In what regard for the ACR? When the bike is bogging down and about to stall i.e. not pulling the clutch in, or when attempting to start the bike?

Keep in mind he quotes when attempting to start the bike; that the engine makes the noise as it locks up, and he has to proceed by letting off the stater button and then depressing it again to get the engine turning over again... Your saying this is a symptom of a bad ACR? If so I find that improbable.

 

You know, Dan, to me this really looks and sounds like it really is the result of that bushing wearing out over time. As that happened, it caused the gears to start running out of proper mesh and wear out, ultimately to the point that they started to lock up due to tip to tip contact.

I really doubt the wear and breakage is due to the engine kicking back during startup or low RPM running. I think the chunking sound you're hearing is the gears locking up, from that idler being able to move around so much. Sometimes it will be in the right spot to roll, sometimes it will not.

The amount and type of wear to the bushing and boss, and all the gear teeth indicate a long term, continuous type of wear. It doesn't look like the result of intermittent impact or overload.

Now as to why that bushing wore out, who knows really? Ultimately it's insufficient lubrication, but why? There are a number of possible contributors.

Anyway, back to the repair...I know you are replacing the idler gear already, but you'll really want to replace every gear in that train because of the wear. Any of those worn/broken teeth will cause wear/breakage to the other gears/teeth if they're put back in service.

 

I enjoy thinking about this much more than my lame interpersonal communication research work at the moment. What your saying is almost the entire accumulation of my progression of thoughts over the last day and a half.

The progressive "egging" of the bushing really got me thinking it was time induced. Could just a bad spot in the bushing and or lubricant.

 

dan, I went back and read some info on the effects of octane. Octane rating is definitely a factor in a higher compression engine and especially under a load. As far as starting is concerned, I actually found some info that indicated that high octane fuel can actually be harder to ignite for starting in some cases because it's not as volatile for quick combustion under the less ideal conditions at startup as compared to when the engine is already running. That sounded weird at first until you think about why lower octane tends to detonate/knock before higher octane fuels...they tend to burn more quickly with less control. That can actually aid starting. Of course, some of these examples are extremes and not to be taken as absolute, blanket rules for all instances. Still, it looks like octane ratings in the normal ranges of 87-92 in relatively normal engines like ours has little to do with starting issues involving detonation. I also thought about the older days of engines that would tend to keep running when you turned them off, but there are other factors at work there that are a little different than what we're discussing here. But...I'm no engineer by any means.

 

Dan,

If Lutz hit the nail on the head with this prediction... then maybe you should spearhead an experiment with this...

Pop in a new bushing and fill the void in with some epoxy... last attempt solution at not splitting both the case and your wallet.

Serious thing to consider. :-)

 

Yeesh...it's way past my bedtime! But I suppose if I'm not the only one posting, I'll post one more tonight.

Another thought, Dan. You didn't mention the condition of the bushing in the cover, supporting the opposite end of the idler gear shaft. No doubt it is also damaged, worn out, or missing. That area needs a close look too.

One more thing to consider - not to jinx you - is that if this failure was causing intermittent lock-ups of the running engine, it very well could have damaged the main bearings on the crank. Check them out now, and if they seem ok, then monitor them in the future.

I would not recommend that...likely to result in a bigger hole in the wallet down the line.. Unfortunately, to fix this any kind of right, it's going to require time and money.

 

Correct, I think higher octane would most definitely make starting somewhat more difficult because it is not as volatile... however it would be better for Dan's issue of pre-ignition for startup purposes though right? (assuming it was an issue).

The way the chemists and chemical engineers were explaining it to me one day when we were chatting in the lab... was basically like this.

Think of taking the head off a cylinder and putting the piston just past TDC (ideally when the forces should be acting on the piston, but not necessarily when the cylinder would "fire" in a running situation)

From here grab two hammers... a two pound nylon mallet, and a 2 pound steel blacksmith hammer.

Now strike the piston with the two pound steel blacksmith hammer ... observe the nasty ping sound and awful transfer of force; demonstrated by minimal movement of the crank (this is the situation of improperly matched octane or "low octane - high compression").

Now strike the piston with the two pound nylon mallet ... observe the plush thud sound and greater transfer of force; demonstrated by greater movement of the the crank (this is the situation of properly matched octane "proper octane - proper compression").

Any incorrectly mixed proportion of octane and compression is bad ... I know everyone already knows this stuff ... I just thought this example was cool because compression is related to improper burn rate, by this I mean pre-ignition isn't always referring to combustion before the spark is given like most assume I think... Instead sometimes pre-ignition can define a situation where spark is sent and ignites the mixture, but creates a catalyst in an already "near unstable" situation and causes an additional ignition from the walls of the head due to the inherent increase in pressure which was due to the initial ignition via the spark and an already "near unstable" situation... in effect the two waves meet in a non-uniform manner and energy is transmitted all poopy like.

K, I'll get back to studying... sorry for rambling

 

I've had the bike since new, I am confident the sound is not coming from the ACR. I wish i could play the sound for you guys I think it would eliminate some of your guesses.

 

The bushing may have worn over time and this may be a combination of problems but none of those gears are moving when the bike is running, so i can rule out that idea because it hiccups when the bike is running at times. I do think most of the damage to the idler gear is from when the two gears finally quit meshing and the freewheel gear chewed up the idler gear.

The idler gear has some galling on its shaft, which could be from the hiccups, and could easily have chewed through the bearing . The hiccup is fairly violent and I can see the gear getting jammed pretty hard into the bearing.

 

bearing in the stator cover is worn thorugh in the same way,but the boss is not cracked. The cases coming from ebay have the bearings in them still. I will check them out and assemble my engines guts into the eBay cases.