Jon, Sounds like it could be valves or it could be a head gasket. A wet test usually indicates ring wear. Take a vacuum gauge to the intake. If the needle jumps around, it indicates valves.
On lean run, make sure your not getting outside air being drawn into the cylinders between the carbs & cylinder I let. I think you said you tried that. In fact, now that I think about it lean conditions would lead to burnt valve Sent from my iPhone > On May 30, 2016, at 2:56 PM, jonpalms <[email protected]> wrote: > > I hope someone can enlighten me on this issue. > I tested my wifes 1986 honda cb450sc nighthawk for compression value. I think > its suppose to be 9/1 compression ratio and I guess that should be 9 times > 14,7, wich is 132,3 psi. I`m not sure this is correct though. Some places I > read that the compression is suppose to be 185 psi. The result from my tests > show appr. 120-125 psi and 125-130 psi and when I added some oil in the > cylinder it just raised a few psi. Hot engine and open throttle. > The bike runs pretty good but its running lean I think, since sparkplugs are > pretty white colored. > Is 125 psi too low? If there is some leak, and the wet test only gave a few > more psi, where can it be..... valves? > > Another thing is the lean running engine. We just got this bike from the US, > and I don`t know its history. I figure a good carburator cleaning would fix > the lean problem. Any suggestions? > > Appreciate some good advice :) > > Jon > -- > You received this message because you are subscribed to the Google Groups > "Nighthawk Motorcycle Lovers!" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at https://groups.google.com/group/nighthawk_lovers. > For more options, visit https://groups.google.com/d/optout. > <IMG_7286.JPG> > <IMG_7496.JPG> > <IMG_7498.JPG> -- You received this message because you are subscribed to the Google Groups "Nighthawk Motorcycle Lovers!" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/nighthawk_lovers. For more options, visit https://groups.google.com/d/optout.
