QuestionHello Bill,
I have a 1973 honda Cb450, DOHC I know she needs a new battery but I usaly get her running however it dose not seem to charge the battery and I think there is a brown weir that should be on the key switch thats not attached. But To the left side there is some oil pooling under the fins on the lower haf and some on the crakcase from it, But it did not run my oil down much, however today It is having a huge problem idling aka needs help or runns at about 3000rpm then when I go to giver her gass to get her outa first she dies. and it wont Idle with the choke open.But also today I saw smoke outa the left tail pipe . .. Im hoping its not the head gasket. also would that case that left side to miss a little? or am I just looking at a bad battery and in need to check my points? or perhaps the valves are letting oil in? its white smoke btw. I have the original tool kit but im at school atm so my sources are limited.
Thanks
Timothy
AnswerTimothy, first of all this is a battery-powered ignition system. ALWAYS start with a fully- charged battery that will pass a load test. Once you have a good battery in the bike, test the output of the charging system with a volt meter. There is a current regulator beneath the battery box that might be bad. You can just unplug it and see if the voltage goes back up. If not, check ALL the wiring connections between the stator on the left side of the engine and up to the rectifier. If you have been running with a low/dead battery, then the rectifier may be fried. You can replace them with a Radio Shack full wave bridge rectifier cube for cheap $$$. Guys sell them on Ebay often.
The brown wire has a spare empty lead up front. It feeds the tail light bulb filament and the spare connector is for non-sealed beam bulbs used in other countries.
http://oldmanhonda.com/MC/WiringDiagrams/MCwiring.php
If you put a fresh battery in the bike, all of your running problems may go away.....
If not, you will need to drop the float bowls and look for signs of water/dirt/debris that may be clogging your jets. The idle jet is VERY tiny, but if the hole is plugged up, it won't idle and will be hard to start.
Oil leaks CAN come from the head gasket, or the valve cover gasket weeping down the front of the engine or the dyno cover on the left has a gasket and o-rings on each screw that can leak oil. Make sure you have enough oil in it at all times. Perhaps the base gasket is failing, though.
Be sure to check the crankcase breather tube coming from the rear valve cover area to see that it is not pinched off, causing excess crankcase pressure to build up which causes oil leaks at gaskets and seals.
There are service bulletins that suggest that both the dyno and clutch cover gaskets be replaced on all 450s, due to deterioration which can cause pieces of gasket material to float up and block the oil flow to the cams, etc. NOT a good thing!
White smoke is generally condensation that should diminish in a few minutes. Oil smoke is bluish and excess fuel is black smoke. You can check the spark plugs for signs of contamination from oil or fuel.
Other issues with 450s are poorly grounded condensers at the frame... remove, clean the metal underneath and reinstall. You might have bad spark plug caps, which are 5k ohm resistance value.
DO check the point gap .014-.016" minimum and then set the points plates so that the right points just OPEN at the F mark and the left points open at the LF mark alignment.
It would be a good idea to check the valve clearances which are basically about .0015 to .002".
An oil leak at the head gasket will not make the engine misfire. Make sure that both carburetor cables are adjusted so that both carb throttle arms pull up at the same time.
I don't know how much of this you are going to be able to do with your motorcycle tool kit. Go to Sears/Harbor Freight or auto parts stores and get a metric combination tool kit with some proper wrenches and sockets.
Bill Silver
