jeanxgrey Posted April 10, 2023 Report Share Posted April 10, 2023 Hi everyone, So, a friend recently brought over his 2011 Sherco ST 2.9 as it wouldn't start. Vacuum and fuel hoses were in no good shape (or let's call it nearly non-existent), Replaced it all and cleaned the carb while I was at it and the bike started fine without air filter and while spraying some brake cleaner into the intake hose and then kept on running fine on its own. Assembled it all and again it won't start. I tested for a spark, but it's very weak and seemingly only one every few kicks. No change to that with another spark plug. So, before I start ordering all parts that *might* be causing the issue (he needs the bike back by next weekend if somehow possible), I was wondering if there's a common issue that I might look into. I thought about CDI, ignition coil and cable, hall sensors, stator... To me it sounds like an issue specific to the starting routine as it was running fine after we got it started with the brake cleaner. I don't really know much about Shercos, used to ride Beta 4 stroke and am now on a Montesa , so any help would be greatly appreciated. TIA. Quote Link to comment Share on other sites More sharing options...
tshock250 Posted April 11, 2023 Report Share Posted April 11, 2023 Stators on these definately an issue. Also as you say, the fuel lines associated with the rear tank dont help. Certainly a model to avoid. Quote Link to comment Share on other sites More sharing options...
jeanxgrey Posted April 11, 2023 Author Report Share Posted April 11, 2023 1 hour ago, tshock250 said: Stators on these definately an issue. Also as you say, the fuel lines associated with the rear tank dont help. Certainly a model to avoid. Well, now he's got the bike and we have to get it fixed somehow. But good to know that is an issue. We'll try and figure out if the stator is ok and then probably put in some new hall sensors. Any suggestions which replacement parts are any good? Quote Link to comment Share on other sites More sharing options...
htrdoug Posted April 11, 2023 Report Share Posted April 11, 2023 Ground wire for ignition is under a mounting bolt for the CDI unit, the plastic housing of the CDI box causes loss of continuity, relocate the ground to another spot and proper spark will be restored. Often the ignition components get replaced and the ground wire gets fiddled with and it restores it's connection and fools the mechanic into believing it was the component they replaced that fixed it, only to have the problem reoccur. Always verify good grounding before replacing any mysterious magical electrical doohickies. Quote Link to comment Share on other sites More sharing options...
jeanxgrey Posted April 11, 2023 Author Report Share Posted April 11, 2023 1 minute ago, htrdoug said: Ground wire for ignition is under a mounting bolt for the CDI unit, the plastic housing of the CDI box causes loss of continuity, relocate the ground to another spot and proper spark will be restored. Often the ignition components get replaced and the ground wire gets fiddled with and it restores it's connection and fools the mechanic into believing it was the component they replaced that fixed it, only to have the problem reoccur. Always verify good grounding before replacing any mysterious magical electrical doohickies. Thanks! Will try this first before ordering any spare parts! Hopefully we're lucky! Quote Link to comment Share on other sites More sharing options...
Strutty Posted April 12, 2023 Report Share Posted April 12, 2023 check you havent pinched the vacuum hoses putting the back end and airbox back on Quote Link to comment Share on other sites More sharing options...
jeanxgrey Posted April 14, 2023 Author Report Share Posted April 14, 2023 On 4/12/2023 at 12:35 PM, Strutty said: check you havent pinched the vacuum hoses putting the back end and airbox back on As mentioned above, this has all been checked and even replaced as they were defective.And we have found that the spark is weak to non-existing. Do you guys know whether the spark plugs are required to have interference resistance or not? Currently it has an Iridium plug with resistance built in, but in a trial shops it states to use NGK BP5ES which doesn't have the resistance built in. With a weak ignition system as in the Sherco this might actually be the cause of a weak to non-existing spark. Quote Link to comment Share on other sites More sharing options...
jeanxgrey Posted April 14, 2023 Author Report Share Posted April 14, 2023 On 4/11/2023 at 11:39 AM, htrdoug said: Ground wire for ignition is under a mounting bolt for the CDI unit, the plastic housing of the CDI box causes loss of continuity, relocate the ground to another spot and proper spark will be restored. Often the ignition components get replaced and the ground wire gets fiddled with and it restores it's connection and fools the mechanic into believing it was the component they replaced that fixed it, only to have the problem reoccur. Always verify good grounding before replacing any mysterious magical electrical doohickies. This hasn't worked by the way. 😕 Spark plug and then hall sensors up next. coils are not available any longer it seems, so fingers crossed that's not it. Quote Link to comment Share on other sites More sharing options...
tony27 Posted April 21, 2023 Report Share Posted April 21, 2023 Splatshop used to have the readings for the stator on their site, not sure if they are in the tech articles at the top of this section Quote Link to comment Share on other sites More sharing options...
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