I've got a 97 Fatty. Of late, until the bike is hot it backfires and farts and coughs and carries on. I let is warm up for about 5 min before taking off, but still sounds like someones getting shot whenever I throttle on.

Recently had it serviced and had new plugs put in.

I'm thinking maybe points? Any ideas?

 

Cheers

has 97 got points thought they were electronic,if its been converted try changing the condensor,had one go on me and it was only a couple months old was doing what your bikes motor is doing,only my humble opinion,

I am an idiot , yes it has elect ignition (Screamin Eagle 2). Should read and comprehend what I write before I post.

 

 

Sounds like carb problems, maybe the accellerator pump that squirts extra fuel in as you throttle on.

Check manifold for leaks. Common enough problem on evo's and easy to solve. Bet it also stumbles a bit when you back it off.

Have you cked your plug leads? one may have a high resistance till it warms up giving you a miss fire under load. hope it helps.

hey Hip, swap out your new plugs for some good old ones, see if that works, i say this because i had a sporty with brand new plugs, NGKs i think, no klms at all, the bike sounded like a firing squad when you reved it even a little, put some good old plugs back in and it ran like a top, no backfiring at all , was then told by a reputable shop that once plugs foul , new or old , they're stuffed, so in this instance that theory was correct

Thanks for the feedback guys. I have checked the exhaust and found that the nuts on the rear pipe were loose. It probably gave a coupla mm clearance at the manifold. Once that was done it didn't seem to be as bad.

I have ridden it since and still plays up, but not like before.

Andrew, I will try some older plugs tomorrow and see how it goes. Tks for the tip.

 

Watch this space.........................