Topic: First Post, 1975 CB550F SS, what i've done & some carb tuning questions...

[Kenzo]

First off hello I'm Kenny, I go by Kenzo and a few names not to be repeated. I'm located in Houston.
The midlife crisis moto bug bit me a while back and bought a KLR fixed it up, then got more into off road, got an XR650. Joined the Trail Riders of Houston(Tx largest & oldest offroad club) and ditched the 650 for an 07 KTM 400EXC. Freshened it up with a 453 short stroke big bore kit (did the work myself) and have been know to race an enduro or hare scramble once in a blue moon.

Great resource here...I've done tons of searches and reading that have gotten me this far.

So I got this wild idea to get a bike I drooled over in High School, did a ton of research and got an orange 1975 CB550F Super Sport locally for $700. Looked decent but hadn't been running in six months or so I was told, hence the low negotiated price. No side covers or airbox and half of the pods missing. Exhaust ended after where the 4 into 1 joined. Also the starter had been removed. Had some one year old receipts of work a shop had done. Basically rode hard and put away wet. One brother thought the current situation was a carb problem the other said electrical. Doh!

What I've done:

Gas tank, petcock and in-tank filter done. The tank had water in it, filter missing and drawing off the bottom/reserve(water).

New points, condensers(gapped & timed), coils, wires, caps & sparkplugs. Have rectifier/regulator yet to be installed...I want it road worthy.

Installed an Ebay starter.

Did a basic carb cleaning, my first mistake, didn't remove/clean emulsion tube or pull the slides & needles. It's obvious water had made it's way into the carb bowls. Replaced the 38 slow with a new 40 slow.

Fresh gas, fuel lines low and behold the bike started and idled ok but there is a bad stumble off idle to 1/8-1/4 throttle, then would clear and rev pretty good when riding around the block. Pulled the plugs 2/3 look ok but 1/4 very black but dry with carbon build-up...rich. Because 1/4 looked similar I thought maybe bad coil so I swapped the coils/wires with the same results. Oil & filter have been changed. Also verified bowl levels with sight tube(2-3mm below carb/bowl junction).

So today I pulled the carbs, pulled one slide and finally got the number one emulsion tube out (frig'n PITA)...bingo, air passages totally blocked. I plan on doing the rest of the carb soon.

I have Uni pods installed and a Moto GP Werks exhaust waiting to be installed.

Carb is a Keihin 069A
Main jet 115(seems big)
Slow jet 40 I installed (38 previously)
273004 Needles 3rd clip down from the top(5 positions)

Long story short I'm looking for jetting advise...I'm thinking getting some 105 & 110 mains, drop the clip one position, replace emulsion tubes as needed. Sound reasonable?

Thank you in advance!
Kenzo

[Kenzo]

Well I finally got an hour to get into the carbs again, removed the slides and remove the emulsion tubes. As I mentioned before there was water in the tank and carbs. Low and behold 1 & 4's emulsion tubes hole were blocked with a pasty aluminium oxide crud. Going to clean everything put it back together and see how it runs while waiting on new parts to arrive.

My main jet O-rings are toast so I experimented with a few wraps of this and it works great. Probably a good fix if your main jet seat are corroded and the jet fit loosely.

Cheers

[harisuluv]

Hi, welcome to the forum.  For pods the standard settings for your bike are:

1.  Needle raised one clip position (lower the clip one position to get this).
2.  100 main jet to 110 main jet.
3.  Idle jet stays the same.
4.  Air screws 1.5 out and adjust as needed.

It is great to clean the emulsion tubes but people if inexperienced are more likely to damage them getting them out and essentially ruin them.  I have seen plenty of situations and even firsthand where the emulsion tubes upon inspection were dirty and blocked, and after making them pristine it did not fix the issues.  That could be the problem, but don't get your hopes up.

Are you doing these tests with the stock airbox or no air filter system at all?

[Kenzo]

okaaa...she's running to the point I feel comfortable to start tuning...

...Uni pods, will be installing Moto GP Werks exhaust(currently stocker chopped off at 4 in 1).

Current carb set-up, new 40 slows(I installed), 115 mains(came with bike & 38 slows), 273004 Needles 3rd clip down from the top(5 positions)...

Currently pilot(slow) to needle transition is ratty and hanging idle when warmed up...SWAG too rich down low.

Going to get new emulsion tubes and the jets you guy recommend.


TIA,
Kenny

[harisuluv]

No mention of air screws.  This is an adjustment on the carbs, have you used it? 

[Kenzo]

just a quick test after full carb cleaning today(was getting late and it's loud), pod's not installed, hacked off stocker exhaust...still need to order new emulsion tubes and jets but...

air screw, tried 1 turn out...then two out...two out a bit better

the plan is install full exhaust & pods, play with it while waiting on emulsion tubes, 110 mains, new 38 slow jets and fresh plugs...begin tuning once I have the parts.

TIA,
Kenny

[Kenzo]

harisuluv, first thank you for your input.

1975 CB550F Super Sport
Moto GP Werks exhaust
Uni Pod Filters

Keihin 069A Carb
273004 Needles

Your suggested starting point:

100 to 110 main jet
38 pilot jet
needle 4th clip position down from the top
1 1/2 turns out on the air screw

I assume you prefer Keihin Jets over replicas?

I will be replacing the emulsion tubes since one is badly corroded on the outside. Did I read somewhere that the F and K use different emulsion tubes?

Preferred vendor for jets or whom ever has the Keihin's in stock?

Thanks in advance,

Kenny

[Stev-o]

Welcome from Lake Travis, Kenzo.  I also have a 550F that I am currently working on, but mine is all stock.

Harisuluv is our resident carb expert, so I would go by his advice.
These motors like back pressure, so with no muffler, you may have trouble tuning. The MotoGP exhaust is awesome, I am jealous! Bolt that pipe on!

There is a couple 550F's being parted out, check the for sale section if you need any parts.

http://forums.sohc4.net/index.php/topic,151364.0.html



Are you going to Harvest Classic in Luchanbach next month?

http://www.harvestclassic.org/activities/

http://forums.sohc4.net/index.php/topic,111515.125.html

[Kenzo]

Yup I've done tons of searches and reading here...great resource. Harisuluv obviously knows his way around these bikes.

MotoGP exhaust going on, pods and ordering jets hopefully tomorrow.

Steve-o, That looks like a fun event and something I will definitely try to make in the future. I run with the Trail Riders of Houston, it's an offroad riding club. I have a KTM EXC 400 with a 453 Kit for my trail, enduro and hare scramble riding. Do a lot of camping, riding, fishing and shooting...you know, fun stuff!

It's a bit of a rat bike at the moment, got it non-running for $700. Another $1000 or so and I'll make it my own.

[Stev-o]

It's looking good, that was a good buy at $700. 

Frankenstuff makes side covers, check the parts for sale section if you need some.

[Kenzo]

harisuluv,

1975 CB550F Super Sport
Moto GP Werks exhaust - Installed
Uni Pod Filters - Installed


Keihin 069A Carb

38 pilot jet

115 main jet (105 to 110 main jet ordered)

273004 Needles 3rd from the top

38 pilot jet

(have 1 emulsion tube ordered, 3 backordered)
(have extra spark plugs D7EA's ordered)

Seems to run best air screw 3/4 turns, still stumbles 1/8 throttle clears out and revs great...a little burble/pop when chopping the throttle. Tried 1, 1 1/2 & two turns out...the stumble seems to happen at a slightly higher rpm but a lot more popping when I chop the throttle.

It was a little disconcerting when I swapped the 40's for 38's that the new 40's appeared to be a little blocked but the bike started and idled great. Now with the 38's I choke it to get it to start first kick *edit* (cold).

I think number on cylinder running a little cooler than the rest base on header color...number one has the emulsion tube that's heavily eroded on the outside. :/

That's it for now until the jets get here and try your recommendations.

Thanks in advance,
Kenzo

P.S. Digging the new exhaust. It's currently a bit of a rat bike but it suites me. Looking at an end game of something like the Blacksquare bike w/o the bling.

[Kenzo]

New jets, emulsion tube(3-backordered) and spark plugs should get here today.

In mean time with #1 appearing to run cooler(to touch at start-up & coloring of new ss exhaust) I...

>Checked the timing, OK

>Checked #4 valve adjustment(was hearing a rattle), OK. Could #4 rattle be due to #1 misfiring? maybe...

>Pulled #1 & #4 plugs...#4 OK, #1 fouled and wet with fuel.

>Cleaned and swapped plugs, briefly restarted and #1 definitely running cool(start-up/idle).

I'll get the new jets & emulsion tube installed. Confirm I'm getting a good spark on #1 and go from there...

Cheers

[flatlander]

the bike looks like it was a great buy, congratulations!
no put a saddle on and go....

[Kenzo]

wellll...

Got the recommended brass, needle clip positions changed and new emulsion tube installed in the #1 carb.

The old #1 emulsion tube looked a lot worse before I cleaned it and the interior is badly eroded/corroded.

Fired up the bike and cylinder #1 is stone cold...Doh!

What's that saying...oh yeah... "when you're up to your azz in alligators it's easy to forget all you were trying to do is drain the swamp!"

Have a good spark but swapped plugs, wires and even coils but the problem persists with #1.

Checked fuel flow, bowl level...all correct.

Checked the timing, valve clearance just in case...all correct.

The #1 plug appears to be a little wet but wouldn't bet my life on it.

I can not see what I could have done to stop the fuel flow out of the #1 carb but I did not blow out the passages since I had just done it a few days earlier.



I plan on checking the compression before I pull the carbs(not biggie I'm getting real good at it!)...what should I be looking for cold 120-130ish psi???


One other thing just entered my mind...is it possible the new MotoGP Werks exhaust has something blocking the number one tube?!? It's possible...I know there was fire in the #1 cylinder before I started this jetting saga...

Also the bike starts, idles and runs amazingly well on three cylinders but it hasn't been out of the garage since I discovered the cold cylinder.

Cheers

[Stev-o]

Curious - where did you get the brass? OEM Keihin?? [I need some...] Thx

[Kenzo]

Curious - where did you get the brass? OEM Keihin?? [I need some...] Thx

4into1 was the only place with a single emulsion tube so I got it and the mains there...not Keihin.

cheers

[Kenzo]

I hope to have time today to get into the carbs and try to figure out why #1 is not firing...I'm somewhat convinced it's a fuel/air issue, unless I've lost compression in #1.

One additional source of the problem came to mind this morning...

...I've been in these carbs several times for cleaning and tuning. The #1 carbs top gasket is torn (new sets unavailable/backorderd) in two places. No missing pieces but may not be sealing perfectly but no major gaps. Could the carb be sucking in through the top bypassing the carb throat/venture messing up my air/fuel ratio??? How critical this this gasket???

Thanks in advance,
Kenzo

[harisuluv]

Fuel, compression, spark.  Process of elimination.

Be sure your troubleshooting/logic is sound.  For example, you said you have fuel in the bowls after checking as if that was a checkmark next to the fuel part of the equation.  Fuel in the bowls means just that, there is fuel in the bowls.  It does not mean it's getting into the cylinder. 

Probably just a clogged slow jet.  Yes I saw you got some new ones, it doesn't mean it's immune to clogging now though.  If your gas tank is not pristine then it could be perpetually contaminated. 

I could have missed it but I see no mention of syncing your carbs anywhere.  Via vacuum or bench sync. 

[Kenzo]

All hail the King of Dumbasses, Lord of Tards...me!

Doh!

Pulled the carbs yesterday, actuated them while walking to the bench...what? ...wait? ...no way! ...how is that possible?

Yes, the #1 slide was in backwards! I'm aware of the nub and slide orientation but there's no nub, slide scratches or mark where it may have gotten sheared off. I probably did it the first time I took the slide off to check the needle and clip position.

I correctly reinstalled the slide, quickie bench sync, installed, fired the bike up and holy crap! What a difference an extra cylinder makes!!! I know I'm going to really enjoy working on and riding this bike! 

I'll have to wait to start tuning next week. My offroad moto club is hosting an AMA/TSEC Enduro race tomorrow just north of Houston.

Still got a ways to go but thank you everyone for helping out.

Have a great weekend!

Cheers

[Kenzo]

I'm still struggling with a stumble when I first turn the throttle/open the slides under load. The stumble happens when launching or when first opening/rolling on throttle regardless of gear/speed, maybe except with very spirited/aggressive riding and throttle application.

No starting, warm-up or idle issues. Revs great in the garage(can't replicate stumble) and no problems or flat spots once past the stumble when riding.

I did reinstall the refurbished TEC points(had installed new Daiichi), set gaps & timing while shimming the plate. Plate lined up about the same place as with Daiichi's. Cleaned and confirmed advancer(full advance ~2400rpm). Even checked timing with cheapo timing light.


1975 CB550F Super Sport
Moto GP Werks exhaust - Installed
Uni Pod Filters - Installed

Keihin 069A Carbs(Recommended settings)
38 pilot jets
110 main jet (stock, 105 115 main jets on hand)
273004 Needles 4th from the top

Bowl fuel levels spot on. Good fuel, flow & filtration.

Replaced one badly eroded/corroded emulsion tube will have all four identical when available(backordered).

Air screw not effecting stumble much...seems slightly better at one turn out. More popping/burble on chopped throttle at two turns out.

What I haven't done(next step):

>install 40 pilot jet
>replace intake orings
>accurate bench sync(only did a quickie sync)
>full vacuum sync
+(edit)checked for vacuum leaks(propane torch)
+(edit)exhaust crush washers torqued to spec

Two of the main jet holders are a bit loose, don't know how important that seal is...before I got the new mains and O-rings it used a bit of PTFE tape to seal.

Any ideas or suggestion I may be overlooking?

Thanks in advance,
Kenzo

[Kenzo]

I'm a little surprised I haven't received any opinions, input or suggestions to my last post.

I'll be going ahead with my "next steps":

>install 40 pilot jet
>replace intake o-rings
>accurate bench sync(only did a quickie sync)

...hopefully this will cure the stumble and after that I'll proceed with a full vacuum sync.

My belief is my pilot is lean when the slide begins to open it is further leaning it out causing the stumble. Without a pumper carb it's always preferable if not a requirement to be rich when first opening the slide(carbs fuel flow lags the air flow)...the way Honda engineers jetted these bikes from the factory.

Cheers,
Kenzo

[Stev-o]

Hey Kenso.....when you go with pods and an aftermarket exhaust, you will not get as many suggestions to solve your issues.
A lot of times it is just trial and error, have you done a plug chop yet?

BTW - what are you doing next weekend?

http://forums.sohc4.net/index.php/topic,111515.150.html

[Kenzo]

Hey Kenso.....when you go with pods and an aftermarket exhaust, you will not get as many suggestions to solve your issues.
A lot of times it is just trial and error, have you done a plug chop yet?

BTW - what are you doing next weekend?

http://forums.sohc4.net/index.php/topic,111515.150.html

I hear ya on the trial & error...always open to ideas or "you seem to be moving ing the right direction" comments.

I barely have time to spend a few hours on my new project bike. I'm an old fart ex-engineer/sales guys that got in the restaurant business...DOH! It's a VERY expensive and time consuming hobby. Plus I still ride dirt bikes off road, enduro/woods type stuff...very active with the Trail Riders of Houston(TRH).

I'm going to post your links over on the TRH Facebook page...we love all kinds of motorcycles and riding! 

Cheers,
Kenzo