G oog le BadWeB | Login/out | Topics | Search | Custodians | Register | Edit Profile

Buell Forum » Knowledge Vault (tech, parts, apparel, & accessories topics) » Dyno Charts/Testing (Show us the POWER!) » Dyno Test Results - CV needles « Previous Next »

This page is to share some dyno results from testing 3 popular CV needles.

NOKK (original equipment in my '99 M2)
NOKV (I believe this needle is original equipment in later M2's, I will verify it)
N65C ('88 XLH 1200 Sportster needle, very popular replacement)

CV Needles Dyno Sheet

The results had a fair amount of variation, I did my best to pick a result for each needle that was representative of the average result.

All of these results were taken with the same main jet, and within a very short period of time between each other.

The test bike is a bone stock 1999 M2. Stock CV carb (some jetting tweaks is all), engine internals are all stock, stock muffler, stock ignition module, coil, plug wires, and 10R12 plugs. The carb slide hole has not been drilled and it's using the stock slide spring. The testing was performed without an air cleaner in place to save time.

Notice that the carb always goes lean when the throttle is first opened, then fattens up as the rpm's come up, eventually ending up too fat, then it comes back a bit.

Changing the main jet (which I did a bunch of) basically moves the whole line up or down without really changing it's shape.

My general impression is that the needles aren't terribly far apart. However, the NOKK line is enough flatter than the others that it's probably the needle I would reccommend. I particularly like how it richens up faster than the others. Carlos, you were right!

Aaron Wilson
NRHS

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

Carlost
Posted on Tuesday, February 12, 2002 - 05:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Wow! This totally makes up for my Buell race ignition module snafu from a while back. :D
Top of pagePrevious messageNext messageBottom of page Link to this message

Aaron
Posted on Tuesday, February 12, 2002 - 05:51 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Hey, when I'm so arrogant that I think I can't learn something, slap me upside the head, okay?

Thanks for (once again) making me curious enough about something to go looking for the answer.
Top of pagePrevious messageNext messageBottom of page Link to this message

Sem1
Posted on Tuesday, February 12, 2002 - 10:40 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Aaron: Thank you very much for the excellent information. I guess the next time I have the carb off the bike I will put the NOKK back in.

Say, if you ever find yourself wondering what next to throw on that wonderful dyno of yours, it would be really interesting to see how the different needles compare when (optimally) shimmed. :-)

Cheers,
Semi
Top of pagePrevious messageNext messageBottom of page Link to this message

Oz666
Posted on Thursday, April 25, 2002 - 04:05 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

If one was testing the effect(s) of the needle, which primarily governs midrange metering, wouldn't one want to do pulls with a mechanism which would provide positive throttle plate stops at 30, 45 & 60 degrees opening? The pulls above really only show WOT where, as soon as there is sufficient airflow (very quickly), the slide rises to the top and the metering would not be much different than using a "needle" with a constant diameter the same as the narrowest point of the needles being tested. (I have not watched the slide on a Buell being dynoed, but other bikes I have seen/watched w/o the air cleaner pull up the slides almost instantly.)
Top of pagePrevious messageNext messageBottom of page Link to this message

Aaron
Posted on Thursday, April 25, 2002 - 06:31 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Watch a CV slide on a Buell sometime. While under load, doing a dyno pull, with the throttle wide open. It comes up slowly.
Top of pagePrevious messageNext messageBottom of page Link to this message

Chrism
Posted on Friday, April 26, 2002 - 05:59 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Aaron, at what point though is the needle all the way up? Working on my '72 Datsun 240 z, the needles were all the up by 4 grand on a 6800 redline. Also, wouldn't the needles have a more specific effect on A/F in constant cruise at say 38 to 4 grand?
Chris
Top of pagePrevious messageNext messageBottom of page Link to this message

Aaron
Posted on Friday, April 26, 2002 - 09:05 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

Chris: The idea here was to look at the shape of the a/f curve generated by each needle. I did not attempt to estimate needle position at any particular rpm, the a/f curve tells the story.
Top of pagePrevious messageNext messageBottom of page Link to this message

Oz666
Posted on Friday, April 26, 2002 - 09:10 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

OK, thanks Aaron, as I said I had not had the chance to observe personally. It also tells me several things:
1.) the stock carb is large enough (or close - esp. looking at your carb change dyno numbers [thank you]) to feed the motor in standard trim.
2.) playing with the size of the slide hole may be helpful, if done carefully.
3.) the needle taper affects metering over a wider range of throttle opening/RPM than I had assumed.
4.) change main jet first.
5.) change main jet first.
6.) change main jet first.
7.) ALWAYS ask, never assume.
Top of pagePrevious messageNext messageBottom of page Link to this message

Used_96_s1
Posted on Tuesday, July 29, 2003 - 03:42 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

According to the folks at Dynojet, their kit replaces the main jet tube due to the fact that the stock tube causes some incongruencies(sp)in the air/fuel ratio world, specifically, the problem of having to run a larger main jet for acceleration that leaves you rich at the top end.

This I do know; when I installed my Thunderslide kit, I went from the Keihen 195 main to a Dynojet 170 main and I'm not 'popping' under full throttle. I do however need to raise the needle a little because I'm 'popping' just a bit at 3/8ths (cruise)throttle.
Top of pagePrevious messageNext messageBottom of page Link to this message

Moody_blue
Posted on Sunday, March 20, 2005 - 07:48 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only) Ban Poster IP (Custodian/Admin only)

After reading the above post's still ask,
For my 2002 M2 I have:
Hypercharger, Staintune exhaust, calibration kit for stock carb.
Carried out carb changes as per instructions but is there a recommended list for set-up from more knowledgeable members, ie 195 main (was not happy with the 180 main), 2.5 idle etc etc when used with various combinations? Also at sea level (Melbourne Australia).
Any help much appreciated
Jeff
« Previous Next »

Add Your Message Here
Post:
Bold text Italics Underline Create a hyperlink Insert a clipart image

Username: Posting Information:
This is a private posting area. Only registered users and custodians may post messages here.
Password:
Options: Post as "Anonymous" (Valid reason required. Abusers will be exposed. If unsure, ask.)
Enable HTML code in message
Automatically activate URLs in message
Action:

Topics | Last Day | Tree View | Search | User List | Help/Instructions | Rules | Program Credits Administration