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blackj · 12-12-2010, 10:25 AM

On a rider last weekend on my 2002 SV650S the bike started loosing power when I tried to maintain a speed just of 80 mph or 7000rpm. It would accelerate up to it fine. But just over 80mph there was loss of power with a drop in rpm. This happend until about 6500rpm when the bike would backfire/pop and then start to accelerate again.

I'm not sure if the bacfire is part of the problem or is a result of the power loss resulting in unburn gas getting expelled into the exhaust system.

Has anybody encountered a similar problem before? and has a fix?

Thanks

MOKE1K · 12-12-2010, 11:23 AM

There is something your leaving out. Perhaps it's been sitting?

Morbo the Destroyer · 12-13-2010, 05:34 AM

That bike has carbs; they may be seriously out of sync and/or in need of cleaning and adjustment. When was the last time the bike was tuned up?

Or: did somebody change the stock exhaust for a performance system? If so, the loss of backpressure could cause your symptoms, especially if there was not a corresponding re-jet on the carbs done with the exhaust change.

blackj · 12-13-2010, 07:54 AM

The bike hasn't been sitting, I pretty much ride to work everyday. Its just a short 9 mile trip so I don't get into that speed range.

The bike is all stock but maybe it could do with a tune up or the carbs being cleaned. I bought the bike nearly two years ago with 22k miles on it just after a service and since then I had it serviced after 3k miles but I didn't have the carb cleaned or adjusted.
Is there anything I could look for that might indicate that this could be the problem?

Thanks

Morbo the Destroyer · 12-13-2010, 08:14 AM

You could pull the sparking plugs and see if they're wet, black, etc. Aside from that, tune up need is symptomatic.

Maybe you just got a bad batch of gasoline, or high-ethanol gas.

sarnali2 · 12-13-2010, 09:45 AM

Looks like you blew a seal.....

MOKE1K · 12-13-2010, 10:12 AM

That would be a little abnormal to have blown a seal this early, but not that it couldn't happen. I think it's from lack of use even though he admits he rides it everyday, you and I both know it needs a little flogging once in awhile. They aren't meant to be babied.

MOKE1K · 12-13-2010, 10:12 AM

Check the inside of the tank for rust, or possibly bad smelling fuel. Pop the tank and inspect the throttle linkage aswell. Then I'd pull the plugs. My guess is the rear cylinder plug possibly. Your not leaving the choke
open are you?

blackj · 12-13-2010, 11:09 AM

I don't think its bad gas as it happened once during the summer, I was on the I-10 in Arizona and it was 114F heat . But at around exactly the same speed.

I might not be running it too hard on the daily commute but I do have a couple of freeway miles so it is getting up to 70mph "without issue" daily.
I replaced the spark plugs about 1000miles ago.

I'm not leaving the choke open, although it wouldn't be past something I could do.

Ultima · 07-20-2011, 03:49 PM

Sounds like fuel is not getting to the carbs. Clean everything. you will need a blow-gun on low pressure.

RA

12-12-2010, 10:25 AM	#1
blackj Registered Member Join Date: Dec 2010 Posts: 3	Power Loss at 7000rpm follow by a backfire On a rider last weekend on my 2002 SV650S the bike started loosing power when I tried to maintain a speed just of 80 mph or 7000rpm. It would accelerate up to it fine. But just over 80mph there was loss of power with a drop in rpm. This happend until about 6500rpm when the bike would backfire/pop and then start to accelerate again. I'm not sure if the bacfire is part of the problem or is a result of the power loss resulting in unburn gas getting expelled into the exhaust system. Has anybody encountered a similar problem before? and has a fix? Thanks

12-12-2010, 11:23 AM	#2
MOKE1K Registered Member Join Date: Jul 2008 Location: Kalapana, Big Island Posts: 3,956	There is something your leaving out. Perhaps it's been sitting? __________________ "YOU CAN'T BOLT ON SKILL" "The only thing limiting your bike, is you" We survived Bush you'll survive Obama! "the most fundamental fact about the ideas of the political left is that they do not work. therefore we should not be surprised to find the left concentrated in institutions where ideas do not have to work in order to survive." --thomas sowell

12-13-2010, 05:34 AM	#3
Morbo the Destroyer Registered Member Join Date: Oct 2010 Posts: 1,309	That bike has carbs; they may be seriously out of sync and/or in need of cleaning and adjustment. When was the last time the bike was tuned up? Or: did somebody change the stock exhaust for a performance system? If so, the loss of backpressure could cause your symptoms, especially if there was not a corresponding re-jet on the carbs done with the exhaust change. __________________ Fun Facts to Know and Tell! Thomas Jefferson wrote that the 1st Amendment erected a "wall of separation" between the church and the state (James Madison said it "drew a line," but it is Jefferson's term that sticks with us today). The phrase is commonly thought to mean that the government should not establish, support, or otherwise involve itself in any religion. Its.......A FACT!

12-13-2010, 08:14 AM	#5
Morbo the Destroyer Registered Member Join Date: Oct 2010 Posts: 1,309	You could pull the sparking plugs and see if they're wet, black, etc. Aside from that, tune up need is symptomatic. Maybe you just got a bad batch of gasoline, or high-ethanol gas. __________________ Fun Facts to Know and Tell! Thomas Jefferson wrote that the 1st Amendment erected a "wall of separation" between the church and the state (James Madison said it "drew a line," but it is Jefferson's term that sticks with us today). The phrase is commonly thought to mean that the government should not establish, support, or otherwise involve itself in any religion. Its.......A FACT!

12-13-2010, 09:45 AM	#6
sarnali2 Aging Cafe` Racer Join Date: Jun 2007 Location: Sittin' down by my window, lookin' at the rain. Posts: 8,132	Looks like you blew a seal..... __________________ "Carpe` Throttelum -Loud Suits Save Lives" "All the BMW riders in the room, I want you to leave. Now. Out. "

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12-13-2010, 07:54 AM	#4
blackj Registered Member Join Date: Dec 2010 Posts: 3	The bike hasn't been sitting, I pretty much ride to work everyday. Its just a short 9 mile trip so I don't get into that speed range. The bike is all stock but maybe it could do with a tune up or the carbs being cleaned. I bought the bike nearly two years ago with 22k miles on it just after a service and since then I had it serviced after 3k miles but I didn't have the carb cleaned or adjusted. Is there anything I could look for that might indicate that this could be the problem? Thanks

12-13-2010, 10:12 AM	#7
MOKE1K Registered Member Join Date: Jul 2008 Location: Kalapana, Big Island Posts: 3,956	That would be a little abnormal to have blown a seal this early, but not that it couldn't happen. I think it's from lack of use even though he admits he rides it everyday, you and I both know it needs a little flogging once in awhile. They aren't meant to be babied. __________________ "YOU CAN'T BOLT ON SKILL" "The only thing limiting your bike, is you" We survived Bush you'll survive Obama! "the most fundamental fact about the ideas of the political left is that they do not work. therefore we should not be surprised to find the left concentrated in institutions where ideas do not have to work in order to survive." --thomas sowell Last edited by MOKE1K : 12-13-2010 at 10:17 AM.

12-13-2010, 11:09 AM	#9
blackj Registered Member Join Date: Dec 2010 Posts: 3	I don't think its bad gas as it happened once during the summer, I was on the I-10 in Arizona and it was 114F heat . But at around exactly the same speed. I might not be running it too hard on the daily commute but I do have a couple of freeway miles so it is getting up to 70mph "without issue" daily. I replaced the spark plugs about 1000miles ago. I'm not leaving the choke open, although it wouldn't be past something I could do.

07-20-2011, 03:49 PM	#10
Ultima Registered Member Join Date: Jul 2011 Location: Bella Bella,BC Posts: 2	Sounds like fuel is not getting to the carbs. Clean everything. you will need a blow-gun on low pressure. RA