Timing was off, and couldn't get both points to fire.

[motorshag]

I know this has been talked about before, but wanted to show something I've discovered while chasing the bunny. I bought this bike from a guy that said the Carburetors needed to be cleaned. So, I decided I would just go through the bike like I always do. I did clean the Carbs and noted that was not the problem... I noticed a few things right off the start that seemed weird to me. The cam chain tensioner was very very tight...(Adjusted all the way in) So I adjusted it back to where it seemed normal. The valves were so tight that I couldn't even move them (perhaps never adjusted?). So I adjusted them the way the should be adjusted (to spec). Then I get to the timing, just can't get it to time right. One of my discoveries was the PO was using a single coil Accel Harley Super Coil. I did not think that was correct, so I put some standard coils on it. Ones I knew worked. I could get the points to gap on the right side correctly but never the left side. Also the timing plate was way off, I had to move it so far counter clockwise and I couldn't ever tell with my meter when the points were closing or opening because ignition mark on the rotor never line up midway between the two marks on the alternator housing. The ignition mark would be almost 15 degrees out or whack. So I started doing some research here, there and everywhere and I discovered through my reading that maybe the timing chain is old (30 thousand miles on the clock) and my be its very worn? I pulled the motor and pulled the cam cover off. Then I saw what was wrong. See the pics...

It looks like one of two things happened when the PO did a rebuild or "something" the chain was removed or replaced. Not sure if it's new or not, but I do know it's got new link

1) The Cam timing mark was not set at 12 o clock while the motor was at TDC?
2) The PO adjusted the chain tensioner out so far that the chain jumped a tooth?

Additionally, I guess my question is this. While doing this process should I pulled the head too? I don't want to, but I guess I should check the pistons to see if they have been hitting the valves?

No I didn't checked the compression. The compression checker was sitting there, I just got excited and then....Sorry I forgot...I guess I could still check it, I've not pulled the head yet.

Just thought this was interesting. Feel free to share your opinions, and/or theories as to why this could have happened.

 

[TwoManyXS1Bs]

Man, that doesn't look good. Your descriptions have all sorts of warning bells going off in my head.

My approach? Declare it DOA, trust nothing, and don't even try to figure out what/why the PO did what he did. Do an absolute complete teardown, consider it as a collection of parts. Then, inspect/measure everything, replace/rework parts as necessary, and reassemble it by the book.

 

[5twins]

At 30K, that motor is most likely in need of a new cam chain, front cam chain guide, a valve job, and at least new rings. What makes you think the cam chain master link has been replaced? That one looks very factory-like. That's how they riveted them, with just a line mashed across the top of the pin. Here's the original I found in mine .....

 

[motorshag]

At 30K, that motor is most likely in need of a new cam chain, front cam chain guide, a valve job, and at least new rings. What makes you think the cam chain master link has been replaced? That one looks very factory-like. That's how they riveted them, with just a line mashed across the top of the pin. Here's the original I found in mine .....

I was just thinking it was because of they way it looked pressed. You're probably correct. Just wondering how it got so far out of wack? Could the chain be stretched that much?

 

[CDNTX650]

It doesn't matter where the link ends up.....the link placement has nothing to do with proper cam to crank timing. What's important is your mark on the rotor at tdc and the mark on the cam or the atu locating pin on the end of the cam should be at 6 or 12 o'clock. I can't tell from your pics if it's lined up. To small and blurry when I blow them up.

 

[motorshag]

I know it doesn't matter where the link ends up....I was just showing that as a reference. I already know the rotor should be at tdc and the mark on the cam or the atu and the locating pin on the end of the cam should be at 6 or 12 o'clock. I know all this. I am just showing that the cam is off when at TDC. My real question is how did it get so off? Not like I care, i'm fixing it anyway, i just am interested in what it's off on the cam and the roter. I'll ad larger pics...

 

[motorshag]

Man, that doesn't look good. Your descriptions have all sorts of warning bells going off in my head.

My approach? Declare it DOA, trust nothing, and don't even try to figure out what/why the PO did what he did. Do an absolute complete teardown, consider it as a collection of parts. Then, inspect/measure everything, replace/rework parts as necessary, and reassemble it by the book.

Yea, I agree. It's looking like I'll tear it all down. I was just curious if anyone had ever seen the cham so far out while at TDC.

 

[retiredgentleman]

Its scary that PO's work on thse engines and really don't understand what they are doing.

TwoMany's advice is 100% and should be followed.

Here's something else to think about. If the PO had the alternator rotor replaced, did he know enough to re-install it properly using the woodruff key. Maybe he didn't even use a woodruff key, and just randomly placed the rotor on the crankshaft. The TDC mark may no longer have any meaning.

In other words, the crank and camshaft may be timed correctly but the rotor is not indexed with a woodruff key. Then again the rotor may be correct but the crank/cam is wrong. If the PO was a complete idiot, both possibilities may have happened.

Trust nothing!

 

[motorshag]

Its scary that PO's work on thse engines and really don't understand what they are doing.

TwoMany's advice is 100% and should be followed.

Here's something else to think about. If the PO had the alternator rotor replaced, did he know enough to re-install it properly using the woodruff key. Maybe he didn't even use a woodruff key, and just randomly placed the rotor on the crankshaft. The TDC mark may no longer have any meaning.

In other words, the crank and camshaft may be timed correctly but the rotor is not indexed with a woodruff key. Then again the rotor may be correct but the crank/cam is wrong. If the PO was a complete idiot, both possibilities may have happened.

Trust nothing!

Crap!!!!! That's the whole reason I posted this in the first place. To get other idea's outside the obvious. I'll have to check the rotor too. That is the real wonder to me. I've rebuilt a few of these before, but for the life can figure what the PO would have removed the cam, and from what 5 twins says, did't remove the link (because that's original). Would they have tapped the cam barrings out, removed the cam, popped the head off to do something inside the motor? Or like you said had the rotor out to replace it... and didn't put the new one back correctly. Thanks Mr retiredgentleman!!!

 

[5twins]

You could probably check that without pulling the rotor. Find approximate TDC using a straw in the spark plug hole and see if the TDC marks align. You can also judge the amount of chain stretch by rocking the motor back and forth slightly with the rear tensioner screw removed and see how far the mark on the cam moves back and forth.

 

[motorshag]

You could probably check that without pulling the rotor. Find approximate TDC using a straw in the spark plug hole and see if the TDC marks align. You can also judge the amount of chain stretch by rocking the motor back and forth slightly with the rear tensioner screw removed and see how far the mark on the cam moves back and forth.

Just checked TDC with a straw....it's not off. That is lined up, as well as the roter. Oh well, guess, i'll be tearing into it more in the next day. I'll keep all inquiring minds updated...

 

[retiredgentleman]

Just checked TDC with a straw....it's not off. That is lined up, as well as the roter. Oh well, guess, i'll be tearing into it more in the next day. I'll keep all inquiring minds updated...

Well at least the PO was not a complete idiot, just a partial idiot.

 

[chizler62]

If your cam timing is retarded it'd explain why your intake valves were tight. Mute point now.


My guess is the clown heard a cam chain noise and tried to adj it then somehow slackened the chain enough to jump the bottom sprocket. Worn chain add worn adj add worn guides add some dipshit and it's possible. Seen dumber things. Before you tear it apart I'd try to loosen the chain all the way and see if you can make it want to jump.

Or could've installed the chain with a ton of front chain slack. I seen people who pull the wrong side tight while aligning the cam marks. Thinking the "adjuster side should be tight. etc

If the valves were hit and bent you'd probably feel it when turning the motor over by hand without plugs in it.

Over the years I've seen a few customers bring in bikes that they "just rebuilt the top end" and basically confused the marks "F" and the advanced mag marks for TDC.

Often on a lot of Jap bikes the mark on the sprocket which aligns with the rocker covers are a half tooth off from chain stretch or maybe the gravity in Japan is different than the US...lol who knows..... People get all "what the hell do I do" about this.

 

[motorshag]

Well at least the PO was not a complete idiot, just a partial idiot.

That made me laugh!

 

[motorshag]

If your cam timing is retarded it'd explain why your intake valves were tight. Mute point now.


My guess is the clown heard a cam chain noise and tried to adj it then somehow slackened the chain enough to jump the bottom sprocket. Worn chain add worn adj add worn guides add some dipshit and it's possible. Seen dumber things. Before you tear it apart I'd try to loosen the chain all the way and see if you can make it want to jump.

Or could've installed the chain with a ton of front chain slack. I seen people who pull the wrong side tight while aligning the cam marks. Thinking the "adjuster side should be tight. etc

If the valves were hit and bent you'd probably feel it when turning the motor over by hand without plugs in it.

Over the years I've seen a few customers bring in bikes that they "just rebuilt the top end" and basically confused the marks "F" and the advanced mag marks for TDC.

Often on a lot of Jap bikes the mark on the sprocket which aligns with the rocker covers are a half tooth off from chain stretch or maybe the gravity in Japan is different than the US...lol who knows..... People get all "what the hell do I do" about this.

Thanks. Yea, the chain was so loose. I had to go check my book to make sure I was right, and not doing it wrong all these years lol... I have been wondering if anyone had ever seen the chain jump a tooth. None of my friend that I wrench with had every seen it, but then again, no one works on 650's around Nashville. The cam teeth look fine, but like you said, he could have had a ton of slack on the wrong sidel, and could have jumped the bottom sprocket. Regardless, it's fun for me to think of all the ways this could have happend, and it's always fun to blame someone else I've decided to pull everything, go get the valves done and have the cylinders checked, maybe go up a size or two. I only paid 500.00 for the bike, and cosmetically it's very nice looking.. The guys here in Nashville ask upwards of 1800.00 for non-runners ( i know crazy), and these dip-wads pay it around here. I think i'll either keep it when done, or I could sell and make a profit. My main desire is to save them all, from all the idiots...

 

[5twins]

Personally, I've never seen a chain jump a tooth, but I have read about it here several times. And now here you are with what seems to be the same problem. Yours looks way off, maybe as much as 3 or 4 teeth.

Most of these bikes are in need of a new cam chain, front guide too. It's not that the chain was inherently bad, it was just never maintained properly by most owners. Also, the adjustment interval of between 2 and 4K given by Yamaha was a bit high. You should be checking it like every 1000 miles. It's a simple procedure while the engine is idling and only takes a couple minutes. I've gotten into the habit of checking mine every time I do an oil change, which is about every 1000 miles.

 

[retiredgentleman]

Where did this "chain jumped a link" story come from? To me its just a myth invented by guys trying to justify bad/stupid workmanship. The engines come from the factory with the cam/crank timed correctly, and if they end up like in the OP's picture, you can be sure that was done by human hands.

Edit: I've known many lads with Japanese bikes through the years, and never heard anyone mention a "jumped chain".
Maybe its a H-D thing???

 

[motorshag]

Where did this "chain jumped a link" story come from? To me its just a myth invented by guys trying to justify bad/stupid workmanship. The engines come from the factory with the cam/crank timed correctly, and if they end up like in the OP's picture, you can be sure that was done by human hands.

Edit: I've known many lads with Japanese bikes through the years, and never heard anyone mention a "jumped chain".
Maybe its a H-D thing???

It came from Honda guys

 

[CDNTX650]

It says it right in both shop manuals for my versys and klr250. Don't move the engine without the cam Chain tensioner in place. New chains are tight and they won't. But old ones are pretty loose.

 

[chizler62]

If you have a motor with a really stretched chain. Half link every 10 or so. I have a few chain stretch tools I made after the OEM ones make by Park Tools. Remove or have worn out adj or guides then let it hang loose spinning the motor over by hand back and forth you can get it to jump a tooth.