Author Topic: 300 sefr top end  (Read 1284 times)

doh13

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300 sefr top end
« on: November 20, 2020, 02:16:39 PM »
Hi I plan to do the top end this winter i bought the bike used and it has 110 hours now.  I have the piston kit ,and required gaskets to do the job but should i change anything else in the top end such as  the Cam chain ,tensioner ,chain tensioner sliders , valves etc? or just check them for excessive wear and go from there? Ps is there any suprizes to expect as this will be my first time rebuilding a sherco 4t.
thanks.

doh13

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Re: 300 sefr top end
« Reply #1 on: January 04, 2021, 07:39:22 AM »
Since no one replied i thought i will post an update which may help someone else, I have installed the new piston and waiting on my valve shims the valves , cams cyl etc was  all still in spec , cam chain tensioner only was a few notches in so the cam chain was still good but i changed it anyways since i had the part.

I used an OEM piston kit and cometic gasket kit  here are the part numbers for the cometic parts incase anyone is interested.
H4850027S (OEM is 3016). There is also a top end kit for that bike which is C3748 (OEM# 5108).  PS these guys make a quality gasket.

doh13

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Re: 300 sefr top end
« Reply #2 on: January 04, 2021, 07:51:06 AM »
heres a couple pics

eralha

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Re: 300 sefr top end
« Reply #3 on: January 07, 2021, 03:43:35 AM »
Hey, thanks for posting this, it will help some one in the future.

cheers.

Rick

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Re: 300 sefr top end
« Reply #4 on: January 18, 2021, 01:47:11 PM »
Are the cam lobes on these DLC coated? They look very dark.
Virginia, USA

doh13

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Re: 300 sefr top end
« Reply #5 on: January 21, 2021, 08:05:46 PM »
Are the cam lobes on these DLC coated? They look very dark.
They could be they are dark but im not sure.

jamracing

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Re: 300 sefr top end
« Reply #6 on: February 21, 2021, 06:33:57 PM »
The valves and combustion chamber look very dirty with carbon, are you cleaning it up? I'd also statically check valves for leakage (spray carb cleaner into the valves, see if it leaks out).


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2020 300 SE Factory

doh13

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Re: 300 sefr top end
« Reply #7 on: February 21, 2021, 08:03:13 PM »
The valves and combustion chamber look very dirty with carbon, are you cleaning it up? I'd also statically check valves for leakage (spray carb cleaner into the valves, see if it leaks out).

Yep i cleaned all the valves and all of the carbon then sprayed it with carb cleaner and no leaks that i could notice.