Timing marks will not line Up

[evdog]

So I post here not often only when completely stumped. So here goes;

1973 TX 650 engine#s650-201847

I bought this bike with 14k miles on it and someone has already been in the engine so I am not sure if parts are correct or not. Valves adjusted to spec, Points gaped to spec, cam chain adjusted, but when timing the engine running with a light the engine is advanced. I maxed out the right sided points and it is close, still advanced. I max out the Left side and it is still advance.

I assume that the cam and crank are not lined up so I opened it up. The cam is 100% vertical and the crank mark is past the Timing mark(retarded) exactly 1/4 inch 8mm. I adjust the chain one tooth to the right, rotate the engine 360, with the cam adjuster back on; the Cam is 100% vertical yet the crank now lines up with the Fire mark. (advanced) I go one tooth to the Left, rotate engine, adjust cam chain, the cam is 100% vertical and the Crank is significantly past the Timing mark. (retarded) I have also been going back and forth a tooth about 15X no luck!

Now I wonder if they are the wrong crank, Cam, Cam chain. The Chain has 102 links, Cam sprocket 34 teeth. Or possibly I am missing something completely to easy. Any input would be great. I really don't want to split the cases to check to see if the crank is something strange.

 

[TwoManyXS1Bs]

You have a stretched camchain.

Moving the crank by one tooth will change the crank position by 21°, about what you're seeing with your finagling.

Mine's stretched even worse than that. The points plate is rotated all the way to the end, and i run a little extra points gap to get it into time. And, it still runs.

Might want to check your advance unit...

 

[evdog]

I did not rule out a stretched cam chain, but it has 14k miles. I have, built i do not know how many, and have yet to run into this problem; a stretch chain that low in miles. Your advise TwoManyXS1bs I appreciate. Ill put it back together and mess with the points gap.

 

[TwoManyXS1Bs]

... I have, built i do not know how many, and have yet to run into this problem...

There have been some interesting experiences here when the advancer is assembled funny, like pins out-of-line, the slotted disc upside-down/backwards, or the pin behind the advancer gouges the advancer's slot, weak springs, worn weight fingers, ...etc. There's also the points cam, which can wear down and give odd timing. And, points screws that protrude past the backside of the timing plate can cause problems...

 

[Paulrxs650]

Out of curiosity, just check that the cam is in the right way round - i.e. the threaded end of the cam on the right hand side of the bike when sitting on it.

 

[pamcopete]

For those confused about the left and right side of the bike: The right side is the side with the right turn signal and the left side is the side with the left turn signal . So, just turn on the key and operate the turn signals. Follow the flashing lights to the side your are interested in. This procedure can be done without actually sitting on the bike, which is convenient and more comfortable if you have the seat removed for maintenance.

Still confused? The turn signal switch has a small "L" for the left side signals and a small "R" for the right side signals.

Need more help? Go on EBay and buy a sidecar kit. Follow the installation instructions and install the side car. When you are finished with the installation, the side car should be on the right side of the motorcycle here in the US depending on how good you are at reading instructions. The left side is the side that does not have a side car on it. To be sure you get it right, have your wife read the instructions for you. Women are better at reading instructions than men, except for operating instructions for dangerous equipment like chain saws, guns and motorcycles which is why you only hear about men getting injured by these devices.

(Note: Do not buy a side car from the UK, Australia, New Zealand, Japan or any of the other 60+ countries that drive on the left side of the road.)

 

[gggGary]

The problem with idiot proof devices like a manual cam chain adjuster is that they keep making smarter idiots. Tighten adjuster til the plunger stops wiggling, repeat, stretched chain.
It's not noted as a common problem with cam chains but early final drive chains were crap.

 

[5twins]

Yes, even with only 14K, if the chain was repeatedly set too tight, that could prematurely stretch it out. There's also a good chance it wasn't set/checked often enough. Yamaha kinda screwed up with their 4K mile adjustment interval. It should be done more often, like every 1000 miles. I check mine at every oil change.

 

[TwoManyXS1Bs]

For those confused about the left and right side of the bike:

Haha. Pete, coffee kickkin' in already?

Another clue is when your bike doesn't start after 30 kicks.

The pain shoots thru the LEFT arm.

... (Note: Do not buy a side car from the UK, Australia, New Zealand, Japan or any of the other 60+ countries that drive on the left side of the road.)

Good advise, same is true for the "non-side" variant, also known as 'car'.


My other XS1B stretched its chain after 10k miles. Demanding camshaft...

 

[pamcopete]

TwoMany...,

Yes. Gotta be more careful in the early hours. Too much energy...

 

[evdog]

So the new chain came in. Installed it and it still did not line up. It seems about the same off, but I figured what the F. I will see if it works. Points, still ways off and the engine is assembled. I do not think I mentioned that the case has been welded so someone before me has messed around with this engine.

Is the Crank on a TX different from a Crank on a late model XS; ie different amount of teeth or size sprocket on the Crank.

Yes the Cam is installed correctly
Yes the Advancer is installed correctly
I have put in two different cam breaker point rods and the lobes. Both rods and lobes are off used engines. I am running out of ideas

 

[pamcopete]

evdog,

Remember what TooManyy said. The points gap affects the timing, so what points gap are you using?

 

[evdog]

The gap between the points I am trying to set to .014. I understand if I narrow the gap or widen it, the timing will come closer to the F mark or further away. What I want to do is to get in the ball park of somewhat close timing. Not .002 or.036 of a gap. I consider .008-.02 gap near the ball park. I am not there.

This is why I think something internal is off, though I tell myself to keep it simple, for it usually is.

 

[5twins]

Yes, the crank on the later 447 motors differs from the early 256 cranks, but it's not so much the crank itself but rather the rods and the cam chain sprocket. The later models use a 106 link cam chain with a .306" pitch. The crank has an 18T sprocket and the cam a 36T one. The early motors like yours use a 102 link chain with a .315" pitch. The crank has a 17T sprocket and the cam has a 34T one.

The later crank can be swapped into an early motor but you would need to change the sprocket, or use a later cam as well, or swap the later cam sprocket onto the early cam. I suppose it's possible someone swapped a late crank in but didn't change the other needed stuff. On the two sprockets, one needs to be half the size of the other for the timing marks to align at every revolution.

 

[evdog]

So I hate to say this but it was something simple. Thank you 5twins for the information and everyone else; but the points lobe was installed wrong. Now it starts, runs, is on the fire mark, yet one carb is not giving gas to the engine at idle. New problem but again thank you everyone for the in site.

Keep it simple stupid

 

[5twins]

That's a new one on me. Care to elaborate on how that happened? I thought the points cam would only go on the advance rod one way, slid on the locating pin.

That carb probably has a plugged up pilot circuit but it could be something as simple as having its idle speed turned down too low.

 

[evdog]

One side has a even circular lip and the other is a perfectly lobed points breaker. I do not know off the top of my head if late models differ from early models, but it seams to work fine.

As far as the carb I figured the same about the pilot circuit, but this is now the, i don't know 10th time, I cleaned them and still same problem. With it idling I spray carb clearner in the intake and no change on that cylinder.i Go on vacation and hopefully something will come to mind.

Again thank you everyone for your replies.

 

[TwoManyXS1Bs]

... I thought the points cam would only go on the advance rod one way, slid on the locating pin...

Good catch, 5twins. The parts manuals don't depict that points cam very well at all.

In the 2-1/2 years I've been on this forum, I've only seen this question come up once, and even then it caught me off guard. Dang it, can't find that thread.

The cam's slot is full length, and the points cam can be installed backwards, but the corner of the points followers may try to climb onto the circular non-cam area. So, the points cam must be installed with the circular, non-ground portion to the rear, with the ground lobe outboard.