Figuring out what Stage Dynojet(see pics) and full exhaust system?

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firro

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Hi All,

As i mentioned in my previous post, i bought the bike like this , the owner has passed away, so im trying to figure out what kind of mods i have.
Can you guys tell by the pictures what stage mod i have? sorry if its a stupid question . im totally not familar with VMAX, slowly getting there though ; i need to get this out for peace of mind.

Firstly lets start with this Dynojet crap :D I was almost certain I had Stage 7, but what makes me doubt are two things and need your help with this.

1. V-Boost is still intact and functional, i've read that its uncommon to have V-Boost with Stage 7 configuration, yet not seldom.
2. I have a sticker under the fake tankcover saying: Dynojet 1

i also have four k&n air filter pods and this big pump( to prevent oil getting there?) thing in the middle of the filters.

And I also believe I have full exhaust system? or just the slipon?

Thanks again!!!

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Remove the CVC cap from a carburetor.

Remove the CV rubber diaphragm.

Remove the slide needle.

Compare it to this chart and see what you have.

Stage 1 is probably not what you have. The parts you have look like a Stage 7. The oil mist condenser, feeding oil back into the engine via the large diameter hose going to the oil filler cap on the right rear of the engine is what is between the 4 air filter pods.

Note that on the 5 slots/needles, the slot closest-to the 'blunt-end of the needle' gives you the leanest gas mixture.

Dynojet Stage 1 is hard to tune, do not buy it, and if you have it, you will probably find after all-sorts of frustration attempting to make the Stage 1 work well, you will be happier going back to OEM jetting.

Dynojet main jet numbers are not the same as OEM Mikuni jet sizes. They (Dynojet) are higher numbers for a same-size equivalent Mikuni size (lower numbers).

The DJ Stage 7 uses an air corrector to limit air inflow for that small port having a brass jet, in the carburetor bellmouth (the top of the carburetor)



1719256013893.png

1719256038945.png
The 'long chart,' courtesy of Sean Morley [email protected]

Note OEM USA bikes do not have 5 slots in the needles, just 1.

From the factory service manual:

1719256885521.png

1719258138684.png

https://www.jetsrus.com/FAQs/FAQ_mikuni_vs_dynojet_vs_keihin_sizes.htm
 

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Remove the CVC cap from a carburetor.

Remove the CV rubber diaphragm.

Remove the slide needle.

Compare it to this chart and see what you have.

Stage 1 is probably not what you have. The parts you have look like a Stage 7. The oil mist condenser, feeding oil back into the engine via the large diameter hose going to the oil filler cap on the right rear of the engine is what is between the 4 air filter pods.

Note that on the 5 slots/needles, the slot closest-to the 'blunt-end of the needle' gives you the leanest gas mixture.

Dynojet Stage 1 is hard to tune, do not buy it, and if you have it, you will probably find after all-sorts of frustration attempting to make the Stage 1 work well, you will be happier going back to OEM jetting.

Dynojet main jet numbers are not the same as OEM Mikuni jet sizes. They (Dynojet) are higher numbers for a same-size equivalent Mikuni size (lower numbers).

The DJ Stage 7 uses an air corrector to limit air inflow for that small port having a brass jet, in the carburetor bellmouth (the top of the carburetor)



View attachment 94566

View attachment 94567
The 'long chart,' courtesy of Sean Morley [email protected]

Note OEM USA bikes do not have 5 slots in the needles, just 1.

From the factory service manual:

View attachment 94568

View attachment 94571

https://www.jetsrus.com/FAQs/FAQ_mikuni_vs_dynojet_vs_keihin_sizes.htm
Thanks a lot for the info!! very useful; i will try to figure out next weekend..

i do remember the old lady saying that the needles were renewed last year.
at the moment the bike has issue when opening throttle from start, it feels like it doesnt get enough fuel when opening the throttle and wants to stall, if i keep the choke half open, then its no issue. So it makes me wonder maybe they have installed OEM needle instead of Stage 7 needle; hence the stalling issue....dunno just thinking out loud :D

nevertheless carb cleaning and sync will happen and a good inspection.
 
I suspect that will likely solve your "I have to run at part-choke" issue.
 
So I'm trying to figure out what Jets are in my carb on the '98 VMAX and if it is a correct tune
I have DJ Stage 7 + K&N pods + 4-2-2 Doma Exhaust
In the floatbowl area, bottom jet is a DJ 190 jet.
From the top area its Mikuni 90.
From the side area its a Mikuni 120 or 170 , its hard to read.
See pictures..
The a/f mixture screw was 5 turns out.. i live at below sea level altitude.
Anyone that can maybe tell me if i should continue running with this tune? The bike isnt running well, im doing carb rebuild at the moment.
 

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Holy shit that thing is drowning.
DJ190's are for under the slide (PAJ2) if you have surging while cruising
MK170's (if original) are normally in the PAJ2 slot
MK152.5's are standard mikuni main and the S7 would usually have you put in DJ 165's (not much bigger then the stock MK 152.5
The MK90's in the top are normal and i'd leave them as is.

My suggested setup to start with:
MK 90's PAJ1 (in the top)
MK 170's PAJ2 (under the slide)
MK 150's or DJ 160's for the main
MK 37.5 PFJ (under the small rubber plug in the jet block)
Needles on the 3rd clip from the blunt end
S7 Springs
Air Correctors
 
Holy shit that thing is drowning.
DJ190's are for under the slide (PAJ2) if you have surging while cruising
MK170's (if original) are normally in the PAJ2 slot
MK152.5's are standard mikuni main and the S7 would usually have you put in DJ 165's (not much bigger then the stock MK 152.5
The MK90's in the top are normal and i'd leave them as is.

My suggested setup to start with:
MK 90's PAJ1 (in the top)
MK 170's PAJ2 (under the slide)
MK 150's or DJ 160's for the main
MK 37.5 PFJ (under the small rubber plug in the jet block)
Needles on the 3rd clip from the blunt end
S7 Springs
Air Correctors
Thanks Sean!

I can confirm I have the following:
✅MK90's PAJ1
✅MK 170's PAJ2
✅MK 37.5 PFJ
✅ S7 Needle on the 3rd clip from the blunt end
❓The springs not sure yet, will inspect later today
❓ im not sure what air corrector is currently in there as it is hard to remove.. but you suggest to have this stock? ( see attached picture)

also im about to order the MK150's for the main since it is much easier to find on the web.
Can I go for this type? looks like aftermarket LINK GMOTO
or genuine Mikuni LINK

THANKS AGAIN!!
 

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Thanks Sean!

I can confirm I have the following:
✅MK90's PAJ1
✅MK 170's PAJ2
✅MK 37.5 PFJ
✅ S7 Needle on the 3rd clip from the blunt end
❓The springs not sure yet, will inspect later today
❓ im not sure what air corrector is currently in there as it is hard to remove.. but you suggest to have this stock? ( see attached picture)

also im about to order the MK150's for the main since it is much easier to find on the web.
Can I go for this type? looks like aftermarket LINK GMOTO
or genuine Mikuni LINK

THANKS AGAIN!!
You do have the proper air corrector which can stay in the carb if you are running the pod filers or a modified airbox. You can get the Mikuni 150's from a number of places (small round head) and I try to stock them too (though am out at the moment and not due back on hand until late this month).
 
You do have the proper air corrector which can stay in the carb if you are running the pod filers or a modified airbox. You can get the Mikuni 150's from a number of places (small round head) and I try to stock them too (though am out at the moment and not due back on hand until late this month).
Thanks a lot Sean, i was able to get hold on a set of Mikuni 150's in EU.
Im finally done with rebuilding my carbs, bike runs much much better!!!

however, i have small correction to make on my first post in this thread..
i said the vboost was intact and functional... well its not, everything is there except the manifolds. I have the DJ manifolds instead. Hearing the Servo motor when turning igntion on made me assume its functional.

now im having a dilemma, should i buy used intake manifolds ( they cost around 200 euros) and connect Vboost to its servo motor.. or keep it as it is ...
 

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