Thanks for the data Mike. Using those figures and knocking 30gms of the +20 piston(to get the std. weight) and recalculating the BF it comes out to 61%. Looks like Ariel aimed low on the BF.

Using the crank /conrod weights on my VB with a reasonable weight piston like the old Hepolite gives a BF of about 54% i.e a lot lower than the "normal" 67%. I never saw the bike running and the previous owner is deceased. Apparently some prewar side valve engines had low Balance Factors. ...

Hi Ian, your photos are close to what I had in mind, leaving the front and back to stop slap and provided for some heat transfer from the piston. I couldn't see the crack in the boss clearly. If you had to do the job again what would you do to avoid the cracked boss? At the moment I am making a jig ...

Hi Brian, I had emailed JP in Oz asking for a cross-section dwg. of the VB piston (11327 JP246) to see where I can remove metal, not had a reply yet. I imagine 12mm off the length of the skirt and maybe 3 mm off the crown. Plus any I can get inside around the pin bosses. Its going to reduce the comp...

Hi All, me in sunny N wales with the 1954 Ariel 600VB. I fitted a new JP 11327 +60 piston to the VB and have ended up with unacceptable vibration. Only run for a few miles, stripped down and worked out balance factor (BF) which came out at a lowly 46%. The old Hepolite would have given a BF of 54% s...

brilliant many thanks.

Hello to all, I have just realised there are several ways to install the cam followers on the VB. I can't find a diagram or valve timings. The cam is stamped A6-664. Can someone confirm the follower arrangement is, end float shim first then inlet follower, then the exhaust follower, and does the bro...

I have an Ewarts type main/reserve tap on my 1954 VB. I tried new corks to no avail. Finally I fitted a pair of neoprene "corks" from Draganfly (PA-34), a bit pricey but worked perfectly, claimed to be ethanaol proof, no leaks or petrol smell in the garage. My tap has threaded plungers. Th...

Hi All, I posted a query about piston weights in Dec. 2017 but the thread got lost . I rebuilt a 1954 VB engine using a +60 JP piston and was a bit worried about its weight (740gm with pin and rings) compared to the old +30 Hepolite( 605gm with pin and rings) , and its effect on vibration. I hoped i...

Hello Paul, I have just finished a rebuild of a 1954 rigid rear, tele front, VB600. The previous owner had hand painted it (not well but liberally) maroon, I haven't touched the paint work, I'm no good with paint. Mechanically I have renewd everything that needed doing (rebore/new piston/new mains/b...