Cam chain tensioner removal: Difference between revisions
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While there have been a few reports of failure, the cam chain tensioner is not a big issue for 250 owners. Leon, a long-time club member and multiple 250 owner, says not to worry about it: "I've never had an issue with a cam tensioner on the Ninja. In this case, fixing it before it breaks may be what causes it to break." | |||
==How it works== | |||
== | The purpose of the tensioner is to take up the slack on the cam chain as it stretches with normal use. So, it's designed to only move in one direction. The springs push on the push rod, which pushes on the cam chain guide. The ball and retainer assembly, in combination with the push rod and the tapered barrel of the chain tensioner housing, form a ratchet mechanism that allows the plunger to go out but not come back in under normal use. | ||
The negative part of all this is that when the tensioner goes, the cam chain can slap around within the engine, tearing off bits of the plastic that are there to help guide it and protect the metal... which then float around in the engine until they get stuck somewhere or do damage. The chain can also jump teeth, in which case the timing is off and the bike runs terribly, or you have that unhappy valve-to-piston contact. | |||
The usual noise for a tensioner getting worn is a loud (usually consistent) ticking on the upper right side of the motor, similar to noisy (loose) valves. If you have these symptoms, and you know the valves to be correct, you should replace the cam chain tensioner. A new one is about $35. Part number for the whole assembly is 12048-1106. | |||
==Tensioner removal== | |||
*Remove the right hand [[How do I remove the fairing, fuel tank, etc?|side panel]]. | *Remove the right hand [[How do I remove the fairing, fuel tank, etc?|side panel]]. | ||
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[[image:cct3ke3.jpg|150px]] | [[image:cct3ke3.jpg|150px]] | ||
== | ==Disassembly== | ||
*Remove the ball bearing and retainer spring. | *Remove the ball bearing and retainer spring. | ||
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[[image:cct4sg6.jpg|100px]] | [[image:cct4sg6.jpg|100px]] | ||
== | ==Reassembly== | ||
*With one hand, squeeze the piston/pushrod and springs into the bore until they bottom out. With the other hand, tighten the set screw until it stops (don't torque it down!). This will hold the piston up during installation. | *With one hand, squeeze the piston/pushrod and springs into the bore until they bottom out. With the other hand, tighten the set screw until it stops (don't torque it down!). This will hold the piston up during installation. | ||
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[[image:100_1659.jpg|150px]] | [[image:100_1659.jpg|150px]] | ||
== | ==Installation== | ||
*Place the assembly over the crankcase mounting position and insert the tensioner pushrod into the hole. | *Place the assembly over the crankcase mounting position and insert the tensioner pushrod into the hole. | ||
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Sometimes, even though you put it back together right, it may take more than one try to get it to "set" properly. If you install it and it still rattles, pull it back out and try installing it again. Sometimes they like to be loved "just so". | Sometimes, even though you put it back together right, it may take more than one try to get it to "set" properly. If you install it and it still rattles, pull it back out and try installing it again. Sometimes they like to be loved "just so". | ||
== | ==More theory== | ||