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Message started by Jackhammer on 06/16/08 at 16:10:54

Title: backfiring at half throttle...
Post by Jackhammer on 06/16/08 at 16:10:54

Hey Guys,
I finally just got my savage over the weekend. Its a '98 and i'm not sure exactly what it has done to it, accept i can see a Jardine exhaust. Anyway, I was out for a little test drive today, and realized something was not right. In any gear when if I give it even 50% throttle it immediately starts sputtering and backfiring. Its as if its falling on its face. It starts and idles fine, however. Anyone know what could be causing this?

Title: Re: backfiring at half throttle...
Post by verslagen1 on 06/16/08 at 17:07:44

A couple things to check,
What's your mileage?
air filter good?
check the in side bottom of the air box, any fuel?
sitting for year with bad fuel, can be gummed up anywhere.
clean your carb, note what jets you have.
pull the petcock, check the screen and passage ways.
check the vac hose and clamps, any leak and it will shut off.
getrdone

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/16/08 at 17:30:14

Yeah, I guess its time to get dirty and see what i can dig up. I don't really know what the mileage is because its falling on its face and backfiring so bad that i'm scared to drive it far. As far as the air filter/box.... ther is no air box, the previous owner removed the airbox and has an open cone filter thier (looks like a K&N). Vaccuum hoses all look good and no leaks are apparent. Tomorrow i'll try pullin the petcock and see if its gunked up in there. Also whats the best way for me to drain the tank and put fresh gas in there? Thanks for the help =)

Title: Re: backfiring at half throttle...
Post by Sandy Koocanusa on 06/16/08 at 18:55:42

Pull the fuel line off the carb, stuff it down in a five gallon gas can's nozzle, and turn the petcock to prime. It'll drain right out.

Edit: If it doesn't drain right out, you'll be a little closer to figuring out the problem. The only thing that should cause that is a plugged screen or petcock passage.

Title: Re: backfiring at half throttle...
Post by Bleemus on 06/16/08 at 19:40:43

"What's your mileage?"

I think he meant how many miles are on the bike not current MPG. Probably helps in diagnosing problems.

Best of luck with finding a solution.

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/17/08 at 04:47:34

Mileage on the bike is 7800. As soon as i get home tonight, i'm going to drain the gas and pull the petcock to clean it up. Then throw some 93 octane in there and see if i can get it cleared up. I talked to the guy who sold me the bike and he said the gas had been sitting in there a few months, but that he added some kind of additive to keep it fresh......
Thanks for the help, i'll let you guys know how it goes this evening.

Title: Re: backfiring at half throttle...
Post by Trippah on 06/17/08 at 04:51:22

With the jardine muff and the cone filter, the jetting in the carb may not be quite right; but the varnish-stale gas is the first and easiest thing to check. Also check the exhaust that there are no leaks. Welcome aboard..

Title: Re: backfiring at half throttle...
Post by rpgpgmr on 06/17/08 at 07:10:45

While I was fighting through my 2-month re-jetting experience I had a similar problem. I had put in a 155 main jet which was waaaay too much. I have eventually settled with a 55 pilot and a 150 main. Perhaps your main jet is too big? As I learned the hard way, bigger isn't always better when it comes to jets.

I also tried trimming the spacer 1/4 at a time, but I ended up completely removing it. I've read the warnings about that and I heeded them, but I had no choice and it runs great now.

Title: Re: backfiring at half throttle...
Post by Sandy Koocanusa on 06/17/08 at 07:20:29

My brain is like the old Texas Instruments 994A I learned on. If it isn't absolutely necessary, don't retain it or it'll overflow... So I've been reading and deleting all the stuff about white spacers, jetting, etc. that applies to the newer bikes. Now there's a new S-40 in the neighborhood that might require my attention on occasion. Guess I better go back and bone up on all that info. I still haven't figured out why 155 is too much for most of the new bikes, but o.k. on mine.

Oh, well. Maybe my brain will stretch to fit?

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/17/08 at 07:28:20

The guy also said he put a "stage 2 jet kit" on the bike. I'm not even sure what that means........ After reading the "Carb 101" post, it sounds like the main jet could be the problem though... Or perhaps the jet needle needs to be adjusted. I wish i knew more about carbs....

Title: Re: backfiring at half throttle...
Post by rpgpgmr on 06/17/08 at 07:36:12

A stage 2 jet kit is a 50 pilot (which is actually a step down for the newer bikes which come stock with a 52.5) and a 152.5 main jet. Like I said before, I finally settled with a 150 main and 55 pilot. There are MANY different setups on this site so you'll just have to experiment and see what works best for you.

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/17/08 at 11:10:02

if i have to order a new jet kit for the carb, can anyone tell me where the best place to get them/ what to get. I looked at some, but there were so many different kinds. Assuming i have the stock carb, what do i need?

Title: Re: backfiring at half throttle...
Post by rpgpgmr on 06/17/08 at 12:20:18

Absolutely. Send member Lancer a pm for his JET SET. It has everything in it that you could possibly need and for a great price too. He is our resident carb expert and has helped me on more than one occassion trying to help me fix what I screwed up. ha ha

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/17/08 at 12:25:33

Great thanks!!! I'll send him a PM right now

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/17/08 at 14:27:50

Well....
I got home... drained all the fuel out (It poured right out with the petcock open, so i'm assuming the petcock isn't all gunked up.) It still seems to do the same thing. If anything it may have gotten worse. It seems now at even 1/4 throttle it backfires and sputters. Maybe it is the jets, i don't know. Anyone got any other ideas?

Title: Re: backfiring at half throttle...
Post by verslagen1 on 06/17/08 at 17:00:17

New to you bike 8k on the clock, been sitting for a while. sputtering like crazy. did the bike ever run right for you?

sounds to me like you need to clean the carb, which is about the 1st thing I did to mine when I got it. And it was supposed to be used regulary.

second, any newly aquired bike is an unknown. There's one thing that needs to be looked at every 5 to 10k miles. The cam chain adjuster. If the guy only used 10-40 dino, there's a chance that it's ready. If it has fallen out, then it could be causing your simptoms. I don't think it's highly likely, but it is possible.

More likely, you need to clean the carb and reduce the size of the jet.

Title: Re: backfiring at half throttle...
Post by T Mack 1 on 06/19/08 at 10:40:23

Plug the spark plug and look at it. Carbon build up from a too rich carb can do what you described.

Trust me on this one..... my bike didn't like the 155 main ..... about 20 miles and I was limping home. Luckily I was only 1/2 block away from making it home when the limp became a snooze...

Title: Re: backfiring at half throttle...
Post by Jackhammer on 06/19/08 at 10:53:30

Thanks for the help guys.
I got it all figured out yesterday evening.
I cleaned the carb and removed the white spacer on the jet needle.
Its now like night and day, no backfire anywhere throught the rpm's up or down, and she pulls like crazy!! Such a fun bike :)
Thanks again for the help