Help! bike runs but wont go.

Docker · May 12, 2013, 02:29:39 PM

Hey guys,

I was lucky enough to have my conrod break and smash my piston on Friday so I've spent all weekend swapping my working top end onto my spare's working bottom end, wired it all up and got it going but there is a problem...
Whenever its in neutral, it freely revs without a problem but misses a few beats now and then and slowly returns to idle revs rather than dropping straight away.
When it is in gear and going along, no matter how much throttle you give it, theres a good chance itll lose power and cut out or when going along itll buck like a bull the whole way and wont go above 10mph.

Anyone have any ideas what might be causing this? I checked all the engine timings, sidestand switch, spark plugs and beginning to run out of ideas.

john · May 12, 2013, 05:50:28 PM

My guess was sidestand switch. You could jump is and eliminate it as a possibility completely. I am not sure where it terminates but would check that end also.

adidasguy · May 12, 2013, 08:09:38 PM

Correct on checking the side stand switch. If the side stand is bouncing up and down, the switch could be opening and closing making the bike run and cut out at random.

Put bike on center stand with side stand up and see if it bouncy. You may need to bend the spring mounting points to insure it stays up tight.

Docker · May 13, 2013, 01:00:12 AM

Already bypassed the sidestand switch so its basically non existant now but still does it

mitch79 · May 13, 2013, 04:13:14 AM

The missing/bucking and in particular the hanging idle are indicative of a lean condition. I would be having a very close look at the sealing between the head, manifolds and carbs. My guess is you have a vacuum leak.

adidasguy · May 13, 2013, 09:38:32 AM

These are also symptoms of running on one cylinder.
Check condition of plugs to see if that is the case. If so, then troubleshoot in that direction.

john · May 13, 2013, 10:23:24 AM

Sell the bike to me for $200 and be rid of it.

Docker · May 13, 2013, 10:34:44 AM

Will look into the suggestions above, thanks guy, also is there any other sensor apart from the side stand switch that might cause this?

Quote from: john on May 13, 2013, 10:23:24 AM
Sell the bike to me for $200 and be rid of it.

sure, let me know when your flight lands in the UK and ill give you directions from there

john · May 13, 2013, 10:35:25 AM

Damn.

Bluesmudge · May 13, 2013, 10:40:59 AM

May also be clogged main jet. Especially clogged main jet on only one carb. Did your tank have any rust in it?

Docker · May 13, 2013, 12:33:42 PM

Quote from: Bluesmudge on May 13, 2013, 10:40:59 AM
May also be clogged main jet. Especially clogged main jet on only one carb. Did your tank have any rust in it?

nope, nothing in the in line fuel filter either, will check carbs though

Docker · May 18, 2013, 09:58:26 AM

Thought id reply and let future googlers know what the answer was for me, the blue earth wire for the engine.

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Help! bike runs but wont go.