Carburetor woes

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MT Pockets

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Good day to you All,

Back in my mis-spent youth I had a shop install a Handle 4-2-1 exhaust on my Vmax. They said they could never get it running worth a hoot with a K&N filter (not pods, the one piece filter similar to the OEM design) so they stayed with the OEM air filter. It never did seem quite right after that but then and probably still now I didn't have anything to compare it against. Never took the bike back to them because I didn't want it broke off in my keister a second time.

A wild chain of events has happened since that install and now. Sadly I've just dealt with it. This spring it was running especially bad so I performed the Shotgun. Much better for about 100 miles then it started running even worse than before. I've finally overcame my reluctance to completely disassemble the rack of carbs and go through them with a fine toothed comb. I purchased K&L carb kits and air cut outs. Also purchased 4 new mixture screw kits because two of the four didn't have the tiny steel washers and o-rings when I took them out for the Shotgun. I am in the process of installing all of these items now. I've been reading a lot on this forum about jetting. Seems like 147 - 150 is where a lot of guys are running on the main. Mine is stamped .170 God only knows if the needle is stock but I can tell you the clip is on the 3rd slot from the "blunt" end.

It does run richer than Oprah for sure. I sure as the Devil didn't get this bike for fuel economy but on its best day 25mpg is tops and it drops into the mid to lower teens with judicious use of my right wrist. Like I said, to me this thing never did seem to run quite right after that exhaust install.

What mains would you recommend I start with? Are there other things I need to be aware of or consider during this R&R?

Thanks in advance,
Brad
 
I swap between 145 and 147.5 with a 4-2-1 and free flowing intake. It depends on how high up I plan to go, but I usually start at about 4000'.

The numeric value of MK and DJ jets are not the same, there is a cross reverence to gauge comparability. 170 Sounds like a DJ number, if it is I wonder if you have DJ needles too.


Jet_Numbers_Cross_Reference_Sheet.jpg

needles_edited.jpg

Also not sure if the "air correctors" are needed for only a drop in K&N, but I have the filter lid as offered by Morley and there was no tuning it w/o said correctors, once they were in tuning was a snap. Here is a thread in which they are discussed. Can somebody explain what air correctors are?

Just some food for thought until the more knowledgeable guru folk arrive on the scene.
 
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You did a good job explaining.

O.P. look at your needles, and tell us which needle you have, if it's Dynojet Stage 1, that's a big part of your problems. Add air correctors and Stage 7 needles, replace your main jets with 147.5 or 1`50 Mikunis, and see how that works.

Here's my chart which I added-to someone else's picture, sorry I forget whose. I think Sean Morley may have submitted the many-needles one.

VMax carburetor needles.jpgVMax carburetor needles-Sean.jpg
 
Thanks guys!

Pretty sure I can confirm that the needles are Dynojet Stage 1 so it would make sense as Casey suggested that the mains are Dynojet as well.

Vmax needle 2.jpeg


If I understand you guys right, Stage 1 stuff is useless. What are expected gains with the Stage 3? Will I need to modify my airb box with Stage 3? What are expected gains with Stage 7? What modifications need done with a Stage 7? I've read Vboost can stay with Stage 7 and that Vboost has to go with Stage 7. Which is it?

I love brutal power, but for now I'd like to have it reliable and streetable too.
 
No you do NOT need to eliminate VBoost, I have Stage 7 and I have VBoost. It also makes it easier to synch your carbs.

X2 to all of the above being exactly what I experienced in keeping the Vboost functional on mione, besides being a unique defining feature of the Gen1 Vmax. Your guidance was very helpful in getting mine tuned right, thank you!

Thanks guys!

Pretty sure I can confirm that the needles are Dynojet Stage 1 so it would make sense as Casey suggested that the mains are Dynojet as well. I love brutal power, but for now I'd like to have it reliable and streetable too.

Those are the same DJ needles I took out of mine, I ended up giving them away on the forum after I tried exhaustively to tune it with those, I was pretty much just pissing up a waterfall. I did get to where I could swap main jets in 15 minutes though, with all the main jets I tried with those needles. I've not read about anyone using stage 3, but the 7s seem highly popular. You already have consensus on the stage 1s haha.

Since your at the part where you will probably be swapping needles and jets I would like to share a tip I learned on this very forum;
Tune from the top down. Find the main jets that give you the most impressive top end/high speed operation and tune down from there to the low speed jets, clip positions yadda yadda. It worked for me, plus I got to see right up front what Vboost is supposed to feel like.

Gen1 has no rev limiter and once you find the right jets/needles it may want to pull right past redline, so be careful. I highly suspect the power you seek will materialize with getting the carbs setup.

Also, I do recall that using the wrong slide spring will be problematic if your slides are drilled. Stage 1 and 7 kits use the same slide spring, which is shorter than OEM if I recall correctly. The PO of my bike did not drill the slides but did use the stage 1/7 slide spring and it was one of my problems. I put the OEM springs in and it was much better. Then I drilled the slides and went with the DJ springs, pretty happy with that. The slides are brittle so handle carefully. I was able to see that my slides were not drilled because the kit included a drill bit. Sorry for the long post but while you have things apart a look at the slides and springs might be time well spent.
 
The slides are brittle
And trying to change the CV diaphragms, you can break 'em. Alorio1 (Joe, a great guy on here, R.I.P.) had a method for removing the CV slide boots, but be warned, the slides can and will crack/break easily! I think using a good pick like a dental pick or one of those sets from Harbor Freight, with the orange handles is a good way to do it. I've also ground-down the metal ring, and then epoxied it back on with a new rubber, but if you take your time I think the pick method will work.

The question on (1) what is the OEM slide hole diameter and (2) what is the Stage 7 drilled-out diameter has been answered if you use the search function on the upper-right.
 
Good evening. I have installed The Morley Muscle Jet Kit using the Mikuni 150 Mains. Synchronized the carbs and took it for a rip. This bike has NEVER ran so good!

Thank you Mr’s Jones and Medic for helping me. Shout out to Sean Morley for providing an excellent product and guidance as well.
 
Another benefit to sorting out my carb troubles is that I went from 25mpg on my best day to 39mpg. Mighty rare day when a guy can get huge performance gains and fuel economy to boot.
 

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