Valkyrie backfiring - FIXED!!!

[Jersey]

Hey All,

Here's the background:

1. Started with the bike running fine, had 60k so decided to change the timing belts
2. New belts on timing was done correctly, but engine was running VERY roughly, found low compression on cyl 2 & 5 (90psi).
3. Pulled heads took to machine shop, they found those two valves were burnt.  Completely reconditioned, new valves for the burnt ones. Reinstalled and compression was great all around.
4. Put belts on, verified timing, hand turned many times. Re-Gapped rockers.  Did everything by the book - literally.
5. Pulled plugs all cyls are black/sooty EXCEPT cyl 4 (middle left side)  That plug is looking like it's supposed to look.


I don't think it's the plugs as they were running fine before... unless there's good reason.
Things I still plan to do:
1. Check coil resistances
2. Check Plug wire resistances


When I was checking the compression the first time, I did disconnect all the plug wires to turn it over.  I'm wondering now if that may have cause damage in the coils due to buildup... Is that possible?

Would appreciate if you could checkout the videos and give any suggestions on what to check.

Thanks all,
Jersey

[Jersey]

I'm going build a Peak Voltage Adapter and see if the Pickups or coils are bad... Considering all (except one) of the cylinders isn't working efficiently, It could be one of the pickups.

[indybobm]

Jersey, don't take this wrong, but...
In step 3 you installed heads and compression was good.
In step 4 you install the belts.
How did you check compression in step 3 if you did not install the belts until step 4.
Has there been some action left out?

[Jersey]

Jersey, don't take this wrong, but...
In step 3 you installed heads and compression was good.
In step 4 you install the belts.
How did you check compression in step 3 if you did not install the belts until step 4.
Has there been some action left out?

Lol.
Thanks!  Yeah, my fingers we typing faster than my brain
Belts on, all assembled, and then tested compression.

Appreciate the point out!

[Jersey]

Update:  Measured the Peak voltages and they're low
1&2  79
3&4  91
5&6  87

This lines up with the #3 sparkplug looking normal and the #4 not look as bad as the rest.

Since the coils are all generating a spark in each of the plugs, this appears to be a bad ICM. 

SOund about right?

[indybobm]

According to your original post, this problem started immediately after replacing the belts. How would that make the ICM go bad? Problem should be at the front of the bike or something else that happened that you did not mention.

[Jersey]

When I tested the compression after putting in the new belts I forgot to leave the plugs in the plug wires to ground out and discharge the HV.  I' ve read that this can cause feedback into the icm and make it go bad.

[falconbrother]

It sure sounds like that timing was off.  Valves burn when they don't seat properly.  They cool by transferring heat into the head.  If it was running good before and all that was done was the belts it's gotta be the cam timing. 

[3W-lonerider]

my guess is the valves aren't set properly. if they aren't seating when closed the compression is gonna come out of the crack.
if it were me I would double check those valve settings.
second guess would be.. are you positive you don't have plug wires reversed on a couple of plugs.
not doughting your mechanical ability. but iv'e been turning wrenches for 40 years and I still screw up from time to time.

[Jersey]

Always appreciate the "did you check....? "   keep em coming!

Compressing is good all around still. 2bl checked wires are correct placement.

Ordered the icm, should be here Friday. Considering the primary coil voltages coming from the icm are all below spec, that still seems to be the best guess.

[oldsmokey]

Really curious for the solution of this problem. Not convinced its ignition.  Not under estimating anything that may have been done, maybe very careful observation of each individual valve train function through complete revolutions?

[Jersey]

Curious about that...if the timing is lined up and it has good compression...what are your thoughts?

[Bighead]

If it was running well before the belt change something was done wrong and timing may not have been done as correctly as you think. And why did you change the belts at 60k?Honda Recommends 100k.
Don't want to sound like an ass but why do people try to fix stuff that isn't Broken?

[Jersey]

If it was running well before the belt change something was done wrong and timing may not have been done as correctly as you think. And why did you change the belts at 60k?Honda Recommends 100k.
Don't want to sound like an ass but why do people try to fix stuff that isn't Broken?

I believe most interference engines will run perfectly well right up to the point the timing belt breaks... it's referred to as 'preventative maintenance' and while I understand the printed 'recommended' thresholds, there were indicators that the belt needed changing.  BUT, I know you're not expecting each and every poster to 'justify' why they did something to your standards... now that would make you an ass if you did expect that.

Really appreciate everyone who's been assisting in trying to solve the problem ...

Cheers,

[trout dude]

I think what i would do is to recheck the timing. Pull belts off make sure  number one is on compression stroke at top and then set all marks  again (they do like to move while putting belts on) and if that don't work start looking at vacuum lines or leaks on vacuum pipes under the head they are a bugger some times.  Just trying to help not questioning your ability.
 

[Jersey]

I think what i would do is to recheck the timing. Pull belts off make sure  number one is on compression stroke at top and then set all marks  again (they do like to move while putting belts on) and if that don't work start looking at vacuum lines or leaks on vacuum pipes under the head they are a bugger some times.  Just trying to help not questioning your ability.
 

No worries and thanks for the suggestion!  I did that actually a couple of times when reinstalling the reconditioned heads/cams.  That was the easiest time to verify since everything was accessible. ol' measure twice/cut one... I think I measured a halfdozen or more.   (Frankly I was afraid of being embarrassed having to go back to the machine shop with bent valves. )  Also had another set of experienced eyes check my work.

Physically, the timing is ok. 

The #3 & #4 spark plugs being ok is what convinced me that the low ICM Primary Voltage was the issue.  Since those cyl's had 'almost' the minimum voltage, it made sense that they didn't have the black soot like the other four cyl's, which had significantly below minimum voltage readings.

The ICM is tracking to be delivered tomorrow, so we'll see if that's the culprit.

[Savago]

This bikes are not complicated but may be a bit finicky for unexperienced people (myself included). Where are you located?

Maybe there is someone in the forum near you that could have a look in the belts.

[Jersey]

Southern Maryland area.  If anyone wants an excuse to ride out, feel free to PM me.  Always glad to have another set of eyes look over the situation.

[indybobm]

My guess would be something with the pulse generators, alignment or damaged.

[The emperor has no clothes]

I think what i would do is to recheck the timing. Pull belts off make sure  number one is on compression stroke at top and then set all marks  again (they do like to move while putting belts on) and if that don't work start looking at vacuum lines or leaks on vacuum pipes under the head they are a bugger some times.  Just trying to help not questioning your ability.
 

No worries and thanks for the suggestion!  I did that actually a couple of times when reinstalling the reconditioned heads/cams.  That was the easiest time to verify since everything was accessible. ol' measure twice/cut one... I think I measured a halfdozen or more.   (Frankly I was afraid of being embarrassed having to go back to the machine shop with bent valves. )  Also had another set of experienced eyes check my work.

Physically, the timing is ok. 

The #3 & #4 spark plugs being ok is what convinced me that the low ICM Primary Voltage was the issue.  Since those cyl's had 'almost' the minimum voltage, it made sense that they didn't have the black soot like the other four cyl's, which had significantly below minimum voltage readings.

The ICM is tracking to be delivered tomorrow, so we'll see if that's the culprit.

I have been following this thread, and also felt the coincidences were too much. I was sure the belts must be off a tooth or two. But if that's not it I think your theory of damaging the ICM by not having the plugs grounded sounds possible. Hoping to hear good news tomorrow .  

[Jersey]

My guess would be something with the pulse generators, alignment or damaged.

I did the electrical tests on the pulse generators and it all showed great... based on that I wouldn't suspect any damage.  

Now, Alignment - different story.  I did carefully check that they seated into the holes properly a number of times while installing.  Checked a few times, loosening the bolts and verifying they re-seated the same way each time.  Is there any other aspect of Alignment I could investigate beyond just doing how the book instructs?

[Jersey]

I think what i would do is to recheck the timing. Pull belts off make sure  number one is on compression stroke at top and then set all marks  again (they do like to move while putting belts on) and if that don't work start looking at vacuum lines or leaks on vacuum pipes under the head they are a bugger some times.  Just trying to help not questioning your ability.
 

No worries and thanks for the suggestion!  I did that actually a couple of times when reinstalling the reconditioned heads/cams.  That was the easiest time to verify since everything was accessible. ol' measure twice/cut one... I think I measured a halfdozen or more.   (Frankly I was afraid of being embarrassed having to go back to the machine shop with bent valves. )  Also had another set of experienced eyes check my work.

Physically, the timing is ok. 

The #3 & #4 spark plugs being ok is what convinced me that the low ICM Primary Voltage was the issue.  Since those cyl's had 'almost' the minimum voltage, it made sense that they didn't have the black soot like the other four cyl's, which had significantly below minimum voltage readings.

The ICM is tracking to be delivered tomorrow, so we'll see if that's the culprit.

I have been following this thread, and also felt the coincidences were too much. I was sure the belts must be off a tooth or two. But if that's not it I think your theory of damaging the ICM by not having the plugs grounded sounds possible. Hoping to hear good news tomorrow .  

yeah we'll see.  I've tried to eliminate each possible thing the best I could... electrical is always more tedious troubleshooting.
Thanks!

[Jersey]

Update:

1. Installed the new (well used) ICM and the primary voltages are avg' 120v (above the 100v minimum).

2. Engine runs but is slightly rough... and slightly less than before with the bad ICM.
HOWEVER, there continues to be some backfiring
  -at IDLE, this occurs very infrequently
  - at 2500 rpm this occurs quite a bit. Sounds like exhaust backfiring... snappy, loud hard pops fire a firecracker
  - 5000 rpm this occurs somewhat frequently (less than mid throttle, more than idle)
3. As previously noted, physical engine noises ore more pronounced coming from approximately center area around the starter... like something is partially loose as it rotates.  With increased rpm this lessens, but still noticeable.
4. Exhaust still spells burnt and noxious, the kind that almost waters your eyes.

At this point, the only thing left as suspect are the coils and something physical in the timing.

I again checked the belt timing. pulled #1 plug and verified that TDC and the timing marks are all the same.  Some have emphasized that TDC be of the 'compression' stroke.  In cars I know that's possible, but this engine physically  only allows the cam key and the timing belt pulley to go on one way... makes me think it's not possible to have TDC be anything other than on the Compression stroke.   ANYONE?  is this a wrong assumption?

At this point, My concerns are now going to the physical noise coming from mid engine.
just don't know how that noise could possible cause the current symptoms.

Two Questions for the Valkyrie owners:
1. Any ideas on what's going on would be appreciated?
2. Any recommendations on a good mechanic in the DC, MD,VA, Del region who knows this engine?

Thanks,
Jersey

[oldsmokey]

HMMMM. Compression test done and good,, was a cylinder leak down test done? I still feel its mechanical.
Something happened.

[Jersey]

HMMMM. Compression test done and good,, was a cylinder leak down test done? I still feel its mechanical.
Something happened.

I agree, mechanical is the leading concern, moreso because the electrical seems to be ok.... 

I didn't do Leak down test since I had the heads redone and the machinist did Vacuum pressure test with flying colors.  The test would give indication of the rings.  Will try it! 

Thanks for the idea!

[3W-lonerider]

since you had everything apart. did you put new exhaust gaskets in, if so did you dig the old ones out first.
second are you sure none of the intake tubes that goes over the top of the carb did not curl up in the back.
third did you install new intake orings or use the old ones.

[The emperor has no clothes]

Going back to the burnt valves. What do you think caused that ?

[Leathel]

backfiring in the exhaust and a drop in power is often a sign of retarded timing....but I have yet to even look if that is possible with the Valk setup, not needed to

[Jersey]

Going back to the burnt valves. What do you think caused that ?

The machinist said it's not unusual with engines that are designed and the carb's aren't adjusted. The covering the outlet ports result in less designed airflow causing a lean condition... Hotter burn and higher pressure.  He said they've seen it a lot

[Jersey]

backfiring in the exhaust and a drop in power is often a sign of retarded timing....but I have yet to even look if that is possible with the Valk setup, not needed to

That was my thought...the setup doesn't seem you allow that. Only thing I can guess is what if both belts are off one tooth on the crank pulley. The marks really appear correct, but what if it's a unique thing for this engine?

[Indianabill]

I have read all of posts and everyone had excellent "check this and thats".   You have checked them off.  My carbs need synced right now on mine..... and it pops/snaps/and backfires a little when there is no load on the engine.  If you had the carbs synced while 2 exh. valves were leaking, the carbs may be out of sync now..... because the engine is breathing differently on those two repaired cylinders .  If it runs good running down the road with a load on it, but doesn't when there isn't a load......my guess is that carbs may be out of sync.  This theory is open for criticism.

[Jersey]

I have read all of posts and everyone had excellent "check this and thats".   You have checked them off.  My carbs need synced right now on mine..... and it pops/snaps/and backfires a little when there is no load on the engine.  If you had the carbs synced while 2 exh. valves were leaking, the carbs may be out of sync now..... because the engine is breathing differently on those two repaired cylinders .  If it runs good running down the road with a load on it, but doesn't when there isn't a load......my guess is that carbs may be out of sync.  This theory is open for criticism.

That's a good suggestion!  I did finally decide to take it to my local mechanic. They're well experienced with these engines. At first listen, the owner was thinking the same thing...so your idea is in good company!

Will see what they discover and keep you all posted.

[Leathel]

I had my air cleaner off Yesterday doing a little work and forgot to do up 2 x clamps on where they sits on the carbs, I got interrupted and when I fired it up it was popping in the exhaust something like the video you had up


Are you sure all the intake pipes are on correctly, Its easy to have the back not sitting right

[Jersey]

I had my air cleaner off Yesterday doing a little work and forgot to do up 2 x clamps on where they sits on the carbs, I got interrupted and when I fired it up it was popping in the exhaust something like the video you had up


Are you sure all the intake pipes are on correctly, Its easy to have the back not sitting right

Good suggestion. I did check all of those to be tight. Also tested with propane to see if there were any leaks.  Seemed to show all of that to be good.

Thanks for offering the idea!

[heavyd]

I again checked the belt timing. pulled #1 plug and verified that TDC and the timing marks are all the same.  Some have emphasized that TDC be of the 'compression' stroke.  In cars I know that's possible, but this engine physically  only allows the cam key and the timing belt pulley to go on one way... makes me think it's not possible to have TDC be anything other than on the Compression stroke.   ANYONE?  is this a wrong assumption?

Maybe I am wrong, but can't the timing be off a full rotation and still have the marks line up? If the marks were lined up with #1 TDC of the Exhaust stroke, what would happen?

[The emperor has no clothes]

I again checked the belt timing. pulled #1 plug and verified that TDC and the timing marks are all the same.  Some have emphasized that TDC be of the 'compression' stroke.  In cars I know that's possible, but this engine physically  only allows the cam key and the timing belt pulley to go on one way... makes me think it's not possible to have TDC be anything other than on the Compression stroke.   ANYONE?  is this a wrong assumption?

Maybe I am wrong, but can't the timing be off a full rotation and still have the marks line up? If the marks were lined up with #1 TDC of the Exhaust stroke, what would happen?

I think you'd have bent valves galore. I also don't think it would even fire up.

[indybobm]

I again checked the belt timing. pulled #1 plug and verified that TDC and the timing marks are all the same.  Some have emphasized that TDC be of the 'compression' stroke.  In cars I know that's possible, but this engine physically  only allows the cam key and the timing belt pulley to go on one way... makes me think it's not possible to have TDC be anything other than on the Compression stroke.   ANYONE?  is this a wrong assumption?

Maybe I am wrong, but can't the timing be off a full rotation and still have the marks line up? If the marks were lined up with #1 TDC of the Exhaust stroke, what would happen?

I think you'd have bent valves galore. I also don't think it would even fire up.

That would have to be 1/2 camshaft rotation otherwise you woud be back where you started from.

[Jersey]

I again checked the belt timing. pulled #1 plug and verified that TDC and the timing marks are all the same.  Some have emphasized that TDC be of the 'compression' stroke.  In cars I know that's possible, but this engine physically  only allows the cam key and the timing belt pulley to go on one way... makes me think it's not possible to have TDC be anything other than on the Compression stroke.   ANYONE?  is this a wrong assumption?

Maybe I am wrong, but can't the timing be off a full rotation and still have the marks line up? If the marks were lined up with #1 TDC of the Exhaust stroke, what would happen?

I think you'd have bent valves galore. I also don't think it would even fire up.

That would have to be 1/2 camshaft rotation otherwise you woud be back where you started from.

Not sure what you mean... could you explain? 

Thanks,

[indybobm]

Not sure what you mean... could you explain?  

Thanks,

First of all, I do not think this has anything to do with the problem. It is just theoretical.

There will be two times the crankshaft pulley will be at TDC, when cylinder 1 is on the compression stroke and when cylinder 1 is on the exhaust stroke. If you have the crank pulley at TDC and the 'UP' wording on the camshaft pulleys is right side up, cylinder 1 is on the compression stroke. If the crank pulley is at TDC and the 'UP' on the camshaft pulley is upside down, cylinder 1 is on the exhaust stroke.

Turning a camshaft one complete rotation would have no effect. It ends up being right back where it started.

If you have the crankshaft pulley at TDC and one camshaft pulley with 'UP' readable and the other camshaft pulley with 'Up' upside down (camshaft rotated ½ revolution) then cylinders 1 & 2 would both be on the compression stroke at the same time. Think of it as a three cylinder engine with bigger pistons. Since the Valkyrie fires on the compression and exhaust strokes, the engine would still run.

[Jersey]

Not sure what you mean... could you explain? 

Thanks,

First of all, I do not think this has anything to do with the problem. It is just theoretical.

There will be two times the crankshaft pulley will be at TDC, when cylinder 1 is on the compression stroke and when cylinder 1 is on the exhaust stroke. If you have the crank pulley at TDC and the 'UP' wording on the camshaft pulleys is right side up, cylinder 1 is on the compression stroke. If the crank pulley is at TDC and the 'UP' on the camshaft pulley is upside down, cylinder 1 is on the exhaust stroke.

Turning a camshaft one complete rotation would have no effect. It ends up being right back where it started.

If you have the crankshaft pulley at TDC and one camshaft pulley with 'UP' readable and the other camshaft pulley with 'Up' upside down (camshaft rotated ½ revolution) then cylinders 1 & 2 would both be on the compression stroke at the same time. Think of it as a three cylinder engine with bigger pistons. Since the Valkyrie fires on the compression and exhaust strokes, the engine would still run.

[/quote]

Understand and thought maybe that's what you meant.  Appreciate the explanation.  For the sake of theory discussion let me ask this:
-Assume belts are off and both the cams are set to "UP" reading correctly
Q: Will having the crank set to Cyl#1 guarantee it to be in proper position to reinstall the belts?

or, Is it possible that the crank could be in either the compression or exhaust stroke at that setting?

After I removed the heads and sent them off to the machinist, I did turn the crank to inspect each piston closely.  The thought came to mind that while the timing marks may line up properly the crank may not have been in the proper stroke cycle for Cyl#1 when I realigned and reinstalled everything. 

Thoughts?