CB750 F2 suddenly won't start.

[Sixtenao]

Hello all,

I am new to this site, but i can see that most people get help from you regarding their problems.

I have a Honda CB750 F2, that has a hard time to start up. Until today, it has taken about 10 tries before the engine starts up. At this point i have to keep it from dying by revving it, but that is not an issue for me.

Today i was going to start the bike, but it was not starting at all. I even tried with starter fluid spray. In the end the battery naturally died out... I noticed that the kickstart had no effect at all either.

My routine when starting the bike is turning on the fuel, waiting for a little while and then giving it a little gas to let the fuel flow just before hitting the electric starter.

I should notice that i rode the bike in heavy rain for a short while the other day, and it made the bike bog down a bit while idling.

I hope you have suggestions both regarding the faulty startup as of today, but also generally in regards to the bike having a hard time starting up.

Thanks!

[TOOLS1]

Welcome. These bikes are naturally cold blooded but should start. When starting one of these bikes you should not need to give it throttle. When doing this it opens the venturi preventing the choke/starting circuit from working properly. Some other things that can cause hard starting are the pilot jets are dirty. The holes in these jets are very small and plug up easily. Another is vacuum leaks. What is the condition of the rubber boots between the carbs and head? I have found that installing Iridium spark plugs really helps with starting/running. They are kind of pricey but well worth the money. As for the bike not running well after getting wet, the electrics are 40+ years old, and I am sure that the insulation and connections on some of the wires, and parts have deteriorated and become susceptible to water.
TOOLS

[Sixtenao]

Thanks so much for the answer.

Frist of all i checked for spark. That was working finely. I Will try to look at the toget things friday (Danish time). I Will give an update!

[Sixtenao]

Just to update - turned out to be the two middle spark plugs that were faulty. I replaced all the plugs with iridium plugs and applied a technique that i had learned in here. Open petcock - wait 20 seconds - kick it to times with electrics off - turn on electrics and hit start. Fires it right up! Thanks for the tips with the iridium sparks, Tools. They sure made a whole difference!