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Old 25-05-19, 07:03 PM   #1
gst
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Default K3 cam tensioners in curvy - power loss and exhaust afterfire

Bought a 2000 curvy about 6 months ago with the usual cct rattle. After going through many relevant threads I have replaced the originals with K3 model. Procedure followed -
1. Removed spark plugs
2. With rear piston at compression stroke TDC, removed old cct and dropped in the k3 one. Timing mark at R. Wound engine anti cw, no strange noises.
3. Followed same procedure for front piston with timing mark at compression stroke TDC.

Engine is running, no rattle, but there is noticable power loss and afterfire at deceleration. After a couple of days, it died during idle a couple of times and sometimes needs to be cranked twice to start.

Any opinions/advise would be greatly appreciated. Read in a thread that both ccts should be removed and replaced at F timing mark, but cant seem to find it again. Is it true? Is the timing wrong know? Remedy?
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Old 25-05-19, 08:23 PM   #2
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Can't see how changing the cct's is going to cause your issue, unless the chain has jumped and the timing is out, but as there are no rattles. Think if you'd got it wrong, then there would have been a big bang.
However you could check the compression on both cylinders to see if there is a loss, which might mean the timing was out and the valves had touched the piston and bent them, but if expect the engine to be noisy.

Perhaps when removing the plugs you've disturbed the plug lead and it's not sparking properly, our you've not seated the plug cap properly or not got the plug in tight?

Have you disturbed the airbox when lifting the tank to get to the rear plug?

Have you trapped the fuel line or not attached the vacuum line to the tap properly?
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Old 25-05-19, 08:30 PM   #3
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Did you turn the engine with the CCTs removed? It does sound like the timing is a bit off, or the camchain is very tight. The K3 ones go straight in, no messing around. You could try relieving the tension and letting them re-set. Normally this means taking them out but with (for example) the K5 ones you can poke a screwdriver down the tunnel and press on the ratchet pawl to let it off (this is after removing the CCT spring). When I fitted mine years ago I admit I just slapped them in, turned it forwards by hand a few times, and fired it up. They work well.
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Old 26-05-19, 07:42 AM   #4
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Thank you very much for your prompt replies. The airbox was removed and refitted and made sure all hoses tightened. Fuel line I have to check. The spark plugs I believe correctly tightened but I will check again. Any ideas about the timing marks? Should they be at F and R respectively or both at F one revolution apart? Indeed I suspect the rear being overtightened if I installed it at the wrong mark. I didn't turn the engine with the ccts out. I appreciate all your help
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Old 26-05-19, 10:14 AM   #5
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Unless you actually removed the cam chain during the fitting of CCT I don't see how timing would be affected. Was the bike running OK when you got it apart from the noise from tensioners ? If any valves have been bent I expect more than just a little loss of power.
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Old 26-05-19, 10:50 AM   #6
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Hi, yes the bike was running ok apart from the rattle.
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Old 26-05-19, 12:31 PM   #7
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Your timing is out as you've used the wrong timing marks when removing the rear CCT.

The F and the R is for a clearance check not for removal (I've made this mistake as well).

Check in the manual (either Haynes or workshop) but the short version is front cylinder first, rotate to TDC and the F mark on the timing. Remove and replace the CCT. Now rotate 360 and the rear CCT can be removed and replaced.

For valve clearance check it is the same but after the front rotate 270 to the R mark and check.

I would suggest you check your timing. Take the valve covers off starting with the front and make sure that is aligned, I suspect this will be fine. Now to the rear where I would guess you're off. Ensure that the engine is at TDC. Take the CCT out align the cams and the chain. Replace the CCT. Rotate the engine twice and check alignment.

And now while you are in there do a valve clearance check.
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Old 26-05-19, 06:37 PM   #8
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Thank you for confirming my fears! Will follow your suggestions hoping I didn't do any damage.
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Old 26-05-19, 07:00 PM   #9
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Quote:
Originally Posted by squirrel_hunter View Post
Your timing is out as you've used the wrong timing marks when removing the rear CCT.

The F and the R is for a clearance check not for removal (I've made this mistake as well).

Check in the manual (either Haynes or workshop) but the short version is front cylinder first, rotate to TDC and the F mark on the timing. Remove and replace the CCT. Now rotate 360 and the rear CCT can be removed and replaced.

For valve clearance check it is the same but after the front rotate 270 to the R mark and check.

I would suggest you check your timing. Take the valve covers off starting with the front and make sure that is aligned, I suspect this will be fine. Now to the rear where I would guess you're off. Ensure that the engine is at TDC. Take the CCT out align the cams and the chain. Replace the CCT. Rotate the engine twice and check alignment.

And now while you are in there do a valve clearance check.


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Old 27-05-19, 05:14 PM   #10
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Default Re: K3 cam tensioners in curvy - power loss and exhaust afterfire

Shows you how much I know!
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