Topic: 1976 550K Project

[mrfish2]

Yeah I put an OEM one on it. I've already got another Vesrah head gasket in anticipation of replacing it again this summer hopefully.

[mrfish2]

Got my slighty used Progressive fork springs in the mail a couple days ago and finally got some time to install them today. They're right at 7/8" longer than the stock 40 year old springs and are soooo much stiffer.

Stock spring length


Progressive spring length


Getting the fork nuts tightened back down was quite a job, but they eventually screwed in tight. I haven't rode it yet but I can tell the front end is A LOT  stiffer and doesn't sag as much.

Ran into a snag with the new 16T front sprocket. Here's the 17T from JT Sprockets mounted on the bike, notice how it sits almost flush with the edge of the groove:


And here is the 16T from Sprocket Specialists, notice how close it sits to the engine:


Something didn't add up here so I called Sprocket Specialists to figure out what was going on. We figured out that I DID order the right sprocket for a CB550 from them, but was supposed to receive a spacer as well that would move the sprocket closer to the edge of the groove and line everything up right. Since I didn't receive the spacer the customer service guy put 2 in the mail for me and had them shipped out that day. I have to say they have great customer service and extremely helpful technicians.

Checked the needle position on the carbs and they were all in the 4th groove from the top (stock position) so I raised them one notch to the 3rd position. Gonna install the new floats and reset the float height via the clear tube method again tomorrow, hopefully with the new air filter it all should take care of my richness problems.

Scored a sweet old K&N single cone filter and adapter from a another member here, can't wait for that to get here and try it out. Also, when I was going over the timing the other day I noticed the 2/3 points weren't making square contact and after reading some thread about that I decided to just replace them. Found a NOS TEC brand points set on ebay so I'll be installing that soon too. More pics to come!

[calj737]

Before you adjust your needle clip position, I'd verify your fuel level. If it's too low, that will contribute to your lean running. Best to make these types of changes in increments to understand the effect of each on the system. Clip and float level changes together can be counter-productive. Unless you know already that each is wrong because you've moved it?

[mrfish2]

I had my float heights set already right at 3mm below the gasket surface Cal, but I was still running rich. I was only getting 15 mpg too. After raising the clip one notch (it's now in the 3rd notch from the top) it definitely runs A LOT smoother than it did riding around town, and my gas mileage has bumped up to 35 (measured this after some hard mountain riding, haven't measured it yet while highway cruising). I also bumped the float heights down a bit to right at 5 or 6mm below the gasket surface. One thing that did change is at WOT when the bike gets over 6 or 7k rpms it starts sputtering as if it isn't getting any fuel, which makes me think the fuel levels are just a little low.

I was riding home from work yesterday and 2 miles from home two cylinders cut out on me, then when I was about a hundred yards from home and they cut back in. Seems like I get one thing working and something else breaks....

Not sure if it's the points, condensers, or a coil, but it was definitely an ignition issue. I had an extra set of Daiichi condensers laying around so I threw them on there. Also, my old TEC 2/3 points hadn't been making square contact on the faces so I've got a set of NOS TEC points to put on there too. Didn't have time to test everything yesterday when I did this but I'm gonna try and get it done today.

[mrfish2]

Put some new plugs in and rode it up the road at WOT. It sputted and backfired on decel, so when I got back I pulled the plugs. #3 and #4 looked perfectly tan, but #1 and #2 were white. I'm thinking my float levels are too low.

Also put in my K&N single air filter today (after riding it at WOT), and it looks sweeet. Had to shorten the breather tube by about 2.5 inches and route it on top of the carbs instead of below them. Scored an early style Moto GPWerks exhaust from another forum member, so I went ahead and pulled the trigger on a main jet kit from Sirius Consolidated with 105, 110, 115, and 120 sizes. Actually ended up ordering 105s and 110s from JetsRUs, along with brand new Keihin 38 slows (something I've been meaning to do for a while to get rid of the junk aftermarket ones I've got).

[Tews19]

I have the same air filter. I don't run it though. How do you like it?

[mrfish2]

Like I said, I didn't put it in until after my test ride today so I've yet to see how it performs. I'm hoping I won't have to rejet anything with it. Why don't you run it?

And I've been thinking about the rejetting with that Moto GP pipe and my K&N filter. I'm thinking that going to 105 or 110 mains should do the trick, along with leaving the needles in the 3rd position from the top. Not too sure about the air screws though. I'll just have to wait till I get that pipe in the mail.

[mrfish2]

So I got the Moto GP pipe and it sounds wicked cool. No more open headers for this guy! Here's some more detailed pics of what my stock exhaust looked like when I took it off:




As you can see they were very rough and were probably a big cause to my tuning/idle issues. Speaking of tuning, I had had one original idle jet and 3 aftermarket jets and so bought some more OEM style from JetsRus. The JetsRus jet is on the left, the original is in the middle, and the aftermarket is the last one. The only difference I could tell were the size of the holes in the stem, with the JetsRus and original being very close, and the aftermarket one having much smaller holes.


So after replacing the idle jets and setting all the floats at 24mm (yes, I know 22 is stock but I don't have the original float needles and float seats in there anymore, they're Keyster brand now and work just fine). 24mm puts the fuel level right between 4 and 5 mm below the bowl gasket via the clear tube method.

Also got 105s and 110 main jets from JetsRus and tried the 105s first. There was a noticeable lack of power and a reluctance to rev past 8k. Here's what the first plug chop looked like for all 4:


So I just got done installing the 110s and here was the result:


This is a lot better than before but still not ideal. Looks like I'll be needing 115 mains now. After getting that dialed in I'll move to the needle clip and idle circuit, which for now they're running pretty damn good.

[Tews19]

Fish, anyway you can get a video of it running?

[mrfish2]

Running at idle? Sure, I can do that tomorrow. What are you thinking Tews?

[Tews19]

Curious of how it sounds. I'm going back and forth on mine if u should bump back up to 110s.

[Stev-o]

Any of the original pipes good?

[mrfish2]

Nope, every single muffler is rotted out and I was basically riding around with open headers. The mounting brackets and exhaust collars were the only things salvageable.

[calj737]

I'd almost suspect your floats are too low contributing to the fuel issues, and not a jet size issue. 4-5mm is a bit low, and yo might try to raise that to 3mm and re-run before bumping your jets.

[mrfish2]

I'd almost suspect your floats are too low contributing to the fuel issues, and not a jet size issue. 4-5mm is a bit low, and yo might try to raise that to 3mm and re-run before bumping your jets.

That's a good idea, i'll try going from 24mm to 23mm and see how it does.

Curious of how it sounds. I'm going back and forth on mine if u should bump back up to 110s.

This one's for you Tews

[mpgholston]

Just read through your thread and was very entertained.  Got my 74 about three months ago and have been sharing some of your pain especially being honked at at red lights while trying to kick her back to life. Mine had been sitting up for 2 yrs+.  I've gone though the common issues: tank rust, dirty carbs, binding front caliper, bad connections/switches, fuel flow, ignition, etc. When I brought the bike home I figured a couple of weeks before I'd get on the road (very naive.) Now I'm thinking I'm about a week away (prob still naive.)

Good luck with completing your rebuild.  The 200 miles I've been able ride so far has been a blast and prove how much worth all the work really is. Man, I wish I was still in college so I'd have some extra time to f*ck with it. Also, the ladies. 

[mrfish2]

Good luck with completing your rebuild.  The 200 miles I've been able ride so far has been a blast and prove how much worth all the work really is. Man, I wish I was still in college so I'd have some extra time to f*ck with it. Also, the ladies.

Having all this extra time to mess with it really makes it easy to get work done haha

I'd almost suspect your floats are too low contributing to the fuel issues, and not a jet size issue. 4-5mm is a bit low, and yo might try to raise that to 3mm and re-run before bumping your jets.

I bumped all the float heights to between 22 and 23 mm (did it all while the carbs were still on the bike, I'm gonna pull them off later to check everything and make sure it's right because I think i might need to move the needle clip again). It seemed to be just a tiny bit better, but still lean. As in I would have to blip the throttle to make it come back down to idle, and I had the air screws at .75 turns out too (with the stock size 38 pilots). Decided to throw some #40 pilots in there yesterday to see how it does and idling in the barn it seemed fine with the air screws at 1.75 turns uut, but rode it to work today and the revs STILL hang up and require a blip to go back to idle. Maybe it's a needle clip issue where the bike wants to stay pulling fuel through that circuit?

While riding to work after the engine got warm I could let go of the throttle and it wouldn't slow down below 4k rpms, does that make sense? I could pull the clutch in too and the revs would stay at 4 to 5k. All of this was while going 60mph. Thought it might be the idle screw but after it finally goes back to idle turning the screw in doesn't affect it much until I know the sucker is turned in too far.

[mrfish2]

Shewww, I've been neglecting my build thread quite a bit. So as it turns out my emulsion tubes were buggered up by a PO, and essentially had a bigger inner diameter than they should have. So after sourcing another set that turned out to be withing spec my tuning has turned out quite well.

I ended up settling with a 115 main jet, needle clips in the middle position, stock 38 idle jets, and air screws at 1.5 turns out. It's still a bit lean in the mid range, but putting the clips in the 4th position makes it run too rich. I'm thinking that oiling the air filter could help a bit (it's currently the STOCK air box with a dry UNI foam filter, I took the K&N filter off because it was STILL lean at WOT with a 120 main jet after replacing the emulsion tubes. I'll save that tuning for another day.) Anyway, the bike runs like a champ (save for a few electrical gremlins) and I couldn't be happier. Now let's strip it all down to the frame!