Inherited Stage 1 Needles with Stock exhaust

[Threebeards]

Thanks All,
I've been working my way through the "carb bible" sticky, it had solved ALL of the issues I was having, it was just the A/F procedure for increasing MPG that brought the odd situation with the A/F screws to my attention.

 

[Threebeards]

Adambweird, were you also running a stock exhaust?
I suppose I should also work on the assumption that the jets have been drilled out to accommodate the needles.
Thanks for the Sudco Diagram Blaxmax, that makes sense after all I'm at cruise RPM for 90% of the time.

 

[Threebeards]

You can make the needles you have work to your advantage as they are tapered in a way the stock are not.
I have stock exhaust and i put stock canadian needles that can adjust and making them lift quicker allows for a quicker response throughout midrange.They do have the same taper as stock needles so the only advantage i get is lifting quicker for quicker response. You have a different taper so you Top end is my main jet and mine is 157.5.- i am in the mojave below sea level though.
I used to live in vegas and at 2600 ft altitude you are better off with a smaller than stock main. I would keep the needles you have and work with them to your advantage. Use your carb sync tool to get your a/f mixture screws set as high as you can get them. Keep turning them out until they reach their highest vacuum and afterwards sync the carbs-- that will help your bottom end.The taper works the transition between the midrange and full throttle/main jet (¾ throttle position). The taper is the least sensitive function of the needle. Changes in the taper have very mild subtle changes in the jetting. The taper also affects the main jet size your carburetor requires. A leaner needle taper will use a richer main jet than a comparable engine/carburetor combo with a richer needle taper.

So Here are my findings, I've decided to mess around with the stage 1's as I have the time.
I removed thr "Y" from the stock airbox to ride home from work (90 miles) absolutely no difference, but the intake noise does add to rider enjoyment, but I think that's already been documented elsewhere ;-)
After getting back to my garage and tools, I tried Blaxmax method of A/F adjustment, still nothing until the final half turn (that's fully clockwise, screwed IN) and all that does is to lower the amount of vacuum.
THEN moved the clips on the needles from the 3rd position (of 5) closest to the blunt end. Did the sync tool trick again, same results.
Anyway went for a ride out to Temple Bar and back to use a tank of fuel, and the results were 35MPG!! So we have a nice increase, I'm happy with this, but, my inner cat with a death wish, will no doubt tinker further at some point.

In conclusion, Thanks to Blaxmax for the encouragement to have a go, I think your taper explanation applies here. There are a couple of unknown quantities here though so seemingly similar situations may not yield similar results.
unknown 1...carb springs could be stock could be aftermarket.
unknown 2.... whether or not the previous owner drilled the jets, and if so how much.
otherwise stock jets, stock exhaust, "Y" removed. stage 1 needles, Can work it seems.
Scuff and Adambweird I believe I am still running rich though (probably drilled out jets) as the A/F screws don't do what they are supposed to yet, AND it'll start with no choke, albeit with very low idle. (I am in Vegas though and its hot already)

 

[Traumahawk]

Stock springs when they are removed are about 7 inches long. If you are running stage 1/7 springs....they will make you run rich as well, because they will make the needles kick in sooner.

 

[Threebeards]

Ah ha! Thanks traumahawk. So the stage 1 springs are weaker? So the vacuum overcomes them easier?

 

[Traumahawk]

well the stage 1 and stage 7.....are the same spring, and yes, they allow the vacuum to move the slide...maybe not faster....but further. So you would have the stage 1 needles pulling out of the main jet even more...making you rich.

Me personally I liked the stage 1 needles, just due to adjustability...BUT...you do have to realize what they do, so you can tune them to run with a Vmax engine.

 

[maleko89]

Farther and faster. I use stock springs with a few coils tied off.

 

[Threebeards]

Mine's 7 inches too!! (Said the bishop to the actress)
So that just leaves the main jets, drilled our maybe not drilled. Would that be a likely candidate for the A/F screws doing next to nothing?
Such an education to be had on this forum. Makes me feel sorry for those whose bikes didn't get a 22 year production run.

 

[Traumahawk]

Could be....but I would check the main jets. Its more than likely that the PO used the complete DJ (dynojet) stage 1 kit. It come is DJ 160 jet= to mikuni 150's, DJ 165=between MK 152.5-155, DJ 170=between mk 157.5's -mk 160's. So its possible the PO just installed main jets that were WAY to rich. A stock Vmax (stock exhaust) comes with 152.5's....but tends to run better with 150's.

 

[sdt354]

Farther and faster. I use stock springs with a few coils tied off.

+1 Mark. 3 coils tied worked well for me. I found a set of springs with length between stage 7 and stock. They most likely came from a venture. They work well too.