Topic: Got rid of my 550K... and replaced it with a 550F and a 350F

[HondaMan]

After some wrangling I got the airbox and plenum mounted.

I spent an hour looking for my hydraulic jack as I was going to remove the engine mount (save one) to make some more space. Never found it, WTH. I figured I would get to work, then look again. I thought I might be able to get away with it without removing the carbs, but not a chance. And then I remember how easy it was to remove carbs with pods, so no big deal. Mounted the airbox and plenum and left them unbolted to the frame, slid the carbs back in, and everything lined up nicely. Had the exhaust off as well, so put in the new seals and cleaned up the chrome behind the silencer. While I ad the tank off, I replaced that one last damn allen bolt on the valve cover and had a look at the tach drive. It's in one piece thankfully so I imagine it is just the seal -- will pick one up next time I am in the USA. Frustratingly found two imperial bolts at the motor mount in the front -- those will be replaced too.

Hooked up all the hoses (am missing the hose for the plenum but I have one on order) and tightened and double checked all the motor mounts, the exhaust and the RHS foot peg. Fired her up and she purred.



Went out for a ride and there is some improvement -- it idled smoothly just after 1k (it was idling around 1.2k before, with a little chugging. It was a lot quieter. But...

Now it's time for diagnosis. It bogged around 3.5-4k rpm, and although I only rode it for half an hour, it got worse. So clearly it is running a lot richer at this altitude (7500 feet) than it did with pods. I'm going to have a look at the plugs, and verify the jet sizes. Some rejetting might be in order as a first step.

The bike ran and pulled really well with the pods, just a little stutter starting off and a little chugging at idle. I could live with both so if it comes to it I could always just throw the pods back on and be content. But I will give rejetting a try, and adjusting the idle mixture. I'm going to give it a 3k-mile tuneup as well.

For anyone else at high altitude, anyone mess with spark plug heat range? I've got either D7EA or D8EA, will have to have a look when I pull them, but wondering if anyone else at altitude has any recommendations. It doesn't ever get too hot here (last year was over 90 for 2-3 days, which broke records, but usually 75 - 80 on warm days, and in the winter down to 35-40).
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Checked the plugs, pretty sooty. Leaned out the idle mixture a little, although I know that's not going to help at higher revs.

Opened up a carb -- 38 slow jet and 100 main. Both have no marking, so I assume they are aftermarket. Stock should be 38/98 so PO must have stepped up the main for the pods. I should add that the o-ring for the main isn't sealing -- it just dropped right out after I dropped the bowl.

That shot's gonna look SO good in my pages...

The richness is due to the pod filters, happens every time. Once you find that airbox, the #7 plugs will be spot-on with (USA type ) Regular grade gas.
Your spark advancer is likely advancing too soon, which also makes for rich running because it makes the cylinders spit back at the intake during late overlap stroke with too much advance on tap for the waste spark. This then leans out the next incoming charge a bit (by burning part of it), making a 'flat spot' starting right around 1600 RPM that lasts to about 2500 RPM. If the advance doesn't come all-in until at least 3250 RPM, it has lots more bottom-end torque. I try for 3500 RPM on rebuilds, if I can get the carbs used on the bike.

[carnivorous chicken]

Ah, thanks for that, will check the advance when I do the tune up!

[scottly]

Checked the plugs, pretty sooty. Leaned out the idle mixture a little, although I know that's not going to help at higher revs.

That was with the stock airbox and pod jetting, correct? Did you ever check the plugs before changing to the stock airbox?

[carnivorous chicken]

Checked the plugs, pretty sooty. Leaned out the idle mixture a little, although I know that's not going to help at higher revs.

That was with the stock airbox and pod jetting, correct? Did you ever check the plugs before changing to the stock airbox?

Yes, with the stock airbox and slightly bigger main jet. And yes, I've checked the plugs a couple times. Rode it a bit up here then did a tune up. Then checked plugs a couple hundred miles later and they looked fine. No sign of any running issues. I've probably put 1200-1500 miles on it up here so far.

[carnivorous chicken]

Updating here as well...

Keihin's next lower jet for this bike is an 80, so I've ordered 98s and will try them with less restrictive air filtering (I've ordered some uni foam). IF that doesn't work, a member here pointed me to a shop in AZ that custom makes jets -- he said he runs 90s at 4000+ feet elevation. That might be my next step if the 98s don't do the trick.

[denward17]

Updating here as well...

Keihin's next lower jet for this bike is an 80, so I've ordered 98s and will try them with less restrictive air filtering (I've ordered some uni foam). IF that doesn't work, a member here pointed me to a shop in AZ that custom makes jets -- he said he runs 90s at 4000+ feet elevation. That might be my next step if the 98s don't do the trick.

If you are still rich with the 98s, a needle adjustment down could help lean it out some, depending where in the throttle range you are having issues.

[carnivorous chicken]

Updating here as well...

Keihin's next lower jet for this bike is an 80, so I've ordered 98s and will try them with less restrictive air filtering (I've ordered some uni foam). IF that doesn't work, a member here pointed me to a shop in AZ that custom makes jets -- he said he runs 90s at 4000+ feet elevation. That might be my next step if the 98s don't do the trick.

If you are still rich with the 98s, a needle adjustment down could help lean it out some, depending where in the throttle range you are having issues.

Yep, thanks, should have added that. Will be giving it a full tune when I get back from OH as well, and will check the advance.

[HondaMan]

It's helpful to note: in the earlier 500/550 carbs (before the last 2 models) the airflow between approximately 80% throttle and wide-open throttle does not change the mix very much. This is due largely to the intake valve's size and the length of those long intake runners. It is very similar (almost identical) to the CB125 singles, which have a 2mm larger carb and similar intake runner: the float bowl level has more effect in the 80%-100% throttle range than does the mainjet.

[carnivorous chicken]

It's helpful to note: in the earlier 500/550 carbs (before the last 2 models) the airflow between approximately 80% throttle and wide-open throttle does not change the mix very much. This is due largely to the intake valve's size and the length of those long intake runners. It is very similar (almost identical) to the CB125 singles, which have a 2mm larger carb and similar intake runner: the float bowl level has more effect in the 80%-100% throttle range than does the mainjet.

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I will check float height at some point, thanks. I've got a clear tube set up so it'll be easy.

[carnivorous chicken]

The shop in AZ that was going to make some jets for me -- I was going to try 92 -- had painstakingly slow responses to emails. Once a day, if that, even though I explained I was going to be in the US and owuld pay priority to get them shipped. They quoted me a price and then... told me they couldn't do it.

But... the uni foam and filter spray I ordered came on Saturday. Today I cut a strip equal to the width of the airbox and folded it over twice after spraying and installed it right up against the hole to the plenum. Started up, idled nicely, took off down the street... and then it bogged. Wouldn't go up a hill. Opened up the airbox and repositioned it so the filter is up against the cover/intake. Roared back to life, climbed the hill, and got me to work with no issues, including a brief stint at 60 in 4th. No bogging, no popping on decel, seems to have done the trick. I am going to take some time and figure out how to mount the foam a little better but this might just work. I've still got Keihin 98s coming which should be in Ohio when I get there, and I'll install when I get back (still haven't done the tune up (but did last summer, only about 1200 miles ago), and now might check float level while I am at it). Will read the plugs as well.

[HondaMan]

The shop in AZ that was going to make some jets for me -- I was going to try 92 -- had painstakingly slow responses to emails. Once a day, if that, even though I explained I was going to be in the US and owuld pay priority to get them shipped. They quoted me a price and then... told me they couldn't do it.

But... the uni foam and filter spray I ordered came on Saturday. Today I cut a strip equal to the width of the airbox and folded it over twice after spraying and installed it right up against the hole to the plenum. Started up, idled nicely, took off down the street... and then it bogged. Wouldn't go up a hill. Opened up the airbox and repositioned it so the filter is up against the cover/intake. Roared back to life, climbed the hill, and got me to work with no issues, including a brief stint at 60 in 4th. No bogging, no popping on decel, seems to have done the trick. I am going to take some time and figure out how to mount the foam a little better but this might just work. I've still got Keihin 98s coming which should be in Ohio when I get there, and I'll install when I get back (still haven't done the tune up (but did last summer, only about 1200 miles ago), and now might check float level while I am at it). Will read the plugs as well.

Nice save!

[carnivorous chicken]

A bit too premature, unfortunately. Went for a longer ride, and it started to stumble. Went out of town last week and came home with a sprained wrist, purple knee, and hematomas on my hip (about 12" around) and thigh from a crazy fall. But I did receive the jets -- Keihin 98s and 35s. Decided that I would pull the float bowls and replace the jets and see what that did. And as I pulled down the #4 carb body, down came... one of the float posts. So I just posted in the wanted section, looking for a #4 carb body (or rack if I have to).

From a solid running bike with pods to wrangling on the airbox and trying this and that to get it running right, knowing I can just put those pods back on. Not sure if I am stupid or stubborn but I'm not riding this one for the near future. Will get a few more things done to it while it's down, though -- tach drive seals, new o-rings for the manifolds, some more cleaning...

[denward17]

I guess #4 carb was your problem all along?

Sorry about your injuries, hope you heel up soon to get back to riding.

[newday777]

Was the fall off from the bike??

[carnivorous chicken]

I guess #4 carb was your problem all along?

Sorry about your injuries, hope you heel up soon to get back to riding.

It's possible. Seems like it was in place but I might have bumped it -- definitely nothing severe, maybe it was just waiting. But regardless, hope to have a replacement carb body, put in smaller jets, move the needle one stop and go from there. Returning to pods is always an option and, honestly, more and more appealing, but I've come this far and want to see it through. Just bummed I won't be riding it at all until a replacement carb gets here. I'll also take it to a shop or two here -- it's Mexico so I am guessing there might be some wizards who might be able to repair it... And thanks.

Was the fall off from the bike??

Skateboarding! I went to an academic conference in Columbus, but there was a skatepark there that I skated back in 1992 (and I corresponded with but never met the guy behind the park). So I met him there and half an hour in I just took a completely random slam, don't know how it happened. I walked it off and skated a little more, but couldn't move my wrist or grab anything, which is why I thought I might have broken something. Was going to wait until I got back to Mexico to get an x-ray, but it felt better the next day (not good, but I could pick stuff uo). My bruises are getting more colorful every day. I'll be fine though, just my turn to pay some dues.

[newday777]

Heal up.

[carnivorous chicken]

Thanks!

[Stev-o]

I guess #4 carb was your problem all along?

Sorry about your injuries, hope you heel up soon to get back to riding.

It's possible.

Was the fall off from the bike??

Skateboarding!

Years ago, I wanted to be one of the "cool kids" and I picked up a long board and headed down to the Galveston Seawall to learn how to skate. About 30 min into it, I took a nasty spill scraping up my left forearm on the rough concrete!  I thought that was enough of that, went home, hung the board on the garage wall where it still is to this day...HA!! 
Wakeboarding is more forgiving, the water has never hurt me.

[grcamna2]

I guess #4 carb was your problem all along?

Sorry about your injuries, hope you heel up soon to get back to riding.

It's possible.

Was the fall off from the bike??

Skateboarding!

Years ago, I wanted to be one of the "cool kids" and I picked up a long board and headed down to the Galveston Seawall to learn how to skate. About 30 min into it, I took a nasty spill scraping up my left forearm on the rough concrete!  I thought that was enough of that, went home, hung the board on the garage wall where it still is to this day...HA!! 
Wakeboarding is more forgiving, the water has never hurt me.

The Beck's poster looks great.

[seanbarney41]

Steve-O, skateboarding is an activity where everyone has to "pay their dues".  Everyone falls off, sometimes more, sometimes less, generally everyday.   The better the skater, the better you are at falling, and skateboards do not work on soft surfaces. lol

I skateboarded everyday from the age of 14 until I was around 30.  I had to stop when I tore my ACL and did not have health insurance.  I still do not have an ACL but I think that the injury avoidance skills I learned though skateboarding have helped me avoid injuries in motorcycle crashes. (knocking on my wooden head!) I have dumped it on the street at least 4 times and always rode home on the bike that I dumped.  A few years ago, I decided to try dirt bikes, as I feared that the "dues collector" might be looking for me after many years.  So now I keep the injury avoidance skills practiced up in the tight sandy trails of Michigan where 25mph is really flying.

[carnivorous chicken]

Years ago, I wanted to be one of the "cool kids" and I picked up a long board and headed down to the Galveston Seawall to learn how to skate. About 30 min into it, I took a nasty spill scraping up my left forearm on the rough concrete!  I thought that was enough of that, went home, hung the board on the garage wall where it still is to this day...HA!! 
Wakeboarding is more forgiving, the water has never hurt me.

Some of us are dumb enough or stubborn enough (or both) to keep slamming. I've had about a dozen surgeries, a few more broken bones on top of those that didn't require surgery, I'm missing my PCL, and I've got a couple of steel plates but... I'm still doing it. When I was younger I had sponsors and so I got to travel and enter contests, but I realized I wasn't going to be one of the top guys (and at that time that was about 2-3 dozen, not the hundreds who are pro today) so I started school. But I still do it, work tangentially in the industry as a side hustle, and this year is my 50th year of skateboarding. I haven't had a surgery or broken bone for about 9 years but I have slowed way down.

[scottly]

Back in my day, there weren't any skate parks locally, so we rode in drainage ditches and the like.
BTW, if you don't find a replacement carb body, member JimF can weld that float post back on.

[Stev-o]

Steve-O, skateboarding is an activity where everyone has to "pay their dues".  Everyone falls off, sometimes more, sometimes less, generally everyday.   The better the skater, the better you are at falling, and skateboards do not work on soft surfaces. lol

Yeah, I get that.  It just seemed my crowd wasnt into it back then, we were riding bicycles and dirt bikes.
But my brother's daughters had longboards and we rode them. I now recall my brother taking a nasty spill and slammed his elbow on the concrete, that was the end of his skateboarding!

[carnivorous chicken]

Back in my day, there weren't any skate parks locally, so we rode in drainage ditches and the like.

Nice. Was this in AZ? There are still some great ditches there, and I skated mostly pools for the years I lived there (and when I go back). We skated the famous pipes that were on the cover of Skateboarder in the 1970s, a long but great story (they're underground now, and a new freeway goes close to them). But yeah, there are also a ton of parks now.

[scottly]

The Funnel was in Lopez Canyon, above Lopez Lake, near San Luis Obispo, CA. The pics were taken in '78, and that was probably the last time I did any serious skating. I had just bought a new Santa Cruz deck for my already old Tracker Trucks and even older Sim's Pure Juice Bowl Riders, and having been there some years before, and living in SLO at the time, I figured that was the best place to check it out.
It got really steep, really quick; if you didn't get out by where the truck in the second pic is, you were going to get hurt.