Having never owned a 72 I don't know if I am missing a part. What holds the front of the aluminum plate at the front under the seat? Seems like a half moon plate with a hole would be there. Chassis 10951140.
The airbox (if correct) should have two fastener holes. An example of the cover below.
https://www.ebay.com/itm/Penton-125-SIX-DAYS-AHRMA-MX-Used-Air-Box-Top-Frame-Cover-1972-WD-RB52/401552070988?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131003132420%26meid%3D57717974dc074a40a8fab0fc0b2a1f84%26pid%3D100005%26rk%3D1%26rkt%3D12%26mehot%3Dpf%26sd%3D352575623062%26itm%3D401552070988%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWeb%26brand%3DPenton&_trksid=p2047675.c100005.m1851
https://www.ebay.com/itm/Penton-125-SIX-DAYS-AHRMA-MX-Used-Air-Box-Housing-1972-WD-RB52/153061123321?_trkparms=aid%3D1110006%26algo%3DHOMESPLICE.SIM%26ao%3D1%26asc%3D20131003132420%26meid%3D57717974dc074a40a8fab0fc0b2a1f84%26pid%3D100005%26rk%3D3%26rkt%3D12%26mehot%3Dpf%26sd%3D352575623062%26itm%3D153061123321%26pmt%3D1%26noa%3D0%26pg%3D2047675%26algv%3DSimplAMLv5PairwiseWeb%26brand%3DPenton&_trksid=p2047675.c100005.m1851
Dale Fisher
Mudlark Registry
Side plate or air intake?
Rick, in looking at the production date of your frame number this bike did not come with the aluminum splash guard that was attached between the frame and the airbox under the seat. A small tab with a bolt hole was added to the frame mid 1972 on the cross bar behind the tank to bolt the front of the splash guard to the frame. Prior to the splash guards early CMF Pentons were sold with a piece of urethane foam placed under the seat to keep water and mud out of the airbox.
Found an answer to my problem in issue #1 of Still Keeping Track. A pattern for a plate the Penton boys must have come up with back in the day. Pays to read our own publications.