More Carb Problems & questions

[wxp]

I rebuilt my carbs this past winter, got them on, sync'd them, got the cables adjusted but still having problems, took them off, cleaned them again put them back on re-sync'd them still having problems. Going to try the shorting out method soon but till then this is what I am experiencing.

Rough idle, seems to be mostly on the left side.  Runs great once up & running @ speed but when shifting gears the rpms remain high, they don't seems to come down properly.  The left side choke is very stiff & will not release unless I use my finger to push it back down.  I have the idle mixture screw on the bottom of the carb approx 1/2 turn out up to 1 full turn & can't seem to get the rpms to come down at speed when changing gears.  All the tubes to carb & from carb to cylinder head are tight so I don't believe there is any vacuum leak.

All Ideas welcome

[Flash]

I would sort that choke problem out first. Something is not right there, especially since you've rebuilt them. Also, make sure your slides are installed correctly and moving up and down freely.

[Yikes]

You might also check that your cables are moving freely and the throttle and choke are returning to the full stop when the throttle is released and the choke is turned to the off position.  Also check that the cam & chain at the twist grip are well-lubed and moving freely.  

[Bengt_Phorqs]

WXP, the enricheners (chokes) are handed, left and right.  Often it's easy to put them back in backwards or otherwise incorrectly.  The cables should not be difficult to move.  I would start by double checking that area.  Did you replace the small gasket in the enrichener?  (Or perhaps there was not one there?)  That gasket is often broken or worn and should be replaced every time you rebuild the carbs if it is damaged at all.  Download a schematic of the Bing carbs and you will see it.

As for the idle air mixture screw, it should be set around 3/4 turn out to start with.  One would think that it the screw to turn when adjusting idle speed but it doesn't work that way.  Use the idle adjustment screw next to the cable.  Until Monte explained it to me I was trying to adjust the idle with the idle air screw.  These pages are replete with information about carb adjustments so be sure to do some searching over the past 12 months.  

[montmil]

WXP, the enricheners (chokes) are handed, left and right.  Often it's easy to put them back in backwards or otherwise incorrectly.

Shoot! The Bengt one beat me to it. I'm also guessing enrichener problems. The brass shafts that operate the enrichener are stamped in the inner ends, L and R, for left and right carburetors. Be sure to use a new gasket.

Pics are not of my carbs but show correct positioning.

Monte

[wxp]

First, thanks for all the input. I did use a Bing schematic & was very careful to make sure the enrichers, i.e. choke, were in correctly & I did use new gaskets.  The new o-ring is what I believe to be "binding" on the left enricher causing it to be stiff.  Everything else that was suggested I checked.  

I also have searched for other info here but have not found a lot, probably not using the correct term in the search bar..  I'll triple check everthing once more & lube the enricher o-ring on the left carb w/some white lithium grease?? & keep playing w/it.

Thanks for the picture, I did note the L & R & if I'm correct there is only one position it will go back together in, otherwise the choke cable will not go into its proper place..

My luck probably some dirt.

[Barry]

WXP, a search for "revs hang up"  should find something. Be sure to change the default date range to "all posts"

[wxp]

I'd like to follow up w/ what I found for others to thinks about.  After thinking about it for a while I decided to look at the throttle cables & the the throttle mechanism at the the throttle.

After lubing the gears & blowing through the cables as best I could & putting it all back together My rev hang ups were not as bad.

So, if you are experiencing rev hang ups btwn gear changes do not forget to look at, clean, etc the throttle cables & gears in the throttle twist thingy.  Gum build up is what i think contributed to the cables not moving freely enough inside the cable sheath, thereby causing everything to kinda "hang up" when changing gears.

In essence, the rev hang ups are not in the carbs so much as it is in the throttle cables not releasing the "throttling" quickly enough due to gum build up inside the cables.

I hope this makes since to everyone & thanks for all the input

[Bob_Roller]

I've been told, to never clean the throttle cables on a BMW bike , but I have been doing it for more than 25 years .

When I clean them, I remove them from the bike and disassemble the splitter .

I take a plastic bag, cut the corner out of it, place the end of the cable with the small swaged metal end into the bag, place a ty-wrap on the metal end of the cable sheath, to try and get a fluid proof seal with the plastic bag .

Then tape the bag to a work bench or what ever you have around .

Place a small amount of alcohol into the bag, move the cable in and out to get the alcohol moving down the cable, then into a drip pan below it .

Repeat as many times as it takes to get a clear fluid coming out of the bottom end .

After cleaning, I would place a light oil into the bag, and then move the cable in and out until the oil comes out of the bottom end .

I do the same procedure on the 'choke' cables, clutch cable and the speedometer drive cable .

The clutch and speedometer drive cables are left installed on the bike, the cleaning and lubing process can be performed with them still installed on the bike .

If you have a 'nervous' speedometer needle, the drive cable is dry .

[wxp]

Yeah, I read several places too that said not to lube the Throttle cables, Cleaning isn't quite lubing, bound to be some dirt build up in there.

P.s. I'm thinking of selling my 1150gs & finding another airhead.. Although the GS is a nice bike, fast, handles well, etc etc, so does my little r65. Would need a large enough bike for 2 up & all the gear for taking trips, any ideas/thoughts on this??

[montmil]

...I'm thinking of selling my 1150gs & finding another airhead. Although the GS is a nice bike, fast, handles well, etc etc, so does my little r65. Would need a large enough bike for 2 up & all the gear for taking trips, any ideas/thoughts on this??

Here's what I'm casually scouting.

http://www.totalmotorcycle.com/buyersguide/BMW-R80RT.htm

Monte