Sputtering...

Quick question. Today on my way home from work, my 81 650 would sputter right after I started it up when I would give it some throttle. Happened for about 2 minutes then it was fine. I did a search and saw a suggestion to put the petcock on PRI before starting it up then switching to ON. Is this normal every day procedure?

 

My XS11 did that last summer. Turns out the vacuum fuel valve would stick closed for the first few minutes of running. I replaced the o-ring in the front and the problem went away. It is not normal for your bike to do this, it will only get worse as mind did until I figured out what was happening. Its is a simple fix, take care of it before it leaves you stranded.

 

Inside the petcock?

 

The petcock most likely needs a kit installed. Len (ChacalParts) has them.

MN

 

Ok, so doing a bit more searching and I read about fuel getting in the crankcase. When I synced my carbs I did it over 2 days, left my aux tank connected with the petcock on PRI. When I woke up the next day there was a puddle (albeit very small) of gas on the garage floor. The carbs were leaking very very slowly over night (about a drip every few mins from what I saw). I thought nothing of it and went about with syncing. She did give me some problems starting, but I figures it was a bubble in the fuel line as I saw a few. Also I have been having some slight low idle issues since. This was all on Sunday. I just checked the oil and it smells like fuel so looks like a definite oil change is in order.

Could this be the cause of those symptoms? Low idle and sputtering? Also, any long term damage from running the bike with fuel in oil the last couple of days (about 80 miles)?

 

Yes , the vacuum fuel valve inside the petcock needs replacing.

 

That would cause fuel in the crankcase?

 

The vacuum diaphragm could leak fuel into #3 carb intake. Or your carbs may need to come off and the needles and seats could be in need of replacement. If that is the case the carbs may need a good cleaning and wet float level adjustment. You would need to set your valves before a sync could be done.
MN

 

I have wet set the floats after and shimmed valves to spec after taking 2 weeks to meticulously clean the carbs. The fuel was leaking from the clear vinyl tube I had hooked up from the aux tank, as it was not set all the way to the fuel nipple on the carbs.

 

What damage does fuel in the crankcase produce, and what symptoms?

Also, if it were the floats wouldn't the plugs be black/sooty or wet from a rich mixture? Just trying to systematically troubleshoot here.

 

Raw gas in your crankcase can and will swell oil seals, damage clutch linings, and thins the oil to the point were excessive wear can damage the engine, you will want to get that out of there ASAP.

Looking at your other thread about plug chops. Your plugs look to good for an flooding condition. Although #1 does look lean.
MN

 

Well that's a relief (as far as the plugs go).

I'll do a proper oil change on her before riding again, as I hadn't done one since I bought the bike. Looks like its going to need a new air filter as well. My guess is the PO flooded it before it sat.

 

So, an oil change with a new filter...run for about 100 miles...then repeat process?

 

Hy dad has had this same problem on his 96 virago XV750! We thought it was the petcock that was leaking fuel into the carbs! (he has had this problem with it in years past!) I has gotten worse, and runs rough idle, and wants to stall. But only for 10 or 15 miles! We have to get new vacuum lines now. I thought this was the problem! And we need to fix it, we are going on a 1000 mile trip in two months!

So glad that I stubled upon this!

 

Does this sound like it will take care of the issue, or is there anything else I can/should do?

Also, I am going to be waiting a few days for a new oil filter, would I be able to get by draining and re-filling the oil for now with same filter? (I have the cage blues today) lol

I realize now that when I re-shimmed the oil had a gassy smell to it in the head...didn't think much about it then. Learn new things every day. :roll:

 

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