Re-jetting AGAIN and air filter test

Boloiii · July 25th, 2007, 05:55 PM

I did a couple more mods that require me to re-jet again. Also I did a comparison test of high flow air filters. Here is what I did with the results they had. Soom of you may recall that I have A/F monitors on each cylinder, these do not give me a direct reading but do give me an indication.

1st. I changed from a K&N filter to a Twin Air powerflow kit with the full dome filter. Result was I went from a rich condition to a slightly less rich condition, but still quite safe.

2nd. I changed from a HMF Eco slip-on to a full Muzzy exhaust. Result was my front cylinder leaned out to the point that I had a slight concern of too lean and my rear leaned out just slightly.

3rd. I installed an EHS filter on my airbox. This has dropped me so lean that the bike will barely run with choke fully on. Problem is I do not think I have large enough jets to compensate so I will have to order them.

Now the test of filters. The reason I went to the Twin Air vs. the K&N is because I was seeing a build up of dust inside the carb inlets and a while back someone here threw out a challenge to compare the Twin Air to K&N. I have this kit at work for testing filter conditions in large dust collectors. It consists of a powdered dye and a black light and you put the dye into the inlet of the collector and use the light to look inside the filters and around the outlet side of it to identify any leaks.
I had the Twin Air filter in the machine already so I started with it. I started the motor and ran it about 1/4 throttle and sprinkled some of the dye into the airbox inlet and let it run for about 5 minutes. I removed the filter and fired up the black light. The outside of the filter glowed like an LED, but the inside there was nothing and in the carb inlets nothing.
I then installed the K&N and ran the same test as with the Twin Air. When I took the filter off and put the light to it, it glowed a little on the inside of the filter. What shocked me was when I shined the light on the carb inlets. It looked light someone put LEDs in my carbs.

My conclusions are this:
1.The Twin Air flows much better than the K&N.
2. The Muzzy flows much better than the HMF. I expected a gain on the fron as I was using a stock front pipe with the HMF. The Muzzy sounds awsome too.
3. The EHS cover mod is just incredible for power gains and will complement my 840 kit beautifully.

Test, Finally put my suspitions to rest. The K&N is just not a fine enough filter for the type of riding I do in the dusty condition.
Regretably, I was not able to get any of the dye to show up on my camera so I can not show the results.

JLUKE · July 25th, 2007, 06:58 PM

Awesome post and test!!! I am in the market for a new filter and wasn't sure of which one to go with. I think you have answered my questions. You said something about a dome TwinAir? Does the filter make up the whole dome like a dirt bike filter? Where can I find it? This is what I am looking for but haven't had any luck finding it.

Boloiii · July 26th, 2007, 01:24 AM

Any dealer that handles Parts Unlimited or you can go directly to Twin Air's website and order it. Also BVC Racing a site sponsor should be able to get them for you.

There are 2 different filter options. A stock style replacement that fits over your stock cage or the Power flow kit that replaces your stock cage with a metal one and opens the top up for flow as well. Watch for sticker shock on the kit, it is going to run around $220 and that includes 1 filter and replacement filters are around $30. The stock filter style is around $20 if I remember correctly. IMO the power flow kit is worth the money if you have a good exhaust or plan to soon.

RainyCreekRider · July 30th, 2007, 07:56 PM

Great post, I have to agree with the K+N lettin some dust by. I've seen it in my bike...come to think of it. I'll be shopping for a filter when I get out of the bush. Learn something here everyday.

Jason McGlawn · August 16th, 2007, 10:04 PM

I am just glad someone has found a way to prove the point that I have been trying to make for the past two years makes me feel better too because now I know that I am not the only devoted person out there. Great post and keep up the superb work.

Boloiii · August 17th, 2007, 02:41 PM

It was and continues to be a painful process. I have torn 3 carb mounts though the process. I am at 180-185 jets and still not large enough so ordering more. I found that Factory Pro makes jets larger than the normal 200 for the Keihin and have inquired with BVC about getting a large assortment of jets.

One note on the EHS cover, it is very loud as you hear all the noise of the airbox and carbs. I am working on a cover to install over the filter that should direct the noise away from my face but still allow the air in.

I need a dyno, this running to the local riding hole is getting old, not to mention I run out of room fast when doing topend runs.

I think I am going to have to invest in a A/F monitor so I can record the runs and then look at the results better.

Now, I am dead in the water as I have found that I have a warped front head and it is leaking compression into the crankcase. 30 psi front 165 psi rear. I have new valves ordered and am having the heads shaved. Doing the valves right away since they had some wear and I have them stripped down and in the machine shop anyway.

Another thing I have found is, the dynojet kit is useless. It is way to rich through the mid range then leans out in the high end. I am going to be playing with the springs to maintain the response of the kit but the needles are just way to thin and short. I have been having more predictable and consistant results using stock needles. I can always order different needles with either more taper or thinner diameter if needed.

mattloxfl · August 28th, 2007, 08:54 PM

Stupid question. What is the EHS cover mod?

mattloxfl · August 28th, 2007, 09:03 PM

STOGI · August 31st, 2007, 10:29 PM

Quote:

It was and continues to be a painful process. I have torn 3 carb mounts though the process. I am at 180-185 jets and still not large enough so ordering more. I found that Factory Pro makes jets larger than the normal 200 for the Keihin and have inquired with BVC about getting a large assortment of jets.

One note on the EHS cover, it is very loud as you hear all the noise of the airbox and carbs. I am working on a cover to install over the filter that should direct the noise away from my face but still allow the air in.

I need a dyno, this running to the local riding hole is getting old, not to mention I run out of room fast when doing topend runs.

I think I am going to have to invest in a A/F monitor so I can record the runs and then look at the results better.

Now, I am dead in the water as I have found that I have a warped front head and it is leaking compression into the crankcase. 30 psi front 165 psi rear. I have new valves ordered and am having the heads shaved. Doing the valves right away since they had some wear and I have them stripped down and in the machine shop anyway.

Another thing I have found is, the dynojet kit is useless. It is way to rich through the mid range then leans out in the high end. I am going to be playing with the springs to maintain the response of the kit but the needles are just way to thin and short. I have been having more predictable and consistant results using stock needles. I can always order different needles with either more taper or thinner diameter if needed.[/b][/b]

I had the same problem with the K&N on my old Warrior. You could see the dust build up in the intake boot. I was told the reason that DJ chose the needle profile was to help with the pilot jet . I was like..."Why didn't they just up the pilot?" IDK......Great test....Good job.