checking NX250 cam chain tensioner

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scrambler
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checking NX250 cam chain tensioner

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Petrus hat geschrieben: Di Jul 18, 2017 3:49 pm One more question, that may be caused by my defective “english knowledge” when watching the manual:
After remove valve cover and remove the cam chain tensioner to test if it works ok (lifter operation) at the end I don’t have to left the rod locks in the retracted position, right? So, how many turns on anticlockwise will I do? The same that I did before on clockwise direction? :?
sorry, I overlooked that last question ;) . For making good I assembled a little how to check the NX250 cam chain tensioner :)

First make sure the the piston is at the upper dead position by aligning the T-mark, then remove the head cover download/file.php?id=9747&mode=view and the tensioner. At that occasion you can check the timing. The timing marks should be parallel.
cam_chain_tensioner removal.jpg
Then check the tensioner - there is often breakage due to some previous owner. Then try to push the rod backwarts, it must not be possible. This is only a static test, if the cam chain is worn out its vibrations will turn the rod mechanism backwarts, the cam chain loosened and starts to rattle - in this case there is a certain fix but a new timing chain would be the better solution.

With a screw driver turning clockwise the rod is pushed back into the housing. After relasing the rod should spring out of the housing. Finally, the rod must be arrested by turning clockwise until there is resistance - then turn a bit more (not too much or you will brake the housing) until the rod is fixed in fully retracted position.
checking_the_tensioner.jpg
Install the tensioner and hit it with a screw driver, finally check the timing chain tension.
cam_chain_tensioner2.jpg

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Petrus
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Registriert: Mo Dez 05, 2016 12:21 pm
Wohnort: Portugal

Re: Hi From Portugal and my “new” NX 250

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Wow!

Great explanation! Even for a dumb, like me! :D

Will do the test and report. At the end, turn fully retracted, more 1/8 to lock and that's all :mrgreen:

I Got a feeling (like Black Eyed Peas) that the problema is the chain. Just a guess. :oops: :oops: :oops:
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Petrus
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Registriert: Mo Dez 05, 2016 12:21 pm
Wohnort: Portugal

Re: Hi From Portugal and my “new” NX 250

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Updating:

The good:
Checked oil filter and was clean. No metal shavings at all.

The rest:
Inspected tensioner per the manual and it works but I don’t know if it works perfect or not! Would be nice to have another to compare! I can hardly move the rod with my hand but with a screwdriver it works just fine.

Mounted it fully retracted… plenty of noise (rattle). Turned it counter clockwise about 2 turns… no noise. Went for a ride (about 10 minutes) and the noise came again! The rod went to the retracted position!

Btw, the chain seems to be fine or having little wearing (to my eyes).

Don’t know what to do! Buy only a new chain tensioner? Buy a new chain too? Try “the grease fix”?

Bike is now with a good friend of mine (part-time mechanic) and he will do a closer look. In the worst scenario, I will buy both parts, he will do the job and, at the same time, adjust valves, if needed.

Just for curiosity, this is the rattling: :oops:


https://youtu.be/lM5gf07Lk1E
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scrambler
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Re: Hi From Portugal and my “new” NX 250

Beitrag von scrambler »

tough decision - I guess it comes down to how much time and effort you want to spend right now. If you apply massout's fix it won’t have any bad side effects and you could change the timing chain in 1-2 years (just like I did). Or you could try it first with a new tensioner, just because changing the chain is way more effort – if the rattle continues even with a new tensioner you could still try massout’s fix (with the old tensioner, of course).

Bytheway, I will also soon post a “how to change the timing chain” ;)
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Petrus
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Registriert: Mo Dez 05, 2016 12:21 pm
Wohnort: Portugal

Re: Hi From Portugal and my “new” NX 250

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Me happy! :D

With a new tensioner the engine is so quiet as ever. Money well spent, even if it was a bit pricey! :oops:

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scrambler
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Re: checking the NX 250 cam chain tensioner

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and for further reading
info_cylinder_head.pdf
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