Author Topic: Sym Duke 125cc. Cam chain guide  (Read 261 times)

gingel

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Sym Duke 125cc. Cam chain guide
« on: May 15, 2017, 05:18:34 PM »
Hi,

I have the Sym Duke 125cc, which supposed to have the same engine as the Megalo 125cc.

In order to replace the upper cam chain guide, Do you have to remove the camshaft?
If yes, when you open the 4 head nuts, do you have to replace the head gasket even if you don't move it?

Thank you.

Syd

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Re: Sym Duke 125cc. Cam chain guide
« Reply #1 on: May 15, 2017, 08:20:35 PM »
I don't know about needing to remove the cam, but if you pull the head you should replace the head gasket. Have you tried to find the service manual?

Tromper

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Re: Sym Duke 125cc. Cam chain guide
« Reply #2 on: May 15, 2017, 11:56:02 PM »
If you can't find one for the Duke specifically the Fiddle 125 motor is likely pretty close, particularly if the year is pretty close.
I note that the head gasket crosses with the Fiddle, & some Kymco models that are air-cooled as well.
http://www.athenaparts.com/eng/products/view/10372/cylinder-head-gasket (here)
http://scooterunderground.ca/knowledge/manuals/ has the 09 service manual for the fiddle.
Give it a look and see if it helps. 
Assuming it's close.  The answer is yes you do need to remove the cam, & as noted by SYD you should replace the head gasket at that point since you're already there and the price of failure is having to do it all over again if ya don't just blow the motor completely.

Cheers
Tromper

08 SYM HD200
07 Suzuki Burgman 650

gingel

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Re: Sym Duke 125cc. Cam chain guide
« Reply #3 on: May 16, 2017, 06:42:31 AM »
Thank you for the asnwers.

The problem that i have, is that the Cam chain is too loose for my opinion.
I tried to replace the cam tensioner, but didn't solve the problem.
When i removed the tensioner i noticed a small dent in the upper cam guide, where the tensioner is pushing against.
The dent is in the shape of the tensioner (small square).

Do you think this is what causing the cam chain to be too loose?

Thank you.

Syd

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Re: Sym Duke 125cc. Cam chain guide
« Reply #4 on: May 16, 2017, 02:40:01 PM »
Is the tensioner adjustable?

redridinghood

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Re: Sym Duke 125cc. Cam chain guide
« Reply #5 on: May 16, 2017, 07:10:26 PM »
It's a chain and chains do wear and get longer... How much longer until it's beyond the service limit/your comfort level... I don't know.

Adding...Sprockets can wear, also

You only need access to 1 link (and a $10 vernier caliper) to measure the pitch of the chain and if with the magneto removed, you could measure a stretch of several links, you could get an idea of how worn the chain is.

You have access to the cam sprocket? If you pulled the cam chain away from the sprocket, what do you see? Daylight between the 2? 🤐

Only adding this to show, where there's a will there's a way.  https://m.youtube.com/watch?v=IkSl0ZUDnZc
« Last Edit: May 16, 2017, 07:42:06 PM by redridinghood »

gingel

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Re: Sym Duke 125cc. Cam chain guide
« Reply #6 on: May 17, 2017, 07:06:38 AM »
Is the tensioner adjustable?


No, it's not adjustable.
Here is a picture of it:


It's a chain and chains do wear and get longer... How much longer until it's beyond the service limit/your comfort level... I don't know.



I actually did an engine rebuild about 23,000Km  (around 14K miles) ago, and the chain and tensioner were replaced.