Topic: HELP! Experts needed for my 78 550k!

[P_Camps]

Hey guys I'm mechanically inclined and never afraid to get my hands dirty but I am not a mechanic and dont have the experience most of you have.  Hopefully I can explain myself properly and communicate what is going on with the bike...

I picked up my 78 550k on July 1st and have been riding it since July the 8th.  This was a project bike built by an experienced member of the Vintage Racing Association.  It was never ridden on the street and I was the first to actually 'plate' the bike.  The bike was registered in 05 and he finished it some time in 08.   Basically he started with a titled frame and built his way up in an attempt to build a bike that was as close to stock as possible, the only thing not stock about the bike was the 4-1 exhaust, which he said is Yoshimura but through research I see that Yoshi pipes and headers are usually black so I dunno about that.

When I first went to see the bike the battery was dead (so he needed to boost it), he actually had to put  a cloth over the air intake and filter in order for the bike to stay on and idle.  He claimed that the reason was it was a non-oem filter (though I think this was more of a sales pitch), we agreed on a price of about $1200 with him buying a brand new battery and see about getting the bike to idle with the intake on.  As I asked him what he thought the bike could possibly need in terms of ‘SERVICING’ in the next thousand km’s, he said a stern “nothing, everything that was put on the bike is in great condition”.  Now the bike was not plated so I could not ride in on the street but I rode it on his 2 acre lot and saw that clutch and tranny worked well (and it still does).  I picked it up the next day and he had a brand new battery in it and the bike was running much better.  When I took it home the first thing I did was change the oil with Castrol GTX 10w40 and a FRAM oil filter.  I also opened up the air intake and noticed that he had cut out a piece of felt and laid it over the foam filter, I left it in there because I didn’t want to mess with it as it was now idling.  

My first ride was a  24km (15 mile) ride to my mechanic (with a borrowed dealer plate) to get the safety certificate…..  in my first ride the engine was very tight and the bike would not go over 100 km/h but with every km it got better and faster, within a few hundred clicks of riding the bike was hitting  140km (88mph), how it got to 140 is a different story.  For example; if I would  be cruising at 4000 rpm and if I wanted to accelerate, the bike would bog down  and ramp up by sputtering/bogging, but soon as the power band hit past 6000 rpms the sputtering would cease and it would climb to about 8000 rpms nicely.  I was hoping that this problem would iron itself out by riding but after 750km’s it was still doing it actually in some ways it was even worse.   Everything led to a carb tune/synch but I decided that there are some things I could do easily before so I pulled the plugs and they had soot on them especially #2 another thing I noticed is that the plugs were not the owner manual recommended D7EV plugs but instead  the D8EV plugs which I’ve learned run colder  then the 7’s.   I got 4 brand new D7EV’s and IT MADE THINGS EVEN WORSE!!! Now the bike wouldn’t climb past 7000 Rpm’s though it got faster… I was now able to hit 155 km/h (96mph) all under 7000 rpms, I kept the plugs in cuz I figured maybe they would break in… On Sunday I went for a 2 hour ride with my buddy and halfway through the ride the bogging and the sputtering got worse…. So remembering the piece of felt, I pulled over and removed it… this didn’t change much (maybe a little more response off the line).  As I got home I parked on my driveway, turned off the bike and realized that I had to go play lotto (I know what an addiction..lol)  when I went to restart the bike it would not restart (weird cuz usually it starts up right away when its warm), so I pulled on the clutch and gave gas and it started BUT now it felt like it was running on 2 cylinders, when I revved the engine it lazily revved up.  I went around the street to see if it would loosen up but nothing… I decided to let it cool down and revisit it the next day.  I tried yesterday and the exact same symptoms showed up…. So today I decided to clean up the old plugs with sum gasoline and a steel brush and see if that was the problem along with removing the air filter element but it did not change anything.  Though I did notice the bottom of the filter housing was wet with gas.  

To be honest I’m thinking COIL or wires….but if anybody could make anything further out of this it would be greatly appreciated..

Paul
 

[climbingaz]

I'm sure some more knowledgeable folks will be along shortly, but some of what you described sounds like a problem with the airbox.  Does the bike have some sort of modified airbox or pod filters?

[flybox1]

As I asked him what he thought the bike could possibly need in terms of ‘SERVICING’ in the next thousand km’s, he said a stern “nothing, everything that was put on the bike is in great condition”.  

I call PO-BS!  
i've got a 1998 subaru outback that dont need nuthin!  
wanna make me an offer  

get yourself a clymer and a shop mannual.
complete the 3000mi maintenance steps.
highly likely an air/fuel mixture problem,
sounds like you need valves adjusted, timing and advance set/checked, and your carbs thoroughly cleaned. when done, clean them again. bench sync them. a NEW air filter, new plugs (if the ones you've got are beyond fouled) NGK D8EA's
while you're in your carbs, note the sizes stamped on the main and pilot jets. confirm they are stock
check your intake boots for air leaks.  set your AF screw to facotry setting, and vacuum sync your carbs.
it should run like a top.

[ieism]

Well, there are some more experienced 550 owners here than me, but I'm sure they'd agree with me on this:

The bike has a non stock airbox/filter and runs crap. Get yourself a stock airbox an filter. Check your carbs are factory spec (jets, airscrew and clean and everything) put the D7ev plugs back in. I practically guarantee you it will run, and be near perfect.

Your coils and wires are fine. Your valves, timing and advance are most likely fine too.

[P_Camps]

thanks for the great tips so far.   Just to re-iterate its a stock air box... the actual foam filter is not...its made for a 550 he just didnt get it from Honda.

[flybox1]

still, if you're wanting to get this bike dialed-in, elimination of variables will be crutial.
you should source a NEW air filter, and then, continue with your regularly scheduled programming maintenance.

[TwoTired]

Step one, review/ reset all the standard 3000 mile tune-up items.

You need to find out if the carbs are still set to the factory specs.  Those settings will NOT be correct for a more open exhaust and a filter with less of a pressure drop across its filter membrane.

The 77-78 Cb550K models were EPA tuned for low emissions.  This meant the carb were far more stingy was gas than prior models.  One "trick" was to make a more restrictive exhaust which allowed the carbs to be set leaner.  The carbs don't automatically know that the exhaust was changed.

While I do like the Uni NU-4055 replacement foam filter.  It does not present the same pressure drop across it as the stock paper one.  This effect the depth of vacuum in the carb throat and that vacuum is what draws fuel through the fuel metering devices.  Less vacuum = less fuel for the same volume of air passing through the carbs.  Finely tuned PD style carbs don't automatically know about induction changes.

Seems like those changes were the double whammy against proper carb tune.

It would seem like the extra felt was a stop gap to make the fuel mix richer.  But felt has a different restriction factor given different velocity/volume of air passing through it.  It may have "fixed" the idle issue. But high RPMs likely went far too rich and sooted up the spark plugs.  Without any felt, maybe it went too lean at the top end and hindered power.

This is all hard to predict without knowing what the current carb settings are.  But, I don't think "felt tuning" is a viable alternative to proper carbuettor settings.

Cheers,


P.S. Are you sure those plugs weren't D7EA?  I'm not familiar with the V labeled spark plugs.

[P_Camps]

D7EA is correct.

Thank you so much TT.  I guess I gotta start dismantling....

I just dont get how all of a sudden the engine could feel so 'lazy' like its running on half the engine....

[flybox1]

empty out your gas tank into a bucket as you slosh it around, and see what wonderful stuff comes out.  the same stuff will most likely be clogging your carbs 

[totty]

For example; if I would  be cruising at 4000 rpm and if I wanted to accelerate, the bike would bog down  and ramp up by sputtering/bogging, but soon as the power band hit past 6000 rpms the sputtering would cease and it would climb to about 8000 rpms nicely

Mine has the same symptoms as this, richening the needles one notch has made it much more ridable but not totally cured it. I'm going to either move them another notch or go up a main jet size.
The carbs are clean having stripped them twice and the filter remains clean. All jets are stock. Exhaust is Motad. The ignition has been replaced by a boyer kit which didn't affect the symtoms.

Do you have the crankcase ventilation plumbed into the bottom of the airbox and the associated bits that sit under the filter? These are missing on mine, the hole on the bottom of the airfilter that sits over those parts has been sealed to prevent air bypassing the filter through it.

[P_Camps]

Well its been since August that I asked for help and I just remembered that I never came back to give an update and thank those who took their time to help me with my bike. 

I solved the issue after all the great advice I received.  All it took was taking off the carbs and giving them a thorough cleaning, I also bench synched them.  I have been Loving my bike. It pulls hard and strong and its all due to the great advice received.   I also figured out that my bike likes the #8 plugs much better then the #7's so I got a new set of those.... Since then I got a new set and its all Gravy...

THANKS AGAIN

Paul