1. This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn More.

Mystery barrels?

Discussion in 'Norton Commando Motorcycles (Classic)' started by Hortons Norton, Jul 26, 2019.

  1. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    Hey guys, still unpacking from our move and came across this barrel from awhile back. Just wanted to ask if anyone had any info. on who could have made this type of setup? The lifter blocks are made of steel and they are different from what is out there that I have seen. Any info. would be great, thanks in advance, Chuck.

    [​IMG]

    [​IMG]

    [​IMG]
     
  2. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    From you pics, they look like Triumph lifters to me.
     
  3. gortnipper

    gortnipper VIP MEMBER

    Joined:
    Nov 11, 2013
    Maybe the stamp is telling you to use bean oil.
     
    Hortons Norton likes this.
  4. Hortons Norton

    Hortons Norton

    Joined:
    Oct 12, 2007
    That's what I thought also, They look like they are well done and someone spent some time machining off the stock tunnels.
     
  5. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    They’d work with a JS cam.
     
  6. fiatfan

    fiatfan VIP MEMBER

    Joined:
    Aug 9, 2015
    I bought the cam/lifter set from JS, and he claims the lifters are copied from BSA. Maybe Triumph had the same layout, I don´t know. A while back I saw an ad on Ebay where a Norton barrel was up for sale with this type of lifters, seller claimed they´d work with the standard cam which the JS radius ground lifters won´t. Perhaps it´s this barrel?
     
  7. kommando

    kommando

    Joined:
    May 7, 2005
    The followers in the pictures are Triumph followers, note the slim slots with holes in the shafts for their oil fed exhaust followers, BSA are similar but not the same.
     
    fiatfan likes this.
  8. marinatlas

    marinatlas

    Joined:
    Nov 4, 2007
    Triumph followers are either 3/4 radius (Std) or 1-1/8 (R) the last one offer more duration as expected , JS one are 1-1/8 as STD or he proposed 7/8 for the big cam (to reduce duration), as anyone tried the 7/8 for a JS2.....?
     
  9. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    I ran 7/8 with my JS#1.

    You’re correct to say that the Triumph followers need to be the 1 1/8 (or R) type, but these can be reground thus by many shops familiar with doing Triumph work.
     
  10. marinatlas

    marinatlas

    Joined:
    Nov 4, 2007
    Thank you Nigel, I have allready a JS1 with 1-1/8 (on a 750), and building a 850 with a JS2 (bought SH from Yves ) and just would like to tame it a bit.....!!
     
  11. Fast Eddie

    Fast Eddie VIP MEMBER

    Joined:
    Oct 4, 2013
    Well, I’m only a layperson with such matters, but IMHO that will work well, especially on a street bike. It will lower the power band in the rev range. It will also give safer valve to valve clearances.

    Comstock radiused mine at 7/8 as part of the top end overhaul and porting of the head. The results were fabulous.

    If my dyno testing is anything to go by, the only negative results you’d find is if you were intending to run a Steve Maney style exhaust. I believe the reduced duration of the tighter radiused followers prevents the exhaust working as intended.
     
  12. jseng1

    jseng1

    Joined:
    Nov 26, 2009
    Grinding a tighter radius on the lifter will reduce the duration and lower the power band slightly as mentioned above and this works well for a street bike (similar to using a mellower cam grind with less duration).

    The down side is that since the lift is the same it adds more acceleration to the flank and that can result in valve float at high RPM (plus you lose some top end HP). If its a big bore bike or a street bike that doesn't rev high - it doesn't matter much. But for a screaming race engine you have to be careful.

    The JS3 (D grind) and JS4 (Sifton 480) are already designed for the 7/8" radius lifters. They need the tighter radius to keep those long duration cams from running off the edges of the lifters.

    I used to put a tighter radius on just the exhaust lifters when I was racing with big valves and struggling to avoid valve clash. The exhaust valves are lighter so there was no problem with valve float and the power band was not reduced much because the intakes were not modified and had the full duration as originally designed.

    If you try this - engrave a "7/8" on the side of the lifters so you can recognize them later.
     
    Last edited: Jul 27, 2019
    Fast Eddie likes this.

Share This Page