soft spot between 6k-7.5k RPM

ASecretNinja · January 7th, 2010, 06:15 PM

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!

Snake · January 7th, 2010, 08:02 PM

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.

Alex · January 8th, 2010, 12:44 AM

/moved to tech...

Verus Cidere · January 9th, 2010, 01:00 AM

You're running lean. I'm having the same problem with my AP exhaust ATM. Shim the needles, bigger main jet, etc.

Snake · January 9th, 2010, 10:01 AM

Chad try this jetting database and add your own info when you are done.

oldbutnewbie · January 30th, 2010, 12:12 AM

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.

nate-bama · January 30th, 2010, 05:59 PM

you could stay in the power band, and presto no worries

Zim · January 30th, 2010, 08:58 PM

Quote:

Originally Posted by Snake

Chad try this jetting database and add your own info when you are done.

What database?

ASecretNinja · February 4th, 2010, 12:18 AM

Quote:

Originally Posted by nate-bama

you could stay in the power band, and presto no worries

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..

nate-bama · February 4th, 2010, 01:43 PM

Quote:

Originally Posted by ASecretNinja

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..

well at first you said kinda a soft spot..but you can't get past 8k? that would sound like a diaphram leak or a unseated intake boot

oldbutnewbie · February 4th, 2010, 06:40 PM

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.

nate-bama · February 4th, 2010, 06:54 PM

Quote:

Originally Posted by oldbutnewbie

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.

todd i live on lookout..wanna race?

oldbutnewbie · February 4th, 2010, 10:40 PM

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.

nate-bama · February 5th, 2010, 06:27 AM

yeah i was kiding about a race, usually goof off on the lookout mountain pkwy

Racer x · February 5th, 2010, 07:17 PM

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.

January 7th, 2010, 06:15 PM	#1
ASecretNinja ATGATT Squid Killer Name: Chad Location: So. Cal Join Date: May 2009 Motorcycle(s): '06 CBR600 Posts: 189	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!

January 8th, 2010, 12:44 AM	#3
Alex ninjette.org dude Name: 1 guess :-) Location: SF Bay Area Join Date: Jun 2008 Motorcycle(s): '13 Ninja 300 (white, the fastest color!), '13 R1200RT, '14 CRF250L, '12 TT-R125LE Posts: Too much. Blog Entries: 7	/moved to tech... __________________________________________________ Montgomery Street Motorcycle Club / cal24.com / crf250l.org / ninjette.org ninjette.org Terms of Service Shopping for motorcycle parts or equipment? Come here first. The friendliest Ninja 250R/300/400 forum on the internet! (especially Unregistered)

January 9th, 2010, 01:00 AM	#4
Verus Cidere ninjette.org certified postwhore Name: Michael Location: Southern NM Join Date: Feb 2009 Motorcycle(s): '91 Honda CBR600 F2 Posts: A lot.	You're running lean. I'm having the same problem with my AP exhaust ATM. Shim the needles, bigger main jet, etc. __________________________________________________ 1991 Honda CBR600 F2, White/Gray, D&D slip-on exhaust, tail integrator, gel grips, Custom undertail.

January 30th, 2010, 05:59 PM	#7
nate-bama North Alabama Mtn. ryder Name: Nate Location: Alabama Join Date: May 2009 Motorcycle(s): 2006 Posts: 537	you could stay in the power band, and presto no worries __________________________________________________ QTRltrPWR

February 5th, 2010, 06:27 AM	#14
nate-bama North Alabama Mtn. ryder Name: Nate Location: Alabama Join Date: May 2009 Motorcycle(s): 2006 Posts: 537	yeah i was kiding about a race, usually goof off on the lookout mountain pkwy __________________________________________________ QTRltrPWR

January 7th, 2010, 08:02 PM	#2
Snake ninjette.org certified postwhore Name: Rick Location: Alexandria, Louisiana Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much. MOTY - 2017, MOTM - Jan '19, Oct '16, May '14	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.

January 9th, 2010, 10:01 AM	#5
Snake ninjette.org certified postwhore Name: Rick Location: Alexandria, Louisiana Join Date: Jan 2009 Motorcycle(s): 05 Blue Ninja 250 Posts: Too much. MOTY - 2017, MOTM - Jan '19, Oct '16, May '14	Chad try this jetting database and add your own info when you are done.

January 30th, 2010, 12:12 AM	#6
oldbutnewbie ninjette.org newbie Name: todd Location: chattanooga Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3	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.

February 4th, 2010, 06:40 PM	#11
oldbutnewbie ninjette.org newbie Name: todd Location: chattanooga Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3	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.

February 4th, 2010, 10:40 PM	#13
oldbutnewbie ninjette.org newbie Name: todd Location: chattanooga Join Date: Oct 2009 Motorcycle(s): 2002 ex250f,1981 kz550ltd, 1999 vs800 Posts: 3	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.

February 5th, 2010, 07:17 PM	#15
Racer x ninjette.org certified postwhore Name: Eric Location: Iowa City Join Date: May 2009 Motorcycle(s): 2008 Kawmeracchi 350 2010 Project X Posts: A lot. Blog Entries: 54 MOTM - Sep '18, Feb '16	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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