January 7th, 2010, 06:15 PM | #1 |
ATGATT Squid Killer
Name: Chad
Location: So. Cal
Join Date: May 2009 Motorcycle(s): '06 CBR600 Posts: 189
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soft spot between 6k-7.5k RPM
Man what a difference temperature makes on our small displacement carb'd engines. I've noticed a bit of a soft spot right around 7k RPM. When I say soft spot, it's the same feeling that the bike makes when its starting to run out of gas. I know it's a jetting issue, but I don't know what it could be. Could shimming the needles take care of the problem? Obviously if I am hard on the throttle accelerating this is not an issue, but I really notice it when I'm semi cruising. It's not a big deal at all, and I bet a lot of riders wouldn't even notice it. I'm really just looking for an excuse to play with my bike lol. Thanks for any help.
Edit: why the hell did I post this in farkles? Sorry! |
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January 7th, 2010, 08:02 PM | #2 |
ninjette.org certified postwhore
Name: Rick
Location: Alexandria, Louisiana
Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much.
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Shimming the needles will help out quite a bit. Cold air is denser and will lean out the air/fuel mixture. Something else you should look at is your filter to make sure it is not clogged and you are getting plenty of air.
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January 8th, 2010, 12:44 AM | #3 |
ninjette.org dude
Name: 1 guess :-)
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/moved to tech...
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January 9th, 2010, 01:00 AM | #4 |
ninjette.org certified postwhore
Name: Michael
Location: Southern NM
Join Date: Feb 2009 Motorcycle(s): '91 Honda CBR600 F2 Posts: A lot.
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You're running lean. I'm having the same problem with my AP exhaust ATM. Shim the needles, bigger main jet, etc.
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January 9th, 2010, 10:01 AM | #5 |
ninjette.org certified postwhore
Name: Rick
Location: Alexandria, Louisiana
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Chad try this jetting database and add your own info when you are done.
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January 30th, 2010, 12:12 AM | #6 |
ninjette.org newbie
Name: todd
Location: chattanooga
Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3
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I had this very same problem 2002 model.I had already pulled the welch plugs and adjusted the idle screws out [factory setting was all the way in on side and 1 1/2-2 on the other].They are now out 3 1/2-4 rounds...this got the engine to run better.Installed a 4mm washer under the needles.Ran great with accelleration=had the 6500-7500 rpm cruising leanout shudders.Installed a 2nd 4mm washer under the needles=fixed it.
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January 30th, 2010, 05:59 PM | #7 |
North Alabama Mtn. ryder
Name: Nate
Location: Alabama
Join Date: May 2009 Motorcycle(s): 2006 Posts: 537
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you could stay in the power band, and presto no worries
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January 30th, 2010, 08:58 PM | #8 |
ninjette.org member
Name: Zim
Location: Bay Area
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February 4th, 2010, 12:18 AM | #9 |
ATGATT Squid Killer
Name: Chad
Location: So. Cal
Join Date: May 2009 Motorcycle(s): '06 CBR600 Posts: 189
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If the bike wasn't slumping at the RPM range I indicated then I would be in the power band, now wouldn't I? At any rate, I'm more interested in fuel economy and not taxing my engine too hard. Looking to sell this thing in the Spring.
I've got the washers, just haven't had time to try this out. Maybe tomorrow! And why is everyone saying 4mm? I thought the DIY said 3mm?! I bought 3mm.. |
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February 4th, 2010, 01:43 PM | #10 | |
North Alabama Mtn. ryder
Name: Nate
Location: Alabama
Join Date: May 2009 Motorcycle(s): 2006 Posts: 537
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Quote:
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QTRltrPWR |
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February 4th, 2010, 06:40 PM | #11 |
ninjette.org newbie
Name: todd
Location: chattanooga
Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3
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4mm is what I used;just for the thickness and trial/error of the situation=sometimes you win! My pipes are factory and the air filter is factory...the bike was so lean I really don't see how it was running.As I had posted earlier,the soft spot was 6500-7500 on my engine...anything above or below was fine...8000 cleared up and it pulled from there.As of now,I took it on a test run up Lookout Mtn. and on some town cruising.The soft spot is not there...just a few thoughts,hope it helps.
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February 4th, 2010, 06:54 PM | #12 | |
North Alabama Mtn. ryder
Name: Nate
Location: Alabama
Join Date: May 2009 Motorcycle(s): 2006 Posts: 537
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Quote:
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QTRltrPWR |
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February 4th, 2010, 10:40 PM | #13 |
ninjette.org newbie
Name: todd
Location: chattanooga
Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3
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well...don't know about a race,but definitely meet up for a ride as soon as this weather gives a favorable break.I'm in Chattanooga.
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February 5th, 2010, 06:27 AM | #14 |
North Alabama Mtn. ryder
Name: Nate
Location: Alabama
Join Date: May 2009 Motorcycle(s): 2006 Posts: 537
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yeah i was kiding about a race, usually goof off on the lookout mountain pkwy
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February 5th, 2010, 07:17 PM | #15 |
ninjette.org certified postwhore
Name: Eric
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I noticed that dip in power from about 7-9 K. Using the programmable Brt-tis ignition I was able to add timing in that area . From about 7-8500 RPM I added 1-2 more degrees of ignition advance . The Dip still shows up on the Dyno .But I could not feel it at all on the street.
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