SuzukiSavage.com - fuel starvation?

Arcreefer

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fuel starvation?
09/25/16 at 20:57:01

Starts no problem... however, between 2,000rpm and 3,000rpm she acts like she's starved for fuel. Died on me today going from a stop at an intersection, then started up after some cranking and blew black exhaust. Just to act like she's starving again until I slowly take her up over 3,000rpm. Anything over 3,500rpm she runs like a raped ape.

But first, some background: I bought a stock 2011 S40 in June. Glued to this site for awhile so I already installed a Raptor petcock, 150 main and 52.5 pilot jets, half spacer, Dyna muffler, K&N filter in stock air box, iridium plug, Mobile full synthetic and added ZDDP. I also installed a tach cause I just like to know.

So what do you guys think could be causing the fuel starvation issue?

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28887 L.A. California Gender:	Re: fuel starvation? Reply #1 - 09/25/16 at 21:11:34 Does the main jet have a washer? If it's missing, the needle can draw up the jet.
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Arcreefer

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Re: fuel starvation?
Reply #2 - 09/25/16 at 21:31:23

Thanks Verslagen! Honestly don't remember the main having a washer. I did the jets a few weeks ago and she ran fine until today, except for a loss of torque at low range after I installed the Dyna. The Dyna I bought had the baffle drilled out so I cold welded a freeze plug in it's place (Thanks Batman!).

Back on point... what does the main jet washer look like? is it metal or rubber? I'll pull the carb tomorrow and look. I'm planning on adding a washer to the jet needle anyway.

I was also wondering if it might be a vacuum issue with the tank? low rpm and it locks up, high rpm and it flows?

Also, I need the screw set for the carb. Do you (Verslagen) sell those? Also need the Versy, etc.,

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: fuel starvation? Reply #3 - 09/25/16 at 21:37:54 Starts up Black exhaust Sounds rich.
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verslagen1

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Re: fuel starvation?
Reply #4 - 09/25/16 at 21:56:59

Arcreefer wrote on 09/25/16 at 21:31:23:

Back on point... what does the main jet washer look like? is it metal or rubber?

thick brass
Quote:

I'll pull the carb tomorrow and look. I'm planning on adding a washer to the jet needle anyway.

both can be done with carb in place... a lot easier.
the bat box tends to get in the way of the bowl drop.
use a strap to pull it back.
Quote:

I was also wondering if it might be a vacuum issue with the tank? low rpm and it locks up, high rpm and it flows?

if it were vacuum, it would shut off after a while.

Quote:

Also, I need the screw set for the carb. Do you (Verslagen) sell those? Also need the Versy, etc.,

See dave's thread in the marketplace, not sure if he's still selling them.
tech section has carb specs, screw sizes shown towards the end.

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batman

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Re: fuel starvation?
Reply #5 - 09/26/16 at 19:55:21

I agree with JOG, I think your running to rich at idle and mid range . I' d move down to a 50 jet and maybe a 2/3 to3/4 (3 number 4 washers) for the needle lift, you have black smoke out the pipe,that's a sign of being to rich, your motor isn't starving ,it's stumbling .More fuel isn't good ,it can cause carbon buildup on valve stems ,piston and combustion chamber,and wash the oil off your rings and cylinder walls( wear ,score)as well as killing your mileage.

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Arcreefer

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Re: fuel starvation?
Reply #6 - 09/27/16 at 13:15:42

I'll be tearing the carb apart this weekend. It's just weird that sometimes it does it and sometimes it doesn't. Acts like it's running out of fuel on a full tank, especially at lower rpm's. I'm beginning to think either the float or the float valve is sticking.

However, I agree it's running rich before it hits the main jet. I can screw the AF mix screw all the way in and it still runs, not well, but it still runs. That's telling me either the needle's too high or the pilot jet is too big, or both? I'll be replacing the 52.5 pilot with a 50 and add a washer to the needle. Thanks Guys!!

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stewmills

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Re: fuel starvation?
Reply #7 - 09/27/16 at 13:27:59

Interesting thread, as I am seeing weird things almost identical aside from mine not aggressively stalling at mid-range RPMs. It shutters every now and then and has never acted like this before and everything else (petcock, vacuum lines, etc) external to the carb checks out.

Keeping in mind my bike has been tuned as it is presently for the last 3+ years and ~6000 miles and ran pretty spot-on. I was trying to adjust my air/mix last night to see if it was just running too rich at idle and as I turned the air/mix screw all the way in (baby-finger tight) the engine barely slowed in RPMs, barely enough for the trained ear to notice it dropped maybe ~100 RPMs at most. In years past this would have choked the bike out as expected given that I have the proper jets.

So why this behavior now with no other changes having been made to the bike? What am I missing?

I don't have soot or black smoke popping out of the muffler as if it is running excessively rich, however, reading this thread makes me feel like i am running rich since the air/mix screw doesn't choke out the bike at full closure (screwed all the way in).

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verslagen1 YaBB Moderator ModSquad Offline Where there's a will, I want to be in it. Posts: 28887 L.A. California Gender:	Re: fuel starvation? Reply #8 - 09/27/16 at 13:34:30 conditions are constantly changing all the time. your air filter could be full of dirt. your jet accumulates varnish. and the weather is changing.
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stewmills

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Re: fuel starvation?
Reply #9 - 09/27/16 at 14:16:02

Well, it has been hot as snot here and high humidity. I guess that could explain the richness since there are less air molecules per volume in hot humid air versus cool dry air?

If the jet accumulated varnish doesn't that restrict fuel and cause leanness? My bike is pretty clean and I had the carb off earlier this year and blew everything out, but I guess anything can happen at any time.

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Arcreefer

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Re: fuel starvation?
Reply #10 - 09/27/16 at 19:05:33

When it comes to adjusting the FM screw, Is it the pilot jet or the needle that would effect it more?

I'm turning the FM screw to the stop and the engine still runs. So I was thinking of downsizing to a 50 pilot from a 52.5 and adding one washer to the needle which currently is at half size of stock. However, I would prefer to do one or the other instead of both and see how it goes. So what do you think, 50 pilot or add a washer to the needle?

I live at about 500' and most of my riding is done between sea level and 3,500.

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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: fuel starvation? Reply #11 - 09/27/16 at 19:16:56 The needle won't affect idle. Drop your pilot one size for starters. I'm around 300' ASL. See my signature. My bike runs great with a 52.5/150 and 3 washers. I don't know why yours would be any different.
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Arcreefer YaBB Newbies Offline SuzukiSavage.com Rocks! Posts: 41 Maui, Hawaii Gender:	Re: fuel starvation? Reply #12 - 09/27/16 at 19:23:43 Kris, have you tried screwing your fuel mix screw to the stop? If so, does your engine still run? Mine does, although slow and rough, but it does still run. I was assuming that closing the fuel mix screw would kill the engine if the pilot was the right size. If I'm wrong, I'd be fine with that. Then I can just leave the 52.5 in place.
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Kris01 Serious Thumper Offline Eat, sleep, RIDE! Posts: 3767 Tennessee Gender:	Re: fuel starvation? Reply #13 - 09/27/16 at 19:26:15 When I tuned mine, I screwed it in and out to find the best idle speed. I never went all the way in so I can't say if it would die. I don't think that the screw is the only source of air though. I think it will still run, just not well. Don't quote me on that.
Back to top	There's no problem that a full tank of gas and a sunny day can't fix! 2008 S40, Rotella T 15W-40 w/ZDDP added, Dyna, 140/90-15, Battery Tender Jr., Seat lift, #52.5/150/3 washers, Raptor IP Logged

verslagen1

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Re: fuel starvation?
Reply #14 - 09/27/16 at 19:32:23

Arcreefer wrote on 09/27/16 at 19:05:33:

When it comes to adjusting the FM screw, Is it the pilot jet or the needle that would effect it more?

I'm turning the FM screw to the stop and the engine still runs. So I was thinking of downsizing to a 50 pilot from a 52.5 and adding one washer to the needle which currently is at half size of stock. However, I would prefer to do one or the other instead of both and see how it goes. So what do you think, 50 pilot or add a washer to the needle?

I live at about 500' and most of my riding is done between sea level and 3,500.

On the savage, it's an air metering, not fuel metering screw. technically, a pilot mixture screw.

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