Topic: CB550F taking to 5000' for summer

[cb550fnewb]

I just got a 1976 cb550 for free from in-law (he owned for over 30yrs) in Ohio.  Its runs good had it out a couple of times. I plan to do a tune up before leaving.  I will be going to Utah for the summer and live at 5000 and will be at between 7 to 8k almost every time I take it out.  Am I going to have any issues with the air to fuel ratio.  What adjust can I make to lean it a bit?  I know i can lean idle but my understanding is that once throttle its eliminated and will be back to rich.   


Believe it has stock jets (would prefer not to change)
Only modification is 4 into 2 exhaust.
has 36000 miles

[iron_worker]

To lean out the mid range you have to adjust the needle clip position (some carbs don't have an adjustable needle so not sure if that applies to your bike). To lean out the upper end and WOT you need to change the main jet size to one with a smaller number. It likely won't need to be changed much if at all.

IW

[camelman]

I rode my 350f over 7000 feet from sea level and didn't have any issues. It started running a tad rich around 5000 feet so i pulled off the top lid on the airbox. That took care of it for me. I was inly at altitude for a weekend though. I'd probably do something more permanent for extended riding at elevation...if the airbox lid trick didn't work out.

[CoachDoc]

I've taken my 550 to elevations as high as 10,000 feet both when it was new and as recently as last Summer (10 days in the high Sierras) with no problems. Very little loss of power noted. I'd follow the KISS principal and don't change a thing. No need.

[cb550fnewb]

looks like ill try the removing the lid on the air box when I get there if I have any issue. I would like to avoid messing with jets as much as possible. Carb seems tuned good for current altitude of under 1k and I can get it to start right up.  Don't mind losing a little power as long as its not hurting the engine.  I am extremely cautious on bikes and very little traffic where Ill be.

Does the 4 into 2 make engine leaner or richer with stock jets?

Leaving in about a month so if any major issues Ill be back on here: 1st motorcycle so I will surely need more help in the future.

thanks

[cb550fnewb]

OK in utah and bike is running very rich and obvious power loss.

I am running 91 octane 85/87 was consistently stalking at 5400

I adjust a/f with screw to get it not to stall while idling at 5400 (where I live) but at 7000  it stalls anytime the bikes idling

When going up hill a 1/2 to WOT feel exactly the same lack of power bike doesn't even seem to attempt to accelerate with throttle after halfway.


Is there a tutorial on how to adjust the needle clip position and how hard is it to change the main jet to lean it?

[cb550fnewb]

oh and could this issue be fixed by adding PODs.....don't want to get into carb unless i have to

[mronegear]

before you pull the carbs, try to run the bike without the airfilter insert. This shoud have almost the same effect than running with pods.
If you wan't to change the needle clip position, 2nd groove from top is the stock setup, so you have to set the needle in the top groove.
By the way, you can change the clip position while the carbs are still installed. You must remove the tank, then you can work on top of the carbs.

good luck!

[Duanob]

" 2nd groove from top is the stock setup, so you have to set the needle in the top groove."

Wrong way. If you want to richen the mix you will need to move the needle clip position down (needle moves up)

Also if you move the needles you will need to sync the carbs again. 

[mronegear]

" 2nd groove from top is the stock setup, so you have to set the needle in the top groove."

Wrong way. If you want to richen the mix you will need to move the needle clip position down (needle moves up)

Also if you move the needles you will need to sync the carbs again.

you're right, but he said that the bike is running too rich, so he has to get a leaner mixture :-)

[cb550fnewb]

before you pull the carbs, try to run the bike without the airfilter insert. This shoud have almost the same effect than running with pods.
If you wan't to change the needle clip position, 2nd groove from top is the stock setup, so you have to set the needle in the top groove.
By the way, you can change the clip position while the carbs are still installed. You must remove the tank, then you can work on top of the carbs.

good luck!

OK check spark plugs to make sure rich.  Definitely is rich spark plug were black.

I pulled the air element drove approx 15 miles and bike preformed much better.  Before uphill, I could only get the bike to get up to 4000 RPMs in 3 thur 5 gear up now i can down shift and keep up speed (pushed it up to 7000 RPM not willing or needing to push it higher.  Before i could only go up the hill 50mph now no problem at 65 mph and could even push it farther.

Filter looks pretty bad not sure what the chance that its near completely plugged?

I ordered a new UNI foam air element if that doesn't work might look into a pod

ALSO after the 15 miles plugs like nearly prefect, maybe just a tad on white side
   

[Rgconner]

Don't do the pods, you will regret it.

[cb550fnewb]

ok will have to currently do something if new air element doesnt lean it down a lot

[scottly]

Sounds like your old paper element was plugged. Be aware that at 5000 feet, your motor will make about 15% less horsepower, regardless of any jetting optimization, due to the thinner air.

[cb550fnewb]

Sounds like your old paper element was plugged. Be aware that at 5000 feet, your motor will make about 15% less horsepower, regardless of any jetting optimization, due to the thinner air.

hoping its the element, I don't know could possibly be the original.  So rich now that there's no difference in 1/2 to WOT.  New uni element should be here by friday.  Nearest shop for me is 75 miles and its pretty small so I have to order everything online