Sputters on acceleration

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Fezztone

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Jul 2, 2019
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Just finished full Kreem removal and tank derusting. Bike starts fine and idles great. Once I accelerate it starts hesitating. Cleaned the pilot jet with wire 2 times and drained the bowl in case there was lingering rust particles. Dirty main jet now or still a pilot jet issue? Twin Amal carbs. Pull carbs and clean?
 
Check stuff...

develop a technique to check each system, then go through the bike one system at a time.

Intake air leak - start the bike and spray around the intake manifold with carb cleaner (did it effect the engine?)

Spark plugs- change them to new (They're cheap)

Timing - get out the strobe

Add a dedicated ground from the engine to the frame or battery (isolastics can insulate the engine somewhat)

Float sticking- pump the bleeder when the engine starts to break up. (did it help?)

Try all the simple tests that you can do without disassembly first. Then you might be moving on to pulling the carb bowls, then jets, then checking the carb body's needle clip's position and placement. You'll find the problem, just be patient and focus on each aspect and keep moving through each one methodically testing as you go.
 
Did the bike do this before the work on the tank? It could be as simple as a plugged up vent.
 
o0norton0o said:
Check stuff...

develop a technique to check each system, then go through the bike one system at a time.

Intake air leak - start the bike and spray around the intake manifold with carb cleaner (did it effect the engine?)

Spark plugs- change them to new (They're cheap)

Timing - get out the strobe

Add a dedicated ground from the engine to the frame or battery (isolastics can insulate the engine somewhat)

Float sticking- pump the bleeder when the engine starts to break up. (did it help?)

Try all the simple tests that you can do without disassembly first. Then you might be moving on to pulling the carb bowls, then jets, then checking the carb body's needle clip's position and placement. You'll find the problem, just be patient and focus on each aspect and keep moving through each one methodically testing as you go.
Click to expand...
Great advice! Thanks!
 
rvich said:
Did the bike do this before the work on the tank? It could be as simple as a plugged up vent.
Click to expand...
It did not. Ran fine actually. But started to sputter and the filters were catching a lot of rust. I assumed rust got into the jets. The bike is new to me so I’m learning as I go. My last Norton was sold 15 years ago and I’m relearning as I go.
 
Probly not a bad call to just clean the carbs. It could be as simple as junk plugging up the needle valve. Have you checked to see if there is a fine screen inside the banjo fitting on the bowl? It might be plugged as well.

PS - I'd still check the venting on the tank.
 
rvich said:
Probly not a bad call to just clean the carbs. It could be as simple as junk plugging up the needle valve. Have you checked to see if there is a fine screen inside the banjo fitting on the bowl? It might be plugged as well.

PS - I'd still check the venting on the tank.
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Screens are there. I’ll dbl check venting as well
 
The real fine grit from the rust still does make it's way past the filters. Not a lot, but just enough to get in there and cause trouble. Your floats will get sticky & needles fail to seal well, and by the time you get it all apart there's nothing except a dark sooty debris in the bottom of the bowl. Filters clog like clockwork too for a while until it all comes out.
I've not used your stuff, but I did use electrolysis & the usual suspects. Without lining it I'll still be cleaning & changing filters monthly until I sprout feathers out my ass and take to winged flight migrating annually with the geese.
 
o0norton0o said:
Check stuff...

Spark plugs- change them to new (They're cheap)
Click to expand...

IMHO this is alway job # 1 whenever poor running is the issue. Spark plugs do degrade gradually, they can also degrade suddenly. Some last for years and lull us into a false sense of ‘it can’t be that’ when replacements haven’t been in that long. And some new ones can be duff out of the box.
 
Had that a couple of times. AC & Champion in particular. Only once with NGK. Eddie is right on the step by step elimination process....That way you don't keep backtracking.

I know o0norton0o started the list, and it makes sense.
 
What FastEd said! If it's misfiring while accelerating, it's more likely a breakdown in the secondary ignition - plugs/wires. That's the first of the 'usual suspects' for such behavior!
 
Fezztone said:
Just finished full Kreem removal and tank derusting. Bike starts fine and idles great. Once I accelerate it starts hesitating. Cleaned the pilot jet with wire 2 times and drained the bowl in case there was lingering rust particles. Dirty main jet now or still a pilot jet issue? Twin Amal carbs. Pull carbs and clean?
Click to expand...

The main jets can be removed through the float bowl drains, for inspection and cleaning.
 
Triton Thrasher said:
The main jets can be removed through the float bowl drains, for inspection and cleaning.
Click to expand...

Yes, they can...IF you didn't over-tighten them when you installed them into the carrier...;)

I seem to do that no matter how hard I try not to...don't know how many times I've had to drop the float bowl to retrieve the carrier with the jet attached. :(
 
MexicoMike said:
Yes, they can...IF you didn't over-tighten them when you installed them into the carrier...;)

I seem to do that no matter how hard I try not to...don't know how many times I've had to drop the float bowl to retrieve the carrier with the jet attached. :(
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It’s the holder that’s not tight enough!
 
Yeah, I know! But it seems that even though I just 'snug' up the jet, a year later unscrewing the jet brings the holder with it. I'm probably overly concerned about stripping the holder/carb body and just need to put some more torque on the holder! ;)
 
Followed all the advice- all the prelim checks didn't reveal anything- New plugs then did a carb sync- learned a lot. That didn'd fix it. Pulled the carbs and MexicoMike and Triton wins with diagnosis- The jet holder was virtually unscrewed. Runs good- some popping at idol and deceleration. Now what I think will be the worst part of the job- putting the stock air filter and boots back on. Thanks all for the help!!
 
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