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Message started by cytocatlady on 04/26/19 at 15:00:50

Title: Backfiring on acceleration/sputtering over 60 mph
Post by cytocatlady on 04/26/19 at 15:00:50

Just a preface: I don't know very much about working on bikes, so please don't assume I know anything. Basically, talk to me like I'm an alien that doesn't understand Earth transportation mechanics. ;D

My Georgie is a 2007 S40 that's got 8,323 miles on it (660 of which my husband and I put on since mid-March). It seems like the bike had only one previous owner and I really don't know what he did to the bike, other than superficial stuff (wrapped exhaust, flipped the steering stem upside down). I honestly can't tell if it's got the stock petcock or not. The bike is mostly reliable, especially after I refilled the battery with distilled water (I hope that was the right thing to do!).

So, for the last work week, my husband has been riding my bike due to a flat on his bike (he doesn't have a car). He's noticed some funny things about Georgie. His belt seems squeaky, for one, but I've seen some threads on this and I think it just need to be realigned. Hubs seems really concerned about the popping/backfiring on acceleration, as well as the sputtering/loss of power over 60 mph. I know the backfiring on decel is due to the lean mixture of the carb, but what about on acceleration? I've never messed with the carb and I don't know if the previous owner ever did maintenance on it.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by Eegore on 04/26/19 at 15:54:32

For the Petcock look at this thread.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1340021926/0

The very first post has a side-by-side comparison of a stock petcock and a Raptor one.

As for the acceleration backfire I will leave that to the pro's here.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by Gary_in_NJ on 04/26/19 at 16:30:34

A failed petcock can cause all sorts of performance problems, especially the bike not being able to run smoothly through the full rpm range. It's always a good place to start when there are performance issues.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by cytocatlady on 04/26/19 at 16:43:16

022220283522470 wrote:

For the Petcock look at this thread.

http://suzukisavage.com/cgi-bin/YaBB.pl?num=1340021926/0

The very first post has a side-by-side comparison of a stock petcock and a Raptor one.

Thanks for that! I definitely have the stock petcock.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by cytocatlady on 04/26/19 at 16:52:40

I wanted to add that the usual decel backfiring has basically stopped and now it's backfiring on acceleration alone.

63696D676C656168363034040 wrote:

So what are the most common symptoms of a faulty vacuum petcock? I don't know that I have the skills or expertise to test mine or change it out.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by justin_o_guy2 on 04/26/19 at 17:11:40

don't know that I have the skills or expertise to test mine or change it out.

Sure you do..
The Petcock swap doesn't even require pulling the tank.
Takes some bending over and a healthy neck, but you can do it. It's a straight swap, zero changes except for plugging the vacuum line.. and who can't plug up a hose?

Title: Re: Backfiring on acceleration/sputtering over 60
Post by norm92de on 04/26/19 at 18:02:26

Justin is right.

Get a genuine Yamaha petcock to replace the stock petcock.

When you get around to changing it be sure that the tank is almost empty. You don't want fuel running all over everything. It is only two screws, no problem really. :)

We can talk you through it. Very easy!

Title: Re: Backfiring on acceleration/sputtering over 60
Post by madmikesmech on 04/28/19 at 09:26:26

As our local pro's have stated... it's a good place to start, as it's likely going to fail sooner or later! It's easy enough for Nearly anyone to do, and make sure tank is nearly EMPTY!

Title: Re: Backfiring on acceleration/sputtering over 60
Post by justin_o_guy2 on 04/28/19 at 13:40:15

Have a gas can handy
Pull the fuel line from the carb
Put the fuel line in the gas can
Put Petcock on prime
Drain the tank
10 mm socket
Remove old Petcock
You can just snip the vacuum line up by the carburetor
We'll get to that later
Inspect the bottom of the tank and look at how the Petcock seals.
If it's not smooth where the seal goes. Fix that..

Title: Re: Backfiring on acceleration/sputtering over 60
Post by cytocatlady on 04/29/19 at 05:22:23

I learned that my husband had been putting it on prime to help the bike start up. He noticed the backfiring on acceleration on Friday afternoon, after a week of using the prime that way. On Saturday, he took it out without using prime to help it start, and none of that acceleration backfiring was happening. On Sunday, we went for a long ride (for me anyway), and I only noticed the usual decel backfiring.

Anyhow, I looked at those videos regarding the petcock, and you guys are right. I think it's something I could do. My local dealer quoted me $38 for the Raptor, so I'm definitely not buying from there. Thanks folks!

Title: Re: Backfiring on acceleration/sputtering over 60
Post by justin_o_guy2 on 04/29/19 at 09:17:22

Got mine locally for$28.00.

Putting it on prime just allows fuel to flow freely, without the vacuum diaphragm being involved, which is how the Raptor Petcock works.

If fuel freely flowing to the carburetor is a problem
The carburetor needs attention.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by batman on 04/29/19 at 21:24:36

Placing the petcock on prime does allow fuel flow to the carb as JOG said , but if there's a hole/crack in the diaphragm ,extra fuel will also flow down the vacuum hose flooding the motor. you should buy a Raptor petcock.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by justin_o_guy2 on 04/29/19 at 22:03:03

I didn't mean to suggest a Raptor isn't needed.
I totally forgot about the vacuum line getting gas.

If your Petcock is that screwed up, you better check out the oil.
Might have gas in it.

Title: Re: Backfiring on acceleration/sputtering over 60
Post by Gary_in_NJ on 04/30/19 at 06:36:00

While the bike may run better on prime, there is no way to stop the flow of fuel. So in time, the crankcase will begin to fill with fuel. This is undesirable, and eventually renders the bike unridable.