feetupfun

option 1. Buy a non-points OSSA flywheel and the In Motion ignition option 2. Buy an ignition from somewhere else https://www.francetrialclassic.com/en/ignition/5010-ossa-250-350-electronic-ignition.html

In Motion Trials (UK)

There should be clearance there. Having new parts does not mean that you are guaranteed the correct clearance. It would be risking damage to run it without clearance. If you need to, make the spacers a bit thinner. Aim for about 0.5mm total clearance.

I didn't mention the key or keyway on the left end. Yes it's common for the key on the right hand end to fail and chew out the keyways and the shaft because it's a dodgy design and people sometimes don't tension the nut properly or they sometimes fit a key that's too long. Depending on the amount of damage, you might be able to get away with machining the keyways wider in the crankshaft and the sprocket and fit a wider key.

So it's just the drive end of the crankshaft that is damaged? It's probably more common for the magneto end to be damaged by the bearing seat wearing the crankshaft down. I've got some with damaged magneto ends and good drive ends so you might be lucky and find a model 80 crank with a good drive end somewhere near you. My comment about the balance holes in the crank wheels also applies to 325 crankshafts being different to 250 crankshafts. Another thing is that early 325 crankshafts have the same diameter crank wheels as the model 80 but after about 75/76, the 325 got bigger crank wheels which will not fit in the M80 cases.

Not certain, but I think the M221 might have two ball bearings on the drive side while the M80 has one ball bearing so the bearing seat on the M221 crankshaft might be too long for the M80 motor. This may not be a show stopper though. It just might mean that you also need some other M221 parts as well as the crankshaft. The other thing to think about is that the 175 crankshaft will probably have different size balance holes in the crank wheels to suit the (lighter) 175 piston. What is it that is stopping you using the M80 crankshaft? (be a bit more specific than whatever being mullered is)

Cool video Bailey. Good to see. I'm now following your Youtube channel David Lahey

Your Lobito would originally have had an ignition switch of some sort for stopping the motor. Decompressors are commonly used for stopping the engine at idle but may not stop the motor when it is in a runaway situation. Lanyard breakaway kill switch and latching kill switch are effective devices for killing the engine in an emergency situation. The lanyard kill switch is the better of the two because the ignition is usually cut off sooner than with a kill switch.

Here's one advertised in Australia https://www.motorcycletyrewarehouse.com.au/300-23 It's a Bridgestone TW9 tyre

Yes it's a normal thing to have the tube creep inside the tyre. It can be quite persistent. If you can get the tube to adhere to the inside of the tyre it won't creep but that can be difficult to achieve. I've found it is less likely to creep if I use a 4.00-4.50 tube rather than a 3.50-4.00 tube. I have also found it happens less with Michelin X11 rears than with IRC rears. If you leave plenty of room in the rim hole for the valve stem to lean over I've found that the tube will only creep so far and the tube stem stops it creeping further (I found this because I got sick and tired of moving the tube stem back straight when it leaned over due to tube creep.)

To stop the motor, the kill switch creates a short circuit from the low voltage ignition wire to the bike's earth. The low voltage ignition wire runs from the flywheel stator low voltage ignition coil/points to the low voltage connection on the HT coil. The HT coil is usually hidden by the fuel tank. On the Bultacos I have worked on, the low voltage ignition wire is coloured black. Bultacos like yours originally came with a connector strip for the wiring on the frame under the front left of the fuel tank. If that is still there, one wire from your kill switch may be connected to the ignition wire using that connector strip. The other wire from your kill switch can be connected to the frame where the HT coil attaches to the frame. If you are still in doubt, post a photo so others can see what you are dealing with

Well the right hand side engine casing is from a Mk3 Lobito. A proper ID of the bike (and the motor) needs decent photos of the bike and the motor

I've seen that on many Mk1 concentric AMALs

With no thrust bearing the release mechanism parts that are rubbing together may have suffered damage from the heat generated by friction. The effect on the bike will be similar to a clutch that doesn't release fully but not exactly the same because this issue does not transmit additional torque to the gearbox like dragging clutch plates do.

The other brand manual is Clymer

There are a couple of workshop manuals written in English for 5 speed Bultacos that are useful. One manual is in the Haynes series and it's pretty good. I just looked and there is at least one advertised second hand on eBay. Search for "Haynes Bultaco Manual". If you have a Mk3 Lobito it is a 5 speed motor and the Haynes manual will cover it.

Yes there is a key on the crankshaft to make sure it goes back in the right place. I don't know what you mean by it having only one spark. It should only spark once per rotation. Yes it's normal to service the points with the flywheel off. The access holes in the flywheel are for the final step when you set the timing. Is it the Mk3 Lobito in your bike list you are referring to? Photos of bike/frame number/engine number of your Lobito may help your quest for information.

How about putting the bike on a stand and applying tension to the top run then to the bottom run. Apply the chain tension by putting the bike in gear and rotating the rear wheel back and forth. The idea of this is to replicate the conditions when it makes the noise You are not looking for the chain catching on anything. You are looking for a spot where metal can touch metal. Possibles include a worn chain guide at the front end of the swingarm or a worn chain tensioner block. Is the tensioner hitting the swingarm?

If it's the AMAL with a tickler, the usual reason people have trouble with cold starts is that they don't tickle them for long enough. Leaning the bike away from the side with the tickler also helps to get more fuel in. The pilot jet is important for hot starts.

The noise disappears when you pull the clutch in because that takes the tension out of the chain which allows the chain to move under the effects of gravity and inertia rather than being pulled into a straight line by the motor. When the clutch is out, one run of the chain is tight and the other is loose - under motor drive the top is tight and the bottom is loose. Under overrun, the bottom is tight and the top is loose. When you pull the clutch in and ride along, both runs are loose and the chain flaps around more.

It's normal to be able to change gears without using the clutch. Your clutch needs attention to get it to release properly. It's normal to have trouble finding neutral with the motor running if your clutch is dragging. Sticking throttle can be a problem with the cable or the throttle slide. A revving engine can also be a sign of an air leak into the engine.

TS 250 models R, J, K, L, M 1971-1975. I figure you are asking about the part that attaches to the rear edge of the flywheel cover and covers the front sprocket. https://classicjapanesemotorcycles.com/products/suzuki-ts250-rl250-sprocket-cover

Sounds like chain touching metal. Look for a worn-out/bent/mis-aligned/absent chain slipper/guide.

https://www.google.com/search?q=images+bultaco+199B&client=firefox-b-d&tbm=isch&source=iu&ictx=1&vet=1&fir=y4BZg-LQuKjJeM%2CUJInkK6fpaB9PM%2C_%3BUkyH0DRK_08fmM%2C0om8ErPu5Dg4TM%2C_%3BEAv52QZxkfZ_VM%2CqzYX65TOnxa2BM%2C_%3BvlROOjIwTh-NQM%2CqzYX65TOnxa2BM%2C_%3BQRz5mfyx_Ti4DM%2Co1G6319z_W26kM%2C_%3BKqRhQn-3dGRBNM%2CH131WeOsI8EraM%2C_&usg=AI4_-kQblQRQvlwkqMuYEnSgfbUc7LXzqQ&sa=X&ved=2ahUKEwi65MLr0dj4AhWR9zgGHSsBD3QQ9QF6BAgKEAE&biw=1366&bih=643&dpr=1#imgrc=EAv52QZxkfZ_VM

1:1 is zero leverage (Sherpa T pre-1970) 1.5:1 is high leverage for twinshock trials bikes (Godden Majesty 250/320, Fantic 240). Some twinshock MX and enduro bikes are even higher leverage. 1.1:1 is a typical for trials bikes made 1970-1975. With Falcons and your weight, if you get the 50 lb springs you will have zero risk of bottoming out the rear end during landings but the the rear end wont work quite as well as it could in rocky stream-bed sections. 40 lb springs would give a more supple rear end in stream bed. You should use the lightest springs you can get away with because if you aren't using all the suspension travel, the suspension action is not as good as it could be. If I was your weight, I would try the 40 lb springs first.