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Post Info TOPIC: Another cam chain noise


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Another cam chain noise
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Hi forum! I didn't want to threadjack the-dirty-commuter's thread so I shall start another topic. Same issue as him. I took my valve cover off, and checked the clearances. All were within spec. The chain worried me a little bit though...if i pushed on the chain in between the cams hard ( not exactly sure what made me to think to do that), it compressed the chain guide and tensioner, but it would not re-tension when I let off. This allowed the chain to have a good 1.5cm of slop. The only way for it to re-tension was for me to pull back on the chain guide. Has anybody else had this issue? I will be ordering a manual tensioner and hopefully that will get rid of the noise...



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The chain is normally only loose like that when it is worn. Did the sprocket marks line up against the head?

I confess that I am not a fan of manual tensioners as they require a fair bit of mechanical know how to set up properly.

Assuming the chain was good, did you take out the tensioner to check it is working properly. It is unusual for them to fail.

Brian



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I should add that the timing chain has proper tension otherwise. It only gets loose if I push on it hard enough to compress the tensioner, since the tensioner wont return unless i pry on the guide.

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I am not sure that this is a fair test.. I assume the piston is at TDC on the compression stroke when you do this ? if not you are expecting the tensionser to rotate the cams against the valve force of the valve springs. Even if the engine is on TDC, the tensioner would have to rotate the inlet cam. The tensioner is designed to take the slack out of the non- drive side of the chain, heavy loading would wear out the guide very quickly. What happens if you rotate the crank (in the right direction) after doing your test.. Does the tensioner return ? If so all is well.. As Brian says it is not a big job to take it out and check its operation if you are in any doubt.



-- Edited by alanwebbo on Monday 20th of July 2015 10:20:28 PM

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I set it at an unofficial TDC- the lobes weren't pressing the valves, but I never checked the mark on the flywheel. I shall do it properly before I ride again and then report back to you guys.

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TTRfan wrote:

The chain is normally only loose like that when it is worn. Did the sprocket marks line up against the head?

I confess that I am not a fan of manual tensioners as they require a fair bit of mechanical know how to set up properly.

Assuming the chain was good, did you take out the tensioner to check it is working properly. It is unusual for them to fail.

Brian


Not trying to be smart, Brian, but I've replaced at least three tensioners in my poor old TTR (lost count). Also, I've kept each one alive for a bit longer by removing them and looking for the polished slip mark on the push rods, then roughing the areas with fine wet and dry. If it'd been really hot weather, I'd pull them apart and add a touch more spring tension.

At my work, most people are starting to get TTR cam chain rattles around 20-25000 km. This equates to roughly 1000hrs of engine time. Somehow, and sadly, I'm rougher on tensioners than most people. (<15000km/750hrs for my WR250R...).

So I've gone the manual route, which has been on there for around 15k I think. Maybe more. Easy enough to set up as long as the chain rattles a bit when the engine is cold. I set mine when the engine is really hot, by backing it off if necessary until the chain rattles, then screw the push rod in until the rattle goes away. Surprising how small the adjustment between rattle and quiet is!

 



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