Carb issue / only idling/starting with choke
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So I’m wondering if those more knowledgeable with carbs can share there wisdom with me as I went out for a blast to copdock bike show a few days back and got home to find my bikes now only with choke.
I plan to clean anyway to carb but just wondered what you think?-first 1/8th turn of the throttle between 0-2/3k there’s nothing and you need to rev further to stop the engine from bogging
-anything after 1/8th turn with or without choke still revs through the circuit happily
-runs fine with choke hot or cold
-engine doesn’t die when you take choke off
-engine only dies when you let RPM’s get below roughly 2/3k rpm.
-choke holds RPM at roughly 4/4.5k, adjusting idle can bring down a little
-will pull in 4th and 5th from low rpm without any struggles -when engine braking rather then it being slow smooth silent it now has this weird chugging effect1 last thing, I’d been forced to put two tanks of e10 through my bike before this started happening
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Please, clean your carb out!
It’s not gonna be the fuel that caused it. You probably ran it on reserve? Drawn some crap into the pilot jet...
It’s worth taking out the main jet and removing and cleaning the needle jet. Just tap out the tube once the main jet has been removed. It can get a bad build up and the small holes get blocked. I don’t think some people even realise it comes out...
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Worst case scenario a crank seal has gone but I'd go for the carb first and make sure its super clean
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@spookdog said in Carb issue / only idling/starting with choke:
Please, clean your carb out!
It’s not gonna be the fuel that caused it. You probably ran it on reserve? Drawn some crap into the pilot jet...
It’s worth taking out the main jet and removing and cleaning the needle jet. Just tap out the tube once the main jet has been removed. It can get a bad build up and the small holes get blocked. I don’t think some people even realise it comes out...
I will, I will! To be honest I never knew about that, wouldn’t have thought to look unless it mentions it in the Haynes menu. I’ll definitely pull it out and check it sometime this week when I get a chance. I need to get a couple of those little fuel filters that sit inside the carb. Took mine out to clean and lost it a while back, one of those plus the in-line fuel filter should save me the carb cleans.
Fingers crossed not a bad seal!
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@stevie-wonder
Same as, when I tapped mine out the first time it was literally half full of ultra fine sand, just caked on! Also half of the holes up the sides were blocked...Don’t think it’s the seal. It’s happening exactly where the idle jet has affect...
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Update:
My bike now just idles really high and won’t go down no matter what.
I’ve sprayed WD40 all around the air boot and intake tract to see if there’s any leaks and couldn’t find anything.I’ve also left the bike to warm up to operating temperature and tried making adjustments and had no luck.
It just idles high and stays at the high idle no matter what.
(You can even put it in first and ride it without throttle and the revs don’t dip)I'm 100% sure neither jets are blocked
idle screw is unresponsive.
Choke doesn’t make a difference however when being ridden flicking it on does make a brief stutter happen before carrying back to normal so I’m guessing the choke is still providing extra fuel.
Any help with this is greatly appreciated as I can’t lie I’m not sure what else to do besides a) Chuck a new plug in her, let her run and get warm and see if the plug colour shows it’s running hotter/leaner then usual or b) finding someone with a decent tester and doing a full leak down test / running the bike and spraying the seals to see if my crank seals gone
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@stevie-wonder Make sure that you aren't tugging the throttle cable anywhere. Also check that the float height is correct.
Always Originate, Never Pirate!
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How does float height effect things and how can it change without manual adjustment?
Throttle cable won’t be the issue, I’ve checked it’s not snagged and I’d had that issue before when I’d put the USD’s on, the extra height of the USD combined with the way the cable was routed meant that turning the bars left would increase the revs a bit.
Thanks again Cal, I hope you’re doing well mate
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@stevie-wonder you recently had carb apart? Sounds like the throttle slide is the wrong way round. Turn it around you will see the angled part that the idle screw should hit.
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@markus-w said in Carb issue / only idling/starting with choke:
@stevie-wonder you recently had carb apart? Sounds like the throttle slide is the wrong way round. Turn it around you will see the angled part that the idle screw should hit.
Isn’t there a slot / groove on the the idle screw side the throttle slide uses when pushing the carb slide back in to the carb body?
I remember when I was putting everything back together trying to put the throttle slide back in and the first few attempts didn’t work at all until tried a different approach / angle so I’m just wondering how easy it would be to have made that mistake.Also if it was just the throttle slide that was the wrong way around that'd mean everything else in the carb would be running okay, no? If everything’s running okay with the carb then logically if you Chuck the choke on when it’s warm it should kill revs / make the bike bog?
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Wd40 isn’t the best for finding leaks, spray it with carb or brake cleaner.
Check your stator side oil seal. Can be sucking air in there...
Ps. Barrel base gasket..
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@spookdog gaskets are all fine and bikes holding compression and wants to run. Managed to take her out for a local ride yesterday with a fresh plug in to see what the plug looks like. If memory serves me right I haven’t got all the tools I need to get the flywheel and stator off so I was hoping
It’s weird though because I’d have thought that if I had an air leak the bike would run extremely lean and get hot? Because not once did the bike ever get warm
Whilst riding the symptoms where the same as before
-really high idle (it sometimes died down a bit during the ride) I haven’t got a Rev gauge so I’m just guessing but majority of the time idle sat around 5k.
-only start on choke, it’d enter powerband (hits hard enough to still lift the front end too) but will start to splutter and struggle to fully Rev out (typical signs of not enough fuel).
-put the bike in gear and it’ll move without touching the throttleNone the less she still ran good enough for her to drink a tank of fuel and get home safe without a breakdown.
I have to admit @SpookDog I have a very strong sense that it is that crank seal that’s gone, all the evidence is there + It’d be due something like crank seal since I’ve owned her a few years now since coming over from France and not once have I had to touch the engine.
Like I explained to my dad when he was making guesses at what’s wrong with it, “you can’t have a fire without air, so that bike won’t be to Rev any higher without air to allow it to do so since like a fire if you smother it with fuel to fast it won’t burn”. I could be wrong but that’s my logic.
Ps hope you’re doing well bud, how’s everything with life and the bikes and scoots?
