Motorcycle Forum banner

1 - 10 of 10 Posts

·
Registered
Joined
·
11 Posts
Discussion Starter · #1 ·
hi, i've searched the internet alot about starting issues for the nighthawk and many of them have the same problem as i do now but no one posted any solutions, just people prodding the internet for answers and not getting anywhere?

i bought the bike for next to nothing. It had been sitting for years. i had the carburetors rebuilt. New spark plugs gapped, and verified that they are sparking. I cleaned out the air filter chamber and installed a new air filter with oil. Gas is getting into the carburetor resevoirs. I have 170 compression in each cylinder. I got the bike started a couple times (didn't ride it just testing components). Then a couple days ago the engine will just crank but won't star. I don't understand what's happening. If i'm getting spark at the plug can it still be an electrical issue? I have gas, air and spark. Isn't that everything?
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #2 ·
also i should mention all gas is new. The tank doesn't look rusty inside but there is some rust at the bottom of the petcock reservoir that i have cleaned out..
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #3 ·
also i just poured a cap full of gas into one of one of the chambers and it started up for a second. Could the gas get rusty in a few days?
 

·
Gone.
Joined
·
17,857 Posts
It can only take but a small piece of crud less then 1/000" in diameter to clog up a carburetor passage, and the in-tank screens and filters won't keep everything from going through to your carburetors. If you put some gas directly into a cylinder, it started and ran for a second, then died, then that tells me you likely have a clogged passage in a carburetor.
 

·
Save them all!
Joined
·
4,278 Posts
Yup, completely agree. Somewhere the gas isn't making it to the cylinder, at least in the proper ratio to allow the bike to start. Are the intake boots in good shape and nice and tight?
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #6 ·
i think all the rubber boots are seated and in good shape. Is there an easy way to check the carb jets to verify if they are clear or do the carbs have to come off. Man that was a pain putting them back on the bike. i think i might flush the gas tank either way just to make sure the rust isn't getting in there?
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #7 ·
also if it wanted to start with gas in one cylinder then does that mean all 4 carburetor jets are clogged? If even one jet wasn't clogged then it would have the same effect no? Does that mean its a gas issue feeding the carbs? There is gas in the reservoirs of the carbs....
 

·
Registered
Joined
·
1,003 Posts
What about the timing? That could be off. You can have all the components, but if they don't synch up together, well, you end up with no start.
 

·
Registered
Joined
·
11 Posts
Discussion Starter · #9 ·
the housing around the clutch cable was secured too close to the clutch bar on the carburetor so when i would pull the cable it would only lift a quarter inch. Since it wasn't on there before and i've never seen one work i didn't know what to look for. it runs great now. Thanks for the help everyone. Now i have clutch problems but i'm going to start a new thread so its more simple for people to find. Thanks again.
 

·
Registered
Joined
·
5 Posts
EASY way to diagnose your problem brother. This will diagnose a number of different systems on your bike. If you don't have a can of STARTING FLUID buy one. Best investment you can do. Get access to the air box cover (under the seat.) While you are turning over the engine with the starter button (killswitch on, In neutral..etc) Spray one or two pumps of starting fluid directly into your air box. The motor will do one of three things. Pick up and start running, make a loud pop, or do absolutely nothing. Since you have spark and have compression I can almost guarantee it will try to idle. If it does keep gagging the throttle to see if you can get the rpms up, you may need to give it a small spray to do this. Let me know what happens. With the result of this test I will be able to tell you exactly whats going on. Easy test. Don't overthink these directions or this issue. This check will do more than you know! Get back to me when you do!
 
1 - 10 of 10 Posts
Top