SuzukiSavage.com - Fuel mixture

IN-S40

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Fuel mixture
04/15/11 at 04:40:27

Since I was was planning on working on the girlfriends bike last night I picked up a new plug for our bikes. Did the girlfriends bike first and plug looked normal, slightly brown on the tip. Pulled my plug and got this:

I'm thinking this is pretty lean??? Carb has stock pilot jet and a 150 main, i'm running a harley softail muffler. I run seafoam in the gas so I would think the carb should be fairly clean... Huh

What do you guys think?

Darren
IN-S40

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Routy Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 2280 Winston Oregon Gender:	Re: Fuel mixture Reply #1 - 04/15/11 at 07:50:55 I don't see any signs of it burning. Assuming it runs good, I'm thinking if this is from normal crusing in mild weather, you may want to richen it up a tad, but only if you were to run it harder in hotter weather.
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IN-S40 Full Member Offline SuzukiSavage.com Rocks! Posts: 128 Michigan City, IN Gender:	Re: Fuel mixture Reply #2 - 04/15/11 at 07:51:24 Forgot to mention I am 2 turns out on the idle mixture screw.
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Chopped Senior Member Offline Hurts Like hell when you shoot yourself! Posts: 499 Stafford, VA Gender:	Re: Fuel mixture Reply #3 - 04/15/11 at 08:30:48 Are you having any issues with the bike... ie... popping or backfire? If not... you are way in the clear! If you are running good and richen it up some, you may end up burning more fuel then necessary. Could increase your performance, but may not. You can always try and then put it back to where it is now.
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Fuel mixture Reply #4 - 04/15/11 at 08:54:45 IN-S40 wrote on 04/15/11 at 07:51:24: Forgot to mention I am 2 turns out on the idle mixture screw. Unless you spend most of your time in idle, the adjustment is not a problem. Any surging? white spacer mod How's the WOT test? wide open throttle back off an 1/8, does it pick up? go up a size.
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IN-S40

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Re: Fuel mixture
Reply #5 - 04/15/11 at 10:25:57

White spacer has been reduced by about 1/3. Seems to surge a little if the engine is running slower like 3rd gear doing 30mph but its is a very slight surge. Otherwise she runs fine mid and top end. I may be over reacting a bit? I just remember from my snowmobile days you wanted a nice dull brown. Not a grey or white but thats a 2-stroke, replaced a few pistons because of that.. I was thinking about pulling the carb and cleaning it in my ultrasonic cleaner but not looking forward to pulling it...

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Routy

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Re: Fuel mixture
Reply #6 - 04/15/11 at 19:49:46

IN-S40 wrote on 04/15/11 at 10:25:57:

White spacer has been reduced by about 1/3. Seems to surge a little if the engine is running slower like 3rd gear doing 30mph but its is a very slight surge. Otherwise she runs fine mid and top end. I may be over reacting a bit? I just remember from my snowmobile days you wanted a nice dull brown. Not a grey or white but thats a 2-stroke, replaced a few pistons because of that.. I was thinking about pulling the carb and cleaning it in my ultrasonic cleaner but not looking forward to pulling it...

A tan color plug is the right color, that leaves a margin for a WOT run on a hot day. Mine looked more like yours, and that was 4,000 mi ago.
But I seldom do WOT more than 10 seconds at a time, and I don't ride on hot days, so I don't need a margin. If you are going to do 80+ for an hr on a hot day, you mite better give it a little more fuel.

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Rich
'07 S40 Blvd stocker, except drilled OEM exhaust and white spacer mod...1/2 (.055)

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IN-S40

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Re: Fuel mixture
Reply #7 - 04/16/11 at 09:37:06

Well I only started riding last fall so i dont see myself going that fast for that long.... lol
I just like to take care of problems before they become big problems, I have found its less expensive that way! I did take the bowl off the carb and from what i could see it looked spotless in there but i know tha doesnt tell all.. Since i normally ride slower, around 1/3 throttle which jet would be affecting it to be on the lean side? I always thought the main came into play around 1/2 to full throttle.

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verslagen1

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Re: Fuel mixture
Reply #8 - 04/16/11 at 11:24:17

IN-S40 wrote on 04/16/11 at 09:37:06:

Since i normally ride slower, around 1/3 throttle which jet would be affecting it to be on the lean side? I always thought the main came into play around 1/2 to full throttle.

You're right it does, but the main feeds the needle jet.
So changing it gives more fuel to the entire range vs. just raising the needle a bit to give more gas earlier.

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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28642 Tucson Az Gender:	Re: Fuel mixture Reply #9 - 04/16/11 at 11:36:19 I think you're worrying about nothing.... but,... at those low speeds, you're mostly running on pilot jet. I base my pilot size mostly on gas mileage. If you run light throttle cruise, and your mpg's are in the 55 to 60mpg range, your pilot is a good size with this engine...
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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Fuel mixture Reply #10 - 04/16/11 at 13:56:45 With a cv carb you really don't know where that slide in the carb is at, at any throttle opening.
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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Fuel mixture Reply #11 - 04/16/11 at 14:38:52 bill67 wrote on 04/16/11 at 13:56:45: With a cv carb you really don't know where that slide in the carb is at, at any throttle opening. I always know where my slide is at... between the bowl and cap... there abouts.
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bill67 Serious Thumper Offline old tired Posts: 8517 genoa city wisconsin Gender:	Re: Fuel mixture Reply #12 - 04/16/11 at 18:46:34 verslagen1 wrote on 04/16/11 at 14:38:52: bill67 wrote on 04/16/11 at 13:56:45: With a cv carb you really don't know where that slide in the carb is at, at any throttle opening. I always know where my slide is at... between the bowl and cap... there abouts. Maybe not have you looked lately.
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verslagen1

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Re: Fuel mixture
Reply #13 - 04/16/11 at 19:39:21

bill67 wrote on 04/16/11 at 18:46:34:

verslagen1 wrote on 04/16/11 at 14:38:52:

bill67 wrote on 04/16/11 at 13:56:45:

With a cv carb you really don't know where that slide in the carb is at, at any throttle opening.

I always know where my slide is at... between the bowl and cap... there abouts. Grin

Maybe not have you looked lately.

Yes, I even twist the grip and it sprung right up.

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Re: Fuel mixture
Reply #14 - 04/16/11 at 19:59:04

, around 1/3 throttle which jet would be affecting it to be on the lean side?
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I can only tell you that mine was quite lean (choke test) surging badly at what I described as 1/8 to 1/4 throttle,.......about 20-30 in 2nd or 3rd gear, and the 1/2 white spacer mod fixed it beyond my best expectation. I agree,.....it wasn't all skill,....maybe I got lucky too.

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Rich
'07 S40 Blvd stocker, except drilled OEM exhaust and white spacer mod...1/2 (.055)

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