‘99 SV 650 Carb help requested…

[RadHawk]

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

[wheelieman14]

The TPS advances the ignition timing at full throttle. You can wire it fully open if running flatslide carbs (which you are not with stock CV carbs) to get 4 degrees of advance. If you hook up an ohm meter, you can read the resistance between 2 of the 3 connector pins. I get ~775 Ohms closed & 4.07K Ohms wide open. Unlikely the TPS has anything to do with the bike not running on both cylinders. the most common problem with the 1st Gen SV650 is the front spark plug cap making a poor connection with front spark plug. Just picked up an 01 SV650 that had been sitting for about 8 years and the carbs were nasty with bad gas and clogged pilot jets. Stock jetting is 15 pilot jet & 137.5 main jets.

[Degsy]

Wirelessly posted

Like bob said. You have an electrical issue. Probably a plug cap loose.

[MarkMarine]

I also found the coil wire crimp ( that spade connector right next to the vacuum lines running into the lower chamber of the airbox) loose. It's in a place that is easy to whack when doing carb maintenance. The other symptom I had when I had this problem was the tach dropping out, which is a dead give-away that it's electrical and cyl-1, and not the plug cap.

[The Snowman]

G1 SVs are notorious for ignition coil issues, especially the front coil. As mentioned above, check the crimp on all spade connectors for both coils.

If you're not already running them, get yourself a set of NGK bare-bones $3 copper CR9E spark plugs. These bikes hate Iridium or dual-electrode plugs. (I have tried both types and found out the hard way.) Make sure the plug boots also fit tightly.

[SVRACER01]

G1 SVs are notorious for ignition coil issues, especially the front coil. As mentioned above, check the crimp on all spade connectors for both coils.

If you're not already running them, get yourself a set of NGK bare-bones $3 copper CR9E spark plugs. These bikes hate Iridium or dual-electrode plugs. (I have tried both types and found out the hard way.) Make sure the plug boots also fit tightly.

odd...ive been running iridium in mine...
not to mention, in 60k+ miles i havent had a coil issue. knock on wood

[The Snowman]

odd...ive been running iridium in mine...
not to mention, in 60k+ miles i havent had a coil issue. knock on wood

I had nothing but issues using iridium plugs. Once I swapped back to the big copper electrodes, I haven't had a single issue.

[RadHawk]

Excellent, all good info folks, I will tough it off again and watch the tach for that dropping out, check the connectors and all. And the plugs...

I had a Guzzi that needed my attention this evening, my main squeeze too...! so I did not get to the SV.

Thanks,
Rob

[carsick]

get yourself a set of NGK bare-bones $3 copper CR9E spark plugs.

My local shop said they were $42 each. Where are they $3?

[nhbubba]

Looks like the going rate is closer to $4-5:
http://www.amazon.com/gp/product/B00...1&s=automotive
http://shop.advanceautoparts.com/web...archTerm=cr9e+
http://www.motorcycle-superstore.com...park-Plug.aspx

[TheIglu]

My local shop said they were $42 each. Where are they $3?

Just pay the $42. If you don't, your shop will close and they will kick your dog.

[nhbubba]

Wow.. I missed the funny. Need.. coffee.. now..

[RadHawk]

I stopped by the local m/c parts shop ta-day to pick up the plugs and have a rainy night of wrenchin'... the fellow there tells me the stock plug for the SV is the NGK CR8E... I bought both.

So which one should I use...?

Thanks,
Rob

[The Snowman]

Use the CR9E. The hotter plug runs better.

[RadHawk]

Use the CR9E. The hotter plug runs better.

The 8E is the hotter plug, NGKs are hotter the lower the number. No...? I trust you SV types to know what to do as you have ridden these critters and must know this stuff.

Thanks Snowman...
Rob

[wheelieman14]

Use the CR9E. The colder plug runs better.

Fixed...

[RadHawk]

Fixed...

gotcha... thanks.

[The Snowman]

Fixed...

What he said.

[SVRACER01]

have you tried svrider.com for your tech questions? not saying that people here wont have answers, just asking

[RadHawk]

have you tried svrider.com for your tech questions? not saying that people here wont have answers, just asking

I Just did hook up there also... Good info both here and there.

Thanks,
Rob

[RadHawk]

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.

Hoping to find some reason for the breaking up in them...