Cam ignition timing 'deflection' (wobble)?

[Ansimp]

Could be more the advance/ drive mechanism, (I have seen similar discrepancies in worn distributors) rather than cam belt drive variances.

 

[C5Performance]

I have a few thoughts.

First, the cams are supported on a layer of lubrication in the cam journals. Yes there can be journal wear, and I've seen plenty of air cooled dirt bikes/ATVs with excessive wear from lack of lubrication (over heating and/or oil that is broken down from wear).

This could explain cam movement in the head (even excessive) but not rotation/wobble. Dan what I try to think of is how a cam with some play in the journals could convert an "up and down" motion of excess clearance into a "rotational" issue. Once the engine is up to operating rpm there should be enough oil fed to a journal to prevent excessive motion, or many not?? But an excess rotation of even 5 degrees would mean an incredible amount of wear.

Idle with a loping engine does cause belt or cam chain wobble on cars as well, but under a load while accelerating there would be minimal variation since the timing belt is pulling like crazy always in the same direction. In my opinion this would "smooth out" any belt bounce that might be present at idle. Anyone who grew up on a farm using belt driven equipment knows this (and yes I did).

SOOOOO....I must remind you that the measurement of 9 degrees of timing variation was performed at idle only. It was not measured at higher rpm (and perhaps it would get better, perhaps worse...we don't know). It is possible, and should be tested further!

Timing advance parts could have caused some of this bounce. The wobble (variation) was recorded using mechanical points so locking the advance parts in place would be a great next step.

 

[slabghost]

In my opinion the wobble term and "problem" is just applied ignorance. With points ignition each set had to be set the same and exactly 180 degrees out with the same dwell. Any variation would give an uneven idle. Add high mileage to the equation and the advance springs stretch and the weights move more erratically. The same holds true with add on electronic ignitions which also added a few degrees variation in that type of sensors. All of this makes idle almost always uneven causing the belts to bounce around a bit. Toss in the fact that the carbs are also older and worn and most are not fully adjusted an even idle is nearly impossible. So cam wobble was the blame for all the worn mis adjusted parts. They must be wobbling look at the belts! :smilie_happy: :smilie_happy: :nea: oh2:

 

[ekvh]

What I recall of cam "wobble" was that when you timed the points, or Dyna, on the first revolution you could set it dead nuts on the F1 mark. Rotate it one revolution and the timing would be lagged up to a half an inch. One more revolution and it would be right on the F1 mark again. This was thought to cause the rattling sound at low rpm. Often it sounds like a rod knock on takeoff. The acceptable fix was to set the timing so it had one fire a bit before the F1 mark, and then a bit behind the F1 mark on the next revolution. Not all bikes did it, and some did it at F2.

I believe it was proven with a dial gauge set to measure the points cam. Too cold here to look, but I wonder if that belt going slack could also be a factor.

 

[slabghost]

Not here to argue but Dan's bike has a motor that isn't new. Doesn't have the old carb rack. Doesn't have the mechanical advance. Doesn't use points or the earlier electronic ignitions. It does have a nice smooth idle with C5 ignition and single 2 brl Weber. Ignition is cam driven.

 

[Ansimp]

slabghost » Fri Feb 13, 2015 2:41 pm[/url]":2uvbsgns]
Not here to argue but Dan's bike has a motor that isn't new. Doesn't have the old carb rack. Doesn't have the mechanical advance. Doesn't use points or the earlier electronic ignitions. It does have a nice smooth idle with C5 ignition and single 2 brl Weber. Ignition is cam driven.

+1 :good:

 

[aussiegold]

Ansimp » Fri Feb 13, 2015 8:14 pm[/url]":3a11lwrg]

slabghost » Fri Feb 13, 2015 2:41 pm[/url]":3a11lwrg]
Not here to argue but Dan's bike has a motor that isn't new. Doesn't have the old carb rack. Doesn't have the mechanical advance. Doesn't use points or the earlier electronic ignitions. It does have a nice smooth idle with C5 ignition and single 2 brl Weber. Ignition is cam driven.

+1 :good:

yes, this makes perfect sense. having the C5 would make the slight cam "wobble " have no effect at all. the little movement that buggers up the points is still there, but now we have a disc bolted to the end of the cam. any " out of round " movement , in my opinion, would have the tiniest effect. or none at all. :whistling:
it used to drive me nuts , setting the points on my 75. get one side right and the other was all out. turn the engine one revolution and it would be way out. the dyna system also was not bothered by the cam movement. but i am sure that the sensors on those things are all over the shop. a bit hit and miss...... :wave:

ps
randikk has some thing about this on his site. he calls it the split timing method. we had been setting points like that for years. nothing new. :moped:

 

[ekvh]

The multiple spark of a C5 would probably ensure a good spark. And at least one at the right time, but if one came a bit early, it could cause spark knock. I wonder how many Goldwings were sold with PO thinking it had a knocking rod when it was early ignition all along. Until I understood the split timing method, mine sounded like it was going to grenade going up slight inclines at idle.

 

[joedrum]

okay this is set up nice ...by you guys ... long time ago when i brought the belt issue up in a thread simular to this about cam wobble ..i tried to explain ..it didnt work ...as paul said this problem is at idle and i agree ...as rpm lowers time for belt flop increases and is at it worse ....when checking timing at idle you are at its worse spot ... right here at idle you can see the flop ...and it is at this point you want to get belts tension right ... ive done this personally on the hooch bike and it for sure with carb system stock or other you can get the motor to idle better...this is not theory ive done it .....it aint much ... but i am highly into tuning with only smart tool is me feel of things ...others might not be....the 2 belt system is great and is way more reliable and stout than a one belt system ...id never want to change that ....

but the 2 belt system is the culprit in the timing mismatch... oldwing piston are on the same position in front and back setups ... when piston is at TDC 1 the other front piston on other side is TDC too just 180 degrees different in timing ....its timing of camshaft is not tied two the other side as the top end or valves operate from the belts ...in the video you see flop in belts ...but it is seperated by the use of 2 belts ..witch i think is a great thing in reliable setup ...but if on belt is in flop mode and the other in taunt mode it doubles the mismatch that can happen .... and this is what the true cause of timing mismatch that starts everything and can lead to advancer variance and what ever....but too and i think for sure as soon as rpm goes up things smooth out and it gets better not worse ....as time window closes in flop and by sight with timing covers off this is totally obvious when the belts smooth out ...so to me ...i have seen and felt how the biggest factor in idle smoothness on a otherwise good working bike is belt tension ....and with done with a c5 used it is like a different motor all together .....since oldwings were made they have never ran as good as they can with the c5 ever ... it just no comparison in the set ups ...and how the c5 stops the timing issue in there trac wants its in play as it has no parts to get out of wack like other ignitions do ...... :thanks:

 

[dan filipi]

ekvh » Yesterday, 8:30 pm[/url]":12cb38fv]
What I recall of cam "wobble" was that when you timed the points, or Dyna, on the first revolution you could set it dead nuts on the F1 mark. Rotate it one revolution and the timing would be lagged up to a half an inch. One more revolution and it would be right on the F1 mark again. This was thought to cause the rattling sound at low rpm. Often it sounds like a rod knock on takeoff. The acceptable fix was to set the timing so it had one fire a bit before the F1 mark, and then a bit behind the F1 mark on the next revolution. Not all bikes did it, and some did it at F2.

I believe it was proven with a dial gauge set to measure the points cam. Too cold here to look, but I wonder if that belt going slack could also be a factor.

Ok so that could be the 6-9 degrees measured.
Now where could that be coming from "on a high mileage 1000"?
The only thing that ads up is belt went slack while measuring or the mechanical advancer moved.

 

[ekvh]

I didn't do this, but as I recall they had a dial indicator mounted the the points cam. They measured the variance and the cam wobbled-varied-changed-whetaever you want to call it, from the T1 to the next T1. Belts may influence, but only because different valve springs are engaged. The first T1 would have the intake valve on #4 and we know the intake spring exerts tension on the camshaft, but the next T1 different valve springs are in play, #2intake is under pressure. What they found was that the points cam changed, I believe left-to-right. This would change ignition timing some as it changes points gap. Their theory was that the valve springs pressing on different parts of the cam made the points cam move.

I am clearly not an expert, just reporting what I've read and understand. Could it have been belt slop all along?? I think measuring a non-running motor should not have the belt play that we see with a running engine, and so the belts are out of the equation.

 

[joedrum]

even motor is not running the valve springs are in play and actually the difference is still all in the belts ....lets face the truth here you are not gointg to move a solid cam or wear the cam carrier before the valves springs gives ....BUT it can push around a loose belt not prestress to right tension big time ... putting c5 on crank is not going to change loose belt either or not prestress right....a right prestress belts will have some deviation ..reguardless where the c5 is at cam or crank .....if the cam were under such stress as this belts would be breaking all the time from to much load.... there not under much stress at all

 

[dan filipi]

Good info Eric, I need to re-read it a few times to picture it in my head what the theory is.

Getting off into c5 which I didn't want to do Joe, at least not yet until we all have an understanding with all the facts and dispel a myth if it is.

 

[ekvh]

Paul was right on farm boys understanding belt slop.

 

[joedrum]

oh2: .... :headscratch: :rtfm: ....okay ... opcorn: .

 

[Ansimp]

I am confused are we all talking about possible problems using timing belts on an engine that has proved to be one of the most reliable, high milage motorcycle engines ever made? :doh:

 

[dan filipi]

Ansimp » 16 minutes ago[/url]":2wwx5kfw]
I am confused are we all talking about possible problems using timing belts on an engine that has proved to be one of the most reliable, high milage motorcycle engines ever made? :doh:

:smilie_happy:

Just a discussion Tony.

Trying to get to the bottom of where that variance in timing is coming from, if it exists, and as such is it only a problem in the GL1000 or other 4 cylinders also.
Add to that, what is the real concern here, or is there any.

The more I read the more I think it's a non issue but I like the discussion and it makes me think.

 

[Ansimp]

I think we would be better off discussing "what brand of beer is better?" :smilie_happy:
If you look hard enough for a problem you will eventually find it!! :yes:

 

[dan filipi]

Ansimp » less than a minute ago[/url]":1i8werft]
I think we would be better off discussing "what brand of beer is better?" :smilie_happy:
If you look hard enough for a problem you will eventually find it!! :yes:

Yes, get to the bottom of it is what i'm after.

Hey, I have no problem discussing what beer is better, just not in this thread. :whip:

Post what you think about the questions, we are listening.

 

[C5Performance]

There is much to think about here. I'm no engine designer, but I see two separate issues/problems/compromises going on.

Allow me to explain (and it will have little or nothing to do with what type of ignition you use).

The first is variation of the cam in relation to the crank. I don't care how you drive the cam (belt, chain, gear) there is variation.
Belts and chains have slack, and gears have clearance or they'd explode when the engine got up to operating temp.
We ran 204 mph at the Texas Mile with a Honda CBR1000 street bike. Guess what? The cams are chain driven and have spring loaded tensioners. We did not melt a piston. It starts and idles perfect. We even used NOS and made well over a dozen passes without issue, and it's still ridden to work almost daily.

So I'd like to measure the variation of a Goldwing cam and crankshaft on a RUNNING engine. I don't care one tiny little bit about rotating it by hand. That doesn't matter to me. All that matters is what happens from 1000 rpm to 10,000 rpm. It can be done a few ways and I'm working on the best method yet.

Second issue....Variation of the left head compared to the right head. Why care about it? Because if the cams are bouncing back and forth from their correct relationship to the crankshaft, then there will be variations of the left and right cylinders. It should affect valve timing as well as ignition events.

We can accomplish both tests at once using three triggers. One crank mounted and one on each cam. Fire up the engine and measure how much variation each of them have using the CRANK as the reference part. If there is a substantial timing variation it could cause running issues or even detonation.

I have theories about the 5-10 degree variation. I believe they were measuring timing swings due to advancer shaft movement. I also know for a fact there is at least 7 degrees of variation on Hall Effect triggers which are used for almost all electronic ignitions.

A fair comparison is to measure variation of the three engine parts, then measure spark variation using an accurate timing light and compare points to magnets, and magnets to optical.

Sorry for the long explanation. I was driving most of the day and had too much time to think :whistling: