Topic: 1977 Cb550k - tappet hits cover

[Stev-o]

your gonna have to find the cause of the blowing fuse.  Best place to start is the fuse box...

I...yes, especially since he just fixed it. See reply #52

[Can550]

So carb #4 overflow leak mystery solved.

There was a hairline fracture in brass tube. Could not see with naked eye.

Filled bowl with water, attached a fuel tube at the drain nipple, blocked the top hole (with finger) of brass tube and blew through gas tube attached. Bubbles showed up a crack from bottom to about mid point.

Soldered it, tight spot for clean job (plus scared to make holes with soldering gun in brass tube). It's not ideally clean or shiny job but did block the crack from leaking.

Surface of solder is quite rough, does it make any difference ?  I can always smoothen it out with 1000 grit sandpaper if needed.

Gas won't devolve it ?




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[RAFster122s]

Gas will not desolve it.  Pull your drain screw and hit it with a torch.  There is a small oring on the drain screw.  The torch should heat the area so the solder flows smoothly.  But, you did clean the area before trying to solder...right?  Steel wool or sandpaper can work and acetone is a good cleaner that evaporates quickly.
After prepping the area....cleaning it before and after you have sanded the area, you should not have a lot of trouble getting it soldered.  After soldering clean any flux off the soldered area.  A bit of flux is ideal for cleaning and prepping the metal for solder after the manual abrasion.

If it is rough as you say, that is a sign of not enough heat.

David

[Can550]

Thanks David
That's exactly what I did and you are right small soldering iron didn't transfer enough heat on to brass tube therefore solder didn't melt quick enough to flow and form smooth shiny surface. I don't have a torch but if it is absolutely necessary, can borrow from a friend. But if it will work as it is, then I'll put the bowl back
Thanks again


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[Can550]

What causes dark but light flow of smoke from pipe #1?

When I removed the top cover, there was a nut stuck in between valve spring preventing it from compressing (I guess). Now would this prevention have cause any abnormal wear on valve/ valve seal/ seating that is causing smoke ?

Would appreciate a route/ direction to investigate
Thanks




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[TwoTired]

What color smoke?

Blue = oil
Black = carbon (gas)
White = water vapor


Nut in valve spring = high wear on cam lobe and cam follower.

[Can550]

What color smoke?

Blue = oil
Black = carbon (gas)
White = water vapor


Nut in valve spring = high wear on cam lobe and cam follower.

It is somewhat black (ish) smoke only from #1

Replaced camshaft, follower and tappet


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[Can550]

Following are photos of my plugs. New R type plugs with some ideling and about 80-100 miles ride going up to 6000 RPM
What is the verdict from plug colours

I shot with and without flash for better visibility


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[Can550]

The nut blocking valve spring compression likely caused the rapid wear on the cam and follower.
This is good reason to curse the P.O.

If you are happy with the oiling on both ends of cam, replace cam and affected rockers.

The casting numbers are to determine which mold the raw casting came from.  If there is trend data for machining operations showing a consistent problem, they can then retire or repair the proper mold.

Be very careful installing the cover, so as not to bend valves.  Many use rubber bands to hold the rockers up with all the adjusters basked way out.  There is a nice warning drawing in the shop manual, showing contact interference.

You are going to be much happier riding with this motor after this repair.

Cheers,

TwoTired
You were so right. Once fixed, I love it
Went for about 100 miles ride and loved it. Response, power and shifting went very satisfying

Few smaller issues to resolve
1- blackish smoke from #1 pipe
2- air filter replacement is due because it shows age and has gone yellow and seems clogged.

Timing, valve clearance, chain tension all done.

It idles between 1000-1100

Choke is fixed

Oh and by the way, fuse blowing issue cured. Couple of wires had electrical tape, removed it and put shrink sleeve and put right length of fuses. However couldn't find 7Amp for head and tail light so put 7.5Amps ?

What would be a SOHC without this forum? No answer !

Many thanks for being so helpful

All members extended support and assistance which is priceless
Cheers and you all be safe


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[seanbarney41]

It's fun to help when folks listen and things get fixed successfully!

[TwoTired]

Blackish smoke is likely soot.  Which cylinder had the bad cam follower?
Wondering if there was extra soot left in the pipe that is now gradually exiting.

What gets my attention is that all the plugs don't show the same deposit patterns.
If the compression is equal on all cylinders, there are no vacuum leaks, the vacuum balance correct, ignition timing correct, there are no exhaust leaks, and all cylinders drwing from the same filter, then something in the carbs is different for fuel delivery.

Cheers,

[Can550]

Thanks TT
I shall hook up my sync tool again to check

However after last sync, I re did (static) timing and changed plugs. Does it call for re syncing ?

I just noticed a little rust hole towards the tail of pipe number 4 which is popping. Will put a dab of JB Weld to close the hole.

It's the same cylinder that had a nut sitting under valve spring that smokes (#1)

Your point of soot deposits in pipe #1 is ver valid, shall re sync and run it for few hundred miles to see if it clears.

When I wiped the baffle opening, all pipes left a black stuff on towel but #1 and 4 were the most.


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[TwoTired]

Only things that change the cylinder draw affect the carb sync; compression, valve timing and lift, or duct leaks.

Exhaust leaks can effect carb delivery requirment, due to cylinder scavenge variations.

The spark plig deposits will tell you if it is still making soot.

Cheers,

[RAFster122s]

There are drains in the mufflers, do not block these or any condensate will not run out of the bottom of the pipe.  That was their intent.
While your sync might be OK it appears your mixture is not correct for all cylinders

[Can550]

There are drains in the mufflers, do not block these or any condensate will not run out of the bottom of the pipe.  That was their intent.
While your sync might be OK it appears your mixture is not correct for all cylinders

Thanks for pointing out. I have seen those drain holes but this particular one is rust hole though very close to factory drain hole


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