OMR, took my quad on a 28 mile ride today. It ran great after all the hassle. Thanks for the advice.

 

01DS650,

You are very welcome. Patience is not easy when your machine seems to have let you down.
I have to pay off some doctor bills from two surgeries and than I will get back to finishing my jetkit. I will let you know when it ready.

Have a great fall atving,

OMR

 

Ok, guys, I did some testing, and I run into something I did not expect.

I started with a stock DS on my dyno, and tested different end caps, and the carb mods to see how much the dyno claims it increases power.

After trying different diameter end caps, I finally settled on one that gives the most peak HP. In fact the stock end peace produced good HP, but low and midrange RPM was very poor. The end cap increased the low and mid RPM power output, but I had to use an end cap with a massive size hole to get the same peak power as the stock pipe.

Then, I started with the carb mods and this is where I run into a "problem".

I for one, I believe in airflow above all else. When a motor breathes freely, power comes automatically.

So, after testing a bunch of DS's they all come out producing more HP WITHOUT the airbox lid. I tried all kinds of different size intake tubes to the airbox, and without fail, when I remove the airbox lid, the power increases. All the DS's I tested had slip-on exhaust systems, and they all used a 190 to 195 main DJ jet. Most of the slip-on pipes I have tested used a 50 to 54mm (speaking under correction) diameter inner tube in the silencers, and they produced good power. All of them come in within 1HP of each other.

The end cap is something new to me, and the cap producing the most HP is much larger than the pipes used on the normal slip-on systems.

Anyway, I ended up removing the airbox lid. The bike is still running the stock intake tubes to the airbox.

This is where I got a big surprise. The bike is already up to a size 200 main jet, and it can handle an even larger main jet. I think I need to go up to a size 210 to get the air fuel mix around the 13:1 A/F ratio. With a size 200 jet, from 4000 RPM onwards the bike is running at an A/F ratio of 14:1, so the motor can make more power if you add more fuel.

I am at 5000ft above sea level, so this is a bit of a shocker to me.

Will the stock carb flow enough fuel for the 210 main jet. I damn well hope so.

I don't like closing up some holes to limit the air intake, to match the jetting. To me, when a motor says it can handle more fuel, I give it more fuel. It's that simple. I like to think about it this way. Closing a air intake hole, to me feels like I am patching the problem with a band aid, instead of fixing the carb to give the right amount of fuel. If you can fix the problem, you will gain even more power than the band aid trick.

Once I am done, I will try the smaller end caps again, to make sure the end cap I picked is the right one, before and after the carb mods.

Now here is the thing. I am actually thinking of redesigning the end cap. The normal end cap is just a peace of billet, without any perforated tube attached to it. If you look at the stock silencer, you will notice that it has a massive purf pipe, to make space for the stock baffle and that whole contraption. I am starting to think that just adding a end cap to that lot, is still creating flow problems. Even with a massive hole in the end cap, it still creates a massive amount of back pressure behind the cap, indicating to me, that there is a problem. The exhaust gasses expand once they reach that opening before the end cap, and it creates turbulence, slowing the exhaust flow down in a big way. I am sure that installing a new perf, running the full length of the pipe, keeping the exhaust gasses compacted will create better exhaust flow, instead of just the cap. To do this, you will need to install a new perf and repack the exhaust, before running the bike. I speak under correction, but none of the end caps I know of requires a new perf or a repack of the silencer. You might just be missing out on some more power, so watch this space.

Once I am done, I will post the dyno results and my findings.

 

Freez,

Now you see why I have modified the emulsion tube.
The stock tube just can't get enough fuel to the motor as horsepower goes up.

I look forward to your dyno runs.

OMR

 

Freez,
Good stuff & thanks for the hard work.

 

what the heck is the emulsion tube?

 

It is the tube that you screw your main jet into.
The emulsion tube brings air down to the top of main jet and emulsifies the fuel so that it can start the atomization process and be easily drawn up and into the throttle body.

OMR

 

thanks omr. i did your mods and i love them. i did not disconnect the balance tube since i have yet to find a filter for it but everything else seems real good. i have a hmf, uni filter, ported intake, and 11-5-1 piston and when i tore the carb apart i found it was totally stock for jetting. i was getting beat by stock raptors. i have since went to a 172.5 main and a 45 pilot with the pilot screw 3.5-4 turns out. the spring was original from 2k so i shortened that as well. holes were drilled in the slide like you described. i have a newer procomm cdi and i keep the idle high to prevent kickbacks. seems to run good with a little inconsistency at idle but i do have a dirty filter right now that may be the culprit, i plan on cleaning it here in a day or two. is there anything else that you reccomend? freez had interesting finds with the lid off but i ride in mud, mud, and more mud and i am not comfortable without the lid. oh..... is there a mod for the emulsion tube?

 

K what i understand about the no lid is that the slide cant open fully for some reason...and that the airbox created bad turbulence without the lid? is that correct...if so what about running the filter directly on the tube to the carb without any airbox at all...that would make it so there is 0 crazy airflow going into the airbox but its all going into the filter??? somone should dyno test this. I still dont see why the slide cant open fully without the lid on...because it doesnt run on vacume if you blow into that tube the slide goes up INSTANTLY...so the more air you are getting into the carb the more air goes passed and into the slide tube causing it to open faster??? My airbox and carb is all apart and i do not no what to do...or what i want to do...but the no airbox at all sounds like it might work good to me.

 

most people that rin the filter right off the carb run a bigger carb like a tm45 etc. these biggger carbs do not operate on a vacuum like the stock carb if i am not mistaken.