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Message started by f204 on 09/16/05 at 13:15:34

Title: Bike wont take throttle
Post by f204 on 09/16/05 at 13:15:34

I installed a screamin eagle muffler on my savage and filed the white spacer down half the thickness the bike starts fine and idles fine but when i give it gas it dies i have no clue what to do now any help would be apreciated thanks

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 13:21:41

did u adjust the air/fuel mixture screw?

Title: Re: Bike wont take throttle
Post by f204 on 09/16/05 at 13:24:01

Yes i backed it out about 3 turns and have tried it at different settings

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 13:28:43

did the bike run with the full spacer and SE muffler?,or did u do both mods at the same time?

Title: Re: Bike wont take throttle
Post by f204 on 09/16/05 at 13:30:09

The bike ran with the se muffler but backfired real bad thats when i filed the spacer down

Title: Re: Bike wont take throttle
Post by f204 on 09/16/05 at 13:31:09

Do you think i need to rejet the carb

Title: Re: Bike wont take throttle
Post by f204 on 09/16/05 at 13:33:05

Is the air fuel mixture screw the same as the idle mixture screw the one with the brass plug in front of it?

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 13:35:02

the SE will back fire more than stock.u may have too re-jet.

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 13:38:11

f204 wrote:

Is the air fuel mixture screw the same as the idle mixture screw the one with the brass plug in front of it?

yeah its the same thing.

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 13:41:03

first u should get some washers and put them where the oringal white washer was,before u filed it down, then try to adjust the idle mixture screw,and rejet like that.dont rejet with the half washer .

Title: Re: Bike wont take throttle
Post by Dynobob on 09/16/05 at 17:08:19

torque wrote:

first u should get some washers and put them where the oringal white washer was,before u filed it down, then try to adjust the idle mixture screw,and rejet like that.dont rejet with the half washer .

That's nonsense.

Regarding your problem...it sounds like a vacuum leak. Maybe you don't have the CV diaphram seated properly. There's a detent and it only goes in one way. You can use heavy grease to hold it in place while reinstalling the top. Are the vacuum hoses installed correctly ? Is the carb in the rubber intake hose well and tight ?

And finally, did you disturb the float ?

Yes, freer flowing mufflers should get a rejet. That consists of a larger main jet, 1/2 white spacer, and 2 to 2 1/2 turns out on the slow mixture screw (the one behind the plug).

Title: Re: Bike wont take throttle
Post by torque on 09/16/05 at 19:07:27

Dynobob wrote:

why is that nonsense? it ran good with the full spacer in why the he11 would rejet if u dont need too, i put my 145 main back in with a baffle less muffler and it runs better than the 160 main, i can hit 100mph easy now.

i just hate for u to do all that work and then it doesnt run then u dont know wtf is wrong!

make sure there is no debris holding open the float valve needle,that would flood the engine.

after it dies do u have to crank the engine for a while before it starts?

Title: Re: Bike wont take throttle
Post by f204 on 09/16/05 at 19:15:21

No after it dies it starts right up

Title: Re: Bike wont take throttle
Post by Dynobob on 09/16/05 at 23:50:17

torque wrote:

A white spacer reduced by 1/2 will work perfectly well with the Harley muffler he has. f204, check some diagrams of the carb (on this site IIRC) and make sure you have everything put back together properly. Something is amiss. Make sure the vacuum line from the petc0ck to carb isn't pinched.

So torque, you have staight through exhaust with the stock main jet and you think your bike is jetted properly ? Do a full throttle kill, then read your plug. Running that lean is destructive.

http://www.motorcyclecarbs.com/jetting/plugreadings.htm

Title: Re: Bike wont take throttle
Post by f204 on 09/17/05 at 04:14:37

Thanks i will check the carb again one interesting note is if i cover the air box and restrict the flow of air the bike will take the throttle and not die

Title: Re: Bike wont take throttle
Post by torque on 09/17/05 at 05:58:21

Dynobob wrote:

So torque, you have staight through exhaust with the stock main jet and you think your bike is jetted properly ? Do a full throttle kill, then read your plug. Running that lean is destructive.

no my bike sure isnt lean thats for damm sure!still backfires(rich condition).
only rejet when if u have srewed up the carb so bad that it dosent run.the savage is a very forgiving
bike same goes for the carb.

u said it backfired with the SE and spacer,it was to rich then,then u filed the spacer down and made it super rich.make sure there are no leaks in the exhaust.

Title: Re: Bike wont take throttle
Post by f204 on 09/17/05 at 06:05:04

Dosent it mean its running too lean if it backfires??

Title: Re: Bike wont take throttle
Post by torque on 09/17/05 at 06:13:01

if it backfires when accellerating its to lean.
if it backfires while decellerating its to rich.

Title: Re: Bike wont take throttle
Post by Ed_L. on 09/17/05 at 06:55:04

Pull the slide out of the carb and check it for dirt, sounds like it is hanging up when you open the throttle. Could also be a vacumn leak or hole in the diaphram. Don't mess around with rejetting the carb yet, you need to get the bike running first before you start any other carb modification.

Title: Re: Bike wont take throttle
Post by savage777 on 09/17/05 at 06:57:35

you said it runs better wth the 145 stk jet than the 160 ...it seems the 160 is way too rich for the savage unless yer running no air box with a cone directly on the carb and no baffles in the exhauast. I 've got a 155 and its just little on the rich side. I get a little soot . 160 is by far to rich with your setup

Title: Re: Bike wont take throttle
Post by torque on 09/17/05 at 07:21:02

savage777 wrote:

i had the airbox removed with a chev 4inch air cleaner,sticking out the left side of the bike.and i do have a straight pipe too.

it was only too rich at high rpms,the 160 and the 145 have the same get up and go power

::) ::) ::) ::) ::)

Title: Re: Bike wont take throttle
Post by lancer on 09/17/05 at 08:33:12

torque wrote:

if it backfires when accellerating its to lean.
if it backfires while decellerating its to rich.

You have that backward dude, it is just the opposite.

Title: Re: Bike wont take throttle
Post by lancer on 09/17/05 at 09:04:30

savage777 wrote:

When I was still running the stock carb, the main jet was a #160(3 over), and the pilot jet was a #55(1 over),the needle had the white piece removed and an extra notch for the clip was created below the original notch(those changes richened the mix in the low. mid, and high ranges), the air passage hole in the top of the slide was drilled out slightly larger for quicker response, and a "dial-a-jet kit" was installed to fill in any lean areas of the curve. This was on an engine bored one size over, silicone carbide treated cylinder, Performance Design muffler, velocity stack and K&N on the carb, and a reground cam....The point being that if your engine is still stock, and the only changes you have made are the muffler and filter, the jetting on the carb does not need a lot of change. Going up 1 or 2 sizes on the main jet and 1 size on the pilot jet should be sufficient for the low and high range of the throttle. There is still one thing missing though...what about the midrange? The needle is the primary controller of the midrange. Removing the little white piece will SLIGHTLY richen the midrange, but for the best result a jet kit is needed. It comes with a new needle with notches for adjusting...but it is also a different shape which also changes the fuel/air ratio. The kit also has a few main jets to play with but no pilot jets. If you really want to do a proper job of jetting in a stock carb I suggest getting a jet kit and a pilot jet. That way you can rejet all 3 ranges, low/mid/high, for the optimum fuel/air ratio from idle to wide open.
I would also suggest that anyone who has not done so yet, go to Mikuni.com, motorcycles, and find the tuning info they have...it is excellent. It explains in detail what to do, and why. There is also some trouble shooting stuff to work with.
As long as you are going to tinker with your engine you might as well learn from the folks that built the carb in the first place.
Go forth and have fun!

Title: Re: Bike wont take throttle
Post by torque on 09/17/05 at 09:29:18

lancer wrote:

You have that backward dude, it is just the opposite.

http://www.type2.com/library/exhaust/backfire.htm

Title: Re: Bike wont take throttle
Post by lancer on 09/17/05 at 10:51:38

I was not able to get the link put in here correctly so I will just type it in.

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

From Mikuni website...Tuning Guide...4. Backfires in Exhaust....................

"It is normal for many high performance exhaust systems to moderately backfire or pop when the throttle is closed from mid-to-high rpm. In fact, one should expect a well-tuned high performance engine to "pop" and "crackle" when the throttle is closed at high rpm.
The popping is a result of the air/fuel mixture becoming very lean when the throttle is closed and the engine is rotating well above idle speed. It is also necessary that the exhaust system have rather open mufflers.

Why This (normally) Happens:

1) When the throttle valve is in the idle position, fuel does not flow out of the main system (needle, needle jet, main jet). Fuel is only delivered to the engine by the pilot (idle) system.
2) The combined effect of the closed throttle and elevated engine rpm is to create a fairly strong vacuum in the intake manifold. This vacuum, in turn, causes a high air flow rate through the small gap formed by the throttle valve and carburetor throat.
3) Under these conditions the pilot (idle) system cannot diliver enough fuel to create a normal, combustible air/fuel ratio. The mixture becomes too lean to burn reliably in the combustion chamber. It gets sent into the exhaust system unburned and collects there.
4) When the odd firing of the lean mixture does occur, it is sent, still burning, into the exhaust system where it sometimes ignites the raw mixture that has collected...the exhaust then pops or backfires.
5) Completely stock Harleys do not do this until open-end mufflers, such as the popular Screamin' Eagle slip-ons are installed. The exhaust must be both free-flowing and have an open exit for the popping to occur.

Other possible causes:

Air Leaks:

Any source of fresh air into the exhaust system can create or worsen the conditions that bring about exhaust backfiring. The most common entry point is the junction of the header pipes and mufflers. Even a small air leak can dramatically increase the intensity or likelihood of exhaust system backfiring.

Lean Carburetion:

While exhaust system popping may be considered normal, it is certainly made worse by an overly lean idle circuit.
Be sure that your carburetor's pilot jet is the correct size and that the idle air mixture screw is correctly adjusted before looking for other causes of popping. The procedure for adjusting the pilot circuit is covered in the TUNING MANUAL."
*********************

The info you referenced was talking of the "pooled raw fuel" in the exhaust pipe that was the result of an overly lean jetted carb. Remember you quote said "temporary over rich"...the temporary is the pooled fuel. I think the confusion was a result of trying to explain in a single sentence, when it needed a couple of paragraphs to do it properly.
I hope this clears things up for you.

Title: Re: Bike wont take throttle
Post by Dynobob on 09/17/05 at 15:40:20

torque wrote:

if it backfires while decellerating its to rich.

The following is a great article which describes deacceleration popping. Since this article was written, the guys on this board have discovered that removing the white spacer results in a rich condition. 1/2 spacer is perfect for aftermarket exhaust. My bike runs fantastic in the midrange. It pulls like a freight train ;D

Quote:

Savage Backfire
(from January 1997 RIDER magazine's Tech Q&A)

Q) I purchased a new Suzuki Savage 650 last July. From the very beginning the motorcycle would backfire when decelerating or coming to a stop. I took it back to the dealer twice before the 600-mile service, and complained about it at the initial service. I have tried different grades of gasoline and they seem to have no effect. The dealer has told me that I should expect backfiring with the design of this engine and that it should decrease as I build up mileage. I have 900 miles on the bike now and backfiring doesn't seem to be decreasing. I have found other riders of Suzuki Savages that are having the same problem. - Jay Coney, Kerrville, Texas.

A) This column receives a lot of mail over the course of a month, and the single biggest gripe among our readers are problems with lean-running. late-model carbureted bikes.

The poor old LS 650 really suffers at the hands of the EPA, and I certainly sympathize with you, Coney. We can fix it, but first let me explain the hows and whys.

When the throttle of any engine is rolled or snapped shut, some fuel is drawn through the engine and kicked out the exhaust without being burned. In abundance, this raw fuel vapor can be smelled, tasted - and when light is passed through it- seen. It's referred to as photo-hydrocarbons or more commonly smog. Yes, there are several other pollutants coming out of the exhaust, but the human senses can't detect them. The manufacturer of motorcycles have three methods of dealing with excessive hydrocarbons. Forcing air down into the exhaust port with an air pump and diluting the outgoing fuel vapor is one method. Kawasaki pioneered this method with their 'Clean Air System', which employed a vacuum-driven pump that puffed air through reed valves placed over the exhaust system. A 'cat' is nothing more than an oven which bakes the hydrocarbons, burning them off.

The most common method is to simply lean out the carburetor. The low-speed and midrange circuits of the late-model carburetor are not adjusted to give optimum performance - they're set up to produce a minimum hydrocarbon count on deceleration. What miserly amount of fuel they do deliver to the combustion chamber when the throttle is closed causes misfire and an audible afterfire in the exhaust pipe.

Now, I haven't mentioned fuel injection or other exhaust gases. As I said, the bulk of complaints from readers of this column is deceleration backfire and also poor idling of carbureted engines. No doubt we'll get around to discussing other emission-control devices and their problems in future issues.

Getting back to your Savage 650, Coney, here's how we can specifically cure its problem. We need to richen those two areas of the curburetion curve that are factory set on the ridiculous side of leanness. Remove the diaphragm slide from the carburetor and look down inside its bore. Two small screws hold a plate over the slide needle. Removing the plate, you'll see a small, white plastic spacer with a hole through it sitting on top of the needle. Throw that spacer away and reinstall the plate. A spring under the needle clip will now push the needle up to the plate occupying the space vacated by the white spacer. The distance that the needle has been 'lifted' is the thickness of the discarded spacer - and that's ideal. With the needle raised, more fuel will flow by it, meeting the actual needs of midrange running.

We can also fatten up the low end of your bike's carburetor by turning out the low-speed mixture screw. To gain access to this screw, you'll need to drill out the brass plug pressed in over it and yank it out with a sheet-metal screw attached to a slide hammer. You'll find that plug up high on the right side of the carb about where the mouth enters the carburetor. Usually Suzuki applies a splash of white paint over the brass plug so that it's immediately noticeable. With the engine warmed up and idling, turn the mixture screw out incrementally until you achieve the highest idle. There will be no doubt in your mind that you're making progress because the idle will come up and sound stronger. At this point, turn the idle adjuster knob out and bring the idle back down to a leisurely gait.

Just these two, relatively simple adjustments will not only eliminate the backfire, they will make an amazing improvement in throttle response and driveability.

The URL for that article is:
http://www.heise-workstations.de/ls650/Reviews/BrucesReview-e.html

Title: Re: Bike wont take throttle
Post by lancer on 09/17/05 at 18:00:43

MMMM...this sounds familiar.

Title: Re: Bike wont take throttle
Post by Greg_650 on 09/17/05 at 22:46:19

Mine has been running a little weak on the low end grunt with an open Raask pipe. Top end great, but weak on the bottom. I just fashioned a new baffle which I hope will bring back a little of the bottom end that my spouse has with her SuperTrapp. Gonna find out with a ride tomorrow.

Clive! What are those numbers for good flow with a straight through pipe again? My new experimental baffle is a rod that is 12" long....

Title: Re: Bike wont take throttle
Post by shawn_b on 09/18/05 at 11:23:02

just my 2cents i tought motors back fire when they run rich i know this becuse my bike only backfires not very offten when i get on it a lot hints raw gas gets mix in there so how and when i gun it and hit the kill switch
i think torque is right :o just my 2cents

shawn ;D

Title: Re: Bike wont take throttle
Post by lancer on 09/18/05 at 11:48:18

There is a difference between accelerating and decelerating.

If you are running with a main jet that is too large (rich condition in high throttle range), for example, when accelerating and when you turn your throttle past the 1/2 to 2/3 throttle position you can experience backfiring, stubling, loss of power, etc. With a main jet that is too small (lean condition) the result will be primarily loss of power....as you said "when I get on it", which means you have your throttle cranked on.

In a decelerating situation with the throttle backed off, a lean pilot circuit will result in the backfiring as discribed in the extensive explanation I posted earlier.

READ CAREFULLY the explanation from the Mikuni site that I posted. That gives a detailed picture of what is happening in the engine/exhaust system. DON'T JUST ASSUME an idea is correct because it SEEMS to be right...READ THE FACTS & INCREASE YOUR UNDERSTANDING.

Title: Re: Bike wont take throttle
Post by torque on 09/18/05 at 13:39:56

everbody is right,websters dictionary states that backfiring is caused by incorrect firing of the engine,therefore if the engine is lean it will backfire,and if it is to rich it will backfire,if the carb is tuned right it should not backfire ,mine only bacfires when i accellerate
to 60mph in 3rd,then let off completely.

it backfired like mad when deccellerating with the 160 at any speed.

Title: Re: Bike wont take throttle
Post by klx650sm2002 on 09/19/05 at 08:17:36

Greg, It's buried someware on technical corner under the name Exhaust design (open pipe)

Clive W :D

Title: Re: Bike wont take throttle
Post by Greg_650 on 09/24/05 at 08:14:51

klx650sm2002 wrote:

Greg, It's buried someware on technical corner under the name Exhaust design (open pipe)

Clive W :D

Okay. My new exhaust baffle is better, but not good enough. More tinkering to do :o