lemur

Sadly yes, nothing that a new engine didn't fix.

Uncontrolled acceleration can be caused from intake vacuum leak. ... that is where you have a very small air leak type hole somewhere between the carb and cranckcase.

Describe the symptoms, there is a huge knowledge base available here, you might be able to do a lot or all the work yourself, as motorcycles go it's not a hard one to learn to work on, almost for certain the original bike purchase included a very good parts and service manual, you need one 👍

Kubota Premium UDT Hydraulic/Transmission Fluid specifically formulated for transmissions with wet brakes as well as power steering and power takeoff units with wet clutches 👍 At a small fraction of the cost of what those other guys use, I can change it out twice as often and still save money.

You're not using the clutch, your reed valves need attention or the previous owner added weight to the flywheel would be my first guess. The 1980's TY should spool up much more quickly compared to a 1970's TY'

You aren't measuring the voltage correctly or your alternator has a problem, your alternator outputs AC voltage. Primary coil can also be meter tested for continuity and should be in the realm of only a few ohms.

I posted how to push fluid back up into a brake reservoir, but the clutch hydraulics are virtually identical with the clutch piston being synonymous to the pistons on the brakes, it's all just simple hydraulics with the biggest difference being it uses DOT fluid or it uses Mineral Oil. There are very few high spots in a clutch hydraulic system where air can be trapped, so bleeding a trials bike clutch is Not generally a significantly difficult task unless you encounter a mechanical problem such as deteriorated rubber bits at either end of the system. Add: parts diagrams show your clutch master to be an AJP model that uses DOT fluid and not Mineral Oil, for a shop to not want to service an AJP clutch they must be a little bit clueless or simply don't want your business, the same parts were commonly used on additional bike makes and models. The Slave cylinder and piston is unique for your bike but the 2 o-rings inside it are nothing special, the rubber o-rings simply need to be compatible with the hydraulic fluids you are using and you can source appropriate o-rings from anywhere that sells o-rings and or hydraulic service supplies.

If your valve clearance has never been adjusted, that's your problem. The adjuster is the same size as a red Robertson socket screw head, you can improvise a tool using a short stick of wood and thread a square head screw into one end of the stick 🤓 have a micrometer handy to test the dimension and feel of the feeler gauges because valve clearance accuracy is critical.

Adjust, repair or unplug the master cylinder so it lets fluid up into the reservoir when the pads are pushed apart, no flow back means you have a problem.

I think you narrowed it down yourself, the problem manifested after you used a pressure washer on it, so you now have water somewhere you should not have water and you need to dry it out. Fortunately water evaporates so dismantle the electrics and dry them out and they will likely function again. On a Montesa that would be the big plug with all the pins that connects to the black box, look for similar connection on your machine. ... and avoid using pressure washers they destroy motorcycles as fast as they clean them.

Yep, you have the most complicated and problematic carburetor design that was ever installed on a motorcycle so that they did not have to buy a fuel injection system from Honda. Most of the problems will be in the bottom half of the carburetor where the ethanol fuel evaporates out of the float bowl and leaves solids and corrodes parts, the top half won't be a problem until the rubber bits start to degrade and lose critical engine vacuum pressure. Avoid ethanol fuels if at all possible.

Tell of too much oil in your pre mix is how badly the exhaust plugs up with unburnt oil residue, naturally fuel rich condition intake also relates to oil rich. Your air cleaner filter needs to be clean and oiled correctly or that will starve the engine of air and lead to rich operation and poor performance, the reed valves need to seat perfect or scavenging pressure will force fuel and compression backwards through the intake so make sure the reeds seat perfect. Compression test is never a bad idea for diagnosis and future reference if you have the equipment. 👍

What octane fuel? If in doubt drop the main jet needle one notch and test ride it 👍

I suspect you are looking at DOT fluid; another test to try, mineral oil does not mix with water, DOT fluid mixes with water very easy. Only your clutch hydraulics would use mineral oil, brakes will always be DOT fluid.

Fortunately I am Canadian 👍 which means shipping is expensive, taxes are high and my money has low value (at the moment). I'd hook you up with Norm the OSSA god if you lived closer, he only lives 2 or 300 kilometre away and you are correct I am lucky to have lots of good rider friends 😎 several are motorcycle dealers and that helps too.

You can buy brand new forks and a brand new shock that fits right onto your bike which is relatively fast easy and expensive, used suspension parts are not worth my time and money unless they are local sourced, I need parts now and 100% working, not more parts that need fixing. International purchase and shipping of parts might be easy where you live, not here in North America, If my Ossa rider friend that owns about five OSSA bikes doesn't have the parts, they likely don't exist in my country, ymmv.

What country do you live in? Guessing UK only because you called it breakers but used parts are not something you shop for internationally. Shocks and forks are not something I would buy used anywhere and you can buy those items new without needing to be OEM branded.

Fuel tap on your bike is a little strange and over-engineered as a result of being fitted with a carburetor instead of fuel injection, Wheel bearings only last a year or three at best. Fork seals wear quickly if the slide bushings are not set perfect, note that when you get new aftermarket slide bushings you might need to do some careful hand file work on the parts to make them fit well, I clean and dry fit the bushings to inspect for clearance, fit or stiction and then finish the assemble.

Most rolling chassis parts and controls are very interchangeable between trials bikes, things like brakes, wheels and suspension assemblies are largely common between models and even manufacturers. We can almost tell you what all parts are going to regularly wear out and need replacement, wheel bearings linkage bearings, fork seals and slide bushings, brakes, levers, tires and chain. Most buy a spare air filter so you can always have one clean, oiled and ready to use. Tether kill switch is normally an add-on to trials bikes and a component that can often cause problems after some crashes. Being a 2007 model you should be replacing all fluids, brake fluid will be done by now if not already replaced.

Add the word Jitsie to your search 👍

I know what engine I would want to hold wide open until it runs out of fuel and not expect it to burn up, it's going to be the Honda.

Now consider the rpm the engine can pull:

Montesa 4-stroke is So much broader in the power band compared to any of the 2 smokes, there would be no keeping with it in the long run. 4T only fire on every other stroke and don't burn oil the entire time.

Unlikely the lubricant is the source of your clutch slip problems, you should have been making measurements of the plates and whole friction plate pack once assembled as well as the spring lengths. Obtaining a service manual is the best place to start if you don't already have one.

Viva Montesa 👍 Competition gearing preference is close ratio gearbox like an MX bike where enduro and dual sport typically used wide ratio gearbox. CR vs WR and once you ride both you will quickly develop a preference.