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Discussion Starter · #1 ·
I'm working on an 85 Nighthawk 450. It sat for a few years and wouldn't rev past 5 grand so I put fresh gas in it and totally disassembled and cleaned the carbs. Now it runs great everywhere past 1/4 throttle but when riding and trying to hold your speed at low rpm's with a small throttle opening it surges. I would think this would indicate that it's lean but playing with the mixture screws doesn't help (from any info I could find, everything 1/4 throttle and below is on the idle circuit). The bike even idles ok with just an occaisional misfire at idle. Also when decelerating from higher rpms it pops like crazy. The only thing I can think of is pulling the carbs off and cleaning them again, maybe I missed something. Anyone ever had this problem?

-Ryan
 

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Sounds like either the jets are too small or the float bowls are set waaaaaaaaaaaaaaayyyyyyyyyy off.;)
 

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BEER!
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I wish that my problem with the Maxim was that minor. It ran great last year (after you let it warm up for five minutes). Now it can't idle for shit, pops like hell when coming down from higher RPMs, and takes forever to warm up (20 minutes or so). We tried screwing with the idle screw (what a pain). I let it sit for 2 or 3 months with 1/4 tank of gas in it and no Sta-bil. :nono I think that really screwed it up.

I don't have the time or knowledge to rip the carbs apart and clean them. I'm going to change the spark plugs (one I checked was okay) and put some carb cleaner in the gas, then run this shit out of it tonight and see if that will work. If not I've got a place to take it to. I'll ask him to check the float bowls and jets.

I've got a sale lined up for it if I can get this taken care of. Then grover gets A/C for his house. :thumbsup

Chris
 

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Discussion Starter · #4 ·
Crazy said:
Sounds like either the jets are too small or the float bowls are set waaaaaaaaaaaaaaayyyyyyyyyy off.;)
The bike's totally stock so I'm thinking the jets are probably clogged, I guess I just gotta break down and pull the carbs apart again.

-Ryan
 

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from exp check spark plugs and wires :) also check the air filter, fuel hoses for kinks. this helped me you know all the stuff I wnet through :laughing
 

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Lovin this Twin
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Ahh older bikes, aint they fun?

Easy things to check.

Filter on the petcock.....
timing may be off, could be why its only good on one end
I believe older nighthawks have a fuel pick up sensor. they go bad often.
check the intake boots for dry rot and cracks, if there leakin it wont run right.
Im guessin you already checked the plugs?

Have fun
 

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Discussion Starter · #7 ·
Re: Ahh older bikes, aint they fun?

HooliganZX10 said:
Easy things to check.

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check the intake boots for dry rot and cracks, if there leakin it wont run right.
Im guessin you already checked the plugs?

Have fun
Beat ya to it. The intake boots were leaking, fixed that and it runs pretty good. Dropped the bike off at the guy's house last night (it was a sidejob). But thanks anyways :twofinger .

-Ryan
 

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Glad ya got it fixed Ryan, The older bikes are way easier to trouble shoot then the newer ones ugh!
 
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