Yamaha ybr help

Pee91 · L Plate Warrior Joined: 19 Jun 2018 Karma :

Im new to the bike scene , recently brought a yamaha 125 fuel injection , bike was running fine idling steady at 1300 rpm , now it idles around 1600 and bounces up and down slightly at 1600 , seems to be using abit more fuel and backfires abit on downchange , any ideas im pulling my hair out
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Ybr 125

ThatDippyTwat · World Chat Champion Joined: 07 Aug 2016 Karma :

Have you changed the exhaust?

If so, put the stock one back on it.
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'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)

Pee91 · L Plate Warrior Joined: 19 Jun 2018 Karma :

Kentol750 · World Chat Champion Joined: 24 May 2016 Karma :

Change spark plug, see what happens then.
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Some bikes.

ThatDippyTwat · World Chat Champion Joined: 07 Aug 2016 Karma :

As said, put a new plug in it.

If nothing, check your air filter, make sure the airbox hasn't got oil in it and rubbers and seals are seated properly.

Spray some flammable stuff (clutch/brake cleaner etc) by the intake manifold (rubber from carb to engine). If it revs up, you have a manifold leak. Could be as simple as it's not seated correctly, a perished O-ring, or it could have a crack.

One at a time, you want to identify the issue, in case it comes back in the future.
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'98 VFR800 (touring) - '12 VFR800 Crosrunner (Commuting) - '01 KDX220 (Big Green Antisocial Machine)