Xr600r dual carb update?

[Backwoods-Bomber]

Also, did you follow the idle mixture instructions in post #14 above? They are incorrect and will result in a slightly lean mixture. Also, these carbs have an air screw, not a fuel screw so the pilot jet portion of those instructions is backwards. Greater than 3 turns means the pilot is too large, not too small.

[Big specht]

No pop on decel it will start fine on first or second kick. It just has a intermittent hanging idle it still has the stock jetting  

[Oupoot]

Hi Big specht

 

One thing you could try i had an issue like this hanging idle, my problem was when i get off the throttle the idle would be high for a second or two then it would return to normal

i have a 83 XL600R i removed the ACV spring from the carb basically disabling the ACV circuit making the idle circuit richer and my bike was working great. the bike may backfire on high vacuum that is to be expected with the ACV disable 

 

if you what to go thru the effort it could help

 

i have not yet put that spring back still riding the bike like this hehehe

 

Regards

Oupoot

 

 

 

[Backwoods-Bomber]

No pop on decel it will start fine on first or second kick. It just has a intermittent hanging idle it still has the stock jetting  

Has it always been like that or is this a new issue that just started?

Typically hanging idle is a result of some change, like the addition of a free flowing exhaust, an aftermarket air filter, or a partially blocked pilot jet. If This is a new problem and none of these items seem likely, I would start looking for an air leak.

[Big specht]

I just bought this bike it was not running when I bought it so I have no history on it. But it does have aftermarket air filter and exhaust. It seems like the slide is sticking cause all I have to do is burp the throttle and normally comes back down and idles good. 

[bork]

springs and cables ok?

 

[Backwoods-Bomber]

I just bought this bike it was not running when I bought it so I have no history on it. But it does have aftermarket air filter and exhaust. It seems like the slide is sticking cause all I have to do is burp the throttle and normally comes back down and idles good. 

If it is a mechanical issue, it should be fairly obvious. When the idle is high, just look to see if the throttle on the carb is up against the idle speed screw.

I would venture to guess that it has been like this since the exhaust was installed and made it run leaner. A blip of the throttle returning it to low idle is totally consistent with a lean hanging idle. Start by turning the air screw way in and see if there is a noticeable difference, if the screw has no effect just go up one size on the pilot jet.

[Big specht]

Ok I will try that. And the springs and cable are fine. Everybody keeps telling me to go to a single carb but I want to keep the duals cause when they are setup correctly they have to perform better than a single. Cause i don't see anybody taking a 4 barrel off and replacing it with a 2 barrel to gain performance!

[zrxer]

Yeah, the dual carbs work great, if they're clean and in mechanically good shape. But that's true for anything, really. ?

I had a hanging idle issue on an XR650R and it turned out not to be any tuning issue but a mechanical one. The linkage inside the slide that ties the slide and throttle shaft together was worn out and the slide wouldn't return to the fully closed position every time because of the vacuum of the big engine. Replaced the linkage and all was good. Not saying this is your problem but it's something to have a look at.

[Big specht]

Ok I still haven't got the carb issue figured out. I've replaced enough parts and double checked all the settings to figure out the carbs are just worn out and need replaced. So what would be a good dual carb setup to run. I'm getting tired of screwing with these junk carbs 

[Oupoot]

3 hours ago, Big specht said:

Ok I still haven't got the carb issue figured out. I've replaced enough parts and double checked all the settings to figure out the carbs are just worn out and need replaced. So what would be a good dual carb setup to run. I'm getting tired of screwing with these junk carbs 

just one more inexpensive thing, have you checked for vacuum leaks the O-rings at the carb boot gets hard and tend to crack at places. there is one guy that have successfully build pumper carbs in his XL

it is an insane amount of work to get this done i am also trying to get a Raptor carbs in my XL but that in on ICE for now. got the Orignal carbs working good

 

 

Edited November 11, 2017 by Oupoot
add link

[Backwoods-Bomber]

85-87 carbs will be direct replacement. Carb model numbers vary as do factory jets but any of those 3 years will work fine. Xl carbs can be made to work but there is a bit of fiddling with choke mechanism and what not.

I would steer clear of 83-84 Xl carbs because they have a larger venturi that can make jetting a hassle. Also avoid California carbs, tons of extra hoses and smog crap on em.

[Big specht]

Ok I will check on some of those carbs. But I would rather put some newer carbs on it. As for the O ring issue I've already replaced them along time ago when I started trying to fix this issue

[Steve George]

Try this. with engine, idling spray carb cleaner in areas around carburetor sealing points, around the intake boot at the engine, and at the air box boot. if you have an air leak, it will change the idle speed.

[Big specht]

1 hour ago, Steve George said:

Try this. with engine, idling spray carb cleaner in areas around carburetor sealing points, around the intake boot at the engine, and at the air box boot. if you have an air leak, it will change the idle speed.

Been there done that it's almost got to be a internal leak somewhere in that carbs 

[dirtjumpordie]

Are you running a backfire screen?  Have you checked valve lash?  

Don't adjust your carb until you can verify that your valves don't need adjustment.  its very easy to check that on these bikes.  

[Big specht]

Been there done that. It's a hanging idle issue that I'm trying to get rid of

[dirtjumpordie]

There is a good web page on this: http://www.deathridge.com.au/how-to-fix-those-xr600r-carb-issues.html

After reading through it, did you replace the pilot screw O-ring?  What are your float levels?

Maybe try disabling the ACV as a previous post mentioned.  That will eliminate that circuit as a variable, which will help you narrow down where the problem is laying.