Topic: Hmmm diferent pipes on CB550?

[74cb750]

Hello,
silly question of the week contestant here:
I have a 1976 CB550 with 1974 pipes on it when I bought it.
My question is, could this be the reason why it is difficult to start
and why it will NOT idle after start up? Choke on or off.
Seems kind of far fetched, but....

I did see an earlier post about kicking it over a few times with the key off
and this has seemed to help with the startup. But it still will not idle until it
is totally warmed up.

Could this problem be related to weak coils? Really, I am at a loss here.
peace,
michel

[apormarkos]

i'm sure the experts will chime in with more wisdom than i have, but my feeling is that if you have any 4-4 pipes (perhaps any pipes at all) on your 550, it should run.  maybe it won't run well, but it should run.  when was the last tune-up?
apor

[74cb750]

It was "tuned up" by the previous owner because of hard starting, right before I bought it
about 2 months ago.
Supposedly the needle position was moved down one.

[TwoTired]

Assuming were are talking about a 76 Cb550K model, the 4 into 4 pipes are the same as the 75 model.

If your 76 was within my reach I would check the head pipe temps to see if they were the same across the cylinders.
Then I would throw the carb sync gauges on it to see if they were evenly adjusted after the needle positions were changed.
I'd also check the air filter(s) for clean.
Then I'd see what the idle air bleed screw settings were and probably return them to stock values if all the rest of the bike was stock, too.
I'd probably do a complete tune up on the bike to eliminate everything else but the carbs.

If the issue persited, then I would take the carbs apart and clean or correct whatever the POs did to them.

But, you know, if somebody put 750 spark plugs in the bike. It will be a cold blooded B*stard.  Put, in D7EAs.

Cheers,

[apormarkos]

But, you know, if somebody put 750 spark plugs in the bike. It will be a cold blooded B*stard.  Put, in D7EAs.

Cheers,

two tired,
speaking of plugs, on my tear down and reseal, i found d8es plugs in my 76 cb550.  are these 750 plugs?  what effect would these have on my bike (here i'm trying to figure out what the po was trying to do)?  of course i'm assuming you know every model spark plug from every manufacturer   
apor

[TwoTired]

D8ES plugs are a colder heat range plug.  This means it pulls more heat out of the combustion chamber and into the cooling fins.

Your find could be a simple mistake.  The Honda dealer has repeatedly tried to sell me 750 plugs for my 550 simply because he was too lazy to look in up and "knew" they all took the same plug.

However, if you are running as high speed on hot whether, a D8 plug might help keep combustion temps down, or at least farther away from preignition and detonation, particularly if your carbs were finely tuned for optimum mixtures.

As noted before, D8 plugs make the CB550 nearly unrideable while it is warming up from cold.  With the D7EAs and my stock CB550s, I suit up with gloves and helmet on, put on choke, start, back off the choke a little and off I go.  For a few blocks I reach down periodically and incrementally remove some choke until it is off and it will idle at stop lights/signs.  It's best to keep the RPMs below 5K during the oil warm up period, anyway.

Cheers,

[74cb750]

This machine has Champion RA8HS plugs.

Tried the kick-it-over-3-times with the kill switch on (or rather the key off, but gas on)
and it does start much easier.

Still will not idle upon startup, so I have wednesday off and will double check the sync,
be back later.
michel

[TwoTired]

This machine has Champion RA8HS plugs.

Tried the kick-it-over-3-times with the kill switch on (or rather the key off, but gas on)
and it does start much easier.

Still will not idle upon startup, so I have wednesday off and will double check the sync,
be back later.
michel

Bleah, resistor plugs.  I've not tried those champions.  And, my experience with Champions in these bikes makes me prefer them as projectiles, preferably with a lake or pond as the target that can't possibly go dry in my lifetime.
If you want it the run well cold, get NGK D7EA.

The 76 does not have a fast idle cam and none of them will idle well at 1000-1200 RPM when cold.  Hold the throttle open with the twist grip. between 2-3K.  With the right spark plugs you can ride it when cold, no problem.

The 74 and prior had a twist grip friction adjust for stand still warm up.  Wasn't until 77 when they put the fast idle cam on the K carbs.
Don't know what they were thinking for 75-76 models.  The user friendly advocates might say, ... oops.

Cheers,

[74cb750]

ok,
we have had some non-raining weather lately....the cb550 has started well once warm.

Still starts hard when cold, but not as bad. Will try to sync them in between working on my other bikes
*(kz1300, GS550E, S2, SL175 and another 1974 cb550 with a 4into 1 with electrical problems).

Hopefully the carbs are out of sync, as it does not idle cold (even if it is warm out). Almost sounds like one or two might be misfireing. Really need to get off my butt, and check it out properly.
peace,
michel

[bryanj]

Sounds to me like you ought to do your own thourough tune up starting with contact gap and timing and if it still wont start properly strip and clean the carbs paying special attention to the pilots. By the way all the 500K and 550K from 71 to 76 inclusive have the same exhausts