SuzukiSavage.com - Engine stumbles at high revs/rpms

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Engine stumbles at high revs/rpms
07/23/10 at 11:43:43

I just got a 2007 S40 with less than 5k miles and it stumbles at high revs on all gears. For example when I am in 4th gear and rev it past 1/2 throttle it stumbles and won't accelerate or maintain speed until I let off the throttle. (does it in all gears) (By shifting up whenever it starts to stumble in the previous gear I can only get to 60-65mph)

Everything is still stock. I checked the to see if there was bad gas in the carb by letting some fuel drain from the carb bowl and the fuel was good. Does anybody know what could be causing this?

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« Last Edit: 07/24/10 at 19:36:45 by running-it-stock »

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weracerc Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 594 Greensboro, NC Gender:	Re: Engine stumbles at high revs/rpms Reply #1 - 07/23/10 at 11:56:31 i use a box end wrench 17mm or 14mm on the oil plug depending on the year - my 96 is a 17mm.....the carb guru's will have to answer the stumble issue.
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jsarsfield Junior Member Offline SuzukiSavage.com Rocks! Posts: 72	Re: Engine stumbles at high revs/rpms Reply #2 - 07/23/10 at 12:47:11 Could be something plugging your main jet either clean the carb or run some Seafoam through it.
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Phelonius Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 1897	Re: Engine stumbles at high revs/rpms Reply #3 - 07/23/10 at 15:27:49 Fer christs' sake it is a Savage! It ain't supposed to do high RPM. Phelonius
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verslagen1 YaBB Moderator ModSquad Online Where there's a will, I want to be in it. Posts: 28884 L.A. California Gender:	Re: Engine stumbles at high revs/rpms Reply #4 - 07/23/10 at 16:18:58 jsarsfield wrote on 07/23/10 at 12:47:11: Could be something plugging your main jet either clean the carb or run some Seafoam through it. +1 clean/seafoam the carb 1st check what size jet it is while you're in there.
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Routy Serious Thumper Offline SuzukiSavage.com Rocks! Posts: 2280 Winston Oregon Gender:	Re: Engine stumbles at high revs/rpms Reply #5 - 07/24/10 at 05:13:54 Did you try it w/ the valve to "prime" ?
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running-it-stock

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Re: Engine stumbles at high revs/rpms
Reply #6 - 07/24/10 at 20:29:16

verslagen1 wrote on 07/23/10 at 16:18:58:

jsarsfield wrote on 07/23/10 at 12:47:11:

Could be something plugging your main jet either clean the carb or run some Seafoam through it.

+1

clean/seafoam the carb 1st

check what size jet it is while you're in there.

While I am cleaning the carb should I install a jet kit from 6-sigmaracing or the KEYSTER CARB KIT. (found both on ebay)
http://cgi.ebay.com/ebaymotors/00-09-Suzuki-Savage-LS650-S40-Carburetor-Carb-...
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.m748&i...
Has anyone tried either of these? Will a jet kit eliminate backfiring/ increase hp, and will I also have to change the muffler, or can I rejet and stay with the stock muffler?

I don't have any seafoam, but I did try some Berryman.

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jsarsfield

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Re: Engine stumbles at high revs/rpms
Reply #7 - 07/24/10 at 21:38:52

Quote:

While I am cleaning the carb should I install a jet kit from 6-sigmaracing or the KEYSTER CARB KIT. (found both on ebay)
http://cgi.ebay.com/ebaymotors/00-09-Suzuki-Savage-LS650-S40-Carburetor-Carb-...
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&_trksid=p4340.m748&i...
Has anyone tried either of these? Will a jet kit eliminate backfiring/ increase hp, and will I also have to change the muffler, or can I rejet and stay with the stock muffler?

I don't have any seafoam, but I did try some Berryman.

I personally wouldn't but any jets from that seller give our very own Lancer a pm if your looking for jets but I still think your a bit premature on your list of things to do ..... Do you know if your running rich or lean?
First thing your should be doing is cleaning your carb the old fashioned way and taking a look at the jets that are already in it the number is stamped on the jets. Also buy some seafoam it is tried tested and the stuff can work but IMHO you should be taking the carb off the bike and give it a 'real' cleaning. Also check to see if your air filter is clean.

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LANCER Serious Thumper Alliance Member Offline Savage Beast Performance Parts Posts: 10661 Oklahoma Gender:	Re: Engine stumbles at high revs/rpms Reply #8 - 07/25/10 at 03:17:27 yep yep .... run the seafoam or the stuff you have if it does the same thing then check to see what main jet you have the symptoms are similar to a TOO LARGE main jet someone may have stuck a 155 in there or reamed out the stock jet and not knowing what the heck they were doing made it way to large
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Re: Engine stumbles at high revs/rpms
Reply #9 - 07/27/10 at 09:08:22

The screws holding the diaphragm on the carb stripped on me. I managed to get one of them out but the other 3 stripped.

I then used a dremel like tool to cut through one of the screws so that I could use a flat head screw driver, but it still wouldn't budge. I tried blow drying it with no success.

Have any of you had success with soaking the screws in wd-40, or heating them up with a solderer to make them come out?

Any other ideas on how to remove these screws?

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justin_o_guy2 Serious Thumper Offline What happened? Posts: 55279 East Texas, 1/2 dallas/la.	Re: Engine stumbles at high revs/rpms Reply #10 - 07/27/10 at 09:50:13 Get a hand held impact from Harbor Freight for 5 bux. JIS tips fit the screw heads right, a #2 phillips just doesnt fit as well.
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