Topic: Final touches (need help resolving 2 issues in particular).

[Lostboy Steve]

Ok first I still get unburnt fuel out of cylinder 1. I checked EVERYTHING. It doesn't affect power, Its mainly just at idle. (I'm starting to think the ignition wire itself may be faulty, but I do get spark.) Could it be the coil? Cylinder 4 fires perfect. After about 10 miles of so I started loosing power and it seemed that the fuel line was empty. No idea whats going on there. Tank is full, petcock is new,system seems to be venting fine, and everything is clean. Then the next morning I turned the fuel back on and the line filled up and bike ran fine. Lastly, I rechecked all my valves and I notice that cylinder 1 intake tappet has to be turned almost all the way in, in order to be adjusted properly. Only this one is like that. Very strange I thought. Again it is adjusted correctly, but turned in way further than the rest. Also, I don't know how much I should be expecting out of this bike. I feel the power is good but after about 8k or so it starts to taper off, maybe step up my main jets to 110 (currently 105). Check out my video, you can hear the cylinder missing on the left side (but its definitely #1). Disregard my slight exhaust leak, I have to replace the studs on cylinder 3 they don't stay tight.

1977 Cb550k cylinder miss

[Bob3050]

Because the adjuster is so far off I would check the #1 cylinder intake lobe. Check the rocker arm travel of #1 intake as compared to the travel of #2 intake. If #1 is a lot less then your cam lobe may be badly worn.
Bob

[vames]

What bike? I used to have a 76 750F that would lean out on one of the cylinders after about 15 minutes of riding only to come back after 15 minutes of sitting. I'd cleaned the carbs many times, checked for air leaks, checked my coils, and nothing. On the millionth carb cleaning, I noticed that it has little mesh/plastic filter baskets wedged in above the float valves. I'd never seen those in any CB I'd ever owned. Surprise, one was caked full of crud, so gas was only trickling and not filling the bowl fast enough when I was riding.

[Lostboy Steve]

I guess a little history would help. Its a 77 cb550k it had an original 9000 miles on it but sat since 1990 so I tore it all apart. The insides other than having been sitting for forever looked brand new. I had all the valves cut and installed new rings on skirt coated factory pistons. Standard bore. I rebuild the carb's completely. The cam in particular had minimal wear if any in some spots. Thanks for the replies!

[Bob3050]

I'm still hung up on the fact that you have to turn the intake adjuster in so far on #1 cylinder. Since you're sure the cam is good I'd suggest doing a leakdown test to see if #1 intake is leaking. Possible bent valve?
Bob

[Lostboy Steve]

I'm still hung up on the fact that you have to turn the intake adjuster in so far on #1 cylinder. Since you're sure the cam is good I'd suggest doing a leakdown test to see if #1 intake is leaking. Possible bent valve?
Bob

I'm hung up as well. I'll take pics when I get home tonight. No, valves were all checked before reassembly. I have great compression and leak-down results after reassembly. lol its bizarre.

[Lostboy Steve]

Are all intake valves the same length? Now I'm worried the machine shop assembled it wrong after I had them cut all the valves. I know they did a bench pressure test to make sure there were no leaks.

[bollingball]

I would think either the valve is short or the rocker is bent. You have all ready ruled out the cam or the adj screw is wrong to short. I don't know I'm just throwing out ideas. How much would you say is sticking out above the lock nut?

Ken

[lucky]

Are all intake valves the same length? Now I'm worried the machine shop assembled it wrong after I had them cut all the valves. I know they did a bench pressure test to make sure there were no leaks.

On a motorcycle you DO NOT cut valves!

No wonder the tappet adjusters are different.
The valves are sitting in the seats at different heights.
You just install new valves and lap, thats it.

It must have been a car garage that did the machining.
They did not know any better.

What i would do now is just make sure all of the valves are adjusted properly.
Make sure the rocker arm is not contacting the top shim on the the valve springs.
Look for marks.


When you get that done, I would  check the compression on #1 cylinder.


AS for the missing on cylinder #1....

Since it is a 1977 I would take the air cleaners off and with the engine OFF turn the throttle and make sure all of the nozzles are squirting especially #1.
If #1 is not squirting then i would pull the rubber fuel tube that goes from the accllerator pump to #1 nozzle and spray some carb cleaner through it.

[lucky]

I would think either the valve is short or the rocker is bent. You have all ready ruled out the cam or the adj screw is wrong to short. I don't know I'm just throwing out ideas. How much would you say is sticking out above the lock nut?

Ken

Rocker is not bent. trust me.
I have seen rockers lightened to 2.5 ounces and with a high lift cam they do not bend.
They are VERY hard steel.

[lucky]

I guess a little history would help. Its a 77 cb550k it had an original 9000 miles on it but sat since 1990 so I tore it all apart. The insides other than having been sitting for forever looked brand new. I had all the valves cut and installed new rings on skirt coated factory pistons. Standard bore. I rebuild the carb's completely. The cam in particular had minimal wear if any in some spots. Thanks for the replies!

Valves cut or valve SEATS cut???

[lucky]

Are all intake valves the same length? Now I'm worried the machine shop assembled it wrong after I had them cut all the valves. I know they did a bench pressure test to make sure there were no leaks.

IF you had them do ANY cutting on the valve then the valves will stick up different amounts. The valve seats can only be cut so many times, and there are wear limits.
With 9,000 miles I am sure they were fine.

You never cut valve faces on a motorcycle engine. Only cars sometimes. Old cars.

[Lostboy Steve]

They are a very reputable high end machine shop. The guy who did the work has been doing it since these bike were new. I'm sure whatever he did was done right. Anyhow, cutting either of the two would make the valve stick up more. (In that case less adjustment would be needed.) I have to take a pic I didnt get a chance last night but I would say NO threads are left after the lock nut, only the smooth part with the slit for a flathead. Everything checks out other than that one rocker being turned in so much. Bike runs good no engine noise but that one cylinder is the one I'm having a slight miss on. The valve cover is off of an older 550. But all the parts other than the shafts (which have no play) are off the 9000 mile engine.

[Lostboy Steve]

And I meant valve seats cut. Yeah... sorry about the misconception.

[Lostboy Steve]

Are all intake valves the same length? Now I'm worried the machine shop assembled it wrong after I had them cut all the valves. I know they did a bench pressure test to make sure there were no leaks.

On a motorcycle you DO NOT cut valves!

No wonder the tappet adjusters are different.
The valves are sitting in the seats at different heights.
You just install new valves and lap, thats it.

It must have been a car garage that did the machining.
They did not know any better.

What i would do now is just make sure all of the valves are adjusted properly.
Make sure the rocker arm is not contacting the top shim on the the valve springs.
Look for marks.


When you get that done, I would  check the compression on #1 cylinder.


AS for the missing on cylinder #1....

Since it is a 1977 I would take the air cleaners off and with the engine OFF turn the throttle and make sure all of the nozzles are squirting especially #1.
If #1 is not squirting then i would pull the rubber fuel tube that goes from the accllerator pump to #1 nozzle and spray some carb cleaner through it.

Its a 550, no accel pump.

[Lostboy Steve]

Note the last picture how the actual cover is much higher than cylinder 2.