Well I did my first dyno runs today to check my jetting. I will get a pic of the graphs posted as soon as I get ahold of a scanner. I maxed out (final runs) at 44hp at 6500 rpms. 39hp at 5500, 32hp at 4500, and 22hp at 3500.

Here are my "improvements" over stock - Yosh stainless header and silencer, Pingry airbox, Proflow foam filter, Outerwears filter cover, Outerwears airbox cover, 25 pilots, idle screws 3L/2R turns out.

I started off with the jetting that was most recommended on the forum, 160/165 mains, needle on 4th clip from the top. It was way lean above 6000 rpm. About 16 for the A/F ratio. Midrange was in the high 13's to low 14's. It wouldn't even rev all the way to 9000.

We jumped way up to 190/195 mains, needles on 4th clip. It was still a little lean between 8-9000 rpm (14.8), but it was really rich between 3500 and 7500 rpms = between 12 and 13 A/F ratio. I didn't have enough time to raise the needles, but the dyno dude told me that raising them 1-2 positions would pull the midrange A/F up to where it should be.

Now, after all this description, here are my 2 questions-
1) Do you think raising the needle clips will pull my A/F ratio up to where it should be in the midrange?
2) Betwen 2500-3500, when I first hit the throttle, the A/F ratio drops from ~16 or 17 down to where it should be. Is this normal? The dyno dude said that it is normal because when you slam the throttle open the engine gets a big gulp of air, and it takes a second (1000rpms) for the carb to catch up. IS THIS TRUE? Or should I go up to a 27.5 pilot?

I am really confused now. I saw another A/F curve they did on a Raptor and it was perfectly straight. Mine looks like a "U", up down up.

I am planning on going back next month for another shot at the perfect jetting. I am sure some of you guys have spent alot of time dyno tuning the raptor, and I really need to gain some knowledge and expert advice so that when I go back, I can make it woth my money.

What are your ideas? Any and all are welcome.

RR1

 

From everything I've read you want to be a little rich at idle and just off idle low 14s, a little leaner in the middle mid too higher 14s and a little rich WOT high 13s. If these readings from the dyno are indead correct you would need to go even higher on your mains and lower your needle (raise the clips). I see no reason to change the pilot jets unless you had lean readings just off idle too 2500, besides the momentary ones you mentioned when first hitting the throttle. That is normal for a carb. without an accelerator pump and especially a CV carb. These are the numbers I'll be shooting for when I dyno mine but how it feels and runs on the trails will be the determining factor. Hope I have'nt confused you more.[img]i/expressions/face-icon-small-smile.gif[/img]

 

I rode it all last year with the stock 22.5 pilots and tried every jetting/needle (MIKUNI JETS/NEEDLE)position imaginable from 150/155 to 170/175 and it ran good, it was fast. But this winter I went up to 25 pilot and a Pingry airbox and it is like a completely different quad. It is REALLY fast, compared with what I remember from last year. Last week I ran it with 175/180 mains, 200 yards, WOT the whole way with a brand new plug. When I pulled the plug - nothing. No black soot, no white soot, just plain shiny metal and fresh white porcelain. The ground strap did have a small amount of deposits on it. 91 octane pump gas (10%ethanol here in MI). Over all it runs really strong.

RR1

ps. I know every dyno differs on HP numbers. I have heard everything for a stock raptor from 30 (14mins virgin'03) to 38. So I am not too concerned with "only" 44hp. It seems really fast to me. A similarly spec'd Raptor with a Hotcams stage 2 and advanced timing only hit 46 hp on this dyno a couple weeks ago. This guy works for the dyno shop and tuned the he!! out of it and had a perfectly flat A/F curve.

 

HP numbers from dyno to dyno can vary quite a bit that's why I really don't pay a whole lot of attetion to hp numbers unless there is a comparison to another quad or mod on the same dyno on the same day. It sounds like that airbox made a big difference if you can truly run that jetting ie if the dyno is correct. It would have been nice to have dyno'ed it with the stock airbox for a comparison..BTW what was the air temp. and alt. when dynoing?

 

The room the dyno is in is temp. controlled at 72 degrees. It was near Clarkston, MI. That is not too far from the Great Lakes, so I don't think it could have been any more than 500 ft above sea level.

When I am cruizing in 5th at ~2000rpm, slam the throttle open, it doesn't bog or fall on its face. It pulls slow up to about 4000 rpm, then it really takes off all the way up to the rev limiter in 5th. I can pull the front tires off the ground in 5th gear. I could never do that last year.

Thanks for all the info guys, but what I really need are some answers to my 2 main questions (see original post).

"1) Do you think raising the needle clips will pull my A/F ratio up to where it should be in the midrange?"

"2) Betwen 2500-3500, when I first hit the throttle, the A/F ratio drops from ~16 or 17 down to where it should be. Is this normal?" The dyno dude said that is because I don't have accellerator pumps.

Thanks!!

RR1

 

Sorry, thanks sixsixT!! I didn't realize it, but you already answered my second question. That makes me feel better :-)

RR1