Trying to figure what kind of carbs are my 86 vmax 540

PhazerMod1 · Post by **PhazerMod1** » Wed Feb 03, 2010 4:50 pm

Just picked up an 86 vmax 540 with mikuni 38mm carbs that don't have power jets. Are these ok to run in a 540? had 270 mains and 40 pilots in it. Motor was fried when i got it.

Bob Vehring · Post by **Bob Vehring** » Wed Feb 03, 2010 6:10 pm

Mine is ported and I don't run an air box. I have 340's in it now, it was very lean in the midrange with 330's. These are PJ carbs

vmax-540 · Post by **vmax-540** » Wed Feb 03, 2010 6:24 pm

The stock carbs were 38 Power jet carbs with 290 mains plus the power jets witch were 135 PTO and 130 MAG, if yours have 270's with out the power jet circuit then that is why it burned down. I would find the right carbs or re-jet yours.Or you could get a couple power jet kits from anyone that sells Mikuni and install them on your carbs just follow the directions that come with the kits for your jetting,If you use yours with out power jets and do the math then you should start with about 480 mains and also you may have to put in larger needle jet. If it were me I would get the right ones and save yourself a lot of headache's, and pistons.

PhazerMod1 · Post by **PhazerMod1** » Thu Feb 04, 2010 10:22 am

Would the float needle and seats from this non pj carb work in my set of pj carbs? I'm having an awful time with my 83 540. I rebuilt the entire motor and when i go to take off it just noes right over and boggs until it can't move. I think it's the float needle and seats but would save me some money if i could switch them out of the other carbs i have.

chrisrider63 · Post by **chrisrider63** » Thu Feb 04, 2010 6:03 pm

Sell the other carbs you have and pick up some stock PJ 38's and set it to spec from the book, my VMAX runs clean and is a one-pull wonder.

Post by **Vmax540** » Fri Feb 05, 2010 11:24 am

Phazermod1, I believe they should work.... Are you sure you do not have a clutching issue causing the bog ? These girls like their engagement RPM's over 4000 and the closer to 4500 the better !

PhazerMod1 · Post by **PhazerMod1** » Fri Feb 05, 2010 1:41 pm

engages right at 4500RPM

Bob Vehring · Post by **Bob Vehring** » Fri Feb 05, 2010 1:46 pm

My guess is that it burnt because it was lean. I'm sure and you can see by the responses here, many are happy with the stock carbs. That doesn't mean they are the only carb that works. Most sleds us non PJ carbs, doesn't matter if they make more or less HP.. Their comes a point when as long as you main is big enough, that in most driving situations the jetting is controlled by the needle and needle jet The only time it runs off only the main ( or main and PJ) is when you are at WOT and then only if the needle is clipped up far enough to be out of the Needle jet.
I have a 535 fan engine, that makes more HP then my VM and runs non PJ carbs, as long as the carbs are jetted correctly, you will be fine.
I have posted many times, having a good EGT gauge and understanding jetting is far cheaper then replacing pistons. People always ask what is right for them, there is no one answer. There is no answer that covers all temps or altitudes. and there is no answer for all the crap gas that is out their. AN EGT gauge tells you whats happening right now, right where you are, If you want to be safe in everything, jet really rich and live with the loss of HP. That's what the factory does.

PhazerMod1 · Post by **PhazerMod1** » Fri Feb 05, 2010 1:49 pm

It shouldn't have been lean, it had 330 mains and like 140 powerjets in it.

Bob Vehring · Post by **Bob Vehring** » Fri Feb 05, 2010 3:35 pm

PhazerMod1 wrote:Just picked up an 86 vmax 540 with mikuni 38mm carbs that don't have power jets. Are these ok to run in a 540? had 270 mains and 40 pilots in it. Motor was fried when i got it.

The first post says 270 mains. If it had old stale gas in it when it happened, it doesn't matter what jets were in it ,If a piece of dirt plugged any of the jets again it doesn't matter what the jet was. At this point you just want to besure you don't do it again, whatever did it

Bob Vehring · Post by **Bob Vehring** » Fri Feb 05, 2010 3:36 pm

Ok, I get it it had 330 in the engine that blew.The carbs that you bought had 270' Right?

PhazerMod1 · Post by **PhazerMod1** » Fri Feb 05, 2010 6:22 pm

almost, two sleds were talking about. 1st sled 1986 vmax 540 i bought had non powerjet carbs and was fried. 2nd sled 1983vmax540 i completely restored, rebuilt engine and has CORRECT carbs on it but doesn't run worth a shit.

PhazerMod1 · Post by **PhazerMod1** » Fri Feb 05, 2010 6:26 pm

I start a new post because im starting to confuse myself also:)

PhazerMod1 · Post by **PhazerMod1** » Fri Feb 05, 2010 6:44 pm

the 270 mains were in the non power jet carbs that were in the sled that is blown. the 1986 vmax

Post by **Vmax540** » Sat Feb 06, 2010 12:56 am

PhazerMod1 wrote:the 270 mains were in the non power jet carbs that were in the sled that is blown. the 1986 vmax

Sounds like a Recipe for a lean condition. PS. please read the Reliability post in the Articles.

VintageVmax.com

Trying to figure what kind of carbs are my 86 vmax 540

Trying to figure what kind of carbs are my 86 vmax 540

ya

Re: Trying to figure what kind of carbs are my 86 vmax 540