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Discussion Starter · #1 ·
Yesterday I wrote a long post describing how my 2000 SV650 Naked started running roughly and popping after I changed the oil. I had overfilled the oil and used crappy oil. Trying to correct the problem I drained the oil, replaced it with Rotella T6, and filled to the correct level.

Next, I test rode the bike, and after a few pops and bogs, it ran great. Problem solved! I thought I had defied the laws of nature (and of Curvydom). My purchase of the bike three weeks ago was genius, as was my wrenching. Unlike other gen1 SVs, mine was not cursed by the carbs! I was quite please with myself.

I was absolutely f...ing wrong!

I backed out of the garage yesterday evening anticipating a joyous ride in the beautiful weather, and the problem returned. It was very hard to start, ran rough, warmed up for about 30 seconds, then died. I could not get it started again. Full choke, no choke, nothing. It would fire up for a second, then die.

Obviously I'm getting fire. It seems to me it is a fuel delivery issue. Because it's intermittent, I'm thinking it may be the dreaded rust in the tank. The bike had a clear fuel filter after the petcock that was a bit gunky, but not that bad. I changed the filter when I changed the oil. I also blew out the air filter with compressed air.

After spending far too much work time reading forum posts, here is my game plan.
  1. Pull the tank and drain it, check for rust.
  2. Remove petcock and clean filter.
  3. Pull carbs and thoroughly clean. Check float movement.
  4. Replace plugs while I have it torn down.
This may be a stupid question, but I have not rebuilt a Mikuni carb in decades. Will it require a carb kit with new gaskets and O-rings? We used to get away with breaking them down and reusing the old bits.

My thoughts are there must be some bad stuff floating around in the fuel system. When I started it yesterday on choke, it ran for about 30 seconds, but it bogged when I reved it. It also ran very rough and had a lot of backfire. Then it died. The thing that is puzzling is the problem went away after the oil change. It may be coincidence, but it's highly irrational.

In fact, I read a post yesterday reporting the same thing after an oil change. Most of the replies to the post said it had nothing to do with the oil change. Of course, I had to reply, explaining the same thing had happened to me, and the issue was resolved with another oil change. This morning I'm eating a breakfast of humble pie.

I'll report back after doing the above. Any advice will certainly be appreciated. If you see some roadkill on your next ride, that would be my ego.
 

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Discussion Starter · #2 ·
One other thing. The bike is stock, apart from a D&D pipe. At least, as far as I know.
 

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Sounds like a fuel related issue to me as well.

You could pull the plugs and see what they look like. You could be starving for fuel (light color) or dumping in too much (dark/wet).

Definitely check the tank and filters/screens, but I'm thinking the carbs need to come off and be gone through.

If you want them gone through, cleaned, rebuilt, adjusted and looking/working like-new, talk to Gordon at www.customcarbservices.com.

He will make sure they are right, so you can cross that off the list.
 

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Discussion Starter · #7 ·
Sounds like a fuel related issue to me as well.

You could pull the plugs and see what they look like. You could be starving for fuel (light color) or dumping in too much (dark/wet).

Definitely check the tank and filters/screens, but I'm thinking the carbs need to come off and be gone through.

If you want them gone through, cleaned, rebuilt, adjusted and looking/working like-new, talk to Gordon at www.customcarbservices.com.

He will make sure they are right, so you can cross that off the list.
Thank you. Yes, I think it is burning quite rich. Whenever I rode it (when it was running), my clothes would end up smelling like exhaust/unburned fuel. Thanks for the customcarbs intro. When I bought the bike, the PO also gave me an extra set of carbs. I can send those to Gordon immediately, and remove and inspect the existing carbs myself.
 

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every time my gen one acts up, it gets carbs cleaned. I always find the idle jets plugged or nearly plugged. I also just replaced the choke cable, that was broken at the y section, as well as the little fitting that the choke cable end goes into on the front carburetor. I believe they were allowing air to leak past due to the nature of the breaks. The choke has never worked right, but does now!. Bike runs like a top again. Just went through this same problem for the third time in about five years with my 2001. We don’t have a good source for ethanol free gasoline here, and I have many bikes. The fix is to ride the bike, and not let gas sit in it. Anyway, I know this now, and will just do annual carb cleans from now on. I’m betting your idle jets are dirty
 

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It sounds like a fuel issue but given the problem is intermittent, it might also be carbon-fouled spark plugs due to burnt oil (a common problem on old two-strokes) from the oil overfill. Was there lot of oil in the airbox?

If the plugs are fouled, do not clean, replace them.
 

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Discussion Starter · #11 ·
every time my gen one acts up, it gets carbs cleaned. I always find the idle jets plugged or nearly plugged. I also just replaced the choke cable, that was broken at the y section, as well as the little fitting that the choke cable end goes into on the front carburetor. I believe they were allowing air to leak past due to the nature of the breaks. The choke has never worked right, but does now!. Bike runs like a top again. Just went through this same problem for the third time in about five years with my 2001. We don’t have a good source for ethanol free gasoline here, and I have many bikes. The fix is to ride the bike, and not let gas sit in it. Anyway, I know this now, and will just do annual carb cleans from now on. I’m betting your idle jets are dirty
I'll check that and get back. Thanks.
 

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Discussion Starter · #12 ·
It sounds like a fuel issue but given the problem is intermittent, it might also be carbon-fouled spark plugs due to burnt oil (a common problem on old two-strokes) from the oil overfill. Was there lot of oil in the airbox?

If the plugs are fouled, do not clean, replace them.
Not much oil in the air box, just heavy residue. I bought some new plugs, which I will install this weekend. Thanks for the advice. And yes, I am old enough to remember the two strokes, having raced them for years.
 

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Discussion Starter · #13 ·
I'm breaking it down this morning to replace the plugs and clean and rebuild the carbs. Here's a few interesting tidbits I found thus far. I'm using ziptech800's guide titled "Dangers of a Lo-Carb Diet" (which is fantastic) to remove and clean the carbs. It would be nice if the pics and links worked, but I can't complain. One of the things he stressed when removing the airbox was to remove the hoses from the "PVC" oil condenser to the base of each cylinder is a certain way. Specifically, he said remove the rear hose at the condenser (at the top), and remove the front hose at the cylinder base.

I was surprised when I found my front hose was completely removed from the base of the condenser, just hanging there. The coil area was also oily, I guess from oil coming from the unhooked hose. I don't know if this would cause the bike to run erratically, but maybe so.
 

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Discussion Starter · #14 ·
Next I unbolted the radiator to give me room to remove the front spark plug. When I pulled off the plug cap I found that the rubber boot between the wire and the cap was cracked. And I had a hard time unscrewing the cap from the wire. When I finally pulled the wire out of the cap I found a strange white substance at the top of the cap. It looked like someone tried gluing the cap to the wire. And at the end of the wire I could see no copper. Maybe this was arcing. Don't know.
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Discussion Starter · #15 ·
Plugs look black and sooty. The rear one especially. It also has oil on it. As I mentioned earlier, I thought the bike was running rich because I smelled like unburned gasoline after I rode it. For anyone who's turned a wrench or two, you know the smell of an engine running rich. Maybe this was an issue, fouling plugs (or a symptom of carb problems). Now I am preparing to pull the carbs.
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Also, I removed the gas tank to check the petcock filter and inspect for rust. The petcock filter was perfectly clean, and no signs of rust in the tank. Oddly, I hear something rattling around in the tank. Will check that later to see what it is. Right now I want to tear into the carbs.
 

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Looks like you are hot on the trail, Geo. Those plugs are BLACK.
 

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Discussion Starter · #17 ·
Looks like you are hot on the trail, Geo. Those plugs are BLACK.
My thoughts exactly. I found some other weird stuff too (cracked fuel line, buggered TES diaphragm, etc.), but I'll get to those in the morning. No much gunk in the carbs, surprisingly.

I'm still trying to find the front plug drain hole. Don't know where to look.

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Yup. Fouled plugs at least.

Look on...I think the left side of the cylinder head. It's about a 3mm hole.
 
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