Fuel Starvation or Flooding?

Gaz-t1esto · Borekit Bruiser Joined: 24 Apr 2008 Karma :

Hey people. Hope someone can help.

Used to experience issues with bike where when riding after about 10 mins the bike would jolt slightly and throw my weight forward as if i had dropped 3 gears and let the clutch out dropping several thousand rpm at the same time and its got much worse, I can now free ride at 50mph....lol Yes, as it starts to jolt and throw me forward, i pull clutch to stop myself being shot off bike and no sooner than i know it, the engine has cut out and im helpless to get it started until i stop. bump starting sometimes works. I have opened throttle to keep it running once i have pulled clutch lever but the bike still insists on dropping revs and cutting out.

What do people suggest is the issue.

My ideas follow:
Carb related?
Fuel Line maybe kinked/trapped?
Fuel Filter? (If it has one....im not too mechanically minded)Led to believe it might be gravity fed fuel but source wasnt 100% sure?
dirty fuel in tank being fed into engine?
Condensation at bottom of tank being fed into engine?
Not enough air mixture?
oil/fuel mixture wrong?
Blocked breather?

Recently changed the plug and its still the same issues.

Problematic vehicle is a CBR125 2006 Plate <<< An unreliable Honda.....for a change....

Blue_SV650S · World Chat Champion Joined: 27 Nov 2008 Karma :

Id start with the blocked breather ... next time it conks out, pull over and 'pop' the fuel cap, if you hear it sucking air in .. well that is your problem isn't it Wink

____________________
The purpose of life is to fight maturity.

Gaz-t1esto · Borekit Bruiser Joined: 24 Apr 2008 Karma :

Gaz-t1esto · Borekit Bruiser Joined: 24 Apr 2008 Karma :

Doesnt appear to be breather or kinked pipe, lifted tank off and had a good look at pipes, all look fine with no kinks, tank very clean on inside....torch was very handy lol and breather pipe at bottom/over flow pipes are all clear of dirt and debris.

stumped for what to check next lol. maybe time for a mechanic.....

Blue_SV650S · World Chat Champion Joined: 27 Nov 2008 Karma :

Paddy Blake · World Chat Champion Joined: 29 Jun 2006 Karma :

There might be water in the bottom of the carb.Turn off the fuel and open the drain screw at the bottom of the bowl.

Paddy.

Cigaro · World Chat Champion Joined: 28 Mar 2007 Karma :

You say it's almost putting you over the handlebars. That doesn't sound like a simple 'running out of fuel' thing to me.

Sounds almost like the engine may be partially seizing and then freeing itself up again, but being a 4t that seems very unlikely. By the way, you say 'Oil-fuel mixture wrong'... you do know that you don't mix oil with the fuel don't you?

Gawain · Nitrous Nuisance Joined: 06 Dec 2008 Karma :

Sounds like lean surging. Could be fuel starvation/vacuum lock. Cleaning the carb may be necessary, are the carb rubbers in good shape?

Noxious89123 · World Chat Champion Joined: 10 Jun 2007 Karma :

sam_w · Two Stroke Sniffer Joined: 04 Sep 2007 Karma :

i had a similar problem to this when i had my chinese bike, it could be a faulty ht lead/coil. A mechanic told me it was behaving the way it did because it wasnt sparking properly or at the right times so mine would jerk forward or cough and splutter and then occasionally cut out. get a multimeter and test your ht lead

Gaz-t1esto · Borekit Bruiser Joined: 24 Apr 2008 Karma :

i wil strip it down this weekend and have a good look if weather improves,

thanks for ideas people Smile

Gaz-t1esto · Borekit Bruiser Joined: 24 Apr 2008 Karma :

Im up2 22k on mines, its used for travelling to and from work and fun rides around scotland Smile

what would the seals on the carb look like if in good shape or even bad shape....

Also, is there a guide for easily stripping the bike of carb etc that i can follow...not being mechanically minded is my down fall...

no smart comments like, pick up the screwdriver or ratchet set and turn away till your heart is content Smile