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SOHC.co.uk Forums => CB500/550 => Topic started by: loafer on September 11, 2018, 03:40:48 PM

Title: carbs or timing ?
Post by: loafer on September 11, 2018, 03:40:48 PM

Hi ,
just got my  550 back together after repairing the transmission,i set the points and timing statickly with a multi meter and got it pretty much spot on with the 2  f marks and the points gap . 14 thou ,
   it starts on the button and ticks over fine ,
   problem is , engne misfires badly over 4000 revs , just wondered what is the best order  to check things .
        bike has been chopped and is running with pods on !! [not good] though it was running a lot better  before i took engine out , though a bit rich , new plugs but same points.
cheers Paul
       

Title: Re: carbs or timing ?
Post by: deltarider on September 11, 2018, 09:10:13 PM

Quote from: loafer on September 11, 2018, 03:40:48 PM

Hi ,
just got my  550 back together after repairing the transmission,i set the points and timing statickly with a multi meter and got it pretty much spot on with the 2  f marks and the points gap . 14 thou ,
   it starts on the button and ticks over fine ,
   problem is , engne misfires badly over 4000 revs , just wondered what is the best order  to check things .
        bike has been chopped and is running with pods on !! [not good] though it was running a lot better  before i took engine out , though a bit rich , new plugs but same points.

Just a check... what exactly do you mean with 'much spot on with the 2  f marks'? Exactly what '2 f marks' do you mean?

Title: Re: carbs or timing ?
Post by: loafer on September 11, 2018, 09:58:43 PM

  1 4  and 2  3

Title: Re: carbs or timing ?
Post by: Trigger on September 11, 2018, 10:02:02 PM

Exhaust leak at the head  ;)
Back fire via the pods  ;)
Carb rubbers sucking air  ;)

Title: Re: carbs or timing ?
Post by: loafer on September 11, 2018, 10:26:53 PM

Points open bang on the firing marks for 1 4 and 2 3 , i  have  put new exhaust gaskets on , dont seem to be blowing , though there is a bit of back firing over 3500 revs , the carb rubbers are all tightly fastened and seem in good nick  , its  running a bit rich though [i think] , the plugs are always sooty when i take them out.
I was thinking of checking timing with a strobe light , but dont really know what the readings should be  , mixture screw ?
or maybe change the main jet size ?

Title: Re: carbs or timing ?
Post by: deltarider on September 12, 2018, 07:10:27 AM

Quote from: loafer on September 11, 2018, 09:58:43 PM

  1 4  and 2  3

OK, just to be sure, here is a pic. In the pic below the static F mark is yellow which should align at idle. Fully advanced the 'two' marks (blue and green) should align. This has to be checked before we go into other possible causes. Sometimes the advancer is stuck, that's why.

Title: Re: carbs or timing ?
Post by: loafer on September 12, 2018, 08:31:03 PM

thanks for the info , i,ll have a look tomorrow , just checked exhaust gaskets and one of them wasnt in properly !! all bent and twisted , thought engine was a bit loud !! runs a little better but still not right