Topic: new first bike

[goldencb550f]

I just bought my first bike and I already love it .  It has a few problems, however.  It is sometimes difficult to start and when I finally get it started it idles a 5000rpms and doesn't go down.  I have tried slowing it with the choke, but 5k is as low as it wants to go.  It also has a rattling noise that the previous owner said is probably the cam chain .  I was wondering if anyone had any suggestions.  I was going to run some carb cleaner in a new tank of gas.  I was also going to try putting a higher than required octane in, but I am not sure what type of gas I am supposed to put in it in the first place.  I live a 6500 feet in altitude (Golden, Co) and I know that octanes change here (regular is 85, midgrade is 87 and premium is 91) so I would assume that I can jsut put in the corresponding equivalent for this altitude.  Any help would be great .

Chris

Sorry, I guess I should tell you what type of bike it is.  It's a '76 Honda CB550F.  It has a blue tank and the side panels are from a CB550, but I personally like them better.

[Bob Wessner]

Chris,

five thousand is pretty high, particularly for a cold engine. I guess the first thing I would check re: the high idle is all the linkage from the grip down to the carbs to make sure nothing is binding and functioning correctly. What are the idle adjustments set at?

As for the gas, I use regular myself, but opinions vary, see poll on this subject at;

http://www.sohc4.us/forums/index.php?topic=3872.0

[nashvegas]

Chris,

Congrats on the new old bike.  By the way what kind of bike is it?

I would bet that your problem may be a five minute fix, on my CB400F there is an idle screw under the gas tank between the engine and carburetors (big brass colored screw notched around the edge so that you can turn it with your fingers, can't miss it).  Turn it clockwise, the engine idles higher...Turn it counter-clockwise, the engine idles lower.  Give that a try (always try the easy cheap stuff first) and see if it helps.  Man I envy you.  You will never regret getting an old SOHC4, a well maintained bike of this type will out last both of us.


Matthew

p.s. if you already know your stuff on bikes, then just disregard this info

[nashvegas]

I keep forgeting to read the usernames.  Do'h!

Ok so you run a CB550F, NICE!  I like the ones that end in F, the 750 guys are always chatting about Ks and KOs and blah blah blah.  Just kidding guys. 

[heffay]

hey golden... welcome to our crew!  i live in boulder... check out the denver rusted nuts yahoo group if you haven't already.  we'll have to ride sometime.

now, onto the task at hand... do not run carb cleaner thru your running motorcycle!  it is not gas and should not be used as gas or as a gas supplement.  it is meant for cleaning the carbs when removed from the bike.

like chris said... check the idle screw.

octane wont affect your idle that much... in fact you may never notice a difference... i'm in the process of experimenting and have no tangible results.

if it continues to run high... you have an air leak somewhere most likely.  (very common with these bikes but not too costly to fix)  just has to do with the age of the motorcycle and the normal life expectancy of rubber especially in the general vicinity of gas. 

[DammitDan]

Heff's right, if you the idle screw doesn't handle it, check out the intake boots from the carbs -> head.

Oh, and buy a shop manual and a set of feeler gagues to adjust your valves .  You might be hearing rocker arms along with that cam chain (makes a loud clicking noise that follows your RPMs)

[eldar]

Adjust your cam chain then do a valve adjustment. This takes care of a lot of noise.
Check the idle knob also check your throttle cables. these can be a big pain as many people do not lube then at all. You can also try to reroute them since a poor routing can cause binding and take away overall movement.

These are all checks that cost nothing

[goldencb550f]

Thanks for the tips guys.  I got the idle to fall to 2000 rpms, I was hoping to get it lower.  I am fine with that for now until I get the cam chain and valves adjusted (again another tip thanks).  Hopefully from there I will be good to go.

Chris

[78 k550]

Welcome,
 I ride a 78 550 I live in Littleton. I think there are a few CO people here. I can swing by and give some info.

Paul

[dusterdude]

hey nash,blah blah blah blah.