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General Category >> Rubber Side Down! >> Stumble at full throttle
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Message started by steely on 06/29/16 at 17:08:33

Title: Stumble at full throttle
Post by steely on 06/29/16 at 17:08:33

Okay guys, I know this has been beaten to death. However, I have been having a problem with this and I am at my wits end.

First off, 1999 Savage, 27K miles, cone filter, Jardine slash cut, carb rejetted 9K miles ago, white spacer mod, side stand switch bypassed, Raptor petcock, vacuum tap capped, cam chain replaced 6K miles ago.

After nearly 9K miles having no problems with the bike, it starts to stumble at the top 1/3 of the throttle. Acts like it is not getting any gas. I replaced the Raptor petcock (I couldn't remember if I bought the cheapie model or got the factory original), I got the genuine Suzuki part this time. I have been through the carb twice, full teardown, cleaning, and rebuild. Cleaned out all of the passages (wearing safety glasses, when you squirt cleaner into one passage it has an odd way of coming out right in your face from a passage you weren't aware of), dipped the carb body overnight. Cleaned the filter. Checked the header gasket, checked the header to head tightness, checked the muffler to header fit. Verified that the gas tank is clean with no trash in it. Replaced the plug. Nothing i can find wrong. darn thing still stumbles.

It ran great before this, this just started happening one day. I am going to go through the carb again, it has been sitting for about 6 months now. I had a grandson, he moved in with my wife and I, and we are currently remodeling our office/laundry room. I haven't had time to mess with it.

I have a couple of ideas, but I don't want to start replacing things willy-nilly. Could this be the coil or something electrical? My carb diaphragms have a small hole in each one, but it had these long before I began having this problem (PO issues). Would this cause an issue if they have gotten just big enough? Should I check my valve adjustment (I don't see how this would cause a problem only at WOT)? Any advice is appreciated. Like i said, I am at my wits end.

Title: Re: Stumble at full throttle
Post by justin_o_guy2 on 06/29/16 at 17:40:58

And the stumbling is not After any mods, ?
All the mods are at least a year old?
The spark plug sits in a crap gathering hole. Clean it out before you pull it.

Have you checked it?

I would wanna run it sans air cleaner to test.

That would be a good time to eyeball the slide to know it's opening right.

Title: Re: Stumble at full throttle
Post by steely on 06/29/16 at 18:11:44

No mods before the stumbling. The mods are at least 4 years old, the last mod i did was the new seat two years ago. The bike was stolen out of my back yard, the driveway runs from the street to my garage at the back of the lot. It was recovered by the police the next day, I was able to go pick it up from where they arrested the guy and ride ti home. He had done some unholy things to the ignition circuit that I had to undo. I decided to replace the seat, the crack head who stole it had a bit of the "local talent" on the passenger seat when he was pulled over and arrested. I decided to not even try to clean it, I just replaced it.

I did clean the plug hole out before I replaced it withe the new one, however, i have not tested the new one. I will give that a shot. A

I will give running it without an air cleaner a shot, wouldn't it be a pisser if that was the problem all of this time?

I will check the slide operation as well. Thanks justin_o!

27383E3924231222122A38347F4D0 wrote:

Title: Re: Stumble at full throttle
Post by justin_o_guy2 on 06/29/16 at 18:31:37

I totally understand. I let a friend have a key to my place once.
I burned the couch.

Virginia Crouch does Not have a virgin crotch.

Title: Re: Stumble at full throttle
Post by batman on 06/29/16 at 20:35:28

"My diaphragms have a small hole in each one."--------They usually don't get smaller over time,you need to find a gas&oil proof liquid glue,there are a couple of makers. At 3/4 to wot the vacuum in the carb is at it's lowest and the diaphragm is trying to pull the slide open ,with a hole it might not be able to.

Title: Re: Stumble at full throttle
Post by VortecCPI on 06/30/16 at 05:27:11

How about a tight valve? When is the last time you checked valve lash?

Title: Re: Stumble at full throttle
Post by Gary_in_NJ on 06/30/16 at 08:38:55

If you think you've ruled out carburation, then I would turn your attention to the ignition module. A misfire at high rpm is the signal they give before they give out.

Title: Re: Stumble at full throttle
Post by batman on 06/30/16 at 09:47:43

3/4 to wide open is in the realm of the main jet ,I'd look at it again and check the float level height setting,and the filter that sets under the float valve seat.Is the brass washer in place under the main jet ? If not ,the main jet wont be fully opening.

Title: Re: Stumble at full throttle
Post by steely on 09/27/16 at 15:28:22

Okay guys! Sorry that it took me so long to get back with an update on this... Life gets in the way.

I cleaned the Carb (again!) - no change.

I checked all of the electrics - nothing out of the ordinary.

I thoroughly cleaned the cone filter - A little better.

I checked valve lash - within tolerances.

I found the broken muffler mount and replaced it - Ding! Ding! Ding! We have a winner!

So, my Savage is back to her old self and running strong! Thank you all for all of your help! You guys are awesome, as always!