can't adjust idle

[jchaffee5]

I own a 78 400
I just cleaned the carbs and reinstalled them and when I started the bike idle is a 5,000 rpms and slowly climbs I turn the idle nob in both directions with no effect. One time when the bike was warmed up and rpms were climbing to 7,000 I put the choke on instead of stalling the bike it dropped the rpms to 3,000 ran rough but would not stall. Question is what adjustments do I need to make on carbs toget bike to Idle down manual only tells of idle knob.I know the carbs are out of sync but from what I have read I should still be able to adjust the idle to 1,500 rpm but the bike will just run rough any help would be apperiated .
Thanks
Chaff

 

[rideOn]

make sure the throttle control moves with the carb end and is not hung up.

 

[terrylee]

Did you bench sync. them before putting them back on? Also it could be your air mixture screws, try seating them down lightly and turning them back out to maybe 1 and half or two turns and see what that does. If it helps just try to adjust them till you get the best idle,then try the idle screw adjustment.Might check your float levels too. terrylee

 

[Larry D]

How were the carbs cleaned ? Do you have any air leaks ?

 

[jchaffee5]

how do I check float levels

 

[jchaffee5]

I don't think I have any air leaks I cleaned by hand and soaked eveything in carb cleaner had a bear of a time getting the floats free the bike had been sitting nine years

 

[jchaffee5]

I don't know how to bench sync I have played with the air screws currently have them turned out 1 and half turns

 

[jchaffee5]

I have been worried about that I have yet to get the throttle to snap back like it should since I got the bike when I first took the throttle apart the return cable had so much slack in it that it bunched up in the caseing. So I disconnected the lines on both ends and they move freely. Once when I had the bike running I disconnected the lines on throttle end. and controlled the bike manually when I pulled the return cable all the way the bike still would not idle down. I think I have a couple problems going on and throttles one of them. More insite to throttle would be helpful

 

[Larry D]

Sorry....I have more questions. We here need ALOT of info so everyone can help you figure this out.

When was the last time the bike ran properly ? Is the bike stock ? Is the air filter clean ? What else have you done as far as maintenance goes ? What's the history of the bike ?

Sounds to me like you're getting way to much air. Which is probably either air leaks at or around the airbox and/or the o-rings behind the inlet boots on the head.

 

[79FiveFifty]

kinda get the impression that your throttle cables are a bit off or the stop screw for the throttle to close.. do you have it set in so far that the carbs arent closing?

Edit* Just noticed you replied and said the push cable wasn't operating properly.. this may help if its a cable issue..

1.) Make sure you've got lots of slack in both the pull and push cable
2.) Set your desired idle RPM with the idle adjust knob
3.) Adjust the pull cable (with minimal slack) so you've got no opening of the throttle when extending the handlebars to the left or right all the way.
4.) Adjust the push cable so it doesn't bind up or tighten when you extend the bars fully right or left.
5.) Twist throttle check for full opening / closing of the carbs and proper snap-back. Grease / replace cables if they are binding on their own.

Since you said with no cables connected, bike will not idle down.. did you replace the o-rings on the little intake manifolds that screw onto the head? Those being flat/cracked might cause that kinda high idle.

 

[jchaffee5]

I know everything about this bike it was my moms the bike has all original parts it only has 23,000 miles on it my parents did regular mantains on the bike the last time my mom licened it was in 95 just before she sold it about 5 years ago she did a tune up on it. she ran it out of gas and let it sit over the winter then sold it to a guy that couldn't get it running sat in his shed untill i got it. it was something else getting the rust out of the take. the air cleaner looks good

 

[jchaffee5]

I don't think so because at one point disconneced the cables on the throttle end and ran the bike manually. But I do have a prob with the cable not sure how to resolve

 

[rideOn]

I don't know how to bench sync I have played with the air screws currently have them turned out 1 and half turns

try this link: http://members.dslextreme.com/users/bikecliff/images/carb_sync_notes.html
when i did a bench sync last month, i used an ornament hanger instead of the drillbit. someone suggested a light behind the carb and adjust all the plates to equal amounts of light under each.

 

[jchaffee5]

I am not the most machaniclly inclinded I just like a good challange so I am sorry if I sound stupid. Just to make clear are the o rings are they the part of that comes off the front of the carbs and goes into the heads and how can I check that for a leak?

 

[rideOn]

how do I check float levels

to set height try this: http://members.dslextreme.com/users/bikecliff/images/carbspec_float_height.html
i might also suggest making sure both sides of each flost are even. you can find the gauge cheap at many places. i got mine at harbor freight for a $10 internet price match. if you don't have one. improvise with a metric ruler and some kind of rigid material that you can cut an "L" to closely match the dimension.

 

[rideOn]

I am not the most machaniclly inclinded I just like a good challange so I am sorry if I sound stupid. Just to make clear are the o rings are they the part of that comes off the front of the carbs and goes into the heads and how can I check that for a leak?

take the boots off. it won't hurt to replace them-they're very affordable from cycleorings.com. this can be a tough job. i had to use a hand impact driver-$10 a auto zone.

check bikecliff's site: http://members.dslextreme.com/users/bikecliff/
look for these topics, they're easy reads and soon you'll be an expert

 

[jchaffee5]

thanks I just check out the link and it sound easy enough can't wait to try it I am getting to be a master at pulling out these carbs this will only be the forth time in two months

 

[jchaffee5]

thanks for the advise from what it sounds like is the bike is not Idleing down because the carbs are out of sync I thought didn't matter I thought the syncing made the bike run smoother

 

[jchaffee5]

your the second person to mention the o rings as far as I know they are the originals from 78

 

[Steve]

thanks for the advise from what it sounds like is the bike is not Idleing down because the carbs are out of sync I thought didn't matter I thought the syncing made the bike run smoother

Smoother, yes, but if one carb is closed and the other one is 1/4 open, it's going to run fast. You need to pull the carbs and visually check the throttle openings to see that they are about the same opening.

Here are two of a four-carb set, you can see the sliver of light at the bottom of the throttle butterfly, they are both about the same:

Adjust the screw between the carbs to get them close like this, then make sure you have the cable properly adjusted to make sure the carbs can close.

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