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Topics - doh13

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Sherco Tech / decompressor starting issue
« on: January 09, 2021, 12:24:08 PM »
 From my understanding of how the decompressor mechanism works it should be fully "closed" when the bike is not running and the decompressor rod  will slightly press on the exhaust valve before the cam lobe  does to let off excess compression as the motor starts, then  centrifugal force from the running motor holds the decompressor "open".

 The problem may be  that the spring  has lost some tension or is not strong enough  and on certain shutdowns the part of the mechanism that keeps the valve open rests on the valve bucket on shutdown preventing the decompressor mechanism from fully closing/resetting.

My thought is that switching to a slightly stiffer spring or adding an additional turn to the existing spring may help the issue because the mechanism may now fully close on a shutdown before the motor fully stops spinning  which in theory should prevent the issue.  I checked the parts list for a 2020 sefr and mechanism looks to be the same p/n as the older models.  I do believe the intake cam timing has been changed on the newer models possibly to try and help with the issue?

The only problem i can see is that if the spring tension is too strong it may cause the decompressor mechanism to stay open at idle causing excessive wear. but if it were to work every time it would save a lot of wear on the starting system.

Sherco Tech / 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.

General Discussion / sefr 300 water impeller torque?
« on: June 30, 2020, 10:50:28 AM »
Hi  after 8+ weeks my parts finally arrived  :o  ,  does anyone know the torque specs of the impeller I cant seem to find the info, in the service manual, and i am assuming i should use some blue loctite as well  Ps why wouldn't the impeller shaft have a left handed thread unless i am mistaken the shaft turns clockwise whick can loosen the impeller.

Sherco Tech / 14 300serf TPS adjustment questions
« on: June 17, 2020, 07:43:50 PM »
Hi im looking for info on the adjustment of the TPS.

 After removing /reinstalling the tps (for cleaning ,yes I regret removing it  lesson learned)  I   get  only get a voltage reading of 0.58v-0.60v (with the throttle  held wide open)   every other vid /forum shows other bikes like ktm the low voltage reading is with a closed throttle and the high reading with it open but i could not figure out a way to put the tps back on to make it have a low voltage reading with the throttle closed i tried turning it every which way but it brings up before i can put the bolt back in and it only seems to go on one way.  what am i missing?  ps  0.58v-0.60 is the lowest voltage i can get as well because the adjustment is maxed and before i took the tps off the adjustment was about in the middle. i know somethings gotta be wrong.

Sherco Tech / Aftermarket Cometic Gaskets for Sherco
« on: May 01, 2020, 07:11:40 AM »
Hi just wanted to let you guys know Cometic recently started making  quality gaskets for Sherco (they weren't listed on the Cometic site  last time i looked)
I ordered a top end gasket kit for my 2014 , SEF-r 300   which is C3748 (OEM# 5108)  they are also working on bottom end kits BTW they are looking for Canadian distributors . 

 "It doesn't include every piece the OEM kit has. But it contains the necessary pieces. The valve cover gasket, and spark plug gasket aren't in the kit, but can be reused. The kit contains the head, base (2020 is a different thickness) Cam chain tensioner, exhaust manifold gasket, Cam cover o-rings, valve stem seals, and spark plug o-rings."

Sherco Tech / 2014 sefr 300 updated ecu maps?
« on: April 17, 2020, 08:02:03 PM »
Hi im wondering if there's any fuel map updates /optimizations :o for the 2014 sefr 300?

Sherco Tech / Water pump woes.
« on: April 15, 2020, 08:53:16 AM »
Hi I just bought a Used  2014 300 sef-r  and before i even got to drive it  i seen oil/rad fluid  coming from the weep hole  :'( which seems to be a common issue  so i decided to look closer . please check the attached photos ,Any idea how the impeller got ate up and the threads ate away?? the only things i can think of is that there looks to be a broken locating  dowel pin on the left that may have somehow gotten into the coolant system. the prev owner said the dowel pin was already broken when he changed the seals also if I order P/N 0935 (water pump shaft ) will i get the updated hardened version of it?

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