02 SV650s Dies mid throttle / need expert eyes

W

WellWell

Member
Hi

Have a gargaged one I bought with 4kmiles. Its clean, clean, clean,

The previous guy put a pipe, airbox and bling lights( took lights off)
I cleaned the stuck carbs and checked for air leaks. (I have seen air leaks do this, maybe something particular with this model to watch out for. I have also seen bad grounds do this - maybe there is a ground test).

Runs without authority and dies around 1/2 throttle @ around 6-7k rpm.
(my hawk gt runs a thousand times better everywhere)

I would like to sort it out..

Any SV experts out here?

(If you are an expert mechanic - I do good bike paint)
 
M

motomania2007

TC/MSF/CMSP/ Instructor
It starts and runs fine correct?

Are you testing it while riding or sitting still in neutral?

If you have it idling and you twist the throttle quickly to full open what does it do?

If you have it idling and you twist the throttle very slowly to full open what does it do?
 
W

WellWell

Member
Hello

I have embedded my answers in your questions

1- It starts and runs fine correct?
--- Yes starts fine- - start circuit is clear---

2- Are you testing it while riding or sitting still in neutral?
-- test is on freeway---

3- If you have it idling and you twist the throttle quickly to full open what does it do?
-- at rest, quick open throttle - very slight miss at stated RPM range, definately revs at rest. NO pop, caugh, smoke,stink or sputter

4- If you have it idling and you twist the throttle very slowly to full open what does it do?
--very slight miss at stated RPM range, definately revs at rest. NO pop, caugh, smoke,stink or sputter

Thanks


BTW battery fully charged- grounds to bike are clean and correct
 
Last edited:
kxmike

kxmike

Well-known member
I had a bike that did something similar and it turned out to be a wire grounding out against the header pipe. It would only happen at high speed when the wind would push the wire against the pipe. Took me forever to find that one.
 
M

motomania2007

TC/MSF/CMSP/ Instructor
So if I read your answers correctly then under load on the freeway if you roll the throttle open as it accelerates up to about 7,000 RPM it just falls on its face and stops?

What if you inch up to 7,000 RPM very slowly does it accelerate through it very slowly?

As it starts to fall in its face what happens if you just slightly crack the throttle in the closed direction. Not fully closing the throttle just slightly rolling off.

Like the other poster you're mentioned it's possible you've got an intermittent electrical issue but I'm leaning more toward some fuel mixture issue as in you are leaning out because the bike can't breathe properly or flow fuel properly under load.
 
M

motomania2007

TC/MSF/CMSP/ Instructor
Since you mentioned the battery have you tested the charging system? You need to make sure that the charging system is producing about 14 volts at about 2,000 RPM.You can determine that by measuring the voltage of the battery with the engine running at 2000 RPM.
 
afm199

afm199

Well-known member
motomania2007 said:
Since you mentioned the battery have you tested the charging system? You need to make sure that the charging system is producing about 14 volts at about 2,000 RPM.You can determine that by measuring the voltage of the battery with the engine running at 2000 RPM.
Click to expand...

Sadly, the Gen one won't even produce 14, but typically 13.8, a constant source of problems.

The problem could be simple carburetiion. 7000 rpm is when the carbs come off the slide needle and onto the main jet. I'd pull the carbs and check both main jets.


PS: OP, you said you cleaned the carbs. What did you do? Did you pull all the jets and check their passages? What size are the mains? If there's a pipe on there and airbox mods, 138 stockers are too small.

PSS: Start it up, let it warm up, and feel the headers. One may be hot, the other warm or cold. SV's run just like you described when one cylinder is not operating.
 
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W

WellWell

Member
hello

I will check list the ideas below

1- bad ground: will have to look around for any spots that could be compromised.
btw - I had a faulty ground on an ATV that did exactly this problem. Could not find problem until I drove the bike at night and saw a spark jumping off the bike as the system was arcing / looking for a ground. Solution was to make a dedicated ground from the ignition to the frame. PRESTO !

Are there any vulernable points/ electrical spots on this bike to look for?

2- 138 jetting too small-
Guess I need to review what the jets are as it suppose to have the Factory Pro Jet kit in it. Not sure if these jets are staggard like the Virago or Hawk gt. If anybody has an upjetted carb, it would be useful to know where you landed, fornt and back.

3- Battery
I suppose a load test would be good idea. Most batteries work sub- 12 V
The battery was origionally dead as can be, but charged right up and starts always. But a load check wouldn't hurt.

4- The bog spot
It bogs as stated regardless of approach. Maybe you can fill me in on what each of these application scenarios would indicate. Most notable, the worse symtom is under ride/ load conditions. Reving this on the stand, the problem isn't highly noticable.

5- Carb clean
Complete teardown and sonic clean of all parts.

6- Cold Header
Good idea. Forgot to check that one.

7-My hunch is a ground or Battery that has a dying cell in it. Now that we are talking about this, I need to check the tank to see if everything is clear on the breathing side and filter side. As this thing sat long enough to freeze the carbs completely when I got it.

Hunch or not, thanks for the ideas.

WW
 
Tom G

Tom G

"The Deer Hunter"
As to testing the ground:
Get a multimeter and measure the voltage between the lead of the battery minus (the middle of the lead pole which comes out of the battery) and the metal of your engine (not paint or other coatings). Do that when the light + high beam are on. Report back the reading. That will test you ground connection.
 
afm199

afm199

Well-known member
WellWell said:
hello

I will check list the ideas below

1- bad ground: will have to look around for any spots that could be compromised.
btw - I had a faulty ground on an ATV that did exactly this problem. Could not find problem until I drove the bike at night and saw a spark jumping off the bike as the system was arcing / looking for a ground. Solution was to make a dedicated ground from the ignition to the frame. PRESTO !

Are there any vulernable points/ electrical spots on this bike to look for?

2- 138 jetting too small-
Guess I need to review what the jets are as it suppose to have the Factory Pro Jet kit in it. Not sure if these jets are staggard like the Virago or Hawk gt. If anybody has an upjetted carb, it would be useful to know where you landed, fornt and back.

3- Battery
I suppose a load test would be good idea. Most batteries work sub- 12 V
The battery was origionally dead as can be, but charged right up and starts always. But a load check wouldn't hurt.

4- The bog spot
It bogs as stated regardless of approach. Maybe you can fill me in on what each of these application scenarios would indicate. Most notable, the worse symtom is under ride/ load conditions. Reving this on the stand, the problem isn't highly noticable.

5- Carb clean
Complete teardown and sonic clean of all parts.

6- Cold Header
Good idea. Forgot to check that one.

7-My hunch is a ground or Battery that has a dying cell in it. Now that we are talking about this, I need to check the tank to see if everything is clear on the breathing side and filter side. As this thing sat long enough to freeze the carbs completely when I got it.

Hunch or not, thanks for the ideas.

WW
Click to expand...

12 volts on a battery is dead. 12.4 is almost dead. If a sitting battery reads 12.4, time to shit can it. The SV650 is a particular problem here, the gen one had a shit Regulator/rectifier that never charged properly even when new. Your battery is not ok. As soon as winter comes, it's dead.

Forget staggering jets on the SV650. We've run literally thousands of dyno runs and seen very little difference.

I still think the problem is in the carbs. Did you PULL all the jets, the float needle, etc?

Check the headers. Sv front cylinders start missing from two things, water in the spark plug hole and the plug wire bouncing up and down and working loose from the spark plug connector and or the coil. Check both.
Check that the retainer that holds the needle in place on the cars has not popped out.

What size jet? What did you do to the airbox? Anywhere from 142 to 162.
 
Last edited:
ST Guy

ST Guy

Well-known member
What kind of air filter does it have? Perhaps it's over oiled.

And the previous owner added an air box? Didn't know anyone made aftermarket airboxes.
 
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