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Discussion Starter · #1 ·
Hey everyone, me again. My timing chain shrunk... I think? I don’t know how this is possible but it won’t fit into the grove anymore. I am lost. It fit on a week ago, but now it won’t. Anyone have a clue? Thank you all.
141187
 

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Check that the timing chain tensioner has been removed before you try to put the cam sprocket on.
Check that the chain is not hanging or binding anywhere around the crank sprocket.
Check the pin for the keyway.
Flip that pin up or down, or put the other end into the back of the sprocket.
If the pin has been put back in any way other than it's original way(even though it is somewhat symetrical), it can have a non visual difference in size, just a few thousandths of an inch will prevent it from going into the groove in the sprocket.
After you get the chain on, rotate the engine 4 turns/strokes and make sure the timing marks are still aligned.
If they are, great. If they are not, then set the marks again, try one tooth retarded, and after 4 turns both timing marks should then line up.
 

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Discussion Starter · #3 ·
Check that the timing chain tensioner has been removed before you try to put the cam sprocket on.
Check that the chain is not hanging or binding anywhere around the crank sprocket.
Check the pin for the keyway.
Flip that pin up or down, or put the other end into the back of the sprocket.
If the pin has been put back in any way other than it's original way(even though it is somewhat symetrical), it can have a non visual difference in size, just a few thousandths of an inch will prevent it from going into the groove in the sprocket.
After you get the chain on, rotate the engine 4 turns/strokes and make sure the timing marks are still aligned.
If they are, great. If they are not, then set the marks again, try one tooth retarded, and after 4 turns both timing marks should then line up.
The chain tensioner is not on right now. I also did not disassemble the head at all. There is no binding of the cam chain at the bottom. When you say pin, you mean the thing that goes into the sprocket to make sure it doesn’t move?
 

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The chain tensioner is not on right now. I also did not disassemble the head at all. There is no binding of the cam chain at the bottom. When you say pin, you mean the thing that goes into the sprocket to make sure it doesn’t move?
Yes, technically it is a key
 

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Take the chain off of the sprocket, and make sure that the sprocket slides on to the cam.
If it does, then double check the alignment and try the chain again.
 

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Discussion Starter · #7 ·
Take the chain off of the sprocket, and make sure that the sprocket slides on to the cam.
If it does, then double check the alignment and try the chain again.
Take the chain off of the sprocket, and make sure that the sprocket slides on to the cam.
If it does, then double check the alignment and try the chain again.
I don’t think there is a need to do that because it fit on about a week ago. That’s why I’m so confused.
 

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I don’t think there is a need to do that because it fit on about a week ago. That’s why I’m so confused.
Lol, well, if you're not willing to lift the chain off again; and check to make sure the sprocket still fits the cam, I guess we'll never know.
The chain did Not shrink, You, the guy working on it...made a mistake somewhere(happens to all of us), and troubleshooting is how you fix it.
Is the chain somehow preventing the sprocket from sliding on to the cam?
Or, is the placement or direction of the shaft's key, or a burr or piece of dirt preventing the sprocket from going on to the cam?
Since you don't know, and especially since the sprocket isn't even bolted on, take 10 seconds and lift the chain off, see if the sprocket will or will not go on to the cam with the chain off.
Either way, you will have an answer.
And either get the chain on, or keep looking further into what is not correct.
It's not going to fix itself.
Good luck
 

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Discussion Starter · #9 ·
Lol, well, if you're not willing to lift the chain off again; and check to make sure the sprocket still fits the cam, I guess we'll never know.
The chain did Not shrink, You, the guy working on it...made a mistake somewhere(happens to all of us), and troubleshooting is how you fix it.
Is the chain somehow preventing the sprocket from sliding on to the cam?
Or, is the placement or direction of the shaft's key, or a burr or piece of dirt preventing the sprocket from going on to the cam?
Since you don't know, and especially since the sprocket isn't even bolted on, take 10 seconds and lift the chain off, see if the sprocket will or will not go on to the cam with the chain off.
Either way, you will have an answer.
And either get the chain on, or keep looking further into what is not correct.
It's not going to fix itself.
Good luck
The sprocket goes on by itself fine. The chain won’t let it get up high enough to go on. I accidentally read your message wrong. I though you were telling me to take the case off and look at the bottom end sprocket holding the timing chain on. My fault. Thank you again.
 

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2015 Raptor 700, Barkers duals, fci, PC5, +3tb, ported head, +1 valves, 5050 cam, 745cc, 12:1,
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Are you able to put the gear on the cam and then put the chain on to the gear?
 
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Discussion Starter · #12 · (Edited)
Lol, well, if you're not willing to lift the chain off again; and check to make sure the sprocket still fits the cam, I guess we'll never know.
The chain did Not shrink, You, the guy working on it...made a mistake somewhere(happens to all of us), and troubleshooting is how you fix it.
Is the chain somehow preventing the sprocket from sliding on to the cam?
Or, is the placement or direction of the shaft's key, or a burr or piece of dirt preventing the sprocket from going on to the cam?
Since you don't know, and especially since the sprocket isn't even bolted on, take 10 seconds and lift the chain off, see if the sprocket will or will not go on to the cam with the chain off.
Either way, you will have an answer.
And either get the chain on, or keep looking further into what is not correct.
It's not going to fix itself.
Good luck
Are you able to put the gear on the cam and then put the chain on to the gear?
i can get the chain half on, but not fully. I don’t want to pry it on because i don’t want to bend or damage the chain.
 

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2015 Raptor 700, Barkers duals, fci, PC5, +3tb, ported head, +1 valves, 5050 cam, 745cc, 12:1,
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I don't want you to break anything but you may want to try and crank the engine to try and feed the chain on to the gear. I do this on my dirt bike rear sprocket and chain all the time.
 

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Discussion Starter · #15 ·
I don't want you to break anything but you may want to try and crank the engine to try and feed the chain on to the gear. I do this on my dirt bike rear sprocket and chain all the time.
I thought of that, but that’s not the correct way it is supposed to go on. It should just slide on perfectly. Timing chains are so fragile in my opinion and I don’t want to bend anything haha. Thanks for the input though!
 

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2015 Raptor 700, Barkers duals, fci, PC5, +3tb, ported head, +1 valves, 5050 cam, 745cc, 12:1,
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Make sure the chain slides whicj apply tensionor force are seated and correct. I'm not sure on the 250 but i know on other 4 strokes they fit into a groove down near the cylinder base and pivot from there to apply tension
 

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Discussion Starter · #17 · (Edited)
Make sure the chain slides whicj apply tensionor force are seated and correct. I'm not sure on the 250 but i know on other 4 strokes they fit into a groove down near the cylinder base and pivot from there to apply tension
I fixed the problem... see post below. Thank you!
 

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Discussion Starter · #18 ·
I FIXED THE PROBLEM! The way I fixed it was, I had someone hold the chain with one finger allowing it to spin freely. I then took a wrench and spun over the engine. After about 3 revolutions I head a bit of a clatter so I went and checked on it. And boom. Just like that it was fixed. Thank you all so much for your help!
 
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