carl ekblom

As far as I know Dunlop only make tubeless rear tyres. Front is always tubed type so no problem. I use Tubeliss to mont tubeless Dunlops on old rims, sometimes running as low as 0,25bar (normally 0,3bar) I would keep the tyre and buy a Tubeliss. No traditional inner tube is needed. Tubeliss costs around 100 eur but is well worth it. However they making mounting little more difficult. Several of my classic trials friends also use Tubeliss and I have not heard of any problem. In case you want to compete, I am not sure they are allowed everywhere.? I was using IRC tr11 before but I think Dunlop is more of an "all rounder" .My experience is that Dunlop 803GP is a much better trials tyre then the older Dunlop 803. I recent years I have been using IRC tr11 , Michelin Competition /X-light and Dunlop 803/803GP on modern and classic bikes At the moment I am happy with the 803GP.

Now I see....The coating is usually greyish. The coating on the inside is still there but little worn. The Crapioli forks need every help they can get so I would replace them all. For a very economical work pehaps I would put them back. Normal forks has the coating on the lower bush on the outside while the upper has on the inside. Must be the opposite on USD-forks On good forks the lower aluminium leg should have the bore anodized on the inside (not easy to do). Crapiolis are not good forks so I don´t know about them. Anodized aluminium has a very hard, low friction surface. I think Beta nowadays own Crapioli and the forks has become much better.

The one on the last photo is busted. They are teflon coated and will function (with possible more friction) even if the coating is worn out. .If it were my bike I would replace them all.

Thanks, So they are MX-hubs. They look little like the ones on road models. Symmetrical is good because it it more easy to find rims that fit reasonable well. It is good to know since the alloy1/2 width Monark-hubs (1955 model) we often use are getting rare and are difficult to find nowadays. I sometimes see the 1/2 width asymmetrical MX-CZ hubs in advertisments but they are expensive. Too expensive for me🙄. But the gold colour is for me a signal of electron🙂 I was told the MZ-hubs also are pre-65 but as you say they are heavy, I would prefer some lighter alternative. Thanks again

PSchrauber: Those lightweight CZ hubs. I think they ought to pre 65 legal everywhere. You know which CZ/Jawa model they came from?

Running backwards😮. As others say: Your ignition is most likely way out of timing. I would check that the flywheel key is there and is in good condition. If so, check the ignition point again and that the breaker plate can be tightened and everyting else ignition related is OK. I have got the information that modern breakers are ment for Lambretta, not Bultaco and that make correct timing difficult......but running backwards🤔

Tennis elbows can be difficult. It is inflammation from being overstressed. Your elbow must have sufficient time to recover between the passes. Try to run only 2 times a week and only one hour/pass. Or only once a week max one hour. It is better to run little then nothing at all. Keep your elbow warm to enhance blood circulation. If it gets cold it may get worse. Use a propriate jersy with long arms and perhaps a riding jacket. Drugs like Naproxen may help litte. Cortison injection probably more but it is in no way a permanent cure. Adjusting riding position, handebar and levers may help little. Try to find a relaxing position. Some exercises to practice in front of TV are also good. The physiotherapist will help you with good TV exercises but remember your elbow needs time to recover between the "in front of TV" passes. Time to recover is perhaps the single most important thing. Elbow must not be static when recovering. You must move it by doing normal activity. It enhances blood circulation and helps the recovering process Good luck

Think they have been out of stock for some time now. Perhaps someone still stock them or you can try to get the best used you can find. Dimension is not standard so it is difficult to find another brand of chain that fits.

Make sure that all parts are correct for your 198A. Even though they look the same they might be different between 2/4-stroke and between Mk1/Mk2 carb. Besides that there are specific parts for some models. Std 2-stroke needle for a series 2900 carb should be marked 2D1 while they for a series 2600 carb should be marked 2B1. Also check that your jet holder is of the correct type and that the air jet is of correct size. Lot of information here www.amalcarb.co.uk.

Perhaps you can make 4 round washers dia 8,1/15mm 3-4mm thick and weld on each side. 4130 steel is popular in USA. The bracket on picture is made of mild steel 4mm thick.

I don't think your 4.8mm left would be an issue but it looks that your hole is sightly oval and that might be an issue that can make your footpegs pointing slightly downwards. Most people feel comfortable if they are horizontal or pointing very slightly upwards. The bolt you have seems to be full length threaded. Better if it is threaded only where it is needed, where the lock nut sits. 8.8 stength is enough for the footpeg bolts. edit: spelling error

Inmotion?

I have bought some classic parts from Spain and I found them to be fast and good sellers. This Corona struggle and lockdowns might cause problem?

https://www.inmotiontrials.com/ have good stocks at OK prices

I don't remember. Was 8-9 years since I did this. I remember I did several things at the same time and suddenly it was quiert? but I am quite sure it was the mechanism that for some reason had went stuck. I made an inspection of parts little later (1/2 year) and found everything to be in good condition. The mechanism is in camshaft. A spring opens the centrifugal device then the centrifugal force close it back to normal operation. Think you have to take the valve cover off to be able to make a close inspection. Mechanism should act on the rocker arm only when kick starting. Also remember it can be difficult to get the rocker cover oiltight after removal. Perhaps ?you can turn the crank by hand slowly backwards a few turns to loose the mechanism if it is stuck. Remove the spark plug first and keep the plug earthened at a safe distance from the spark plug hole to avoid sudden flames from the cylinder As I remember there is a cam chain tensioner accessible from outside. Think you can remove it and check if it is OK? I don't think it is a loose valve guide or something equally bad as your engine sounds to run OK but IF the centrifugal mechanism not works properly your valve timing will not be correct

Check your camchain and your centrifugal valve opening device. It opens the exhaust valve at kick starting only. The centrifugal force from cam puts the valve into normal action as rpm increases. If stuck, engine will make this type of noises you have l

If yokes are parallel, everything others the same, it would move the front wheel approx 20mm rearwards. Bike should be more stable when running straight.

I measured 27.5 degrees steering angle on 199B and 25.5 on 199A. Perhaps precision in my setup but the sum of steering angle, yoke offset, stanchion rake and front wheel offset is little unusual. My 199A feels unstable when running straight. Bearings an everything is OK as far as I know. C-C stanchions Sherpa is 165mm and C-C Alpina 170mm. Wheelbase 199A (unloaded, rear wheel in front position) approx 1315mm.

This is from memory. 355 vs 340mm shocks only have a very minor effect on fork angle and can be neglected. My Alpina yokes are parallel and have approx 30mm offset and are more heavy then Sherpa yokes. More offset means less trail Sherpa yokes have a 1,5-2 degree rake reducing the trail. I have measured a number of them and 1,5-2 degrees is the best I can say. When fork is springing down (Sherpa non parallel yokes) trail will increase making the bike more stable. So the bike will be little more stable when going straight downhill or applying front brake but turning might be more difficult C-C distance is bigger on Alpina yokes. Alpina also has a different front wheel with 140mm brake. Can be differences depending on model and I am not shure Bultaco were consistent all the time. You must check. I can check tomorrow C-C Sherpa vs C-C for what I belive is Alpina

As far as I can remember original are angular contact bearings without cage. Axial capacity can be up to 50% of radial capacity in a deep grove radial bearing . That´s why they frequently use hem nowadays as steering bearings. Also in the past in Norton Commando (6205 I think). But I have not found any radial bearing that fit. A tapered roller bearing is really not needed but I think original part is more expensive. Something like 100eur or so while the Pyramid part can be 1/3. I don´t know about the radial load capacity for the axial bearing in mention. The manufacturer should be able to tell. Perhaps they can be made fit. Original is 25x45x11 Pyramid is 25x45x12. KT25 is 25,3x43,5x11,8. My experience is that smallest play in the steering beam will show up as an annoying clunking.

The markings on the Pyramid bearing are Japan NTN 25x45x12 45H 25H Pyramid sales number is BR44

I had some issue with changing gears a few years ago. It turned out to be a broken spring. Was not expensive To see the gear selector mechanism you have to remove the clutch and clutch basket. I think you need a special tool to hold the clutch hub when removing the centre nut

30205 is 25x52x16,25 The Pyramid bearing for Sherpa is 25x45x12

I think they are non standard dimensions. Pyramid Parts also stock the conical bearing

Plastic tanks from InMotion are not very expensive and should be good for 50 years or so. I have one original 199A plastic tank and one 199B original plastic tank and they are good. Not very glossy but do their job. I have not found any quality marking but I´m quite sure they are made of HDPE To the best of my knowledge painting HDPE don´t work. Painting plastics is difficult (not lasting) or impossible. Colour is added during the manufacturing process and will often be dull or 1/2 dull Tupperware (PP) can be more glossy but not from paint.