SuzukiSavage.com - 25 MPG?!?! WTF?

Bobber Fett

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25 MPG?!?! WTF?
09/02/12 at 16:34:14

I've been putting this post off for a while because I've been insanely busy, but with the cold season coming I can drop the engine and do some work on it.

I'm getting 25 MPG consistently. It's a 1987 with 21000 miles on it, and I bought it not knowing what has been done to it in the past. When I bought it, it had a problem with a broken decomp solenoid cable, so it was killing a spark plug every 2 weeks. After fixing that, my spark plugs last for ~6-8 months before they go and are black when I pull them.

I haven't messed with trying to lean the carb because if I let off the throttle, I get a slight popping that I'm told is a sign the bike is tuned fine (if not a bit lean). The carb has been sonic cleaned within 1000 miles.

Any suggestions as to where to start looking fellow savages?

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Routy Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 2280 Winston Oregon Gender:	Re: 25 MPG?!?! WTF? Reply #1 - 09/02/12 at 16:38:37 Anytime you're using too much fuel, and smokin spark plugs, why not do Sero's petcock test ? Or at least plug the vacuum line to the petcock and run it on prime.
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Oldfeller--FSO Serious Thumper ModSquad Offline Hobby is now "concentrated neuropany" Posts: 12671 Fayetteville, NC Gender:	Re: 25 MPG?!?! WTF? Reply #2 - 09/02/12 at 16:48:33 +1 on Routy's suggestion. http://suzukisavage.com/cgi-bin/YaBB.pl?num=1251932429/1 Serowbot's test takes out half the possible issues with one simple test, then you can focus on in on the half that remains (whichever half that is).
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Bobber Fett Junior Member Offline SuzukiSavage.com Rocks! Posts: 64 Chapel Hill, NC Gender:	Re: 25 MPG?!?! WTF? Reply #3 - 09/02/12 at 17:17:10 I forgot to mention that I'm using a Raptor petcock. Is the Sero's procedure still worth looking at?
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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: 25 MPG?!?! WTF? Reply #4 - 09/02/12 at 17:33:45 sounds like it was rejetted way to rich.
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Bobber Fett Junior Member Offline SuzukiSavage.com Rocks! Posts: 64 Chapel Hill, NC Gender:	Re: 25 MPG?!?! WTF? Reply #5 - 09/02/12 at 17:45:55 Yeah, since I haven't really touched the jetting, that is definitely a possibility. I have no idea what it was when I bought it. The black spark plugs also support that theory... Any indicators besides the black spark plugs? How long should a spark plug last in a properly tuned savage?
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28637 Tucson Az Gender:	Re: 25 MPG?!?! WTF? Reply #6 - 09/02/12 at 18:04:03 Too rich causes pops, too... I get pops when I go over 7500ft... that elevation makes me rich, and causes pops... You're way too rich... the pops, plus the fowling plugs,.. indicates much richness... ...
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Charon

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Harvard, NE
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Re: 25 MPG?!?! WTF?
Reply #7 - 09/02/12 at 18:07:19

How long should a plug last? Good question. I pulled mine when I did the nominally 11000 mile service. I think it was 10500 miles. If I hadn't already bought a new plug, I would have put the old one back in, and given it no further thought for another 20000 miles. It was clean, the edges were sharp, and the gap was correct. My '07 is box stock, except that I removed the cover over the idle mixture screw. I think, after I tinkered with it, it ended up just about where it was before I bothered with it. My fuel mileage is in my signature. By the way, the exhaust pipe is not discolored, as can be seen by the picture.

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IMG_0777.JPG

« Last Edit: 09/03/12 at 06:36:17 by Charon »

Eschew obfuscation.

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Bobber Fett Junior Member Offline SuzukiSavage.com Rocks! Posts: 64 Chapel Hill, NC Gender:	Re: 25 MPG?!?! WTF? Reply #8 - 09/02/12 at 18:25:14 And here I was thinking the pops were a good sign and that 6-8 months was a decent time for a motorcycle spark plug. That's why you guys are the experts and I'm the n00b. I'll post the numbers on the jets and go back to stock. I bet I can find the default jet numbers on the forum somewhere. Thanks a bunch guys.
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Paraquat Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 2206	Re: 25 MPG?!?! WTF? Reply #9 - 09/02/12 at 19:12:04 http://suzukisavage.com/cgi-bin/YaBB.pl?board=tech;action=display;num=1098869040 --Steve
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Bobber Fett

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Chapel Hill, NC
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Re: 25 MPG?!?! WTF?
Reply #10 - 09/03/12 at 09:50:43

I pulled the carb and the main jet was 152.5 and the pilot was 42.5. The previous owner had already gotten rid of the plug, and I have no idea where he had that set. I turned it all the way in, then backed it out 3 turns.

Think the jets were the culpret? I thought a smaller jet size was better for fuel. The jets were covered in a greenish-white powdery substance (kinda like a light copper oxide), is that typical?

Side note: I hope I don't have to go back to the 42.5 pilot because I dropped the darn thing between the cracks in my deck Shocked

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Serowbot

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OK.... so what's the
speed of dark?

Posts: 28637
Tucson Az
Gender: male

Re: 25 MPG?!?! WTF?
Reply #11 - 09/03/12 at 10:10:09

42.5 pilot?... Huh

... Das' tiny...

Well,.. jets ain't causing you 25mpg...

Float is sticking,.. or petcock is leaking... or there's a hole in your gas tank... or, someone's stealing yer' gas...
One of those four...

PS... you is gonna' need a pilot jet of some kind in that hole... Grin

...

PSS.. green is patina... it's more collectable that way... but, for running, I'd clean it off...

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Ludicrous Speed !... ... Huh

...

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Bobber Fett Junior Member Offline SuzukiSavage.com Rocks! Posts: 64 Chapel Hill, NC Gender:	Re: 25 MPG?!?! WTF? Reply #12 - 09/03/12 at 10:23:30 I replaced the pilot with the 47.5 and the main with the 155 (went back to stock). The float seemed lose. Does this mean that my gas mileage will go down???
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: 25 MPG?!?! WTF? Reply #13 - 09/03/12 at 10:34:50 Not sayin its related, but I spose valve timing could cause some loss of MPG, but hows that tensioner? 21,000,, if it hasnt been looked at, you better..
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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: 25 MPG?!?! WTF? Reply #14 - 09/03/12 at 10:40:20 check your float level. connect a piece of clear tubing to the drain, open the drain and set the petcock to prime. gas level should come up to the bowl gasket.
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