Bike loses power sporadically

[skinny]

What would cause a bike to loose power while riding? this is inconsistant and speed / gear and load seem to have no relevance. It just doesnt have power sometimes usually while riding along and trying to give it gas it sounds like the bike all of a sudden starts running on 3 or less cylinders (due to exhaust note change).

Is this likely to be electrical or fuel related?

[koba]

Most likely electrical.
Pulse coil, Ignition coil or Black Box.

If it last for a reasonable ammount of time it would be good if you could check for spark while its going on...

Start reading...

[FJRider]

Most likely electrical.
Pulse coil, Ignition coil or Black Box.

If it last for a reasonable ammount of time it would be good if you could check for spark while its going on...

Start reading...

What he said ... check the plugs for crud / gap ... it doesn't take much to rob a few horsepower ...

Fuel filter blocked ... ?? kink in the fuel line ???

I would say fuel ... electrical is usually all go or NOTHING ...

[koba]

I would say fuel ... electrical is usually all go or NOTHING ...

True.

I had a particular incident in mind, If it is an instant drop in power and stays at the same low level of power which causes it to struggle to even do a hundie kays look at the pulse coils and ignitiopn cols because one half of the engine isn't working.

It it is more of a cough and splutter and is less sharp/consistant I would look at a fuel problem.

Its real hard to relate stuff like this though a keyboard!

I would check everything anyway, starting at the fuel tank breather... there can be some real obvious things like fuel filters etc but less obvious ones like a damaged carb diaphragm.

[stify]

I would say fuel ... electrical is usually all go or NOTHING ...

well how can I top this gem of an internet diagnosis....

[FJRider]

Start it in the dark ... and look for spark where there SHOULDN'T be spark ... a short in the leads ...

A dodgy lead would cause probs like this ...

[CookMySock]

Does it do it after riding for quite a while? Does it come right for a while if you stop? Worse at night or in cooler weather? It might be the fuel tank vacuuming down.

Steve

[YellowDog]

I have had incredible results from similar problems by changing HT leads.

Good luck.

[stify]

[QUOTE=DangerousBastard;1129646699 It might be the fuel tank vacuuming down.
[/QUOTE]

ok the last internet diagnosis isn't anywhere near this gem....I've been a mechanic for the last 20 odd years and never heard of this one....maybe you should stick to what ever the fuck you do during the day....

[skinny]

Its a discussion i did ask for peoples opinions. Obviously not everyone is a mechanic and its the risk i take for starters when people cant even see it or ride it or knowing its history.

[skinny]

do you test the spark like a car with a screw driver in the lead and arc it against the engine?

[skinny]

its pretty instant i will have trottle and then all of a sudden i have sweet F all. then i can hold throttle in the same position and after a few seconds it will come back and other times i need to change gear. Even tho none of these always work. Could be i just go over the right bump and the powers back again.

[koba]

its pretty instant i will have trottle and then all of a sudden i have sweet F all. then i can hold throttle in the same position and after a few seconds it will come back and other times i need to change gear. Even tho none of these always work. Could be i just go over the right bump and the powers back again.

Either be prepared to spend ages checking everything and doing lots of learning or take it to someone who already knows, you really aren't going to get too much useful diagnosis over the internet.

[skinny]

for someone whos hands on it can be a money saver too. Ive been to mechanic before who wouldnt have a clue what they are doing but charge you to go through all the options that i can do myself.

[Ragingrob]

Could also be reg/rec failing. I've had this problem and experience similar symptoms. There is a troubleshooting flowchart for the reg/rec if you have a search around, sorry bit busy at the moment to look myself.