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Discussion Starter #1
Howdy Howdy.

Did a valve adjustment recently and jetting change on the carbs (including removing the jet shims), I had to remove the cam holder to heli-coil a bolt my friend broke inside the cam holder as well but it shouldn't have effected much.. and have come forward with an issue of a greyish color exhaust coming out of ONLY the rear cylinder and smells burnt but not sweet indicating it's not coolant.
Could this be an issue of A/F? Could the valves be set incorrectly?
I've been racking my brain and google for a few days about this now.
I checked the intake boots, and they seem fine, no major cracking or breaks (I also used silicone on the outside just to be sure). the idle jet is the same as stock with 2.5 turns out roughly. Which is the same as previous so the rough idle and smoke wouldn't make any sense.
Figured a collective opinion might be more helpful than one person trying to attack it alone.

https://photos.app.goo.gl/cP5t6WGV1M5SkvBCA

It's usually like this, sometimes worse for a second or two.
 

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Did you have to move the valve adjusters very much? Usually they are only out a thousanth or so and don't need much of a turn to adjust.


Pull the spark plugs to see what their color and appearance is.
 

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Discussion Starter #4
Did you have to move the valve adjusters very much? Usually they are only out a thousanth or so and don't need much of a turn to adjust.


Pull the spark plugs to see what their color and appearance is.
They weren't terribly off, but we brought them within spec and put everything back together after a double check.
I had to helicoil the thread that was broke off, but removing the entire camshaft holder couldn't have done much for the adjustment no?

And in regards to the sparkplug, it's still quite fouled up from the previous jetting (which was realllllly rich. Part of the reason I messed with the needle and main jet to bring it down)
 

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Maybe start with new plugs and go from there.
 

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The rear cylinder which is burning the oil is the same one that was running in your words "realllly rich" previously. If this condition lasted long wnough, there's always the possibility that the excess fuel was washing the oil off the cylinder and scored the walls themselves.


I'm just trying to brain-storm here and not trying to diagnose it at this point.
 

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New plugs are always a good start giving a "clean slate" spark plug diagnosis.

I'm joining Chuck in the brain-storm.

I know from past experience with my 750 ACE that the mis-routing of choke/enrichment cables can create problems with the plunger thing in a carb not going fully into the hole despite the choke control being fully pushed in.

This causes a high idle on the effected cylinder and blackish smoke from the one cylinder, when the engine is throttled up.
This is usually accompanied by "the neighbor's lighting the charcoal grill" smell.
 

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Discussion Starter #8
The rear cylinder which is burning the oil is the same one that was running in your words "realllly rich" previously. If this condition lasted long wnough, there's always the possibility that the excess fuel was washing the oil off the cylinder and scored the walls themselves.


I'm just trying to brain-storm here and not trying to diagnose it at this point.
Well, the smoking wasn't prominent before, this happened with the recent (I guess you'd call it) full tuneup of the valves and misc.
I did put new plugs in, and it didn't change anything. Gonna take it apart tonight and see if the timing is off (as the honda dealership suggested) incase we did accidentally change the valve lashings off-timed.
 

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If you didn't unbolt the cam gear and slip off the chain the cam timing should still be where it was.
 

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If you didn't unbolt the cam gear and slip off the chain the cam timing should still be where it was.
That is true.

I think what the dealer's advice might be considering is the valves may have been set at the wrong cam position, it is a bit if a stretch, but the crank timing positions do line up twice per cam revolution, so two potential choices and only one of them is the right place to adjust the valve clearances.
 

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Discussion Starter #11
I just took the rocker arms off where the cam holder is.
Didn't directly mess with them.
But friend said he might've adjusted them at the wrong time rather than at TDC
 

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Possible it was on the wrong cylinder TDC mark. If you take out a spark plug and put a plastic straw or small dowel into the cylinder and turn the engine slowly till the piston is at the very top TDC, and all the valves are a little loose, that is the correct position.
 

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Discussion Starter #13
Possible it was on the wrong cylinder TDC mark. If you take out a spark plug and put a plastic straw or small dowel into the cylinder and turn the engine slowly till the piston is at the very top TDC, and all the valves are a little loose, that is the correct position.
I'll check that next, I'm hoping it's something as simple as that and not a scoured cyl wall/piston.
I'd be sad as hecc.
It's a teardown kinda night at Midnight LOL
 

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A compression test may be in order. Wide open throttle should be up to 180 + pounds.
 

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Discussion Starter #16
Alright, small update here.
I redid the valve adjustment for the rear cyl. They did seem quite a bit loose.
I'm also going to put a 102 and a 106 Stage 1 jet kit that I removed before back in and setting the needle to 2nd notch down from the top.

Hoping with all of this done.. that it's all set and good.
 

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Discussion Starter #17
Alright, well.
I for sure did things right this time around, put everything back together, made sure it was all relatively decent in terms of jets, tubes, settings, etc.
my last idea is possibly a carb sync???

Like, beyond that there's major issues like piston rings or scoured cyl wall.
 

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Discussion Starter #18
After letting the engine warm up so I could sync things, it basically spews smoke now when accelerating even in Neutral..
I'm going to compression test it tomorrow to see if it's the piston rings.

If it isn't.. then i'm at an ABSOLUTE loss.
 

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Discussion Starter #20
1) When was the last time the bike ran perfectly?

2) What changes were made to the bike after it was running perfectly?
Before I did these changes really, though it wasn't "perfect" as the rear idle has always been kinda lumpy and I was having some low-RPM shakes.
Which is what caused me to assume it was valves really.
 
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