tyres, makes it unstable over 40 compared to a road or trail bike. There are road legal classic "enduro" bikes around as well (e.g. Yam IT175) but again they're very off-road focussed. You don't say what the history of the bike is but before trying more sprocket variations make sure the bike is running as its best: new spark plug check timing check carb jets and settings are set to standard (if the rest of the bike is) clean the air filter check exhaust is not blocked brakes not binding tyre pressures etc Having said that, a 17 front sounds very over-geared.

Aggressive towards various parts - yes. Better for the environment? It doesn't manage that unfortunately, say the Brazilians etc whose rain forests are being chopped down so that the big companies can grow "bio-fuel" crops. The EU didn't see that coming. That's my 2 p's worth.

Crikey - this chemistry lark is a bit complicated. Aspen also sell a pre-mix fuel so i guess they use a 2T oil compatible with their fuel. In my ignorance i've used supermarket 2T oil with Aspen fuel - seem to have got away with it!! It's difficult to know what's best with old engines, but i try to stick with non-synthetic oils for engines over 30 years old - just my choice - no scientific tests done by me to back up this plan and I'd use 4* fuel if i could get it.

It's Aspen fuel for me as there's no 4* my way. Even my local BP ultimate has ethanol in it. Modern vehicles are designed to cope with ethanol - older ones aren't.

Maybe the fork springs have sagged with age and use. You could get a new pair with a "poundage" suitable for whatever weight you are and that should solve the problem.

A less worn TY175 carb! Seriously though, what are you trying to achieve - more power, more low rev torque, other?

Problem half solved - the shop have now sent a 25w bulb. I'd still like to understand the electrics tho....

The headlight blew on my TY175 so I ordered a 6 volt 25W/25W replacement. However the shop have sent me a 6 volt 35W/35W bulb. According to my calculations the 25W bulb uses 4 amps and the 35W bulb uses 6 amps. My Haynes manual says the unregulated AC circuit relies on the correct wattage bulbs being used. Has anyone else used 35W bulbs? Is it that critical?

Note that in the UK the unleaded of today is a different beast to the unleaded of 10+ years ago, due to the ethanol now added to it. I'm a fan of the Aspen fuel mentioned above.

I got "maximum value" out of the brake pads on my mountain bike avoiding this preventative maintenance game, and when the front brake eventually failed, the bramble bushes at the bottom of the hill provided all the retardation required.....

Good news folks - we have an MOT! I stuck with the original electrics after working out the wiring, fixing the switch, and got an AC horn off ebay. It's barely louder than the engine though :-( I've since seen motoduro sell one that looks a better bet. Mud here we come :-)

I'm not sure my digital meter can handle the AC the TY gives out. I've done a bit more digging and apparently there are AC and DC horns. Most are DC, and AC ones are/were fitted to things like old Vespas and they make a noise like a duck call !! So it looks like I need to either fit an old scooter horn or wire a small battery in for my DC horn.

I'm looking to make my TY175 road legal and have got the original lights working but not the horn. I've tried a good quality 6v horn but no sound. I'm guessing it doesn't like the Alternating current non-regulated voltage electrics. Has anyone got any tips?

On the plus side from this post at least we're aware who these NIMBYs and kill-joys are now so can treat them accordingly.

One thing I've never found a definitive answer to - if you oil or copper grease a bolt thread, do you need to lower the torque figure used, as the friction will be less?

Sounds like a fuel supply problem. Start your investigation with the cheap and easy options - Is petrol flowing from the tank? Is the petrol in the tank fresh? Is petrol reaching the carb? Is there petrol in the float bowl? Take the air filter out (only briefly for the test) to see if it then runs.

Ethanol in modern fuel is a disaster, particularly in older vehicles, lawnmowers, fibreglass tanks and anything with a carb. It causes carb'd engines to run weak as it has extra oxygen atoms compared to normal petrol so you should up jet size. I use Aspen fuel (Google it) in my trials bike and garden machinery. It's not cheap but it's cheaper than a wrecked tank, carb, engine etc.

Another vote here for Halfords Pro stuff. The Sealey stuff I've bought has been good too.

It could be a worn part or two in the gearbox, but check the basics first. Try putting fresh 10/30 or 10/40 mineral motorbike oil in the gearbox first, and also check the clutch adjustment. It could also be the gearchange mechanism is sticky and not moving the gears fully so try taking off the cover behind the gearlever and check it's all moving freely and is greased up. If it's still doing it then the g'box may need an overhaul. BTW it's a Trials bike, not a trail bike! (see also enduro, scrambler, motox, etc that it's not) :-)

Great bikes but get those frames braced at the rear shock modified top mount before the frame cracks or fails!! There's some big forces going into a section of the frame that was never designed for it.

I would only go for a hotter plug if you experience plug fouling, otherwise you risk a glowing plug causing pre-ignition and then next your piston has a hole in it... :-(

I've had this issue on my old Yam RD400 roadbike - you can't have too many 2-strokes :-) . It was because I was missing a baffle in the air filter box. I know the TY air filter box is a completely different beast, but it looks like the Yamaha engineers realised the issue on the RD was caused by air pressure pulses in the air box affecting the mixture on the overrun, and engineered the air box accordingly. I'm not sure how this helps you resolve the issue on your TY, but it may avoid you chasing your tail !!

Playing safe at 40:1 in mine as it doesn't get used as much as I'd like.

I bought one off ebay and (so far!) have been lucky with it. It's a great newbie ride and doesn't bite. The gear change has part of its mechanism behind a cover next to the lever. A bit of grease and fiddling sorted it without dismantling the engine. I understand any kick start related issues are a lot more involved to sort. There are lots modified in some ways (bits of frame sawn off to save weight etc), so look at lots to see what they are generally like. Nearly all of them have had the oil pump removed so you run on pre-mix. Not a problem if done properly. Mine has lights so could even be put on the road.