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Message started by roddy on 11/15/19 at 18:40:11

Title: carb questions
Post by roddy on 11/15/19 at 18:40:11

hi. i'm back. my s 40 does act like it is misfiring at just off idle. it gets better after warm up. i have been reading about the white spacer, number 4 washers etc. did the s 40 run like that off the show room floor? and if so, why did they not fix it? mine also has a slight backfire when i turn off the bike. any comments? thanks to all that have offered help, Roddy

Title: Re: carb questions
Post by DragBikeMike on 11/15/19 at 19:06:32

Yes, the S40 runs like that right off the showroom floor. It's the old hiccup, pop & shudder. The factory sets them up on the ragged edge of lean. Generally, once the engine is fully warmed up they run acceptable, but I wouldn't define the as-delivered operation as "good".

You will be pleasantly surprised with just how much better it runs with the idle mixture screw adjusted properly and the jet needle raised a bit by thinning the spacer. It really is like night & day.

Good luck. 8-)

Title: Re: carb questions
Post by verslagen1 on 11/15/19 at 19:14:59

1st, I'd clean the carb.
Your hesitation maybe a clogged main jet.

Title: Re: carb questions
Post by BrokeAss on 11/15/19 at 20:16:43

The Savage/S40 starts, idles, sounds and runs horrific in stock form. That's why the battery in this little 650 single is bigger than the one in my 1700cc V-twin. Open air intake, open exhaust, and generously jetted carb wakes it up into a pretty fun little romper that'll start in just one rotation off a battery 1/3 the size. Happy modding.

Title: Re: carb questions
Post by roddy on 11/18/19 at 08:40:17

thanks for the info. seems like buyers would pregnant dog to hi heaven with a new bike that stumbles like it does. i will try your fix and thank you again for the info....ps the seat is a little short haha

Title: Re: carb questions
Post by Gary_in_NJ on 11/18/19 at 09:47:42

I don't think the battery has anything to do with the jetting. The starting nature of the the Savage (or any engine for that matter) has to do with the force (a factor of volume and compression ratio) the starter motor has to overcome, the motor used in the starter (diameter, length, and number of winds) as well as the reduction gear ratio used in the starter motor gear train.

There is no correlation between the two.

Title: Re: carb questions
Post by BrokeAss on 11/18/19 at 11:06:18

6F65616B60696D643A3C38080 wrote:

Just observation there, Chief. In stock form it takes about 2-3 seconds or 5-6 rotations to get a Savage started, and it's not at all difficult to drain that big battery if it's having any trouble at all getting going. After stage 3 mods it starts after just one rotation and I'm using a battery 1/3 the size (the battery specified for the Raptor) on my bobber builds. Suzuki engineers must have spec'd that gargantuan hunk of lead and acid for some reason, it's not as if the electrical system on an S40 is complicated or demanding in any respect. I understand what you're saying as I have an Associates and Bachelors in Electronics, but the only reason that battery has to be so big is for capacity since the starter has to spin the motor gratuitously to finally start in the very poorly jetted stock form. Get the engine tuned correctly and the need for all that reserve capacity evaporates.

Title: Re: carb questions
Post by Gary_in_NJ on 11/18/19 at 11:58:00

Well, I'm a little slow, being that I only have a BS in Aerodynamics, so you'll have to bear with me.

What are "stage 3" mods? Either a bike is jetted properly or it's not. I usually make that happen in a single stage.

The physical "size" of a battery doesn't mean crap. The chemistry and density are what matter. The Lithium battery (4.250x3.375x2.250) I have in my bike(s) spin the starter much faster then the lead-acid boat anchor that was removed. Glass mat (AGM) is also a superior to the lead-acid battery that comes standard in the Savage.

Just my experience, Chief.

Title: Re: carb questions
Post by verslagen1 on 11/18/19 at 12:33:43

Let's stay on message.
For those that can, take a ride.
For those that can't, Easy rider.

Title: Re: carb questions
Post by Gary_in_NJ on 11/18/19 at 12:45:32

7A697E7F606D6B69623D0C0 wrote:
Let's stay on message.

Well, alrighty then.

Roddy, can you give us some information about your bike such as, year, mileage, modifications? Is this a bike that is used a few times a week or a bike that sits for months at a time? Can you describe the misfiring?

Also know that a carbureted bike will typically run poorly when cold. Jetting is changed to improve throttle response with a warm engine. You typically don't rejet to improve cold engine performance.

Title: Re: carb questions
Post by roddy on 11/18/19 at 17:09:40

hi. thanks for the message. my bike has 5600 miles and it's a 2012. no modifications. carb was rebuilt by the seller 2000 miles ago. there are no marks on any boltheads indicating to me it has never been worked on except for a new tire and oil filter i ride on both hiway and streets. the misfiring is tolerable but if it can be easily fixed, i'd like to apply it to my bike. thanksagain, roddy

Title: Re: carb questions
Post by Gary_in_NJ on 11/18/19 at 17:27:51

So a misfire can be from something as simple as a fouled spark plug or old fuel. However with that said, US S40's are jetting lean from the factory to pass US emission requirements.

Given that the bike has been ridden 800 miles a year since new, there is a good chance that the carb could use a simple cleaning. When the carb is being cleaned is a good time to review the jets installed and determine if you want to make an adjustment. You mention that the carb has already been serviced. It's possible that the jets were changed at this time, so a cleaning would give you the opportunity to see what jets are currently installed in the carb.

Also, if you have contemplated any changes to the exhaust or intake, you would need to rejet anyway. So maybe this is a good time to inspect the carb and make mods.

There are quite a few good posts in the Technical Reference section (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1181745927) on removing the carb. Read those threads and if it's something you want to undertake, we can walk you through it.

Title: Re: carb questions
Post by BrokeAss on 11/18/19 at 19:13:11

2C262228232A2E27797F7B4B0 wrote:

***************************

I'll use smaller words with fewer syllables...

Stage 3 means unrestrictive intake, unrestrictive exhaust, and requisite jetting. Pretty much everything one can do without opening the engine and changing the innards. I'm aware of the differences between old school lead acid, SLA, AGM, Gel, and Li-Ion batteries. I like Anti-Gravity batteries very much but that price tag can be tough for some customers to swallow, especially with a budget build on a budget bike.

Anyway, back on topic - a properly breathing, freely exhausting Savage starts so much more quickly and easily than a stock bike, so less reserve capacity is required. Voltage is strength, cranking amps is stamina. No need for so much electrical stamina when the engine doesn't struggle to start. You claim the Suzuki engineers spec'd such a large turd of a battery because of the size of the starter, windings, etc... But that makes me wonder how my 1700cc Nomad starts with essentially the same size battery when it has to run an ECU, a servo-driven throttle body, a fuel pump, two injectors, and a starter capable of spinning two cylinders that are each 200cc larger than the S40's...and the simple answer is, in stock tune the S40 is a battery killer. If it wasn't for how well this bike responds to mods and how easily the chassis can be customized, I'd absolutely hate it. It's quite frankly a terrible motorcycle right out of the box. So while you see no correlation between battery capacity and jet sizes, there very much is in this case.

Title: Re: carb questions
Post by Hiko on 11/18/19 at 19:57:00

333526323D313830666D6C67540 wrote:

I have the same year bike as you with the same mileage
My bike when I bought it behaved like yours I am at sea level or up to a few 100 feet above Thanks to the info on this site I have :
Changed the main jet to 150 the pilot jet is stock
Lifted the needle by reducing the spacer by 1/4
Fitted a Dyna muffler
Pulled the plug on the idle screw and it is now at 2 turns open
The bike now requires a little choke until it warms up and then runs very sweet no hesitating no backfiring some times just a little puff on shutdown I do not intend to change anything else as far as the motor is concerned very happy as is. These mods were done about 3000 miles ago

Title: Re: carb questions
Post by batman on 11/20/19 at 09:20:57

Comparing a Nomad to the Savage ? Any bike with more than one piston is going to require a smaller battery(depending on other needs) , the piston in the Nomad may be of larger displacement , but the stroke is usually shorter , or the closing of the intake valve maybe earlier , making cylinder pressure much lower at cranking speeds ,even more so if the cam shows any overlap , the Savage has no overlap. Show me the decompression releases on your Nomad , it has none, that should give you your first clue. Tuning your carb hasn't much to do when starting the motor (cold startup), when choking the carb, the quantity of fuel/air mix is more important than the quality. Your carb isn't tuned when the choke is pulled out , it's flooding the combustion chamber in hopes that at least some of the fuel will mix with air and produce a spark ,where most of the fuel will be in contact with the cold combustion chamber, piston and cylinder walls and will be condensed .

Title: Re: carb questions
Post by BrokeAss on 11/20/19 at 12:17:35

2023362F232C767A420 wrote:

Comparing a Nomad to the Savage ? ...the piston in the Nomad may be of larger displacement , but the stroke is also much shorter...Show me the decompression releases on your Nomad it has none, that should give you your first clue.

VN1700 ENGINE: Bore = 102mm*
Stroke = 104mm*
Compression Ratio = 9.5:1
(*per cylinder)

LS650 ENGINE: Bore = 94mm
Stroke = 94mm
Compression Ratio = 8.5:1

So, what were you saying about the shorter stroke and lower compression in my Nomad versus the Savage? Are you seriously trying to argue that a 650cc beginner bike engine is harder to crank over than a 103ci V-twin??? And I only used my Nomad as one example, did I mention I've been building and flipping bikes for a living for six years??? Do ya think I've ordered and replaced a battery or two in those six years? The size of the battery in the LS650 always incites laughter on my part, it looks like something you'd find in a Sportster 1200, not an MSF course motorcycle. Yes, the Savage has a solenoid compression release to relieve its whopping 8.5:1 compression, but there's no ECU, or fuel pump, or injector, or anything else demanding whatsoever on the bike. And the mere FACT that I'm building and running these bikes off a 12v6.5ah AGM or Gel battery after proper tuning is quite telling.

I've seen some Post Count Cowboys in my days, but you guys really take the cake. Sorry for intruding on your little information monopoly you've spent years establishing here in this little forum, I won't be darkening your doorstep any more...

Title: Re: carb questions
Post by Gary_in_NJ on 11/20/19 at 13:04:11

The jetting is so lean on the s40 that its causing climate change.

The battery on the S40 is so large because it contains a nuclear reactor to overcome the lean jetting.

Dumbass knows everything and we're just a bunch of...oh wait.

Title: Re: carb questions
Post by roddy on 11/20/19 at 17:34:22

THAT'S why the battery bos is chrome......it's chrome plated lead

Title: Re: carb questions
Post by ohiomoto on 11/21/19 at 05:51:46

This is a great forum with a lot of knowledgable and helpful folks. I think it would be better if we all dropped the posturing, chest-puffing and arguing.

A stubborn fool considers his own way the right one,
but a person who listens to advice is wise.

Title: Re: carb questions
Post by roddy on 11/23/19 at 18:05:44

chest puffing? huh? don't be such a snowflake. please,sir