smotorboy wrote: ↑18 Jul 2023 14:38
Durability is a key factor in our success for certain.
It has taken "Years" to work out the cylinder cooling issues and the oiling issues when operating at 175%+ of OEM power levels.
What we have Learned :
Change the oil OFTEN !!! or you WILL trash your bottom end plain bearing inserts and C/S journals from sludge buildup in the C/S internal oil passageway
Overhead oiling of the valve rockers, springs and valves makes for quieter cooler running cylinder heads.
Stick to a 8000 rpm redline instead of 8500 rpm....The power falls off after 7800 rpm on these engines like you can't believe and higher than needed rpm stresses everything without any real gain!
Food for thought,
Robert "Smitty" Smith
Invaluable information for those of us who like to (or at least used to) press on at times WFO.
The 250 tacho on my 2C/375 naturally has a 250 (8750) red line. Though TBF when speed hill climbing you don't really have time to study it so "some revs".
What oil are you running?
My 375 is vibrating more than I recall recently. The bottom end was last apart 35 years ago, plus I think being in a small tube 250 frame with only 3 front engine mounting points (the main one having been beefed up to M10 bolts) lets the vibes through more.
Having said that, my oil change regime suffered a bit over the last couple of years due to simply not riding it much. It gets 10w/40 semi-synthetic.
Oh well, probably time to swap back in the rebuilt engine with timing side roller bearing conversion and switch over the 375 with Kanguro heads top end. Then I would really like to put the genuine L5 cam from the Forgotten Error power unit in to the refreshed engine. That could also do with some gear bushes. The 375 tends to drop out of gear occasionally too. Worn selsectors perhaps though I think the late Phil Smith may have addressed that way back when.
I have a fleet addition for longer VMCC section runs. A Honda (there, I've said it) CB250RS Deluxe (Brrmm button version), so I could strip both engines down and mix/match/renew.
What could possibly go wrong?
