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Did you have to rejet after installing 3" snorkle

  • Did Not have to rejet after installing 3" snorkle with no additional mods

    Votes: 10 34.5%
  • Had to jet down after installing 3" snorkle with no other mods

    Votes: 2 6.9%
  • Had to jet-up after installing 3" snorkle with no other mods

    Votes: 6 20.7%
  • Had to rejet after installing 3" snorkle, however additional mods were involved.

    Votes: 11 37.9%

Rejetting After 3" Snorkle Installation

9K views 56 replies 19 participants last post by  NMKawierider 
#1 · (Edited)
This thread is mostly for all the carbed Brute owners but all you guys with carbed machines are welcome to post here.

A while back we went to the 3" air box snorkel because most everyone had to jet-down when they installed the 2" due to the additional restrictions.

However, there have been a few that report they did have to make some jet change after installing the 3" after all. Some had reasons that include cutting out the air box port to make it larger, or additional bends that others didn't make , turning the 90 or 45 forward into the wind, some also added full pipes and CDIs along with engine mods. These are understandable.

However, a few folks did have to re-jet that made no other changes or mods after installing the 3" snorkel. This is what we are looking to understand better.

Lets do the poll and post-up your experience. Lets hear your entire snorkel story and include any extras you might have done....and the elevation where you live and how much you had to go...either way.
 
#2 ·
Interesting poll for me. I have to go to the 3" soon and this will help if I encounter problems. Right now I have glowing tail pipes and hopefully I can find someone with an exhaust gas tester before making the change and re-test afterwards. I'll be watching this one.

Should be linked to the 2 or 3" thread.
 
#3 ·
if your pipes are glowing your already to lean, moving up to a 3" will increase the airflow and thus lean the motor even more. your gonna have to move to larger jets., this will enriching the air fuel mix. and lower the temps. just keep cleaning and checking your plugs this is the best indicator of fuel mix.
 
#5 ·
and others here think different. I thought lean already but the Guru's say different so I'll have to experiment with snorkels.
 
#4 ·
My friend dis a 3" center and hmf exhaust and had to rejet. Was getting too much air. He should have pics up here of it. Hes southernbrute750
 
#6 ·
Did the 3" snorkle on my 05 brute and was getting entirly way to much air. Only other mods to affect this was my HMF untility exhaust. once it was all said and done i had to cover half or a little more than half of the intake in order for the bike to go anything higher than idle. my elevation is right at sea level or maybe 10 -20 being in southern louisiana.
 
#7 ·
Any body else have anything pertaining to this matter? im really interested as to what everyone had to do or didnt have to do when they did a 3" snork as NMK said.
 
#8 ·
I have the mimb set up and stock everything else . Did a stage 1 dynojet kit just like the instructions say and I'm happy for sure. Follow the directions exactly. I am in the northwest panhandle of florida and it said different settings for different levels. Don't just put in the jets though . U have to do the needles.
 
#10 ·
Maybe the key to this is what exactly people are doing to thier stock air-boxes. Meaning are they connecting the 2or3" directly to the factory opening or are they modifying the factory opening to fit the snork pipes. It would sure make sense that leaving the factory opening alone and connecting the 3" to it should cause zero problems with air/fuel ratio's. I can see where the 2" would cause some problems because it's smaller than the stock factory opening in the air-box.
 
#12 ·
I didn't mess with the stock opening. Just connected my 3" rubber 90 directly to the stock opening.

That is really strange as I said in your picture posting, should have made almost zero difference in jetting. Oh well You have it going so live and learn.
 
#13 ·
Yeah. That's the way I'm taking it Hahaha. I fi have to say I feel for my bike being carbed, throwing the 3 inch snorks on there and jetting made a pretty good difference in my throttle response.
 
#19 ·
Give me a couple til monday and I'll see. Been gone for a month and can't recall for sure. I changed the snorkels shortly before comiong to work and when I noticed the glow i didn't ride it much. If it backfires it is was, as I recall, always from the exhaust.
 
#16 ·
my stuff is all in for this ( thanks VOGIE ) and i will update after i install everything ...

great thread nwk !!
 
#17 ·
This is all good information on this 3" snorkel stuff. Thanks guys. I think this will help lots of people.

Like I said in another thread, looks like just adding the 3" is making some get more air. I wonder if making the air come around the stock deflector is harder for it then shooting straight in through a tube. Well, at least its not restricting it like the 2" was. Hay, anybody ever try a 2 1/2"?
 
#18 ·
This is all good information on this 3" snorkel stuff. Thanks guys. I think this will help lots of people.

Like I said in another thread, looks like just adding the 3" is making some get more air. I wonder if making the air come around the stock deflector is harder for it then shooting straight in through a tube. Well, at least its not restricting it like the 2" was. Hay, anybody ever try a 2 1/2"?
Yes there was a thread and when I asked the guy if he got the 2.5" at a pool supply business he never answered. Maybe it was on the other sites?
 
#21 ·
3" snorkle

OK guys,just throwing in my findings here. I am installing a 3" pvc intake. I purchased the drainage type pvc fittings in thinking that schedule 40 pvc pipe would fit into the drainage fittings - the sch.40 pipe and sch. 40 pvc fittings are larger than the 3" drainage pvc fittings.Also if you had bought a 3" rubber 90, the ends accept 3" pvc,but the inside of the rubber 90 is 2 1/2".As soon as I get some drainage pipe,I'll post back how she runs after the 3" center snorkle is installed.
 
#22 ·
if i do 3'' snorkels on my bike am i gonna have to re-jet again? i have full biggun dynatek cdi and 155f/160r and its running good. i really want to snorkel my bike but i really dont want to re-jet again.
 
#23 ·
As of right now its kindest hit or miss with the jetting. It seems as though us guys down here in the south closer to sea level have to re jet. Then people at higher elevations are having less issues with it. That's the only thing I can honestly think of. Only thing you can do is give it a shot. If you have your needles close with your cdi and exhaust, you may only have to do some very fine tunning.
 
#24 ·
actually i think i had the worst time jetting because of what i did and im at about 3000ft elevation. i had to put a 750 jet kit in but thats not a big deal. so basicaly its gonna be trial and error
 
#25 ·
I have the same jet setup 155/160 and 2" snorkles,my bike topped out at 80 Km/h . with your mods and 3" snorkle I think you will be fine
 
#26 ·
3" snorkles

If you want to test the 3" snorkle set up out,without installing the actual snorkles,just take a 3" rubber 90,install it on the stock intake without the 3" piping,and run the bike to see how she does with jetting.I'm at 158/160 main jets {kehin},and the bike pulls great.
 
#28 ·
If you want to test the 3" snorkle set up out,without installing the actual snorkles,just take a 3" rubber 90,install it on the stock intake without the 3" piping,and run the bike to see how she does with jetting.I'm at 158/160 main jets {kehin},and the bike pulls great.
Also have to take in consideration of the amount of bends off the 3" rubber 90*. The that alone will alone more "free flow" compared to running your snorkles up and out
 
#29 ·
Okay, thought I'd post my experiences, even though I'm running 2". So far I've found too many factors to consider, elevation is bigger than I thought. First the machine, I got it used, with a muzzy, the previous owner said he didn't need to rejet, once I got the machine home I could tell it wasn't running quite right, the smell and hesitation, and some backfiring. Now, I did the snorkels much the same as the MIMB, with one difference, instead of a 3" 90* rubber, I used a 3" to 2", and used 3 90's instead of a 90 and 45. Which, compared to MIMB, means I restrict the flow even more. After doing this, my bike runs a lot better, and now it's just a little bit fuel starved (if I cover half the intake snorkel, it takes off the start with less hesitation, but it's still there, I need to increase fuel maybe 1 size, I backfire a lot less, mostly when letting off the throttle quickly on a long, faster stretch).
All this said, I'm still running on stock jets, but I ride at 3000 feet, where most people are closer to sea level, or below 2000 I think. The air is much richer closer to sea level, until you start looking into humidity factors right at sea level. I am planning to take my machine in to rejet for a little more fuel, but that aside, as far as I can tell, too much air has been my problem even at higher altitudes where the air is thinner... It seems to me like using 3" here, or lower altitudes would pretty much force you into rejetting, simply too much air. Now I realize the original airbox has a 3 inch intake, but I wouldn't be able to wrap my head around going to 3" and then having to face it forward to force air in, unless the machine was already rejetted for other reasons prior.

Since I don't run 3", I won't vote on the poll, but I would say that you'd pretty much have to rejet going to 3" anywhere below.... probably around 5000 feet, give or take? If you want some real numbers to work with, google "air density versus altitude". From 0 to about 7000 feet, there is close to a third drop in air density, it's pretty significant.
 
#30 ·
3" snorkles

Completed the 3" center intake snorkle made from 3" thin wall drainage pvc. After running the bike I found that at about 1/4 to 1/2 throttle,I have a hesitation. Time to play with reshimming the needles. I have factory needles NFKK/NFKL with # 40 pilots at 2 3/4 turns out on A/F screws,and Kehing main jets at 158 f/160r. With just the 3" rubber 90 installed the bike ran perfect,after adding the additional pipe,the bike developed the 1/4 - 1/2 throttle hesitation. Back to the drawing board with checking for air problems.
 
#32 ·
3" snorkle

With the 3" center snorkle,I tried to reshimm the needles - first I had one shimm on each needle from the start. Then I tried two shimms - then tried three shimms. Did'nt go to well. I did try turning on the choke,and the idle went up in rpms,and the lean stumble cleared up.Should I try larger #42 pilots, larger mains,or trysomething else?
 
#33 ·
With the 3" center snorkle,I tried to reshimm the needles - first I had one shimm on each needle from the start. Then I tried two shimms - then tried three shimms. Did'nt go to well. I did try turning on the choke,and the idle went up in rpms,and the lean stumble cleared up.Should I try larger #42 pilots, larger mains,or trysomething else?
What do you have for pilots now? I once tried 42s but they were too much.
 
#34 ·
Just finished the 3" snorks and it runs good but it seems to be flooded when I first try to start it not sure if it's the new dynatek or what
 
#35 ·
3" snorks

NMK,I currently have # 40 pilots installed,so thats why I was thinking to go to # 42 pilots? nathen53,need more info on how your carbs are set up - what size pilots,wheres your A/F screws set at,main jet type and sizes,what needles are in,and what mods you have to engine,what size snorkles? nathen53 have you checked you chokes on each carb to insure they're not stuck on,and have you checked your valves and or plugs lately?
 
#36 ·
NMK,I currently have # 40 pilots installed,so thats why I was thinking to go to # 42 pilots? nathen53,need more info on how your carbs are set up - what size pilots,wheres your A/F screws set at,main jet type and sizes,what needles are in,and what mods you have to engine,what size snorkles? nathen53 have you checked you chokes on each carb to insure they're not stuck on,and have you checked your valves and or plugs lately?
I don know what I have in my carbs guy I bought it from said it had been jetted when he snorkeled it 2" but it didn't run good. I just changed it to 3" today and runs good just hard to start it not the valves or choke cable and all I have I a hmf slip on could it be the the carb vent lines I changed the size of the line to a smaller one to run it to the pod?
 
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