oldaz

Been a bit quiet for the last week, too much farm work and wife in hospital, but life goes on. As mentioned above I've started on the power unit and got the clutch side pretty much sorted - still have to get the cover welded at the front lower edge. No cracks in the timing (right) side cover, but where the chain has come off the front sprocket the seal and side of the case is pretty chewed up - also a fair amount of play in the drive bearing on that side, so looks like I'll have to split the engine after all. Still don't have the wheels back, discovered the drive side bearing in the rear wheel has been loose at some time and partly chewed out the hub, so getting the hub machined to take a larger bearing on that side, then re-spoke it. The more I find the more I'm convinced this poor bike wasn't looked after very well in it's former life. Will order more gaskets today and look into getting the cylinder and head hydro-blasted to remove external corrosion. Now to salvage the right side case where the seal and drive bearing goes. Finished sorting sheep this morning, but it's about 44C in workshop already today, so think I'll stay inside and give it all a miss - maybe a couple of Coopers dark for lunch??

Find Michael Waller on youtube and have a look at his BSA builds, it will give you an idea of what's involved and possibly steer you in the right direction re BSA frames.

Got a picture of it, pretty basic arrangement, made one for my bike at 9mm from lever face to end of brass - 15mm overall. Clutch arm to cable angle is 90 degrees as it touches, so should be OK - if not it's easy to shorten it a bit. There are 6 different part numbers for this part and they are all different lengths - seems there's half a mm between each size? Anyone know for sure??

More research tells me this little follower thing should be brass, although some mentioned steel. Mine was steel and what's left of it isn't much good except for the part that locates on the lever. I looked on inmotion site and they have the brass ones in stock, but more importantly (for me) is they have pictures. The parts list shows several different part numbers for this item and all are different lengths, suggesting you change it out for different clutch packs or to allow for clutch/linkage wear. Anyway it's enough information for me to make a new one, just have to work out what length I need. Might have to get a replacement for the 3 leg pusher as well, will see what happens. Found a nice size piece of brass and made a new follower - made it 15mm overall with a 6mm deep slot for the lever. Set the 3 leg pusher up and machined the contact face, then polished it. Set the side cover back on and without a gasket, the lever is about 15mm off the side cover join when everything contacts. Added a piece of gasket material and the lever to cable angle is almost exactly 90 degrees, so I reckon it should be about right. Contact and operation is as smooth as you would want, so fingers crossed. The screw on cable end is the right length on the screw side, but only 2mm long on the other side, so looks like I'll have to find or make another longer one. Will get the side cover crack welded while it's off, then I can probably put that side back together. Need to confirm the drive shaft taper will match the new sprocket and cut a keyway in the sprocket - hoping the taper and bearing is OK, but will check it out.

Brass thrust bearing?? Is the follower between the clutch lever and the 3 leg pusher supposed to have a brass end bearing? Pictures??

Started cleaning up power unit, found clutch case cracked from contact with rocks, the clutch follower that goes between the lever and the 3 leg pusher is trashed so badly I can't see what the end is supposed to look like, the face of the 3 leg pusher is also trashed, otherwise that side looks to be in reasonable condition. Got the 12 tooth sprocket off, drive shaft is a bit chewed up and key is a bit worn, should be able to salvage the shaft and put a new woodruff key in there - no keyway in the new 9 tooth sprocket? I read somewhere that the taper is enough to hold them, but given the shaft condition, I believe for safety I'll have to cut a keyway in the new sprocket. The drive bearing (behind the sprocket) has a bit of slop in it as well, so looks like new bearing and seal will have to go in there. Already got the new kick start return spring also recut the clamp on the lever, cleaned it all up, rebuilt the contact points for the folding part and will replace the ball detent in there after I get it chrome plated. If anyone has a picture of what the end of the clutch follower where it contacts the pusher is supposed to look like I would really appreciate seeing it.

Made an adaptor and fixed the petrol tap problem, fitted the stainless nyloc nuts to the front mudguard stays, then got stuck into it and made the engine stand. Wheels will probably be another week due to repairers work load and other commitments. Got the power unit mounted in the new stand, then had a bit of a struggle but got the timing cover off before I had to get back to farm duties. The picture doesn't show it, but there are screws set in the 4 corners of the bottom of the stand to adjust level if needed - also compensates for welding pull ;-)

From the numbers it looks like you have somewhere around '77 model. The number is about 4000 after mine and I know they made 4400 of my model, with the '77 being the next model after. The handlebars are genuine Montesa alloys, maybe original - I don't have experience with later models and there are always little differences. Like I thought the left twist grip is a spare for what-ever reason and this is not normal. The air box looks correct but has a small inlet spout that wasn't used on the earlier models - earlier models had a rubber 90 degrees between the air box and carb so the box sits horizontal - I've seen one other picture with the box mounted like yours. Looks like a nice bike.

Have you checked with southwest in USA, or inmotion in GB, both have web pages and you can make enquiries.

I bought on off USA ebay, same seller advertises every week, latest is ebay item 182929150577 The cota 247's don't come standard with 2 throttles, maybe you could follow the cables and see where they go? Or if it only has one cable to the carb, the PO may have kept a spare twist grip on the left side ?? The frame number should be on the side of the head-stock and start 21M******, it should also match the engine number stamped near the front engine mounting. You can check those numbers against year of production online at southwest site. As mentioned above, a picture of the twin throttles would be handy.

Try dis-connecting the kill switch and check again - divide and conquer.

So, wheels not back yet, so on to the tank/seat support. Cleaned it up, plenty of cracks in the gel-coat, couple of leaks where there's like pin-hole punctures on the sides, one patched hole underneath and mounting holes chewed out. Looks like a 150mm long burn mark on the right hand side about where your knee would be?? No idea what that would be from as the exhaust is on the left side? Oh yes, PO had a wonderful time with the petrol tap, these tanks have a moulded in M12x1.25 steel female thread for the tap to screw into, looks like PO cut a 7/16" whitworth thread on the tap and screwed it in there with a couple of rubber and steel washers to try and seal it. I managed to salvage the thread in the tank, so that's a bonus. I also had a win with the paint, the underside of the tank and under the sticker remains was some original colour and I found a place that will match it. After showing them the tank today the guy suggested a 2-pack paint that won't be affected by petrol, so I was able to collect a large rattle can this evening. The can is interesting as it has both parts of the 2-pack in it and the hardner is only released when you're ready to paint and you give multiple thin coats with a 3 to 5 minute flash time between coats - hope I don't stuff it up - will find out when I get the tank back from repairs. Other than that, the 9 tooth sprocket arrived and the chain is on the way, getting ready for the power unit - gaskets arrived about a month ago - might get a chance to make the engine stand tomorrow.

I used to ride the old Brit bikes off-road late '50's through the '60's, even road some trials on a 250 AJS back then. For information, there's a guy name Michael Waller has some very informative videos on youtube, describing how he builds pre '65 trials bikes - think you would enjoy the series. I'm getting closer to completion on the Montesa Cota 247 version Ulf Karlsson and thinking of doing something like a pre '65 for my next project.

I've spent a fair chunk of the last few weeks making those sorts of parts for my 247. Local hardware shop is a good source of stainless bolts and nuts. Otherwise a piece of suitable scrap/bolt/whatever gets turned into what I need. Guess it depends whether you can find them, afford to buy them, or whether you have the skill set & equipment to make them.

More little bits done, mostly on the front end. New mudguard stays made and fitted, mudguard fitted, coil fitted, stainless lower gaiter clamps arrived and fitted, handlebars, grips and levers all in place and the rest of the brake parts repairs/modifications completed. Now if I only had the wheels back.... Hoping to get the tank out for repairs next week after I get the paint matched on Wednesday then a couple of busy weeks on the farm, maybe get the wheels back during this time, then start on the power unit.

Sounds like the typical brake arm, mine was made the same way and bent/twisted like yours when I got my bike. The cable retainer had been fitted wrong and the front wheel was in backwards, so plenty of angles were wrong. The brake arms seem strong enough when they are straightened out (takes some doing to get them right) and the cable angles are correct. If I find mine starting to twist under pressure with the angles correct, I'll make new brake arm/s as needed or find stronger alternatives.

The cota 247 hub could be laced into your rim, but make sure you get the one with the correct spoke count. Some are 36 spokes, where I believe you need 40 spokes to suit. There are NOS cota 247 hubs and brake plates for sale online that may do the job. You will probably have to modify or replace the front axle as well. Might be worth checking a Yamaha TY 175 or 250 front wheel.

Lots of little bits done, foot pegs finished and fitted, axle ends recut square & new stainless washers, made new wheel spacers including one to replace the speedo drive, brake operating levers repaired and painted and so it goes - lots of little bits ready for when the wheels and brake plates arrive. Still have to modify the hinge points on the "alternative" brake shoes, but looks like they will fit OK. Aluminium arrived to make the front mudguard support brackets so that's next - hope it works out, then clean up the tank for fibreglass repairs. No pictures this time - will wait until the wheels are back in. Does anyone know the paint code for Montesa red?

Bought some bits off eBay and ended up with enough bits to make up the forks. Refurbished the sliders and tube nut relief valves, replaced all seals, O-rings, gaiters and circlips and fitted back to the bike - had to see it with the new handlebars in place. Now making new spacers for the footrest springs and refurbishing the axle assemblies. Wheels are away getting hydroblasted and rebuilt with new spokes & nipples - the nipples were steel and badly rusted, the hubs and brake plates corroded - meantime I'm doing the brake fittings.

If you go to the "Montesa Cota 247" topic you'll see a picture of my bike when I cot it and you can see the pressed steel one for my '75 model along side it. I believe there's supposed to be a curved mesh piece in the opening. I created a separate picture from the original.

Got the shocks fitted up and like how they look. Made new bronze bushings and stainless hinge pin for the brake pedal, then the rear mudguard arrived, so fitted that as well. Picture shows the chain guard in place so I could mark it up for shock clearance. Completed the taper roller bearing conversion to the triple tree, fitted it up and did a preliminary pre-load on the bearings as well.

A little more progress today, got the swinging arm back in. Picture shows the home made (custom?) chain protector sandwiched between the frame and the swinging arm. I bought a block of rubber from Precision Hytec and cut the new one from it - total cost about $7.50 - to get the same part from Spain would have been over $150 with most of that for postage. Will fit up the rear shocks next. The mounts have a 7.2mm hole through them and the shock is normally only held by an E clip. The clips were missing and I got new ones, but it didn't look very secure, so I also decided to tap the mounts to M8 and put some stainless button head cap screws in there.

Thanks for the input folks, as well as your informative answers I was also prompted to do some research online to catch up with modern chain development. Very interesting reading - seems the X ring chain may arguably be the best overall design, but the lighter weight and design combined with even better steel alloys of the new style forged 3D type looks like the best match for trials and other off-road performance bikes.

I believe it would tend to attach/weld itself to aluminium sprockets under pressure, so you would need to run steel sprockets which would obviously weigh more.

The problem with titanium for a drive chain is it's ability to stretch and bend a lot further than a comparative steel item. The strength wouldn't be a problem, it's only when you get into the higher grades of both metals that steel comes out on top, but the stretching wouldn't do your sprockets any good. There's a relatively new design drive chain that's noticeably lighter than the conventional chains we're used to, one brand is EK ThreeD race chain. The forged side plates are smoothed right out and have a hole in the middle, the actual height of the plates is slightly less than the same size in regular chain, but the strength is better than most due to added chromium in the alloy. The chain uses a riveted joining link as well. It looks pretty with an almost chrome type semi-polished smooth finish and the design is said to improve power at the wheel due to less chain drag.