cylinder 1 and 4 exhaust cold to touch.

[Killianf1]

which means they are not firing. And rpm will not register correctly.

I tried to start it today, and it wouldn't. I charged the battery, and it still wouldn't. After turning the throttle a bit, she fired up. With the throttle about 1/4 turned, I can keep it running, which is how I discovered the outer pipes are cold. As soon as I open the throttle or try to let it go to idle, it dies.

I checked for spark, which they have, but don't know exactly what to do next as I am a mechanical and motorcycle noob.

I did clean the carbs and they are getting fuel flow, so I don't think the problem is there. Any help would be appreciated. I tried looking in the sohc4 forum, but had little luck (those guys are beyond my skill for the most part).

In particular, I'm looking for the idiots guide to finding out why my 1 and 4 cyl. aren't firing.

Thanks

 

[pablohoney]

I am not too good at engines yet, but I might try unplugging the spark plug cables on cylinders 2 and 3, then pouring a little gas directly into cylinders 1 and 4 through the plug port then quickly putting the plugs back on and try to start up , if it fires up for a moment then dies then you know. If it does, then you know that the problem lies with the intake. If it doesn't start, you could check the compression. Hope this helps.

 

[CBGhia]

You have spark, but is it coming at the right time? You should check your points and timing for the 1-4 cylinders (they share points and coil).

Well... I am assuming this is a CB something or other, if not then ignore what I just wrote.

 

[Killianf1]

yes, it is a cb550, 78. Does anyone know a good resource for how to go about checking the points and timing, because I really don't have a clue. It makes sense that timing could be way off, since 1 and 4 both run together on the same circuit. All I have is the internet, a clymer manual, and a desire to have a working bike without resorting to dropping it off at the dealer ($$$$.$$) Also, I moved up here about 2 years ago and haven't really met any other riders besides the harley "changed the oil at the dealership" crowd, so I'm kinda on my own for this.

 

[CBGhia]

start here:

http://forums.sohc4.net/index.php?topic=5752.0


Any questions you have about a CB550 can be answered there.

 

[rockcitycafe]

well, it sounds like you have battery that isn't in the best shape... if that's the case, replace it asap, any old bike i've worked on has had mad problems if the battery is below voltage or just not up to sourcing proper current. second, pick up a timing light, they're cheap at harbor freight or ebay or whatever, and you don't need the best one in the world and it will give you a world of insight into what's going on. since the 1 and 4 are not firing, it almost certainly sounds like a spark problem, could be that the point 1-4 is so far delayed that it's not firing. i would go through checking the dwell, condition of the points surface, and point timing...

 

[Killianf1]

you've all given me a great starting point. My battery is junky...I don't know how old it is but I have to recharge it if it sits too long, so I'll try that first. Unfortunately I'm going to lose two more weeks of valuable michigan summer riding time as I will be out of town...hopefully I can get it going before the snows start flying. Thanks again!