Hi, I have a 1986 1200 Sportster but it only goes 75mph, I have done a compression test and both firing fine and correct. When on the motorway it only does 75mph can anyone come up with any ideas?? I am stumped unless the fueling is wrong or someones restricted it somehow thanks                                                                                                                                                                             

If it's running smoothly, no missfire, clean plugs that are the correct colour, etc. then that's bloody slow, even for a Harley. Any sign of the engine having been stripped in the past? It's possible that it's been rebuilt badly, cam timing off or something like that.The review I just found says 64bhp/110mph standard, so ~75mph when restricted to 33bhp doesn't sound too far off. Any way you can check with the previous owner?Check that the throttle slides are opening fully. Check for washers installed within the inlet and exhaust pathways.                                                                                                                                                                             

dose  it over heat because it could also be the advance retard mechanisum not moving properly allthough sounds like GBeldon maybe right  take pipes off and check for restrictions ect                                                                                                                                                                             

There is a 33bhp  Kit for 883 sportys don't know about 1200's though. if it's fitted it'll be in the carb.If it isn't obvious like a restrictor stopping you from opening the butterfly fully or by making the bore of the carb smaller then try another carb.
                                                                                                                                                                             

Assume you've just bought the bike, and never known it any different ?                                                                                                                                                                             

was just going to say that we're all assuming you've just bought the bike from someone (in which case the 33bhp restrictor is most likely).   Otherwise if it's just started happening and you've had the bike a while... ive no idea lol.   Welcome to the site though!                                                                                                                                                                             

Have you changed the rear sprocket? with a different size/tooth count thus changing the gearing,just a couple extra teeth will rob your top end,whats the acceleration like?Does the engine struggle or sound/feel like its overrevving Your cam gearing should be factory colour coded to align them properly so nobody should be able to get them wrong.

Hi FXR, welcome to the site.   Not sure he's around anymore, as he hasn't responded since his first post.   Hope you'll stick around longer.  U might wanna give him a nudge.   Cheers                                                                                                                                                                             

He is still about Matt and is still visiting :-)                                                                                                                                                                              

Not an American import by any chance? They run very weak to comply with super strict US emissions, Califronia models in particular are strangled to hell. Mate who used to live in CA brought his Gixer 750 (newer model, fuel injected version) over with him from the UK,  and it was way faster and had much better acceleration than similar Gixers of the same year floating around LA, which were strangled to death!! Just a thought....probably wrong!!

maybe he hasnt got bacl yet  as the bike is very very slow !! lol                                                                                                                                                                             

Wheely Nealy, i had to read that twice then , i was a bit slow too, but then it sank in and i still laughing , thanks for cheering my morning up ,                                                                                                                                                                             

haha ment to say " back"   lol my bad