Carburetor Jet Tuning - Updates on 1st Post

[Greg Cothern]

Terry on my sons bike it has the DD jets and shims with K&N and muffler mod.  Pilot jets are 2 7/8 out if memory serves me.

[TLRam1]

I was going to post this under the Vacuum thread than decided it is better to start a new thread.

What I am reading under the "VACUUM LEAK" THREAD is a bike with a K&N and pipes benefits from a 3rd shim, is that correct? If that is the case it should help on all 3rd generation bikes with the same set-up, correct?

What has been anyones experience?

Has anyone upped the pilot jet? Pilot jets are too small with the 3+ turns out, how much difference that will make, I don't know.   

Are there starter jets in these carburetors or what acts as the accelerator pump?

Tried different needle jets?

Anyone taken the main jet higher than a 105, what's your take?

I have not researched any of the above and somewhat asking these questions premature as I am not ready to take the plunge and dedicate the time yet but this info will help form some opinions.

In the future I had planned to buy various sizes of jets and spend a few days tuning mine in but this might give insight as to what will work or what has been tried.

I will change the above as "I would like to in the future".  Time and needs are always the issue.

Any input you have will help us all out, so speak your minds, opinions and experiences.


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This is where we are at currently.

From my readings and input from Magna owners, a stock Magna would benefit from the DD Kit. For sure you need to add a Shim and turn Pilot screws out to 2 3/4 turns.

Pilot Jets (#40) for a stock Magna work well, once you do a couple of modifications a change to #42 Pilot Jets would be of benefit. Personal choice, depends on how much you want to spend and how finicky you are.

Greg's beliefs are, Cobra exhaust does not flow as much air as V & H's and my findings are parallel with this. This is subject to change with more Cobra exhaust testing.

I believe most of these are around 500 ft above sea level. High altitude you will have to be on the leaner side.

So far it is coming down to this.
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Stock Filter

Stock Exhaust

Shims – 1 (additional)

Pilots screws 2 ¾ Turns out.


I have read in several places this statement, I have nothing to back this up but thought I should include the info----- The DD jet+shim kit is designed for a bone stock Magna including the exhaust. In fact, it is the factory stock setup for Non-USA Magnas.

Option,
               #105 Mains

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Lance – (L J BAD MAG)

K & N air filter

Exhaust Mod

Shims – 1 additional

Mains - 105

Pilots screws 2 ¾ Turns out

Option,
              #42 Pilot Jets
              #108 Mains

Lance - Right now it runs extremely good, no flat spots in the rpm range at all.  I think the 108 jets will make it pull harder on the top end though.. MPG 48.


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Greg (Greg Cothern)

K & N air filter

Exhaust Mod.

Shims – 1 additional

Pilots screws 2 ¾ Turns out

Option,
              #42 Pilot Jets
              #105 Mains

Greg - My son's bike is setup like this and it is almost perfect.

I have read in several places this statement, I have nothing to back this up but thought I should include the info----- The DD jet+shim kit is designed for a bone stock Magna including the exhaust. In fact, it is the factory stock setup for Non-USA Magnas.


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Greg (Greg Cothern)

Project 96

Stock air filter

SuperTrapps

Dyna Jet Kit - clip in 3rd position (from top or bottom)????

Shims ??

Pilots screws ?? Turns out

Options,  ???


The SuperTrapps have all the provided discs (I will have to count again I think it is 9 discs per side but maybe only 7) installed.

Greg - This setup so far seems good down low and midrange.  I have not had enough ride time to make a complete informed decision though.


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Lawrence (lragan)

K & N air filter

Cobra Exhaust

DD kit which includes

Shims – 1 (additional)

Mains - #105

Pilot screws 3 Turns out

Lawrence - Starting improved, solved the mid-range issue.  Popping on deceleration disappeared mileage dropped from 50 to 45 MPG.

Option,

Additional shim may be of benefit but untested.

Not tested, IMO, I think you could comfortably change the Mains to #108.

Probably should change to the #42 Pilot Jets


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Allen (roboto65)

K & N air filter

Jardine Megaphones exhaust

Shims - 1 (additional)

110 - Mains

45 - Pilots

Pilot screws - 2 3/4 turns out


With what I have done it is ALOT better almost pulls the front end up and it goes all the way to REDLINE, does it need more tweaking, yeah probably, but it is close for sure !!!!!!

Note: possible go to 42 pilot jets and lean the idle jets a 1/4 turn more.

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Matt (Magnatic)

K & N

V & H exhaust

Shims - 2 (additional)

Pilot - #42

Mains - #110

Pilot Screw - 2 3/4 turns out

Option,
           #45 Pilots
           #112 Mains

Bike runs strong with seamless powerband up to redline. Issue is some popping on decel so I will go out another 1/4 to 1/2 turn on the Pilot screw. May try112 Mains & 45 Pilots.

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Chad (chadschloss78)

K & N air filter

V & H exhaust

Shims – 2 (additional)

Mains – #110 or #112

Pilots - #45

Pilot screws 2 ¾ turns out

Chad - Torquey, super punchy midrange and unstoppable top end.

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JETS:

112 Main:
PN: 99101-GHB-1120

110 Main:
PN: 99101-GHB-1110

108 Main
PN: 99101-GHB-1080

45 Slow Jet:
PN: 99103-MT2-0450

42 Slow Jet:
PN: 99103-MT2-0420

This list will probably need to be tweaked as people test and try these settings but should be better than before.   

These settings are in MOOT Member bikes and actually working so they do have history behind them but might need tweaking as we become more experienced with various setups.

[TLRam1]

The purpose of this post is to give as accurate information as we can to people reading and spend less time dialing in he carbs.  If there are any issues, let me know.

Greg (and anyone else) check this out, see if this is more inline with what you were saying?

I updated,

A. Left and changed some of the Options.

B. Put in the statement I have read for informational purposes

C. Included names, their statements and links to the names if one has a specific question for them.

D. Pulled the Mains on the first 2 posts but added as an Option along with a footnote.


As you guys tweak further and the results are favorable, lets make the changes. 

 

[Greg Cothern]

Terry I will be tossing in another setup to the mix soon as I get some more testing done.

On my Project 96 I have SuperTrapps, Dyna-jet kit, and stock air filter.  The SuperTrapps have all the provided discs (I will have to count again I think it is 9 discs per side but maybe only 7) installed.  The Dyna-jet kit has the clip in the 3rd position. 

This setup so far seems good down low and midrange.  I have not had enough ride time to make a complete informed decision though.

[L J VFR]

Terry, some updates to my bike.  I now have the 105 main jets in, in place of stock 102's.  I have also richened up my pilot circuitry to 3 turns out.  I have since done the muffler mod, where I cut off the resonators. I put the end plates back on.  I have the 108 jets I purchased from chad, however, I am going to run this set-up for a while to get a feel for how it runs. Right now it runs extremely good, no flat spots in the rpm range at all.  I think the 108 jets will make it pull harder on the top end though..  My mpg has dropped from 45-49mpg to 42-45 mpg. I contribute this to bigger mains and richer pilot circuitry.  I could also be just driving it harder because it runs better!

[TLRam1]

Updates done.

Greg you have a few question marks on your Supertrapp setup.

Lance when you change your setup and see improvement, get back with us.

Some of the Options are Untested. If anyone test them with negative or positive results, changes can be noted.

Allen and Chad what jets are you not using-want to get rid of?

Anyone one who might have jets, post what you have and maybe a few guys will purchase your leftovers.

[roboto65]

I have a set of 105s and 40 pilots will be getting the 42s unless someone wants to trade LOL

[Greg Cothern]

Lance, I personally dont think your bike will improve with the 108 jets.  I feel it will be too rich.

K&N, muffler mod, and DRP 105 jets with 1 extra shim and 2 7/8 turns out is working GREAT on my sons 96. 

Cant remember if you installed a K&N, if you didnt, I would suggest that on your current setup. 

I ran the 96 with muffler mod, 105s, and 1 shim on stock air filter and it was rich, MPH dropped.  It ran smooth but was rich.  When I added the K&N it picked MPH back up and continued to run smooth through the rpm ranges.  Plugs confirm its very close on mixture.

Again just what has worked best for me and the several I have tweaked as well as confirmed with the many talks I have had with Dave Dodge on his dyno results when he put together his shim jet kit.  The K&N wasnt out at that time, and this does leans things a bit, so with aftermarket exhaust one might think about a 108, but I do not think the stock exhaust even with modifications will flow enough. 

To rich of a setup and you will induce greater carbon deposits in the engine...  I see this very issue all the time on my RC airplane engines...

[L J VFR]

Greg, I do have an K/N filter on.  It is running pretty good right now. My mpg has dropped some though.

[TLRam1]

Let me know if you need them, or if anyone else may need them. i also have the 107.5 jets i ordered but never installed, 110 jets, 42 pilot jets and the stock 40 pilot jets and stock 102 main jets.

Chad had these available from an earlier post.

[roboto65]

I know we already know this but with my heavy hand going to and from work I would hit reserve at 94 to 95 miles not good LOL. Anyhow I was coming from work this morning and did 65 the whole way and GUESS what. it was 110 miles before I hit reserve.    "What we have here is a failure to let off the throttle"

[Greg Cothern]

You also have there LARGE main jets SUCKING your fuel tank AND wallet dry quicker!

[doc.jet67]

I have a 99 Magna with somewhat of a muffler mod.  The previous owner drilled three (3), 3/8 inch holes in each of the muffler back plates but the resonators are still attached.  I currently have carbs off and have installed two (2) additional shims to the stock needle set up and will be putting in a K&N filter when it goes back together.  I live and ride in the Ozark mountains of Arkansas which is about 1400 feet above sea level.  Today I ordered a set of 110 main jets from my local Honda dealer but am having second thoughts about installing them and am wondering if I should try to find a set of 105 mains instead.  I've also considered leaving the 102 mains and having the holes in the end caps welded up but am still not sure if the 102 are big enough even with the mufflers put back to stock. I'm also not real sure how the difference in my altitude differs from the way you are setting up in Texas.

[TLRam1]

Doc, we are about 500-600 ft. above in Dallas.

The 110 mains will be too rich, the 105's I would think would be fine. Much of this is subjective depending on your setup. Some run 2 extra shims and they are okay, others run 1 extra and they are ok. Shims are easy enough to play with and can be added or removed w/o carb removal. 

Whatever you decide, ride it a bit to get a good feel than report back and let us know what worked for you.

[doc.jet67]

Do you think the 102's would still be to lean even if I get the mufflers welded back up?  Also, help me make sure I'm thinking right here, if I'm another thousand feet higher in altitude than you are, my air is a bit thinner and I would need to set up just a tad leaner than you would in Dallas.  Is that correct or am I thinking backwards?