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drdyno

Member
Joined
Feb 26, 2018
Messages
19
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Location
phoenix
I'm an experienced drag racer and motorcycle collector, but I am absolutely new to V-motors.

I'm looking for a carb tip from some forum pro which I will appreciate greatly...
but first a little more background.

I decided I just HAD to have this beautiful red 2005 like MINT with 4000 mi.
Paid Xtra for the mint part.
Bike ran fine for me until I heard another guys well tuned bike with a Kerker competition baffle and pods. (by ran fine, I mean i rode it a couple times. I have many bikes, and they all have to take turns with me, except during the brief honeymoon period).

So any ways the other guys bike sounded FANTASTIC. It took me right back to my days on the strip. I could even smell racing fuel and burning rubber in my mind!

I almost bought that bike, though slightly rough around the cosmetic edges, Just for the tune!

Instead, I bought a competition baffle for my full, silver coated, kerker 4-1, and the Innovate LM-2 system for logging AFR. I wanna use it on my other bikes anyway- but right now, I gotta have that SOUND!

Long story short, and damn I'm retarded, but a few trips while logging rpm, g's, afr, and pipe temps showed me that cylinder 1 coil was UNPLUGGED. First thought in my mind was the guy unplugged it to sell a bad cylinder... but nope. compressions all good.

not all cylinders responded well to idle mixture screw changes so a rebuild was indicated.
besides afr was off the chart lean at idle and I had a "hanging" idle after throttle blip.

cruise afr was high also 16-18 but WOT dropped to 9!

So I rebuilt carbs. mains from 170 (assumed Dynojet) to 165MSD.

Needles I actually dropped a half notch on intuition. they look like dynojet needles with the clips now on the second notch down from the fat end.

The idle air jets are 90 (Dynojet?) on top and 150 (Dynojet?) on the side.

The idle fuel jets are now 40, were 37.5.

my mixture screws are now 2.5 turns, same as before.

The springs appear dynojet.
The slides are drilled.

The only thing I noted on the rebuild was some little pieces of looked like broken rubber out of one of the idle mixture circuits.

The carbs are reinstalled, synched and the coils all connected.

Before you laugh at me driving around a 3 cylinder v-max, remember- I never rode one before and to be honest, it's not a huge difference! disconnect a coil and try it!

Now as laughter subsides... here are my new numbers and my request for guidance.

Idle is now ON the charts at 17-18 ish, and may not be a reliable number as i am using the Innovate tailpipe probe versus a weld in bung. BUT the throttle response is way improved and snappy with no hang or droop when blipping.

cruising afr is right in line seeing numbers from 13 to 15 and cruises with alacrity.

WOT however, while strong, is very rich at 10.5 afr, and the inside of my competition baffle is beginning to show it.

So my question to you experienced vmax tuners is this. What jets do you suggest i pop in for the mains? I would like to move all the way from 10.5 to 12.5 or 13 for WOT with the minimum number of carb pulls. Did I tell you this bike is MINT? I can hardly bear to touch screwdriver to screw without having a new screw on hand.

So from present 165 MSD which I think might be comparable to dynojet and probable similar to 155 Mikuni. I don't think going one size down to the stock 152.5 mikuni will take me as lean as I want to go. But if I do maths and assume a linear relationship, I get numbers in the 130's and that sounds nuts. So I think I might try a dynojet 150, or do you guys think that's too lean?

I live in Phoenix, about 1000ft.

comp baffle in.

stock air box with k&n
 
Try 147.5 Mikuni. I see Phoenix is 1124 ft above sea level.

Welcome to the crowd.
 
You probably have a dynojet stage 1 kit in your carbs.

The general consensus is that kit is a waste of time, and money. There are many old threads on here where guys have spent hrs and hrs swapping jets and never got it right.

If you want to get the most out of the bike go for a DJ stage 7 or, even better, the muscle jet kit from Sean Morley. Its a bit cheaper, same top end, better low end.

If you dont want to buy a whole jet kit, check out the carb forum. There is a sticky that has pages of carb setups that members are running. I would think 147.5/ 145 mikuni would be close for your main.



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Thank you gentlemen for your advice.

Unfortunately, I wasted a session making assumptions about the size of my existing jet.

Existing mains were 165MSD according to bag.

I assumed that was the same as 165 dynojet.

I did maths according to diameter figures in jet comparison charts.

And the figure I arrived at was .066 dia. based on that false assumption.

.066 is right in line with your recommendations, and it turns out that a #51 drill bit is .067 right between mikuni 145 and 147.5

So I popped those in rather quickly since I'm getting practice now.

Result: Richer at WOT by half a point AFR.

What??? So NOW I gauge the "165's" I took out and they are somewhere between .063 and .067 based on go,no-go. I have no handy way to gauge actual diameter. but it looks like this is more in line with keihin labeling.

Looks like I gotta re-think.
 
Damn I'm getting fast.

I put the ones marked 165 which gauged somewhere between .063 and .067 in for the primary air on the side and took the ones from there, marked 150 and gauging between .058 and .063 in for the mains.

progress. WOT mixture in range. :clapping:

Now I'm gonna drop the needles half a notch, log a trip to the bank at spectrum,
and I'll try to post a screenshot of the chart for you all (If I'm not in jail).

To be clear, by gauging, I mean I try go, no-go with the back end of a letter drill bit, then measure the drill bit with a micrometer.

These jets came out of little baggies marked "165 MSD" or "150 MSD".
I also have some marked "170MSD" which gauge about .068
 
This thread is a great reference to get you in the ball park
http://vmaxforum.net/showthread.php?t=16981

If it were me, I'd stop pissing around measuring jets and such.
I'd pull the carbs. I clean them, set the floats per instructions on this forum, and install a muscle jet kit with genuine mikuni jets. See the thread above, find a few guys that have similar setups and altitudes and use that as a guide.
 
Results.

As you can see 12.1 AFR at WOT.

13 to 15 other times

letting off throttle always goes lean.
 

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Raped ape status achieved.

back in the barn with your time capsule brethren!

Next...

Let's get rid of that idle surge on my 95 ninja.
 
Hmm, Mike-
Measurements and calculations got me where I needed to be.
I did read all of those setups. I also rebuilt my carbs as stated.
I ended up pulling them three times, 1 more than I needed to because I DIDN'T measure the first time.
My point is that we strive to develop the intellectual power to overcome adversity and master our technology.
Or we could simply copy others and assume a thousand variables are all equal.
I did mention my results are confirmed with wideband and acceleration data.
If any one is interested, I will be happy to share the maths I used to project my target jet diameter.

Sorry I sound this way Mike, but your pissing post was mildly offensive.
 
Why would you find an attempt at helping you offensive?
If you ever have any problems you need help with in the future, snarky comments aren't the best way to get assistance.

That being said, glad you got it running, and thank you in advance for any assistance you may be able to offer fellow members in the future. My bike is looking at a carb overhaul soon, and I will be counting on my brothers here for advice.

And, welcome to the forum.
 
Umm, because you suggest I clean carbs I just rebuilt. And that I stop wasting time determining the size of my jets, and because you use words like "pissing", and "snarky".
I think all of these things are plainly mildly offensive Mike.
Simple observation.
 

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You do realize I'm not Mike, don't you? All I was trying to do is let you know these are really good people who are only trying to help. Nobody tries to offend anyone, but the BS has been known to fly around here.
 
Sorry if I offended you Dr.D.

Glad to hear its running well.


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Don’t know why you’re sorry. Neither you or Bill said anything wrong.

Drdyno, welcome to the forum, and congrats on owning an iconic muscle bike. As you can see, there’s a lot of knowledge and friendly helping hands accessible here on this forum. Look forward to your future posts, and the modifications you may make to your bike along the way.


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Cool. Looking forward to your participation here. The fact you own a Max automatically makes you a good guy in my book.
 
If any one is interested, I will be happy to share the maths I used to project my target jet diameter.

I've never heard a scientific explanation on jet sizing. Everything I learned, or read, was about feel, plug color, and some trial and error.

I would be interested in the math used to determine jet sizing. I'm always open to learn something new.
 
I've never heard a scientific explanation on jet sizing. Everything I learned, or read, was about feel, plug color, and some trial and error.

I would be interested in the math used to determine jet sizing. I'm always open to learn something new.



I’m interested as well.


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