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Message started by PMo85 on 02/05/15 at 08:18:06

Title: Bike is cutting off on deceleration
Post by PMo85 on 02/05/15 at 08:18:06

So here is the skinny on my issue. Recently my bike started to pop a little more than usual when coming off the throttle. Whether I eased off or flat out let go from wide open. Now if I'm at half throttle or more and have to decelerate quickly (let go completely or throttle down at a quick pace) the darn girl shut off. Happens 2nd - 5th gear

Any ideas as to what the heck is going on?

Title: Re: Bike is cutting off on deceleration
Post by Serowbot on 02/05/15 at 08:36:08

Is your idle speed high enough?...

If so,... it might be time for a Raptor pet... :-?...

Title: Re: Bike is cutting off on deceleration
Post by PMo85 on 02/05/15 at 08:43:28

She sounds like she is idling high enough. Not sure what the RPM's should be around though or how I can decide since there is no tach....yet ;)

Does the pet normally go out within the 1st 2 years of the bike?

Title: Re: Bike is cutting off on deceleration
Post by Serowbot on 02/05/15 at 08:52:41

Not normally, no... but, 2 year old bikes don't normally die when you let off the throttle either...
;D...

Title: Re: Bike is cutting off on deceleration
Post by Gary_in_NJ on 02/05/15 at 09:21:11

The popping indicates a lean condition. Fuel starvation from a failing petcock certainly would cause this especially with the reduced vacuum that a fully closed throttle would produce. An obstruction in the fuel line is a potential problem as well.

Make sure that the carb boot between the carb to the head is not compromised or loose. Less likely are a dirty air filter (it would really have to be clogged) or a failing ECU.

Title: Re: Bike is cutting off on deceleration
Post by PMo85 on 02/05/15 at 09:30:50

Thanks Serwo & Gary. I'll look into replacing the pet. Do you have a Model #?

Question; How do I check or know if my RPM's are correct? :-/

Title: Re: Bike is cutting off on deceleration
Post by Serowbot on 02/05/15 at 09:40:15

Without a tach,.. you sorta' don't... but it should purr smoothly, not lope or stumble like a Harley...

Here's a test for the petcock...
This, is a link...-> Test your Petcock,.. don't just turn it to Prime.. (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1251932429/1) ;)...

Title: Re: Bike is cutting off on deceleration
Post by verslagen1 on 02/05/15 at 09:58:15

110C2E7974410 wrote:

Question; How do I check or know if my RPM's are correct? :-/

maybe this will work for you...

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1303712067

Title: Re: Bike is cutting off on deceleration
Post by Steve H on 02/05/15 at 13:15:38

A fully closed throttle increases vacuum. The vacuum tap is on the intake side of the butterfly.

I've never had your problem so I'm afraid I can't help with it.

Check the petcock...it could be leaking into the vacuum hose. If there's any gas in that hose, you've got a bad one.

Title: Re: Bike is cutting off on deceleration
Post by verslagen1 on 02/05/15 at 14:09:23

A clean carb is a wonderful thing.

Title: Re: Bike is cutting off on deceleration
Post by Dave on 02/05/15 at 14:16:06

3F247D7E7F787A754C0 wrote:

It could be dying from being too rich...or too lean.

When you close the throttle, the needle drops down into the jet and closes off fuel flow....and the only fuel that goes to the engine is through the Pilot and Idle fuel circuit, and whatever may be added by the TEV valve. If your Pilot jet (the smallest orifice in the carb) has any kind of deposit, varnish, corrosion or junk in it....the mixture may have gone so lean when you close the throttle that the engine can stop running.

Also when you close the throttle - the vacuum on the engine side of the butterfly does increase. If the fuel pet thingy vacuum line is on the engine side of the butterfly...and if the diaphragm is going bad and allowing fuel down this path...the engine could also stall from being too rich. The sound of this would most likely be noticeable, as the engine will "burble" rather than the noise most commonly associated with the banging and backfiring of a lean mixture.

Title: Re: Bike is cutting off on deceleration
Post by justin_o_guy2 on 02/05/15 at 15:50:53

You're not gonna hurt it if you Jack the idle a little high... just idle it up some, just short of ridiculous,and see if that changes how it acts.
How is it running,other than the cut off from deceleration?
Start okay? Any other changes in it?

Title: Re: Bike is cutting off on deceleration
Post by MnSpring on 02/07/15 at 10:51:03

Don't know if this helps. When I first got the 06 S40.
Used to, 'race', with a buddy on a HD.
(Within Speed Limit Of Course)
From Stop light to Stoplight. ALWAYS beat him.
(However on the open road, I would get to 60, then he would, blow MY doors off)
When I suddenly backed off throttle, at the light, most of the time the motor would kill.

Now it doesn't do that, (at least last fall)

The only thing that changed, was, the PO, used cheep Ethanol gas, I use, Non-Oxy gas, and after a couple of tank fulls, that, 'motor stopping, after sudden throttle down and breaking', stopped.

When it did that, the only thing I did, before, was raise the idle to about 1050. But it didn't stop, until I had run 2-3 tank fulls of good gas through. Raptor and tweaking the carb, did after the, 'fast idle down motor stopping', stopped.

So I am thinking, running the Non-Oxy gas, 'cleaned' the carb.

Title: Re: Bike is cutting off on deceleration
Post by Dave on 02/07/15 at 11:40:20

7655684B4952555C3B0 wrote:

So I am thinking, running the Non-Oxy gas, 'cleaned' the carb.

Probably not.....the non-ethanol gas does not require as much air as the ethanol does. What happens is the fuel mixture is just a tad bit richer when you run pure gasoline. So....your engine doesn't suffer quite as lean of a mixture when you have the throttle closed suddenly. The E10 gas is actually pretty good about keeping things clean - however it can corrode aluminum parts if you just let it sit and don't run the fuel through regularly.

I have a generator with the ability to drop down to idle when you are not using power - then when you pull the switch on a drill or saw - the engine jumps up from idle to operating speed. The generator was built when all fuel was ethanol free - and the carb does not have any mixture adjustment. If I run ethanol free gas the mixture ratio is good, and the generator runs fine. If I run E10 pump gas - the mixture is just a bit lean and the generator stalls when it tries to jump up to the operating speed from idle.

Title: Re: Bike is cutting off on deceleration
Post by oldNslow on 02/07/15 at 12:14:07

Dave wrote:

Quote:

the non-ethanol gas does not require as much air as the ethanol does. What happens is the fuel mixture is just a tad bit richer when you run pure gasoline. So....your engine doesn't suffer quite as lean of a mixture when you have the throttle closed suddenly

If that's the case - and I've got no reason to believe its not - then I wonder if running non E gas might reduce the tendency of a completely stock S40 to backfire on roll off and shut down, since those characteristics seem to be blamed in part on the excessively lean factory jetting

I'm going to experiment as soon as the weather here warms up enough to ride. I've just located a station near me that sells 91 octane non-E gas. It's a little more expensive than the 87 octane E-10 that I've been using but not by a lot.

Except for turning the mixture screw out about a half turn from where it was when I removed the plug, the carb on my '06 hasn't been touched. Stock exhaust. The bike runs fine but it does pop if I snap the throttle shut abruptly ( I usually try to roll of slowly) and it afterfires a bit when I shut it down most of the time.

Now that I can get the Non E gas without searching for it I'm curious to see what difference it makes. I'll run it this coming summer and see what happens.

Title: Re: Bike is cutting off on deceleration
Post by Art Webb on 02/08/15 at 09:22:41

wish I had no E gas here
I can buy av gas and that's non e, but it's high priced

Title: Re: Bike is cutting off on deceleration
Post by justin_o_guy2 on 02/08/15 at 10:16:31

If mine hadn't growled and grumbled and occasionally farted loudly I would not have enjoyed it as much as I did. Like a hot rod car, it snarled on acceleration AND deceleration,, Not to say that there was not a time when an exhaust leak didn't have me embarrassed to ride with people. I hadn't found this place yet. And I don't have the brass to AntiSeize those skinny little bolts and torque them to 20 foot pounds like Verslagen..
So, Know it's not leaking first, then tune it to run as strong as it will, then, the notes it sings as it runs through it's range are just the machines sounds..a different exhaust will create a different sound. Finding one that doesn't choke the performance or create an obnoxious,raspy on the nerves kinda sound, Supertrap does that, but, they are expensive,, but they do build a short one that might fit the look you're after..

How high are you wanting it to go? Would your design invite rain into the pipe? Would that even matter if it did?

I don't pretend to have all the answers, but classmates in college Thanked me for asking the questions that helped them make A's.

Title: Re: Bike is cutting off on deceleration
Post by KiwiGeek on 02/15/15 at 00:19:57

This thread was helpful. I have just bought my S40 and was trying to decide which local petrol station to visit. One is cheaper but an e10 blend the other is more expensive but is not an e10 blend. I think I will stick with the non e10 blend

Title: Re: Bike is cutting off on deceleration
Post by Steve H on 02/15/15 at 18:58:21

Mine runs better on non-ethanol gas.
It's smoother, sounds better, doesn't make quite as much noise. Hard to explain....it just feels better. It also gets slightly better mileage.

I do like all the little burbles and pops and the nice bang after I shut it off. Gives it character.

Title: Re: Bike is cutting off on deceleration
Post by Dave on 02/16/15 at 07:53:42

7269303332353738010 wrote:

I do believe the TEV (Throttle Enrichment Valve) was most likely set up to run with non-ethanol fuel....and the E10 fuel does lean out the mixture a bit as the ethanol needs more air for compete combustion than gasoline does.

I need to look at a carb when it is apart....and see if there is any way to make the TEV flow a bit more fuel than it does stock. Some folks mess with the spring to allow it to come on sooner - but I believe the key to success would be to flow a bit more fuel when the TEV operates.