Ariel Owners Motorcycle Club

Plenty of earlier motors have no direct oil feed to the big end. Rollers don't need much oil. Nev

Tony, is there something specific about the later 350 big end that would make it superior to the earlier one? I have access to a free 1080-29 big end, but do not want to fit it if there is a good reason not to. Do you have a part number for the one you suggest?

All the taper pin big ends for 1926-58 vertical singles except Colts are the same apart form the position of oil holes or lack thereof prior to 1929, so you can use the 1080-29 or 1080-26 or 1085-36 although original -29 and -36 should not be interchanged as the oil holes moved. All modern repro ones have both oil holes and only require the locating pin to be inserted into the correct hole.

Thank you Roger, that is good to know.

Upon further inspection of the crank assembly I have found another complicating factor. The connecting rod has the part number of a 1927 dual port 497cc OHV engine (A6/247; 1100-28) . According to my '26-'30 parts book this con rod was only fitted to this OHV engine for this one year. I am not sure what makes this particular OHV con rod different from the other models or years, or indeed what makes the dual port OHV con rods different from the single port OHV or the SV con rods in general. Looking at the photo it is clear, based on the accumulated oil deposit, the A6/247 con rod has been functioning in the SV engine for some time. Can any of the Club/Klub Black Ariel experts enlighten me? Will this con rod continue to function in a SV engine with a 'correct' SV piston, or should I be looking for a A6/148; 1110-27 con rod?

A little while ago I obtained a better cylinder from Karol. However, whilst the fins are mostly intact and the overall appearance/condition is much better than the one that came with the engine, it is still beyond the limit of reboring. It measures over 0.090 oversize. So I have arranged to have it sleeved to standard size. The machinist who will be doing the job has found an appropriately sized sleeve, and I have bought a standard JP piston from Drangonfly. I see the recommended piston clearance is 0.0045 - 0.0065, does this clearance also translate to a sleeved engine?

It's standard Practice to allow extra clearance when a sleeve is Installed. Heat doesn't escape as well. Nev

A sidevalve conrod is usually LONGER. Nev

Nev, I kind of need to know how much extra piston clearance to allow. I am spending quite a lot of money reclaiming this barrel and I do not want to end up with a siezure, or alternatively, an underpowered, noisey and/or excessively smoky engine.

I have determined I can't use the '27 connecting rod as, whilst it appear to be the correct length, it uses a 3/4 inch gudgeon pin (same as the other '27s) not a 1 inch as per the new '28 piston.

Side valves run Hotter and distort the Bore More. What OD is the bush? You CAN use steel on steel. Most try to run the Piston too tight and risk seizure. A lot of CAM means less skirt contact and the Piston gets Hotter. The Piston is tapered and smaller at the top of the skirt, and where the rings are is even a few thou less.I recommend 3 comp rings and no oil rings. As for the clearance it was 3.5 thou per inch for a solid skirt Piston in those days and we tend to ride faster. A bit of Piston slap when you first start is OK. As it warms up it will disappear. They used to say "If it doesn't rattle when cold don't trust it. Many sidevalves are Made unreliable by reboring them. They tend to run better when they Have Miles on them and you just fit new rings. Heat the Piston on a stove and try shoving it in the Bore. Oil rings have a lot of friction and that is Heat. Put a relief under the Bottom ring . That's how it was done in the 20's and ARIELS didn't use oil rings till 1949. Nev