Author Topic: unleaded valves  (Read 1106 times)

0 Members and 1 Guest are viewing this topic.

Offline neil10

  • Hot Shot
  • ***
  • Posts: 315
unleaded valves
« on: March 15, 2008, 01:27:44 PM »
 I'm using lead replacement with petrol  wandering if I realy need to if valves are hard anyway?

Offline old750

  • Enthusiast
  • **
  • Posts: 211
  • Hippy ass bike.
Re: unleaded valves
« Reply #1 on: March 15, 2008, 02:01:13 PM »
I've also wondered if valve seals need to be changed as I've read in my mopar magazines that they would post 1972 or around there.

Offline Gordon

  • Global Moderator
  • Really Old Timer ...
  • *****
  • Posts: 12,114
  • 750K1, 550K2
Re: unleaded valves
« Reply #2 on: March 15, 2008, 04:52:13 PM »
The sohc4's do not nead leaded gas.

troppo

  • Guest
Re: unleaded valves
« Reply #3 on: March 15, 2008, 05:42:51 PM »
do a search on this one, i did and found that aparently all the SOHC`s are designed to run on unleaded.
i was a little worried about this too
cheers
troppo

Offline Big Jay

  • Expert
  • ****
  • Posts: 1,252
    • CBRzone
Re: unleaded valves
« Reply #4 on: March 15, 2008, 06:04:33 PM »
Interesting. The valve seats are pretty soft, especially by todays standards.

Jay

Offline City Boy

  • Hot Shot
  • ***
  • Posts: 689
Re: unleaded valves
« Reply #5 on: March 15, 2008, 10:50:37 PM »
I can't refute newer seats are harder than old,however,in all my near 40 years of playing with the sohc units,I have yet to see one with bad seats from normal wear and tear!Maybe I'm just lucky.
'52 Kiekhaefer Mercury Rocket Hurricane KG4H
'70 750/RC 1000 Original Owner
'83 1100F

troppo

  • Guest
Re: unleaded valves
« Reply #6 on: March 15, 2008, 11:04:11 PM »
Well i was wondering about whether i needed to run with an additive or not to prevent valve seat damage, so i did a search about it, like i told neil10, and found this post where gordon put it very clearly

http://forums.sohc4.net/index.php?topic=25808.0

i dont believe everything i`m told so i kept searching and the general consensus is that you dont need a fuel additive to run unleaded petrol.
cheers
troppo

Offline mark

  • finds nothing amusing about being an
  • Old Timer
  • ******
  • Posts: 2,939
  • we're out here and this is where we are.
Re: unleaded valves
« Reply #7 on: March 15, 2008, 11:48:05 PM »
My downloaded 500-4 manual is missing the engine theory page, so I cannot speak as to the construction of those valves. The 350 twin book that I have says that those valves are faced with stellite; says nothing about seats other than instructions for cutting with hand tools. I haven't tried grinding any Honda m/c valves yet, but stellite is some pretty hard stuff. I would be surprised to find that the seats were something harder than cast iron.

As for the stem seals... if original, they are over 30 years old. All of the rubber pieces that I have removed from these engines have been as hard as rocks. I would not hesitate to replace them.


Happy trails.


1976 CB550K, 1973 CB350G, 1964 C100

F you mark...... F you.

Offline eurban

  • Master
  • *****
  • Posts: 1,625
Re: unleaded valves
« Reply #8 on: March 16, 2008, 06:01:59 AM »
As they say, the proof is in the pudding boys.  Leaded gas been unavailable in the US for more than 20 years.  These engines have been running fine on unleaded for a very long time.  And yes there is science to back up these results.  Honda used valve seats of sufficient hardness.