feetupfun

I have only got Ross' message machine so far so don't know for sure but I wouldn't hold out much hope for original 123 handlebars. Time zones are easy. If you are in the USA or the UK just phone Australia in the middle of your night and you'll be pretty close. He probably has an email address but I don't know it yet.

Beware about front ends on 348s and 349s. Yes the forks legs are interchangable but the triple clamps put the fork tubes at different centres. The 349 had the tubes closer together. If you are using the 349 triple clamps in a 348 consider the front wheel width and fuel tank clearance.

There was a bit of chat about someone looking for Cota 123 parts a few days ago. On my last visit to a bike wrecker at Tiaro, Queensland, Australia, the owner had most of a Cota 123 for sale. If anyone is interested in it, please contact the owner (Ross) on +61 (0) 7 4129 2771. Please consider the time zone before you phone Ross.

I'm just about to do a pre-purchase inspection and test ride on a 2001 REV3 200. Is there anything special to look out for with this bike? I am familiar with 2001 REV3 270 and the well known Beta problems with ignition stators and carby connector failures. What I'm after is any problems particular to the 200. I'm told that the bike has recently had new rings fitted and that the reed land needed trimming to remove a bump. Thanks

The long wheelbase Montesa you were warned about is the red tanked model Cota 349. It was from around 1980 and has a longer swingarm than the later white tanked 349. If you don't ride in competition (need to turn tight) the longer swingarm of the red tank 349 makes for better steep terrain riding. The 348 series (76 to 79) handle and turn well, have good power and are all red. However the only light weight red Montesas of the 1970s are the ones with the small motors ie 123 and 172. The 247s are the same weight as the 348s. Depending on how tall you are, you may find the 123 and 172 a bit small.

Don't have a cow, Luke. Have a look at your first post again. It doesn't say you are getting a 250, just a Scorpa so it was pretty hard to work out what you were on about. They do make 125 4 stroke Scorpas too which are the bikes people usually want more power from.

Luke Are you getting a two stroke Scorpa SY250 or a four stroke? I suspect there is a bit of confusion about what Scorpa you are talking about.

Doesn't the photo of new Scorpas lined up outside the Scorpa factory posted by Ben R in this string show the latest SY175 including the rear mudguard?

We do get IRC tyres in Oz, I run one on the GG300ec of mine in the summer. The importer is located in Victoria, Bruce Collins used to import them. Thanks Splint. I haven't seen an IRC trials tyre yet but will now be on the lookout. From the sounds of what our friends from overseas are saying though the IRC probably isn't ideal for the dry riding seasons where I live.

Dunlops are better than Mitas and Pirelli but not quite as good as Michelin. We don't get IRC here in OZ so I don't know about them. It's pretty simple as someone else said: You get what you pay for. If you want rim protectors buy a cheap tyre. If you want to win in competition, buy the best. When the others start making tyres as good as Michelin, their price will go up to suit.

"Pinky" TY250 Yamahas don't have pink frames. The pink bit is the seat/rear mudguard. The fork legs are blue. They also were the only air cooled monoshock TY250 model to have a front disk brake. They were the last air cooled TY250 model made and were sold here in OZ from 1991 to 1993. The watercooled TY250Z came here in 1994. The only parts shared in common between the Pinky and the TY250Z are the front wheel.

If you have a set of bathroom scales you can weigh it one wheel at a time and add the two weights together to get the total weight. My guess would be that the steel tank air-cooled monoshock TY250 in competition trim ready to ride would weigh between 88kg and 92kg. With indicators and lights, speedo and mirrors it would be a few kg more.

The 220kg on the Japanese frame plate is probably the maximum legal all-up weight of the bike including rider/s. The usual abbreviation is GVM (gross vehicle mass).

29er suggested greasing the mating parts when you reinstall the flywheel. I hope that doesn't mean the taper? Mechanical drive tapers should be assembled dry and clean ie no water-dispersant, oil or grease. You are increasing the chance of another sheared key if you put grease on the taper. The suggestion to use lapping paste on a damaged taper can be helpful once any high spots caused by the key failure are carefully removed. If the damage has cut up the surfaces too much and key failures recur even when the flywheel is re-installed properly, loctite can be used as charliechitlins suggested but the flywheel may need heating to release the loctite next time it needs to come off.

Dear Charlie These are two of my favourite bikes and I often have trouble deciding which to ride. First the differences in geometry and weight: The TY175 has a 48.5 inch wheelbase. The TY250 is 50.5 inches. The TY175 has a more raked steering head angle (less steep) but with the same triple clamp offset so it has slower steering than the TY250. Both wheels, brakes and the front ends are interchangable (except for the dished sprocket on the TY250). The TY175 forks have skinnier tubes and have lighter springs than the TY250. The TY175 (83kg) is 10 kg (22.4 pounds) lighter than the TY250 (93kg). About 8kg of this difference in weight is in the engine. Riding them: Chalk and cheese. In sections, the TY175 feels much lighter than the TY250 and because of this can be ridden much longer without taxing the rider's endurance. However the TY175 has a unique feel to the front end that I've never come across on other trials bikes of the same era. The front end never feels totally confidence inspiring on obstacles. There are a few possible reasons for this: The forks flex noticably in rocks with an adult size rider. The steering rake is more like an MX bike of the era. The handlebars always seem too far back even when they are rotated well forward in the clamps. I am only 1740mm (5 foot 10 inches) tall. On my competition TY175, I've moved the pegs down and back to give more room and have fitted the front end from a TY250. This improves things a lot but the front end is still not as good as say a Cota or OSSA or the TY250 of the same era. The TY250 front end is more refined than the TY175 but one is always conscious of the TY250's weight when in sections. Both bikes are capable of turning as tightly or even more tightly than most of the other bikes probably due to their relatively short wheelbases. If there was a forte for both of them, I'd say it was in tight turns. The first TY250 had a motor that was not as forgiving at low revs as later model 250 motors but they are all are very competent and run very evenly and smoothly with standard settings. The first model TY250 flywheel was lighter than the later models and the porting was different too. The B and later TY250 motors all lug and rev out with magnificent gusto. The TY175 motor has noticably less grunt than the TY250 as you would expect but has the widest usable rev range I have ever witnessed on an old trials bike. It runs strongly right down to the point wher you could count the strokes yet will rev out far higher than other similar era bikes. This proves to be very important in competiton because you can run gearing that provides great clutch-out control at low ground speed yet the bike can also get to a usefully high speed in the same gear. The TY175 would usually be the bike to choose if you wanted to score the least points at a trial but because of the front end and cramped riding position does not feel as satisfying to ride for me as the TY250. In case you are a bit of a hoon, both are fantastic for pulling extended wheelies on. The TY175 makes the better trailbike ie the handling is quite good at higher speeds and when sitting down. I don't know why but suspect it is because of the slower steering. David Lahey Self confessed twinshock trials nut Gladstone Australia

Da Make is referring to what in English is called a "floating" rear brake. They have been used on bikes for many years. The theory is that the rotational forces generated about the swingarm pivot by applying the rear brake are transmitted directly to the main section of the bike frame to prevent these forces causing the rear suspension to compress or extend. Amongst other things, they require the brake backing plate to be able to rotate freely about the rear axle. The added weight of the additional axle bearings and longer torque arm required for this meant that it is a feature not usually seen on lightweight trials bikes and certainly not on any trials bikes ever made by Yamaha. It was popular on MX and road oriented (trail) bikes of the drum brake era. Note that a rear disc brake does not avoid the problem fully because a disc brake still generates a torque about the swingarm pivot which tends to compress the rear suspension (lift the wheel). The difference between disc and rod operated drum brakes that Da Make mentioned is that the force exerted by the drum brake actuating rod is avoided with hydraulic braking. The effect is also avoided on drum braked bikes that use sheathed cable actuation (OSSA MAR and Suzuki RL250). A similar concept for the front suspension was in vogue in about 1978. It was sold as a kit for popular MX bikes I think by Preston Petty. It used a floating front brake backing plate and a rod which transmitted the braking force up to the triple clamps. It worked exactly as intended but people soon discovered that having the forks stay extended as you brake into a corner actually made it worse for cornering so they dropped from favour. Some modern cars have anti-dive geometry built into the front suspension.

Here in OZ the Mitas competition trials tyres are also far cheaper than Michelin, Dunlop and Pirelli but due mainly to their low profile shape (shorter contact patch) they perform quite poorly in trials competition compared with the others. However one thing that Mitas trials tyres are good for is if you want road registration for your trials bike they have US DOT approval so can be used on the road here in Australia and are far better than any other trials type tyre that has DOT approval. Mitas trials tyres also sell like hot cakes for flat track (sliders) racing on decomposed granite tracks where previously the rear Michelin XII trials tyre was the favourite (because they are far cheaper but perform on that surface just as well). By the way the standard retail price for a rear Michelin tubeless XII here is AU$180 which is virtually the same as 60 UK quid. David Lahey Queensland Australia

Jesus with his knowledge of Spanish is spot on here. The late 1960's OSSA trials bike made famous by Mick Andrews was called an OSSA plonker in the USA and the name has eventually caught on elsewhere. When sold new elsewhere it was generally called the OSSA MAR or OSSA Mick Andrews Replica. Plonker was simply a generic term for any trials bike at the time. When I started looking at TODO Trial website I used the machine translation into Australian (it's a bit like English) so I could read about the history of some of the Spanish bikes and was at first stumped because the machine translation of OSSA MAR is OSSA SEA. I eventually worked out that the translation software read MAR as Mare, which is probably Spanish for ocean or sea. There are some other weird translations from Spanish like the Wild Level (Montesa Cota) and some other weird thing I don't remember which really means Honda TLR200. After you read a (fair) bit of the machine translations it almost makes sense (sort of). Plonker certainly came from the characteristics of early trials bike engines as does "bogwheeler" from people increasing the flywheel mass of their old 4 stroke trials bikes using "bog" (lead). David Lahey Australia

179/180 pounds sounds a bit on the light side for a TY175 that is ready to ride and has a sidestand. My TY175B has had the oil system and all the lighting and its wiring removed and weighs 186 pounds ready to ride with a near empty fuel tank. Maybe the fibreglass seat/tank unit makes a big difference? Mine still has standard steel tank and seat base. Maybe gravity pulls harder here in the southern hemisphere? Don't be tricked by the weight quoted in the Haynes manual. Modern tyres weigh a fair bit more than the crap Japanese Dunlop tyres on brand new TY175s so don't forget to add a bit for those modern Pirelli tyres. The TY175 certainly feels a lot lighter to ride than other popular twinshock bikes of the era which generally weighed somewhere around 205 to 210 pounds ready for competition. for mcman56 Yes early 1990s trials bikes such as Gas Gas do weigh about the same as a TY175. David Lahey Queensland Australia

Left side shifting on Bultacos worked well from the beginning in 1975. The shifter shaft being extended through to the left side is a good design. The shift action is best if you use a rigid steel shifter as sold by Sammy Miller. The ultra lightweight aluminium shifter which came with my LH shift Alpina was a bit springy for my liking. As far as Sherpa models to watch out for, I seem to remember a mid 1970s model Sherpa that uses the old style rear hub with brake and sprocket both on the left and a bowden type cable coming from the RH brake pedal. This is a pretty dodgy arrangement because it reduces sensitivity for the rear brake. Alpinas, Fronteras and Pursangs from 1975 had rear hubs with brake drum and sprocket on opposite sides so the RH brake had a simple rod back to the brake arm. I don

Steve The new Talon sprocket without keyway works fine on my 348 Cota provided the shaft is clean, undamaged and the nut is tightened correctly. I don't know if the 330 is the same arrangement but my 348 also had an old keyed sprocket on a taper which I recently replaced with the unkeyed Talon sprocket. Options for removing the old sprocket are to make a special puller or cut the sprocket off with an angle grinder. I have heard that the sprocket will loosen by riding the bike with the nut loose but would not recommend it in case the key shears and damages the shaft taper surface. I have had great success using an 100mm angle grinder with the chain removed and the gearbox in gear. Take care not to grind too far. If you can see where the keyway in the sprocket is, grind there to reduce the risk to the shaft. It took about 2 minutes to get it off and no damage to anything. David Lahey Australia

Rockhopper You have good taste in bikes. 348 Cota timing is 1.8mm BTDC or 17.5 degrees BTDC Ignition points gap 0.4 mm Sparkplug gap 0.5 to 0.6 mm Sparkplug NGK BP5ES or Champion N12Y Cota 348 comes standard with MKII AMAL concentric (square body round slide AMAL same as what came on Bultacos of the same era) AMAL model 2626/402 Some people fitted a Dell Orto carby to replace the AMAL on the 348. My 348 goes great with the standard AMAL carby with standard jetting. AMALs tend to wear out needle jets and needles quite quickly but parts are usually readily available. New AMAL and MIKUNI carbies are available for the 348. David Lahey Australia

Ignition points gap 0.3 to 0.4mm Spark plug gap 0.5 to 0.6mm Ignition timing 1.8mm BTDC

Dear kcj Here in OZ we call it a pneumatic impact driver or "rattle gun" and with one of those driving the socket head screw at the bottom end of the slider and with the fork leg assembled, the screw should loosen easily. If you need more force on the damper rod to hold it still, assemble the forks and wheel into the bike and compress the forks. A bike trailer and tie downs works well for this. Once you have done it once, you will probably be able to change fork seals in about 20 minutes next time. PS It is good in theory to make a special tool for next time but it is usually not necessary. David Lahey Australia

DG Shannon with his 247 Cota said exactly what I also think about twinshock trials bikes. Where I live, it is legal to compete in Twinshock class on SWMs, Fantic 240s and OSSA TR80s and they are certainly easier to win a trial on but there is no way I'm even slightly interested because I have no connection with trials bikes made after 1978. They look way too modern for my taste. Due to impressions cast deeply on my psyche back in the 1970s, I get wobbly knees when walking past my 1975 TY250B, 1976 Cota 348, 1976 KT250 and 1974 250 MAR OSSA. If I wanted a bike that felt modern to ride, I would ride my modern bike. Thankyou DGShannon. Great to hear your message and your Cota 247 is certainly a lovely bike. Vive la difference David Lahey Queensland, Australia