carl ekblom

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.

British tank Edit resized

Alpina tank: https://www.ebay.de/itm/Bultaco-Sherpa-Model-Gas-Petrol-Fuel-Tank-With-Cap-Aluminium-Made-GEc/153824255290 Sherpa tank https://www.ebay.de/itm/BULTACO-SHERPA-ALU-BENZINTANK-NEU-BENZINTANK-ALU-BULTACO-SHERPA-ALU/182822949409

https://www.ebay.co.uk/itm/BULTACO-SHERPA-ALU-BENZINTANK-NEU-BENZINTANK-ALU-BULTACO-SHERPA-ALU/182822949409 Claimed to be Spanish also J&C Fabrications in the UK https://www.facebook.com/JC-Fabrications-934592909952839/ Sorry, no experience.

My 74 had black frame, 17/20 inch whees and Pirelli tyres(crap!) Suspension was not good. Bigger Montesas were better. As far as I can remember 73´s had grey frame but the same wheel sizes? I think some people replaced the rims for 18/21?and Dunlop tyres

My old manual says 2,5-2,7 for 199A/198A, but it is written in Spanish?. I think 2,5-3,2mm is good. You may have to adjust later due to personal preferences.

From behind looking forwards What I believe is original 199A rear wheel 67mm is outside WM2 rim

Yes, they are nice bikes. Good project?. Little curious about the throttle. To me it looks like the one for Beta 4T and it should be a very quick throttle for a normal round throttle valve trials carb. I think they from the beginning were made for 38mm(?) motocross carbs