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Discussion Starter · #1 ·
So last year my 1980 Ski Doo Citation 4500 ran great till the end of the season when it started to loose a spark in one cylinder intermittently and had to limp back to garage. I replaced the plugs a few times with varied results. I put it away till now as snow is on the ground. At this time I pull plugs and rest on cylinders and pull over to see varied strong spark to very weak to no spark. It does try to sputter upon starting at this time, but that is all. I do not suspect plugs as they are new. I do get wet plugs after a few tries so fuel doesn't seem an issue as well. I wonder about the coils and if there is a way to test via volt meter ie. ohms. If so which wires? I have blue with red stripe and black from top coil and solid blue wire and black from bottom coil. Both coils have a solid blue to ground. These all yield together and head into the lower engine case. There is the plug cable itself from each coil to each plug also of course. What else may cause this symptom? All thoughts welcome. I appreciate the help and feedback.
 

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Time to pull engine & clean & check points. If in not great condition they should be replaced. Time engine & go. These sleds were noted for point issues, Usually if it is coil it will work or not work. 99% bet it is points
 

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Discussion Starter · #4 ·
Was afraid of that lol. Ok well never did before. I have obtained a manual so see what happens, thanks
 

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Discussion Starter · #5 ·
Ok so far I did remove the engine and haven't been back since. I just almost bought a 1996 Ski Doo Formula S 380 but the seller and I just could not meet at a price. This has now given me some inspiration to maybe get that classic back on the snow. I have decent mechanical skills, but no real idea on how to go and diagnose the external or internal coils or the points and condensers ect... I am not sure the full procedure of tear down. I see a mark for what looks like timing under the oil pump when I removed and stopped there. Not sure if I should be taking note on position before I remove the big nut and what looks like a flywheel? I see inside behind this disk and the points ect... I have a manual but it reads like I have done this before and takes for granted that I have not. I like step by step lol. Any help would be great if someone has the time. Thanks.
 

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If you have the motor out and up on the bench, you can easily remove the starter recoil, the fan pulley, and then the flywheel. You will need a puller for this. Once you have the flywheel off you can have a good look at the points, condensers, and wires. Then you will be able to file your points and set them to the proper clearance(.014"). Then you can diagnose it from there. It's one step at a time. Good luck and keep asking questions on this forum as you move along with it.
 

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Discussion Starter · #7 ·
Yep I am that far. I see what looks like a lightning bolt as well as a mark on flywheel. Timing mark I assume. They are not lined up and do not know where in the stroke the motor is at. Do I take note at this time for position? Use a permanent marker? Will it only go back together one way? Is there a key slot or something when the flywheel comes off? Or do I just remove the big nut and pull the flywheel and stop worrying? Once I am past flywheel how do I know if points are dirty? I don't know how they look when they are clean. I will have to get a feeler gauge right? I think that is what it is anyway. To check space where point makes contact. If and when clean and adjusted, how much resistance should I feel while checking clearance. I imagine I need to push or pull thru the gap right? Or is it more like spark plug gap? I will stop there for now. Don't want to get too far ahead. Thanks.
 

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Discussion Starter · #8 ·
It is snowing like crazy right now. Must be in a band here in North Greece, NY right now. It is driving me nuts lol. Gotta be an inch an hour right now. I live on a state highway which is kept pretty clear and you could ride on it right now. I am so working on this sled today.
 

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Yep I am that far. I see what looks like a lightning bolt as well as a mark on flywheel. Timing mark I assume. They are not lined up and do not know where in the stroke the motor is at. Do I take note at this time for position? Use a permanent marker? Will it only go back together one way? Is there a key slot or something when the flywheel comes off? Or do I just remove the big nut and pull the flywheel and stop worrying? Once I am past flywheel how do I know if points are dirty? I don't know how they look when they are clean. I will have to get a feeler gauge right? I think that is what it is anyway. To check space where point makes contact. If and when clean and adjusted, how much resistance should I feel while checking clearance. I imagine I need to push or pull thru the gap right? Or is it more like spark plug gap? I will stop there for now. Don't want to get too far ahead. Thanks.
Yes there is a key and it only goes one way. You won't need to mess with the timing unless you loosen the stator and move it, which you won't be. Yes you will need a feeler gauge and a points file. You can use some very fine grit emery cloth but the file works better. As long as the points are not pitted or worn round(they should be flat where they meet each other) then you can file them, clean them with a lint free cloth, and then gap them. The shaft has a lobe that opens the contacts as it turns. Turn the crank until the points are open fully and then set them with the feeler gauge. After you set them, spin the crank around a few times and recheck the gap, just to make sure. Also you can add a drop of oil to the wick that rubs on that lobe. Once you have the flywheel off you will understand.
 

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You won't need to mess with the timing unless you loosen the stator and move it, which you won't be.
As soon as the point gaps are altered the timing is changed, therefore the timing should be verified. Small changes in point gap=significant changes in timing.

An increase in point gap advances timing.

A decrease in point gap retards timing.
 

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I did not think the little bit of adjustment on the points would cause the timing to be off enough to make a difference. I have not adjusted timing after setting points before(mostly because I don't have a dial gauge for finding tdc). The cheapest I have found for a dial indicator locally was $50, and it didn't have a wheel on the end. It is something I have wanted to buy, but sledding is a hobby for me and I try to do it on a budget. Perhaps I should buy one.
 

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I did not think the little bit of adjustment on the points would cause the timing to be off enough to make a difference. I have not adjusted timing after setting points before(mostly because I don't have a dial gauge for finding tdc). The cheapest I have found for a dial indicator locally was $50, and it didn't have a wheel on the end. It is something I have wanted to buy, but sledding is a hobby for me and I try to do it on a budget. Perhaps I should buy one.
0.002" to 0.004" change in point gap can change timing by as much as 0.020" or 0.030" or more.

The timing marks and a timing light made from a flashlight are all thats needed for the average rider.

The 377's are one of the easiest point engines to time as well.

Just my 2 cents worth......
 

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Discussion Starter · #13 ·
Excellent feedback guys, thanks. I will get into it tomorrow hopefully after getting my hands on a gauge and file then. I am pretty sure I have a puller around here that might work. I will update of course and probably have questions, but this gets me started. Thanks again elanguy and Old Sled Nut.
 

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Discussion Starter · #14 ·
I retrieved all but one tool to start the job today. I have to find and or make a tool to hold the flywheel while I spin off the big nut. I am thinking of getting 3 longer machine screws of same thread and using the holes the pulley attaches to the flywheel and fabricate a handle even with wood shaped on the scroll saw. So tomorrow will get into it and clean some points.
 

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A time honoured (and factory recommended) way to hold the crank while removing the clutch or flywheel is to insert a 3/16" rope down a spark plug hole.
 

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Discussion Starter · #18 ·
I see the logic and ease, thanks Dirt mover. I got the nut off using a scrap piece of wood and drilled a pattern using the pulley and used some longer screws. It worked well also. I did hit a snag though. Upon removing the flywheel/magneto I had a casualty. My puller failed. Must be seized on there good. I used a penetrate spray too. Puller rated for 2.5 tons pulling force. On there good. Pittsburgh brand puller. I am now stuck till I get another puller. I am afraid to use heat as the coils are right behind it ? Been here? Office equipment Bumper Audio equipment Font Automotive exterior Wheel Automotive tire Bumper Tire Motor vehicle Automotive tire Tire Motor vehicle Crankset Vehicle
 

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Discussion Starter · #20 ·
Ok the rope will keep the piston from rising thru full stroke and stop the crank from spinning. Won't put too mush stress on a crank bearing? How much rope and 2 cylinders, 2 ropes? I held the puller with a wrench to keep from spinning the flywheel. Do you think that is what broke the puller? The stress on that particular arm of puller resisting the twisting motion against the wrench? I cannot verify if that is the same arm that broke. I don't believe it was though. In the pic with the wrench it is not touching the bottom right, the one that broke. Should it be that hard to pull it off? I think I am the first to pull it so it has been there for 33 years. I noticed some damage on spun wire on coil thru flywheel window afterward. Puller touched coil slightly and didn't break any of the copper wire spun on it but it did crease a line down it. Like as if you were to run a finger nail along it making a creased line. Hope it is ok. Automotive lighting Fluid Amber Drink Metal
 

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