Engine that has ran hot. What I found when replacing timing chain and guide.

Tully

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Last summer I built a 77 xs 650. During the build I replaced electronics with mikesXs PMA kit. The bike ran and idled fine. I did however have to advance the timing as far as the kit would allow to be able to reach the correct timing mark. I would take the bike for a ride and after about 10 miles the bike would start to lose power and it would be very hot. Or what I believe to be hot. The bike would back fire through the carbs and would not start until it sat for about 45 minutes. I did end up with shavings in the oil that I was told could be from the timing chain guide and falling apart. I parked the bike purchased a new timing chain and guide. Also the gaskets to complete the job. When setting the engine to TDC and taking off the valve cover the cam was off 180 degrees. I replaced timing chain and guide and have put the timing marks to where they should be buy the book and many videos that I have watched. The bike again runs fine. I am just waiting for a warm day here in Northern Minnesota to take it for a ride to see if it will keep running and I can get more 10 miles out of it and I can start riding it to work and weekends like I intended. Question I have is would this cam being installed 180 degrees off cause the bike to run hot?
Also the timing chain that I removed did have the master link that looked as if it was after market or at least it was not an endless chain.
The guide was bad and did need to be replaced.
 

gggGary

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The cam rotates at half speed compared to the crankshaft. The sprockets have 18 crank and 36 cam teeth. So if you had rotated the crankshaft one full turn (360) the cam notch would have turned 180 and been at the correct straight up instead of straight down position.
Your engine (cam) was timed correctly, position was correct at 180 off. Just at "compression TDC" on the other cylinder, as they are timed 180 different at the cam or 360 different at the crankshaft. Hope I made that clear.
A comparison of various two cylinder engine configurations, our engine is the first type, a 360 parallel twin.
A worn or stretched cam chain, or the guide rubber falling off, will cause the ignition timing issue you noticed.
 
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Tully

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The cam rotates at half speed compared to the crankshaft. The gears have 18 crank and 36 cam teeth. So if you had rotated the crankshaft one full turn (360) the cam notch would have turned 180 and been at the correct straight up instead of straight down position.
Your engine (cam) was timed correctly, position was correct at 180 off. Just at "compression TDC" on the other cylinder, as they are timed 180 different at the cam or 360 different at the crankshaft. Hope I made that clear.
A comparison of various two cylinder engine configurations, our engine is the first type, a 360 parallel twin.
A worn or stretched cam chain, or the guide rubber falling off, will cause the ignition timing issue you noticed.
Makes perfect sense just back to the drawing board for heating. :(
 

WideAWAKE

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You getting oil to the top end? Can pull the valve covers when you fire it up to make sure.

You built the motor? - piston to wall clearance too tight, ring gaps too small - both will make for a hot motor.

What do your plugs look like.

Sure it’s not a problem with your ignition? Sometimes they go bad (or come bad) and go funky when they heat up.
 
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jpdevol

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Running hot can also be caused by too advanced ignition timing or too lean carburetion....

To double check, spark should occur at idle (~1200rpm) at the 'F' mark indicated at the red arrow and at the yellow arrow above 3000rpm
stator housing (2).jpg
 

WideAWAKE

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:agree:

A plugged gas cap another possibility on a runs for 20 minutes scenario.

Ahhh yeah. Been there before.

And I’ll mention it if you got online filters as well. They can clog and cause the same sort of issue.

Photos attached are of a filter that I got that had a seal that obviously wasn’t ethanol proof. Made a nice grilled cheese haha.

623E1F1C-0DBD-4EF6-8880-73D2CE54156D.jpeg
38C6616E-4FFB-4D36-B218-E34E6B32A8D9.jpeg
8EA2025D-59E8-4776-8EE1-901DBD8E7FBA.jpeg
 

Tully

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Running hot can also be caused by too advanced ignition timing or too lean carburetion....

To double check, spark should occur at idle (~1200rpm) at the 'F' mark indicated at the red arrow and at the yellow arrow above 3000rpm
View attachment 240718
so I may have that wrong and that is the problem I am guessing. And this is the result of crappy directions from MikesXs. I will retime this tonight with my timing light.
 

Tully

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so I may have that wrong and that is the problem I am guessing. And this is the result of crappy directions from MikesXs. I will retime this tonight with my timing light.
And if I look hard enough I am betting that I have the email stating from Mikes to have the bike timed at the 15 degree mark at idle.
 

Tully

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And if I look hard enough I am betting that I have the email stating from Mikes to have the bike timed at the 15 degree mark at idle.

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November 7, 2019 Motorcycle Electrical, Motorcycle Generator Brushes, Motorcycle Ignition, Motorcycle Pistons, Motorcycle Tools, Motorcycle XSCharge, Tech Center

How To: Install The XSCharge XS650 PMA Kit​

MikesXS_PMA_Kit_XSCharge-1024x1024.jpg

XSCharge XS650 Permanent Magnet Alternator Installation Instructions​



1. Remove the shifter, footpeg and side cover.
2. Remove the chain guard that is mounted to the shift shaft and remove the wire from behind it.
3. Remove the original charging system. Begin by first removing the two Phillips head factory screws from the stator assembly. This works best when using an impact driver. You will not be reusing them so do what is necessary to remove them as they can be hard to remove. Remove the stator assembly.
PMA-1.png

4. Remove the rotor assembly. First, remove the retaining nut and lock washer. The easiest way to remove the rotor from the crankshaft is with a factory threaded puller which can be purchased here. Be very careful with these type pullers to not damage the threads on the end of the crankshaft. The crankshaft is tapered and you should be able to put some pressure on the puller and using a hammer tap the lead screw on the puller and remove the rotor.
PMA-2.png

5. Remove the small locating pin at the bottom of the crankcase.
PMA-3.png

6. Take the new adapter bracket and stator assembly and check it for fit. It should fit fairly snug inside the alignment tabs on the engine case. The clearance on these alignment tabs and the height of the mounting bosses can vary some from the factory so do not force the adapter bracket into place. You can mark it and use a file if necessary to get it to seat against the engine
block and mounting screw bosses.
PMA-4.png

CAUTION: Make sure that the plate fits completely against the threaded mounting bosses where the mounting screws go. Check both sides and if there is a gap behind the adapter on either side between the adapter and the mounting boss, use the extra small washers, supplied in the kit as a spacer. Only use them if a spacer is needed.
PMA-5.png

When the fit is correct, install the woodruff key back in the crankshaft if you have removed it. Using the two socket head screws, flat washers, and lock washers that are supplied in the kit, now it’s time to mount the adapter. These screws should be applied using Blue Loctite. Do not overtighten these screws as you can strip out the engine case.
(The first picture is only to show the screw location, your bracket will have the stator already mounted)
PMA-6.png

7. Carefully line up the key slot in the rotor with the woodruff key already located in the crankshaft and slide the rotor on, being careful to not dislodge the key. Install the crankshaft nut and lock washer snuggly but DO NOT tighten completely. Rotate the engine slowly, making sure that there is no rubbing or scraping of the stator and rotor. If this occurs, you will need to remove the rotor, loosen the adapter bracket mounting screws and realign the bracket and retighten the screws. When this is complete, check again, making sure of proper alignment and then, torque the crankshaft nut to 29 ft-lbs.
8. Route the wires through the cutout in the engine block and press the rubber grommet into place. You may need to carefully trim the black outer wire cover to get a correct fit. You can now route your new wires behind the chain guard on the shift shaft and reinstall. This is what the assembled unit should look like.
PMA-7.png

PMA-8.png

9. Reinstall the side cover with the inspection cover off. Now, you will need to mark TOP DEAD CENTER (TDC) for timing purposes since the original timing marks were on the discarded factory stator. You can mark the TDC mark on the lower flange of the side case behind where the inspection cover goes. There is a notch in the case below the flange. Make your TDC mark line up with the
right side of the notch.
PMA-9.png

Remove the spark plugs. Slowly rotate the engine so that the piston reaches its highest point of the stroke. You can see this through the plug hole using a light or you can locate this by placing a soft object like a drinking straw into the plug hole and watch it reach its highest point on the stroke.
When you have located TDC, hold the crankshaft perfectly still and you will need to mark a line on the rotor in line with the TDC mark you previously placed on the flange. Mark it accurately with a marker and then you can scribe the line with an etching tool. Make another line on the flange at .500 inches to the left of the TDC mark that you made and that gives you the 15-degree mark.
 

jpdevol

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And if I look hard enough I am betting that I have the email stating from Mikes to have the bike timed at the 15 degree mark at idle.
To be clear: I have not read the Mike's instructions (and some ignitions do static time at full advance). But, the end (running) result should be the same as above pic regardless of ignition source.
 

gggGary

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15 degrees is in agreement with factory timing, running slightly retarded from that is acceptable, even desirable. I'd be setting at 10 degrees.
Timingmark.jpg

BUT timing at full advance is MUCH more important. Full advance must never exceed the factory mark or 40 BTDC

timing rules.jpg


timing2.JPG
 

Jim

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On any ignition system, there's two points.... idle timing and full advance timing.
Idle timing determines how hard or easy starting is.
Full advance timing determines whether or not you're close to burning a hole in the pistons.
I'll leave you to decide which is the more important of the two....
 

jpdevol

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Hmmm. OK, I pictured a stock rotor/stator and you have the PMA rotor.....so a little different.

What I might do is find TDC mark the rotor AND sidecase TDC, then use a degree wheel to determine where "idle F" (15*) & "Advance F" (40*) should be on the sidecase.

I'll find ya a printable degree wheel......
 

Tully

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To be clear: I have not read the Mike's instructions (and some ignitions do static time at full advance). But, the end (running) result should be the same as above pic regardless of ignition source.
I am very grateful for you knowledge today. I am crossing fingers and hoping that this is the issue.
I did not build this engine. to answer other questions.
 

Tully

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Bike wont even run at all unless it is on that 15 degree mark that is shown on the mikesxs install. So I am not sure what to think. Its just depressing. I am not the person that has the money to drop this off at a shop and can work on a car all day long but am stumped when it comes to a 1977 xs 650. Just dont have a clue. I am still hoping with this new timing chain and guide that she wont heat when it warms up around this area. I am going to have to run it at the timing marks that the bike decides to run at and hope for the best. For all I know the engine was built or worked on that didnt do justice to the rings and who knows what else.
 
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