Topic: 1976 550K Project

[mrfish2]

Replaced the plug caps with new NGK's and that seemed to help a lot. Two of the spark plugs were foulded too. Measured the resistance on the old plugs and got 10.5, infinity, 13.2, and 9.7 (first number corresponds to first cylinder and so on). So the new caps helped the idle tremendously, but the #4 cylinder is still cold.

My parents visited me this past weekend and my dad noticed the bike was blowing a little bit of blue smoke out the back, so i have a compression gauge on the way (none of the local places had the right size that would fit the spark plug holes). It might be time to replace the rings, and I'll probably drop in the 650 cam while I'm at it.

[mrfish2]

Still having trouble getting it to run right and it's no where near in the shape I want it in, but on my way home tonight I just had to stop and snap a quick pic with my phone of the cool streetlight scenery. Enjoy.

[mrfish2]

Small victory today: finally have the use of my electric start! No, I didn't rebuild the right hand controls (though that is on the to-do list). Thanks to the guys at Cognito Moto I got a small push-button switch that I could wire in place of my original starter switch. Please don't yell at me for drilling a hole in the headlight bucket haha, I was gonna mount it in on the headlight ears where I had taken the turn signals off, but it was too small to fit well.

[rb550four]

Is there fuel in the #4 bowl ? When the bowl drain is open, does the fuel run strong out the bottom?
If you lay a plugged in spark plug across the head on #4 do you get steady spark? What color? and is #1 pipe as hot as  #2 and 3?
+1 on the carb clean if it hasn't been done yet. New needles and brass bits....in a dirty carb doesn't make much sense. Do a good cleaning. Blow out every orifice , then do it again. examine every piece ,every O ring, make sure each open orifice blows air out the other side especially the fuel supply in #4. Set your float height on each correctly and button them up. A nice vacuum sync never hurts either.
  If it isn't carbs , it would be spark, check all the plugs ,caps, and wires(especially if someone cut them short)make sure they are all sparking with a spare (new plug that works)
Have you changed out the 40 yr old condensers ? just wondering.

Soryy, I just read back a page , didn't Cal mention all of this already?

[mrfish2]

Is there fuel in the #4 bowl ? When the bowl drain is open, does the fuel run strong out the bottom?
If you lay a plugged in spark plug across the head on #4 do you get steady spark? What color? and is #1 pipe as hot as  #2 and 3?

Have you changed out the 40 yr old condensers ? just wondering.

Fuel does run strongly out of the bottom. I've still got to find some time to check the float level by the clear tube method, but now I've got other worries as I'm getting gas in my oil.

It sparks a strong blue spark across all four plugs, but after riding up the road the cylinder is still cooler than the other 3. And yes, #1 is just as hot as #2 and #3. I'm starting to think it might be a valve issue.

[rb550four]

Valve issue? Why? Have you given it a compression test and found very low to nothing in #4?
How much fuel was on the #4 plug after the ride?
 Are your overflow tubes plugged? You need to set those floats correctly  and if you think the float pin is hanging it up , clean the floats were the pin goes through , polish the brass pin so it slides nicely into the floats. This hang up wouldn't have anything to do with plyer marks would it? Is that the needle we are talking about? If it isn't, and we are talking about a seating issue with the float valve, there is a toothpaste trick somewhere on this forum that would help it seat better if it's sticking.
Sounds like a carb clean is in order again if you haven't done it already. You are using compressed air right?
  My guess is your carbs are still dirty, the overflow is clogged,and either the float pin has been boogered up to where it won't allow the floats to operate properly or the float valve is not seating or is installed upsidedown....in any event I think your over flow  is flowing down the #4 cylinder, passing through the rings and ending up in your oil while is rests and fowling the plug when you run...that's my guess. Have you checked your oil ,does it smell like fuel?
  And if this is all or partly true,  you  need to address these problems before they turn into a BIG problem.

[mrfish2]

Valve issue? Why? Have you given it a compression test and found very low to nothing in #4?

Compression test proved nothing was wrong, I was wrong to assume a valve issue.

How much fuel was on the #4 plug after the ride?

Quite a bit, it was wet with gas.

Are your overflow tubes plugged? You need to set those floats correctly  and if you think the float pin is hanging it up , clean the floats were the pin goes through , polish the brass pin so it slides nicely into the floats. This hang up wouldn't have anything to do with plyer marks would it? Is that the needle we are talking about? If it isn't, and we are talking about a seating issue with the float valve, there is a toothpaste trick somewhere on this forum that would help it seat better if it's sticking.

All the brass has since been polished up and carbs have been cleaned as noted below. I didn't find any plier marks either, everything was smooth. The needles are original parts, but the float valve needles are new (and have been cleaned again).

  My guess is your carbs are still dirty, the overflow is clogged,and either the float pin has been boogered up to where it won't allow the floats to operate properly or the float valve is not seating or is installed upsidedown....in any event I think your over flow  is flowing down the #4 cylinder, passing through the rings and ending up in your oil while is rests and fowling the plug when you run...that's my guess. Have you checked your oil ,does it smell like fuel?
  And if this is all or partly true,  you  need to address these problems before they turn into a BIG problem.

I make sure to turn the petcock off when I park the bike, but I think you're right about it getting past the rings somehow. And yes, the oil smelled strongly of gas. I have since drained it.


I've done quite a bit of work over the past couple days. Bought a gallon can of Gunk Carb Dip and proceeded to tear down the carbs again for a nice soak. They cleaned up better than I expected. After I reinstall them on the bike I'll be checking I set the float level accurately with the clear tube method.







While they were soaking I started to tear down the top of the motor to go ahead and do my 650 cam swap. Upon trying to loosen the cam chain tensioner I realiezed it was stuck. I let it soak overnight from PB Blaster but it still wouldn't loosen up. Ended up having to cut the nut and screw off.



Now I'm waiting on another bracket to come in the mail so I can replace the broken screw and put my cylinder head back on. I'm also waiting on my buddy to get here to help me get the head off. I'm hoping I don't find anything unusual once I get it pulled off. And hopefully I can reuse the head gasket too, my budget is tight right now.

Also decided to cut the front off the front fender. The orginal owner laid it over once and it ground the fender stay and fender a little bit on the side. I have to say I'm happy with the result of cutting the fender, it looks a little bit better. Just used tape to mark where I wanted to cut and used a Dremel to do the cutting.





Oh yeah, when I was reassembling the carbs I had a scare of tightening one of the pilot jets too tight and it sheared off in its hole. I ended up being able to get it out with a small tapered tap.





All of the gas-smelling oil has been drained out of the bike. I still need to get some more oil to cycle through it and get the rest of the old oil out, but that'll happen later this week. I've also been gathering parts to do a dual disc conversion with 750 brakes and a GL1000 master cylinder. That might have to wait till the summer though.

[mrfish2]

Pulled the head off the bike to discover (per Hondaman's observant eye) that the #4 piston rings weren't sealing at all, so it's confirmed that's how I was getting gas in my oil. (#4 valves are on the far right)



Measure the cylinders to check that they were within the spec limits (they were), then proceeded to check the ring gaps as well. Almost immediately broke the top ring off of one of the pistons when I tried to remove it....



And this is how she sits now. Gotta finish getting the old base gasket off before I can go any further.



So now I've got a set of rings on the way (the $40 set on ebay from Cruzin Image) and when they get here I'll hone the cylinders as well. I was trying to avoid putting new rings on but in the end it's the smart thing to do. I went from a simple cam swap to an almost top end rebuild...

[Stev-o]

Did you measure your cylinders?  Might be time for a big bore kit!

[SOHC4 Cafe Racer Fan]

I think they were in spec according to his post.  That said, it might make sense to do the cruzin image 600cc kit while you have it torn apart.  Only $120 for the whole piston kit.  That combined with a port job will wake up the motor.

[mrfish2]

I really want to do the big bore CruzinImage kit, but can't afford it at the moment. The cheapest I've been able to get a local machine shop to quote me on boring and honing the cylinders was around 400 total. I've read good stuff about that kit on this site so I'll be saving up to do it in the future.

[Stev-o]

$400! Send them up to me, $40/hole is what the local shop charges me. $400, that's robbery!

+1.  I just paid $50/hole for my H1 and that included chamfering the ports (2 stroke)

[mrfish2]

Hmm...maybe they didn't understand what I wanted done. Still, even if I found a place to do it for $50/hole I couldn't do it for a while.

[SOHC4 Cafe Racer Fan]

You should think about Cal's offer. I just sent him my cruzinimage pistons for thermal barrier and dry film lubricant coatings. Much cheaper than anywhere here local.

[mrfish2]

If it comes to that then I might consider it, I appreciate the offer.

Anyway, the rings got here today, a lot quicker than I thought, so i went ahead and installed them along with honing the cylinders. I had spent the last couple days cleaning off the old base gasket material. Put the new base gasket on, installed the rings, and put everything back together. Sorry I don't have any pics, it was getting dark and I was excited to have everything back together. I stopped after I got the new 650 camshaft installed, so tomorrow I'll be putting the rocker cover back on along with the carbs and checking them via the clear tube method. I'll also cycle some oil through it to make sure I've got all the old gas-stained oil out, then drain that and put fresh oil back in it. So just another day's work and it should be back to running condition, I just hope I did everything right and nothing unexpected happens. Still waiting on some copper crush gaskets to get here for the exhaust.

On a side note, DO NOT buy the Advance Auto brand honing tool, it was a piece of junk. I made it work for what little I needed it for, then returned it. I can't even describe how much of a piece of junk that thing was. It's entire design was piss poor.

[mrfish2]

Thanks for the reminder on that Cal, checked the torques the next day and everything was good to go!

So since then I've gotten everything buttoned back up (after polishing a few parts on my bench grinder with a buffer wheel) and she's starting to look like a bike again.



I had a hard time getting her to fire up the first time, and discovered my 2/3 points weren't opening at all. Reset the gap and timing and she lept to life (albeit not very smoothly). So the next thing to check were the float levels via the clear tube method, and all 4 looked like this:



I had set the levels with a caliper to 22 mm before putting the carbs back on, but it seems another member was right in assuming that the new float needles require a different float height. I had checked all 4 today, but only got 2 adjusted before it started raining. I'll finish up the other 2 tomorrow. Also to make sure I wasn't getting any trash from my tank I attached some clear tube to the petcock and ran it to a clear jar, and luckily nothing bad came out so don't think anymore trash will be gumming up the carbs (for now....).

I'm also still having issues with getting the headlight to come on and having some oil weepage around the cam tensioner screw (i think). The headlight worked fine before I pulled the top end off but now it doesn't want to come on so i'll be checking all the connections tomorrow as well. I have an assortment of o-rings to try in place of the old one on the cam chain tensioner screw, hopefully that will solve the oil issue. I wasn't able to find anywhere around the head or base gasket that was leaking.

[mrfish2]

That's a neat trick, I'll have to try that!

Set the float levels all to roughly this level (+/- 1 mm):



But I'm still having an idle issue. It starts up fine, and even runs strong through all the gears, but won't idle for anything. I've adjusted the valves, cam chain, and set the timing. I benched synced the carbs before mounting them, still have to buy a vacuum gauge though. I'm not sure what else to check....

Oh, and the headlight decided to come on today for whatever reason. That thing is more buggy than my little cousin's ant farm.

[jtran000]

subscribed!  i'm about to tear into my build and the first thing to do is carbs.  Thanks for all your info thus far! 

[mrfish2]

If i turn the idle screw in (as in way past where it should be) then it'll idle fine for a minute around 1100, then go way up to around 3000. So yeah, it'll surge a little. Giving it any choke kills it. This has gotta be a fuel issue, right?

[mrfish2]

Yeah my next idea would have been to adjust the air/fuel screw, right now I've got it at 1.25 turns out. I replaced bits and pieces from Napco rebuild kits a while back, specifically all the pilot jets, main jets, and float needles and seats. All of that was due to when i got the bike most of those pieces were missing. I left the original needles and emulsifier tubes alone though, simply hit them with a brass brush and some carb cleaner to make them shine again.

Yes, all four headers are equally hot.

The exhaust is the stock 4 into 4, but it's badly rusted out where the muffler is welded to the header. The baffles are still there, though it's definitely louder than stock.

Edit: I just remembered it's still got the original paper air filter in it, i haven't been able to find a suitable replacement yet.

[mrfish2]

Yep, no leaks around the boots.

[mrfish2]

All 4 of them look like this, and they were brand new NGK D7EA's when I installed them roughly 20 miles ago.

[mrfish2]

That's some good info, I'll be sure to save that link. Going off of that it seems it's running pretty rich, but does that affect the idle?

[seanbarney41]

How long did you let it run before you tried to set the idle speed?

[mrfish2]

I let it get good and warm before trying to set the idle screw, but no matter what I did it still wouldn't idle. After it has sat overnight it'll start right up on the first kick, jump up to around 3k rpm and stay there for a few seconds, then drop down and bog out.

If I dropped down a size in pilot jet (from 38 to 35) do yall think it would help any?

Tried to go for a long ride the other day and when we stopped for a break i discovered I had lost about a quart of oil. Figured out it was my head gasket. Guess re-using the old one wasn't such a good idea.