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Old 05-27-2013, 06:09 PM   #1
radguzzi OP
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Question ‘99 SV 650 Carb help… any experts here...?

‘99 SV 650 Carb help requested…

This might be a long story so get comfy, others will just pass it up as it they will have no interest in the subject and that’s fine.

I picked up a 1st gen SV 650 a bit back, bought it as a non-runner so I knew I had to get in the carb-a-shooters first.

The poor thing had not been stored properly so I suspected the low speed circuit would be plugged and the battery was low. The previous owner mentioned that he thought it might need diaphragms but given his penchant for shoddy maintenance practices, I did put not much credence in his opinion.

I charged the battery and actually started the SV albeit running on one cylinder so I tried some Seafoam just to do it. Oddly enough, while rocking the motorcycle back and forth in an attempt to mix the Seafoam with the fuel, the SV would intermittently run on both cylinders. Nice and clean but then it would go back to breaking up.

Now I will go through the carbs completely, I would never just run Seafoam through it as a cure all and Hope that it would work.

I took the carbs off and sure enough found that one low speed jet was plugged tight. Ah ha, gotta be it. Threw it all back together and it acted just the same.

So, my questions are:
Are there any components in particular to pay attention to while the carbs are apart…? I do realize that the jets need to be clean but…

What on earth would have allowed the intermittent running on both jugs like I described…?
Floats with holes in them…? Or simply dirt on the seats of the metering needles…?

What symptom does a hole in a diaphragm present…?

Oh, this thing has a TPS too (Throttle Position Sensor) never seen one on a carbed engine before now… Would that be suspect…?
All right,

Thanks for any insight, just know I will go through the carbs totally but any guidance as what to look for specifically is appreciated.

Best,
Rob
 
 
 
 
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Old 05-27-2013, 09:40 PM   #2
clapped_r6
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not an expert, but i have gone through sv carbs a few times.

first off, you gloss over the low battery. if it's too low, one cylinder doesn't fire so well, or at least that's what happened with mine. make sure the electrical connections at the coils are tight, had a loose one there as well (which may explain it would run when you moved it, maybe a better connection was made?) also, know that the charging systems on the first gen is kinda suck, read the forum at svrider for way detailed info on that.

there's probably some schmeg that isn't allowing the gas to get where it has to go. pull them apart, take the diaphragm caps off and have a look. any fuel passage is suspect and should be blown out with some compressed air. my money is on electrical, but maybe there's something not allowing fuel over to one carb. maybe the fuel crossover hose is funky on one side?

i doubt the holes in floats, but i'd look anyways. there's probably junk on the bottom of the bowls that should be taken out. a hole in diaphragm would mean it wouldn't rise with intake vaccuum enough, running lean if at all on that cylinder. would idle fine however.

tps - unless the PO is a boner and started messing with it, i doubt it. there should be a factory paint mark to see if it's been messed with. probably blue paint pen.

what's the tach doing while this is happening? if it's doing weird things, look electrical fo sho

edit: pull the plug of the cylinder not firing. it will be clear whether it's not getting fuel, or too much fuel. does it smell like unburned gas while running as a 325cc single?
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Old 05-27-2013, 11:01 PM   #3
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Warning: I am not an expert--I've just got a little experience here. Hope this helps.

You might be jumping ahead of yourself based on what the previous owner told you. I'm very much guilty of this myself and ending up on the wrong track, so stick to basics and be VERY methodical. Check the easy stuff even if it seems stupid. Here goes:

SV manual. The full one is very helpful when it comes to carbs. Get one if you can.

Battery. Check voltage both running and ignition off. Twins take a pretty good battery to turn them over and start. Yours probably needs replacing if the bike sat for awhile.

Make sure both plugs are firing. Heck, time to replace the plugs anyway. Check all connections if not firing, consider a bad coil, connections, or plug wire. I had a bad (intermittent) coil connection, and spent way too much time trouble-shooting what I was sure was a fuel problem.

Drain any old fuel from tank and replace. Make sure the petcock works under vacuum.

Pull the Airbox. Check the choke connections, make sure they are attached and working. Start engine and look down each carb when running to see if fuel is being pulled in each carb when revved partly. When off, use a finger to pull back the slides and make sure the needles pull back and are not loose, floating detached.

Pull vacuum slide caps. (can be done without removing carbs). Inspect and make sure they are assembled correctly. You'll need a set of needle-nose pliers for this. Note how things are assembled, or use the other carb or a parts guide if you get screwed up. Be very careful with the small springs and o-rings under the needles that will jump out and commit suicide. Just a side note, I've had c-clips break several times on the top end of the needle and had the needle floating around loose in the carb. Inspect diaphragm. Reassemble carefully, you can pinch and cut an o-ring here pretty easy. If you don't have c-clips, you probably have stock needles.

Still having problems? Time to turn the carbs over. Drain and pull the float bowls. Make sure the float needles are moving, not stuck. I'd replace this assembly anyway, along with the small filter here. Pull jets and inspect again for boogers, re-assemble or replace. Make sure float height is equal.

Try to run again.

Can you do a compression check?

Past this, I'm stumped.

Good luck!

SV's rock!

cjohns screwed with this post 05-30-2013 at 09:38 AM Reason: spelling of course!
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Old 05-28-2013, 07:00 PM   #4
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All good info for a sanity check guys, I will go through the carbs for sure and all that you mentioned and be careful about anything I touch.

I do have the manual so I will check on the procedure for proper float height as well.
The battery is up, I have not yey done a compression check but will.

So is the C Clip thing a common shimming trick with these...? I have done that on both the Transalp and the Hawk GTs, they respond well to that with other mods.

The idea of watching the tach is a good hint also for electrical vs carbs issues.

Thanks, back soon.

rd
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Old 05-28-2013, 10:13 PM   #5
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iirc, my tach wasn't working when firing on one cylinder, and one coil connection was the culprit. hth
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Old 05-30-2013, 09:32 AM   #6
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C-clips are used on adjustable needles for tuning. Sounds like you are pretty much in the know on this. I have these on a race SV, and have pretty much gone to carrying multiple spares. Had to draw a diagram to remember how all the little parts go together. Put things back together way too many times by flashlight!

Another problem with '99 I have been through was the voltage regulator. Nearly burned up the yellow 3 wire stator wires and their attachments. Bottom line is you end up replacing the regulator with a CBR regulator and replacing some of the wiring. MUCH information on SVrider.com about that there. I know this is probably not what you are dealing with now, but something to keep and eye on--specifically the attachments (I think there are two?) from your stator to the regulator. Grab a cup of coffee, and google SVrider, D'Ecosse, and MOSFET.
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Old 05-30-2013, 04:31 PM   #7
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Its worth pulling the sparkplug caps, then running a small drill bit through the drain holes then spraying compressed air into the sparkplug hole. The front cylinders tend to take on water which grounds the plug and stops it firing.

I've also had an issue with the connections too the ignition coils. They can look tight but if they come loose it'll only fire intermittantly. I just disconnect them and pinch them a little with pliers to tighten them up.

Both can be done without pulling the carbs.
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Old 05-30-2013, 06:59 PM   #8
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Well I took a few minutes and pulled the tank off, drained the remaining fuel, cleaned the fuel tap, there was not any gunk, checked the coil connections, pulled them off and pushed them on and off three or four times to insure the contacts are clean, checked the new plugs for spark, all good there.

Then I thought, well I should check the old plugs... they checked out fine too.

We have experienced an early hot spell so I took a blast on one of the Guzzis and I will go through the carbs tomorrow.


Sevv,
Not familiar with the location of the drain holes that you mention... Will they be obvious...? I'll go have a peek. the Red Sox are ahead... for now...

cjohns,
I have discovered the SVRiders forum also...

Thanks all,
Rob
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