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Running rich?


Scruit

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'04 Suzuki Volusia 800 - carb / electronic ingition.

How do I tell if it's running rich? I know other Volusia owners who claim 40-50mpg and I'm getting 33mpg. Thinking I may be running rich, but dunno how to tell...

Edited by Scruit
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It's really tough to tell by looking at plugs anymore with the fuel today...

You need to get to a shop with a dyno and the ability to "sniff" the bike and get an exact showing of fuel mixture. Don't go by what your plug "looks like". Get a professional with the air/fuel meter to really tell...

My plugs are white and we don't run race gas. It's not too lean at all...

Exhaust tips are no way to tell anymore, either... Used to be that white/grey or touch of brown was too lean. Bikes with carbs...

That doesn't hold true anymore, either...

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It's really tough to tell by looking at plugs anymore with the fuel today...

...

Exhaust tips are no way to tell anymore, either... Used to be that white/grey or touch of brown was too lean. Bikes with carbs...

That doesn't hold true anymore, either...

That sucks, I did not know that about engines now a-days.

Well, you could try to adjust it yourself with the a/f mixture screw. Go out until it is too rich and sputters and dies, then too far in until it speeds up and dies. Halve the turns out and you have the theoretical middle point. Your best bet is a shop with a braked dyno where they can analyze the exhaust gasses and just tell you, but that costs money and I am cheap.

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That sucks, I did not know that about engines now a-days.

Well, you could try to adjust it yourself with the a/f mixture screw. Go out until it is too rich and sputters and dies, then too far in until it speeds up and dies. Halve the turns out and you have the theoretical middle point. Your best bet is a shop with a braked dyno where they can analyze the exhaust gasses and just tell you, but that costs money and I am cheap.

Today's bikes don't have mixture screws like the older bikes had on their carbs... Hence why dynos or FI kits like the Bazaaz and new PC are such a worthy investment...

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  • 2 weeks later...
  • 3 weeks later...

Pulled the plugs today. Here's what I got:

Sparks_20101010.jpg

Funny that one seems to be rich (left, darker one - rear head of the V-twin) and the other seems to be lean (white) yet it's a single carb?

I've been told this bike runs lean from the factory so it can meet EPA regs. But the soot suggests rich, so I'm not sure what's going on.

The engine and fuel/exhaust are 100% stock. The only thing I've changed is I did the valve clearances earlier this year. To be honest, I'm thinking the power loss came about the same time. I'm going over the valve clearances again to be sure.

The dealership on Park Mill Run Dr (dunno what they call themselves now - their website is ohiomotorcycle.com) wanted $300 to check the valve clearances. I can do it in 30 mins, so I'm sure they can a well. I'm in the wrong business if 30 mins of work gets them $300.

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K, now I *know* there's something wrong...

After I did the valve clearances before I was having trouble getting the bike over 75mph - but as I was only on country lanes I figure I just didn't have time to accelerate etc.

I redid the valve clearances again, only thing time I went a little loose (thinking the clearances were probably too tight before). Went form no ticking at all to an audible ticking sound while the engine was running. And now I can't get the bike over 65mph.

I'm leathed to spend $300 on something I can do myself in a short amount of time - but apparently I'm doing something wrong because every time I touch the clearances the bike's performance gets worse and worse.

When I first got the bike it could do 95mph on it. Don't ask how I know. Specs list the top speed a 99mph.

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At 4k miles the bike was:

- Top speed 95mph. 0-60 in about 6.5 seconds. Valves were quiet when the bike was cold and a little tappy when the bike was warm.

I adjusted the valves to make them all a little tighter. .005 In, .008 Exhaust.

- Top speed 75mph. 0-60 in something closer to 10 seconds. Valves were quiet when the bike was cold or hot.

So I tried to adjust them again. Couldn't even get the feeler guages in there. This time I stuck with .005 Intake, .008 Exhaust, tightening the valve until I could only just feel friction on the feeler. Started up the bike - no good. Valves made a heck of a racket.

So I tried to adjust them again. Again I went with .005 Intake, .008 Exhaust, tightening the valve until I could only just pull the feeler out when the locknut was cinched down :

- Top speed 65mph. 0-60 in something like 15 seconds. Valves noisy when cold and hot.

So what is the trick here? Am I using the right clearances? What is the trick with the amount of drag I should expect from the feeler guage?

If I use the idle speed adjustment and wind the idle up a bit then I can get the bike to 70mph...

Edited by Scruit
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There needs to be a "Throwing in the towel and going to the dealership" smiley. :(

After redoing the valve clearances 4 times and always coming up with the same result I'm done messing with the bike. I'm taking it to the local Suzuki dealer for them to take a look at it. My guess is a carb problem.

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