SuzukiSavage.com - stumbling problem

pitbullcustoms

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stumbling problem
11/04/09 at 18:18:29

Ok so i have had a problem with my bike for awhile which made me put my bike up way to early and havent had much time to fix it... at part throttle it is very doggy and you have to roll on the throttle you cant snap it quckly it seems like its running rich but i havent done any carb work to it and i have a drag pipe and an intake filter on it... but i did notice if i put the petcock on reserve and pull the choke it runs like a brand new bike... any suggestions on what it might be going on??

Thanks Corey

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: stumbling problem Reply #1 - 11/04/09 at 18:20:22 Its lean as heck.. What happens if you just pull the choke & leave the petcock on "Run"? Maybe the diaphragm is getting hard or the vac line is cracked & not delivering enough vac.
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pitbullcustoms Junior Member Offline SuzukiSavage.com Rocks! Posts: 57	Re: stumbling problem Reply #2 - 11/04/09 at 18:25:14 the petcock is converted to an On OFF reserve type petcock ummm havent tried running it with out the reserve but will do that tomorrow and see what happens
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: stumbling problem Reply #3 - 11/04/09 at 18:51:03 If its not a vac actuated unit, it shouldnt matter. If the choke makes it run better, youre lean.
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28649 Tucson Az Gender:	Re: stumbling problem Reply #4 - 11/04/09 at 20:19:19 lean,.. like Justin says.... Probably have a partially clogged jet or sticky slide... Try some Marvel mystery oil (a teaspoon per gallon),... and/or some Seafoam,....or Lucas additive... If that don't work,... you need to pull it and clean it manually...
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sakara Senior Member 2005 No Login Offline Thumpalicious Posts: 313 Lockport, NY Gender:	Re: stumbling problem Reply #5 - 11/05/09 at 07:39:26 I agree that you're lean as h3ll, but other than carb cleanup, I think this is the problem: "i havent done any carb work to it and i have a drag pipe and an intake filter on it." Rejetting, white spacer, or at least adjust the idle mix screw!
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pitbullcustoms Junior Member Offline SuzukiSavage.com Rocks! Posts: 57	Re: stumbling problem Reply #6 - 11/05/09 at 16:57:43 ok another question what jets do would work the best for my application and what exactly is the white spacer mod? sorry carbs are kinda new to me lol
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thumperclone Serious Thumper Alliance Member Offline PGR rider riding with respect Posts: 6057 Grand Junction Colorado Gender:	Re: stumbling problem Reply #7 - 11/05/09 at 17:38:16 check basic carb tuning (by lancer)in the tech section.. you let more air to flow,in take and drag pipe,now need to add the right fuel mix.. i may not hve the tech post title correct but its a simple enuff system/method that i was able to do it!!
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Serowbot YaBB Moderator ModSquad Offline OK.... so what's the speed of dark? Posts: 28649 Tucson Az Gender:	Re: stumbling problem Reply #8 - 11/05/09 at 17:49:55 Jetting very much depends on elevation and temperature...
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pitbullcustoms Junior Member Offline SuzukiSavage.com Rocks! Posts: 57	Re: stumbling problem Reply #9 - 11/06/09 at 18:02:32 i live in Vermont not really sure where to start with rejetting it what jets does it have in it stock? what jets are you guys running?
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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: stumbling problem Reply #10 - 11/06/09 at 19:16:37 Whats your elevation. NOOOO, not how tall are ya, how far above sea level. Temp & humididity matter, too. On a cool day, air is denser, so theres more O2 in there needing gasoline to create that perfect explosive ratio. Toss some humidity in & SOMething changes, but youll need one of the guru types for those details.
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Routy

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Re: stumbling problem
Reply #11 - 11/07/09 at 04:48:38

Quote:
Ok so i have had a problem with my bike for awhile
------------------------------------------------------------------
Your statement insinuates that this has not always been a problem. If so, the problem is NOT rejetting, or adjstments like the"spacer mod".

Your discription says its running very lean, so there is a carb problem, either dirt in jets or a bad diaphram or other malfunction in the enrichment system.

If you attempt to modify or adjust before finding the real problem, you could get into worse trouble than you are now.

But if by per chance, it always has ran like you describe, then ignore the above.

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

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pitbullcustoms

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Re: stumbling problem
Reply #12 - 11/07/09 at 07:32:49

its been this way since i about the bike just got worst after i changed out the broken exhaust... all i can really tell ya about elevation is its around 1500 feet and humitity bepends on the day and the month so our weather changes pretty much as much as you change your underwear and im not tryiong to be a smart ass either just a rough idea of Jets would be good

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LANCER

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Re: stumbling problem
Reply #13 - 11/07/09 at 08:16:42

pitbullcustoms wrote on 11/04/09 at 18:18:29:
Ok so i have had a problem with my bike for awhile which made me put my bike up way to early and havent had much time to fix it... at part throttle it is very doggy and you have to roll on the throttle you cant snap it quckly it seems like its running rich but i havent done any carb work to it and i have a drag pipe and an intake filter on it... but i did notice if i put the petcock on reserve and pull the choke it runs like a brand new bike... any suggestions on what it might be going on??

Thanks Corey

its been this way since i about the bike just got worst after i changed out the broken exhaust... all i can really tell ya about elevation is its around 1500 feet and humitity bepends on the day and the month so our weather changes pretty much as much as you change your underwear and im not tryiong to be a smart ass either just a rough idea of Jets would be good
Posted by: Routy

When you said"drag pipe" I assume that it is an open pipe ... ? ?
If so, you created a double problem. A more open exhaust created an even leaner condition than stock, which was lean to begin with, and you also introduced an exhaust system that is inherently unstable where tuning is concerned. A stock engine with an open drag pipe will be virtually impossible to jet/tune for correct fuel/air ration in all throttle ranges. A drag pipe will only work best at near wide open throttle on an engine built for it. For a stock road bike it is the worst choice you can make. A muffler, for best running, should have a volume of 10x the cylinder volume, and the baffle system to control sound to the desired level for rider and societal laws. Well, at least for the rider anyway.
Point is, the engine needs a decent muffler to run well and be able to tune. The drag pipe my look good but is like a "never satisfied partner" otherwise.

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Serowbot

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

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Re: stumbling problem
Reply #14 - 11/07/09 at 08:18:08

O.K.,,, Short answer,...
I would start with a 152 main/55 pilot and 2/3 spacer mod... drill out the idle mix screw and set to 1 1/2 turns out.
Then see from there...
Instructions on spacer mod are in the Tech section...

Stock is 145/52 on new Us model...

Do make sure that your carb is in good working order before you make any corrections from there, or you will be correcting problems with jetting and get everything out of wack... it's a simple carb and easy to clean and work on....

and Lancer is our resident expert tuner,... so consider his advice on that muffler... Sportster muffler conversions are very popular here, and they add a little performance and look and sound nice. Some people do run open drag pipes, but they are more for style than performance... you loose a lot of torque, but they will drive the neighbors crazy, if you're into that...

Here's some general ideas on tuning...
Quote:

In general...

thinner air = go leaner

hotter air = go leaner
more humidity = go leaner
higher altidude = go leaner

thicker air = go richer

cooler air = go richer
less humid = go richer
lower altitude = go richer

Barometric pressure effects jetting in a big way, humidity, air temp, and elevation. Some places have extreme variations in barometric pressures and if you live there, your pipe will blue. I live in the high desert and temps can change 40 degrees f in a couple hours, humidity can vary wildly too. No way to jet for that.

A good indicator of overall jetting is the weather...if popping/backfiring increases on humid days, or at higher elevation, that indicates rich....less popping at those times indicates lean.

To test the main, accelerate from 30 or 40 mph, in 4th or 5th gear at full throttle for several seconds, then reduce throttle by about 1/8,...if power increases for a second, you are lean on the main jet. Go up one jet size and test again.

#4 teflon washer from Ace hardware is exactly 2/3 thickness of the stock spacer and will fit perfect. It comes in white or black. It is just what you want. One and only one. It will measure .066",... stock is .1"...

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« Last Edit: 11/07/09 at 09:27:43 by Serowbot »

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