main jet with exhaust mod

4398 Views 27 Replies 8 Participants Last post by mr.losi, Dec 30, 2003

rich

Discussion Starter · Nov 21, 2003

I just did the exhaust mod today and was wanting to know what main jet i should run?

This is what I have right now:

K&N filter

Dyno jet 144main

3 turns out on mixture screw

clip in the third groove on the needle

exhaust size now is 1 1/2 with the spark arrester still in.

Should I take the spark arrester out?

1 - 20 of 28 Posts

RockyRincon

· #2 · Nov 21, 2003

What exactly is the exhaust mod and how do I get it? Is it the one that I heard about on another forum as follows:
a replacement end cap for the Rincon's exhaust pipe with a shorter, much wider tip. It is said to increase low end power.

sparky

· #3 · Nov 21, 2003

Dont change anything unless you are SURE you are lean...at the MOST you will need to go up to the 146 main.

It looks like we have the exact same set-up including the Mudlites and the color(LOL).

I drilled out the muffler baffles and added a 1 and 3/4" opening (with spark arrestor). After that I thought I would be able to run a 146 or 148 main and I lost all top end...mid-range and low end was good, but top end would barely go over 50 mph.

Then I spoke to DJ and they said to go back to the 144. When I did, the prob was gone and top end was back. This mod DOES NOT flow as well as an aftermarket pipe so you cant use those recommendations all of the time.

I think 660T is the only one Ive heard of who is running larger than a 144 successfully with just the mod.

BTW...does yours run OK with the needle on the third notch instead of the second notch? What difference did it make when you moved it?

And second, what spark arrestor are you using? I had to use a Grizz 660 spark arrestor because I couldne get the Rincon one off without mutilating it.

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rich

Discussion Starter · #4 · Nov 21, 2003

yes it runs fine with the clip in the third groove it had a bad bog in it with the needle in the second groove.Also Im using the stock spark arrester I managed to get it off without to much damage.I tried a 148 jet and it had loads of bottom and mid power but seem to run a little rich on the top end so I went back with the 144 jet and it didnt seem to have the bottom or the midrange power anymore.I want the power it had with the 148 jet without the richness on top I think I will try the 146 and see what happens.

rich

Discussion Starter · #5 · Nov 21, 2003

Rocky 4x4 you take your stock exhaust end cap and make the tail pipe a larger size some people take the spark arrester out and some fit it to the new tail pipe.I used 1 1/2 inch pipe some use 1 3/4 I didnt go that big because I didnt want the added noise.After doing this you may have to rejet it and mess with the carb settings to get it right which is what Im doing now.

sparky

· #6 · Nov 21, 2003

Didnt moving the needle to the 3rd notch give you back some of your low and mid-range??

Yellow650Rincon

· #7 · Nov 21, 2003

Don't mean to run off-topic, but where in the hell did you guys find your stainless steel pipe? I had the muffler shop order some for me, and it has been backorded for two damn weeks!!

sparky

· #8 · Nov 21, 2003

I went up to the local mill where a friend works and looked through the machine shop scrap pile....believe it or not, my piece already had the bend welded on to it...

rich

Discussion Starter · #9 · Nov 21, 2003

Q,I had to move the clip before I did the exhaust and now after the exhaust it is gone with the 144 jet in.

Yellow650,I used a stock piece of exhaust header off my 929rr that I had replaced with a after market pipe.It looks exactly like the tail pipe on the Rincon.The size is about 1 1/2 inch in diameter

Yellow650Rincon

· #10 · Nov 22, 2003

The guy at the shop even went around town looking for some S.S. pipe and couldn't find any. (He's a pretty nice guy for doing that though)

So, it may be awhile until I actually get my exhaust mod.

sparky

· #11 · Nov 23, 2003

You dont have to use SS pipe. We used regular steel pipe on the 660 mod.

Yellow650Rincon

· #12 · Nov 23, 2003

I would use regular steel on mine, but I don't want it to rust. And I know it would rust pretty fast.

WOOD

· #13 · Nov 24, 2003

I run a 148 Dyno Jet with the clip in the 3rd notch(I think)3 turns on the air/fuel 1-3/4 outlet with no spark arrestor and it runs VERY well good on low end where I wanted it.My bike turns 26" Outlaws like crazy in the thick stuff.

Also not sure if this goes for all Midas Muffler shop's,but the one here keeps stainless in stock.

rich

Discussion Starter · #14 · Nov 24, 2003

I tried running the 148dj and it seemed a little rich on the top end so now im at the 146dj I will see how that does. I also didnt go very big on the exhaust mod either I went with 1 1\2 I know most are going with 1 3\4.I havent been able to ride much sense putting the 146 in so I will follow up to see how it is doing

lbierhorst

· #15 · Dec 1, 2003

I used 1.75" o.d. thick aluminum pipe and cut the screen off of the stock endcap. It slid just perfectly over the end of the inside section of pipe. Very snug and stays on by itself. Had a machine shop fab a new encap with this pipe welded to it. I'm running the dj 146, 3 turns out on air/mix. It seems to run well but really feel it lacks top end. It seems to flatten out at 50mph or so. Turning 27" mudzilla's pretty decent.

sparky

· #16 · Dec 1, 2003

RedRincon...thats because youre too rich on top...that exhaust mod doesnt allow enough flow to run the 146 main. Drop down to the 144 main and you will see your performance start to improve.

HEADS UP FOLKS: Its not about how big of a main jet you "CAN" run...its about PERFORMANCE! Actually, the "smallest" main you can run with the best performance is where you want to be.....as long as you are on the safe side of lean.

If you are flattening out on top above 50 mph, and all else is well, then chances are that you are running too large of a main jet.

lbierhorst

· #17 · Dec 1, 2003

Q, I forgot to mention that I did drill 15, 1/2 inch holes in the last baffle wall and I am at about sea level. I have the K&N filter and pre-filter installed. Do you think I should drop dowm to the 144 or try to move the clip to the 3rd notch. I could stand to use some more grunt on the bottom end as well. Any help is appreciated.

sparky

· #18 · Dec 2, 2003

Red,

Both...move up(down) to the 3rd notch on the needle and down to the 144 main. I already assumed you had BOTH baffles drilled out.

I have as much surface area as you can reach drilled out of my baffles and it still doesnt flow like an aftermarket exhaust - and it never will....Im at about sea level as well; or below 1000 feet anyway. I also have the K&N .

Im telling you from experience - not guess work. If you have the mod anywhere near mine, and you are flat on top, then you are too fat/rich/big on the main jet...call Dyno jet and they'll tell you the same thing.

Fomoco has a high flow exhaust and a 150 jet (I think) and is only 2 turns out on the mixture screw. he may be onto something. Im goint to try my same old 144, 3rd notch on needle, and close my mixture screw to 2 turns and see what happens.

Too rich will bog you down, and too lean will burn you up....I dought youre too lean if you are flat after 50 mph....

lbierhorst

· #19 · Dec 8, 2003

Hey Q, after opening up my carb this weekend I realized that I had installed the 148jet instead of the 146. I moved the clip to the third notch on the needle and put the 146 jet in. I am now able to pull a wheelie from a dead stop on level ground with a little tug on the handle bars. If I kneel on the seat with my feet on the back rack I can stand it up. Also with the 146jet I can feel it pulling an accelerating at the 50mph mark but ran out of road at the time but I can tell it wanted to keep accelerating. THanks

RickeyBell

· #20 · Dec 8, 2003

Red,

Was this wheelie with the 27" tires, bumper, & winch installed? How did it do before the kit? I believe our two environments will be close to the same, high humidity, warm temps, and close to sea level.

1 - 20 of 28 Posts

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