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Another Cam Chain Tensioner Question

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I recently rebuilt my 06 450 R and installed a new cam chain, valve job, piston and rings ect. Ran great first run. Dialed in carb. Second run, hard starting backfireing. Checked timing skipped a tooth. Retimed. Ran great. Third run. Cold start. Took off 1st kick very cold weather. Stalled would not start. Checked cam timing jumped a tooth again.

What would make a new cam chain jump time so easily? The auto cam chain tensioner seems to work alright. No broken spring ect. Did I not have the chain tight enough with the stock cam tensioner. I let the tensioner snap in after I pull the screwdriver out which was turned out and held in place.

I've never seen a chain jump so easily. Bike has undergone only one rebuild not a lot of hours. I don't overrev only trail ride. I originally thought I sheared a woodruff key on the flywheel (11 oz) but all is fine there.

Could the auto cam tensioner be backing off with an engine hiccup? Is there any way I can rule this out be taking the tensioner apart and inspecting it?

The bike is stock and runs great otherwise.

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I suffered the same problem with mine,, unfortunately the single cam engines are very hard on the crank gear.

The solution for mine was a new crank..I even went so far as a maunal tensioner. still killed chains and skipped in a single ride session...

I have seen a stator cause the same symptoms... hard starting was the only other constant symptom on that bike, week spark unless you kicked like you wanted to get hurt.

good luck

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So with yours the lower crank gear was slipping in the crank causing the timing to shift. I have great spark. I removed the resistor in the cap and put in a stainless steel post. Works great to improve spark. I guess I could mark the crank and gear to see if this is moving.

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I would bet one of the gears/sprockets are moving, could be either, I've seen both.

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I'm prepared for both. I made a manual tensioner and will put some punch marks on the crank gear. Anyone have any luck spot welding the gear with a Mig?

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Gasit, Did you weld your crank sprocket? I was reading your post on the Cam Gear post. If the cam gear slips you can not restore performance without degreeing the cam and ignoring stock cam settings.

The crank gear can slip and be retimed moving the cam chain, if you are close to the timing marks which my bike is doing. It is slipping between a tooth after every ride or so.

My questions is......is there enough room to spot weld the crank gear on the crank and the flywheel.

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are you checking the timing marks after letting the cam chain tensioner snap into place? not doing so will give you the wrong marks, as the chain tightens the timing will retard at least 1 mark.. check marks with tight chain.

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I do Melk, I even crank the engine a turn. All I know it starts first kick once lined up and it will get off a half a tooth or so forcing me to turn the cam gear a tooth on the chain. As for the ACCT I took it apart and could not see an issue. If it retracted, which I don't see how it can being a screw with spring tension on it, the engine would make obvious cam chain sounds after the chain jumps or before a shut down.

The tensioner failure must be catastrophic, even with a broken spring on the 06 tensioner I don't see how the screw could retract suddenly to cause damage. I think the lower crank gear is slipping or the cam guides are self destructing causing piston clashes. Then the owners are forced to replace the lower ends and the cam chain tensioner gets the blame.

I really think the crank gear is slipping. I don't ride hard but do have an 11Oz flywheel. I installed a rekluse rode it for about 15 miles the next day it started first kick cold, stalled and timing off again. I checked the woodruff key on the flywheel before the first time it did it and all was fine.

I can reset the timing in 20 minutes from start to finish, this is the 3rd time. I make sure my view is level with the marks ect.

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Gasit, Did you weld your crank sprocket? I was reading your post on the Cam Gear post. If the cam gear slips you can not restore performance without degreeing the cam and ignoring stock cam settings.

The crank gear can slip and be retimed moving the cam chain, if you are close to the timing marks which my bike is doing. It is slipping between a tooth after every ride or so.

My questions is......is there enough room to spot weld the crank gear on the crank and the flywheel.

Yes, I welded the crank sprocket. When it slipped, I also, re-timed it a couple of times (moved the cam 1 to 2 teeth) before I figured out what was going on, as my cam was already welded and everything was new.

You are correct, the only way to properly time the cam is with a degree wheel.

Is your crank aftermarket or oem? mine is aftermarket.

How many hours are on yours? mine was new

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As for the ACCT I took it apart and could not see an issue. If it retracted, which I don't see how it can being a screw with spring tension on it, the engine would make obvious cam chain sounds after the chain jumps or before a shut down.

:busted::thumbsup:

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I am the second owner of a low hour 06. Lower end is stock, top end was just replaced with SS valves and new exhaust guides. Only engine mods are, 11oz FW, Weisco basket and Rekluse.

I'm going to spot weld ASAP. Thanks for proving it works! Is your cam after market. I'd like to degree the cam in but can't find specs. I can only find TDC.

I love this bike. The KTM guys I ride with are always knocking me. I ride single track and hills. One day I'll tell them about the Rekluse.

Thanks again for helping me stay on these pesky little problems so I can keep irritating the KTM guys.

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I'm going to spot weld ASAP. Thanks for proving it works! Is your cam after market. I'd like to degree the cam in but can't find specs. I can only find TDC.

My cam is after market. Have you verified that it is not your cam sprocket moving? I've heard of the sprocket mount slipping on the cam, it is pressed on..

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It may very well be. I retimed the other day and it won't start, not back fireing but just won't take off. I still have to check my woodruff key on the flywheel to rule that out. I was hoping it was'nt the cam because I don't have any specs to degree it back in. How can I check this without buying a new cam? I plan on tearing it apart tonight.

It would save me a world of headaches if I can retain the stock cam. I can always spot weld but won't have to reshim ect. I just had the head all redone with new valves and exhaust guides.

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Thanks Gasit I'll use a protractor to check the degrees best I can.

I systematically adjusted the timing a tooth each way and tried to start it and got it lined up. I think I was eyeballing the marks unevenly on each side making me off a tooth. I was working in a somewhat confined space. I removed the cam and tried to move the gear holder on the cam and could not detect any movement. I then marked the cam with some marks if it does move I can see it. I measured lobes for wear and inspected the decompressor also. I was all set to buy a new cam but am not completely convinced it moved now.

I also turned in the cam chain tensioner a half turn from contact since there was some movement in the guide and chain.

So far runs good about 20 miles on it. But will see if it stays put with successive rides.

Thanks for your support on this thread. The Cams specs are interesting.

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