Part throttle hesitency? - SV650.org

Taipan · 09-10-09, 10:42 AM

Hi All

Noticed my bike has been running increasingly rough this last 3-500 miles. Its okay if you nail it, but on part throttle its very jerky, almost like lean surging but kind of more defined? Sometimes it smooths itself out though?

I'm guessing its fuel related as it never backfires. Would this be a symptom of water getting in the petrol per chance? Or what would you think it might be?

Many thanks

the_lone_wolf · 09-10-09, 10:48 AM

Would help if we knew what bike you had, even carbs or EFI would be a start...

Taipan · 09-10-09, 10:51 AM

Quote:

Originally Posted by the_lone_wolf

Would help if we knew what bike you had, even carbs or EFI would be a start...

Yes it would woudn't it!

1999 carbed naked. K&N and scorpion street extreme stubby.

09-10-09, 11:37 AM

When was it last serviced? Have the carbs been balanced recently?

Luckypants · 09-10-09, 11:58 AM

Gotta say carb balance was my first thought as well.

Taipan · 09-10-09, 11:59 AM

Quote:

Originally Posted by Scoobs

When was it last serviced? Have the carbs been balanced recently?

Dont know and dont know unfortunately. Although i would add this is a developing problem rather than one it came with.

09-10-09, 12:00 PM

Anything to do with colder weather ??

HT leads, mixture need a tweek ??

09-10-09, 12:03 PM

I would get those two done first (service and sync). If you don't know when it was done it would be a good place to start. If you can't afford the expense of both, just get the carbs sync'd.

It doesn't sound like water in the fuel. I've had this. If the bike has been standing for a while all the water will be on top of the fuel, it is only after the bike has been running for a while and the water gets drawn through the carbs, that you get a wooley throttle. It also gets worse if you nail it. The only way to cure this is to drain the tank and float bowls and fill with fresh fuel.

the_lone_wolf · 09-10-09, 12:08 PM

Quote:

Originally Posted by Scoobs

It doesn't sound like water in the fuel. I've had this. If the bike has been standing for a while all the water will be on top of the fuel

ORLY?

Water is denser than petrol, so the petrol should float on top of the water...

09-10-09, 12:11 PM

Quote:

Originally Posted by the_lone_wolf

ORLY?

Water is denser than petrol, so the petrol should float on top of the water...

ORLY?

Just saying what I found mate. Which ever floats on whichever, it always ran from cold, but then started spluttering after a mile or two.

However, it DOES get worse if you nail it, so on the face of it, I would say that this is not the main problem.

Always difficult to diagnose without sight of the patient though innit.

09-10-09, 10:42 AM	#1
Taipan Member Join Date: Mar 2007 Location: Basildon, Essex Posts: 785	Part throttle hesitency? Hi All Noticed my bike has been running increasingly rough this last 3-500 miles. Its okay if you nail it, but on part throttle its very jerky, almost like lean surging but kind of more defined? Sometimes it smooths itself out though? I'm guessing its fuel related as it never backfires. Would this be a symptom of water getting in the petrol per chance? Or what would you think it might be? Many thanks

09-10-09, 10:48 AM	#2
the_lone_wolf Captain Awesome Mega Poster Join Date: Jan 2007 Location: Hamble Posts: 4,266	Re: Part throttle hesitency? Would help if we knew what bike you had, even carbs or EFI would be a start... __________________ Official "Dumbass of the Year" 2011 (•_•) ( •_•)>⌐■-■ (⌐■_■) Deal with it...

09-10-09, 11:37 AM	#4
Scoobs Guest Posts: n/a	Re: Part throttle hesitency? When was it last serviced? Have the carbs been balanced recently?

09-10-09, 11:58 AM	#5
Luckypants Moderator Mega Poster Join Date: Jul 2003 Location: Nr Ruthin Posts: 7,079	Re: Part throttle hesitency? Gotta say carb balance was my first thought as well. __________________ "Your Viffer sounds like it is raising hell! Spot on." - Witchery 17/4/08 Snow Plough Appreciation Society - Member #3

09-10-09, 12:00 PM	#7
LK-SV Guest Posts: n/a	Re: Part throttle hesitency? Anything to do with colder weather ?? HT leads, mixture need a tweek ??

09-10-09, 12:03 PM	#8
Scoobs Guest Posts: n/a	Re: Part throttle hesitency? I would get those two done first (service and sync). If you don't know when it was done it would be a good place to start. If you can't afford the expense of both, just get the carbs sync'd. It doesn't sound like water in the fuel. I've had this. If the bike has been standing for a while all the water will be on top of the fuel, it is only after the bike has been running for a while and the water gets drawn through the carbs, that you get a wooley throttle. It also gets worse if you nail it. The only way to cure this is to drain the tank and float bowls and fill with fresh fuel. Last edited by Scoobs; 09-10-09 at 12:04 PM.

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