Thank you for letting me join your group I have a problem with my CB 900 FA can...


Thank you for letting me join your group I have a problem with my CB 900 FA can anyone help me I think I have the camshaft lobes facing the wrong way possibly 180° out do the camshaft slopes point forwards or backwards at top dead centre as the bike turned over and there is a spark and petrol but she will not fire up any help would be appreciated thank you

%d comments
  • Hi mark the camshaft loves on no1 cylinder depending which stroke your on either face each other or away from each other not same direction , to be honest I do so many engines without in front of me can't remember if point away or at each other , so go by the cut outs on end of camshafts they should face each other and level with gasket surface

  • As long as number 1 and 4 pistons are at TDC and the cam lobes on cylinder 1 and 4 are facing each other or away from each other you are ok,if the lobes are facing each other you are on the induction stroke and if they are facing away from each other you are on the compression stroke

  • Thanks Keith for filling in there had a few beers so didn't want get complicated and mess it up

  • Thanks for your help l will have a look

  • I meant to post the service manual but can't seem to find it now

  • Thank you for your link to your Google Drive I tried to download it or print it unfortunately I can't as it's on the Google Drive if you don't mind if you find it would you be able to email it to me so I can print it thank you

  • Sure, PM me or tell me your email here and I'll email it to you when I can find it.

  • These were the most cam-position related pages I found by browsing quickly. You can find all the manuals on

    Just need to register first then go to forum/technical documents and articles.

  • Well the timing is ok but only running on two cylinders 4&3 but not 1&2 it looks likes it blowing the petrol out the back of the cards 1&2 if the cards were over fuelling would this cause this?

  • I guess if the fuel isn't igniting it could cause that too? Did you check for spark on cyl 1&2?

  • Fuel misting in carbs is generally common even on fully working engines but not sure about these. Never run mine without filter on.

  • Hi yes I have a good spark on all cyl just don't know what to do next

  • I have new carb inlet rubbers and new cutoff values and and cleaned the carbs

  • Inspected carbs so everything opens/closes and is adjusted as it is supposed to? If youre sure timing and spark is good I would assume that it could be carbs, cyl compression or valves most likely? Probably some people here with more experience but that's my guess.

  • Mark if it's blowing back then most likely you still haven't got timing correct on cams , inlets are opening when they should be closed

  • Are your valve clearances set correctly. For best results they should be set to a minimum clearance of .13mm or .005'' set the piston at TDC with the cam lobes facing away from each other on each cylinder to check