Marks 4 into 2 jetting question

[vmaxrooky]

Ok so I have a lil more info for you all. The jets in the side of the carbs are 170 and the jets in the top are 100 the needle has 5 clip places its in the middle and a washer(shim) on top and a plastic thing on the bottom... At 3000-4000 rpm's it sounds like a top fuel car idling then about a hair delay in twisty the throttle and wham its on so don't know where to go from here clutch has been replaced so I'm not loosing fuel mileage from that it still only gets 20-22 MPG haven't dug into the mains yet or had the carbs sync'd...

 

[ninjaneer]

when you say "side", do you mean underneath the diaphragm? i would expect 170s to be mains. the only way to get at the main jets is to pop the rack. are you popping the rack? that's definitely not a stock needle--the point is very aggressive. based on your other thread, it sounds like you have a stage 1 setup--single k&n.

 

[ninjaneer]

ahhh nevermind. PAJ2s = 170. got it

 

[vmaxrooky]

Ya not sure what I have got the bike this way and yes under the diaphragm is 170 then I pulled the stock air box off has a replacement K&N not like a big one its about 3" tall and oval with a tab in the bottom that holds it in place to the air box... Took the Air box off and the jets in there were 100 and that's the needle I pulled out... If you guys need more info guess we will have to wait till I pull the main jets?? Just thought maybe someone knew based on that needle and what jets I have located you guys might know what if any jet kit has been installed... If you guys need more info ill have to pull the carbs off and see what size the mains are thanks for the response ninjaneer...

 

[vmaxrooky]

I'm probably 100 or so above sea level here in Turlock,CA

 

[ninjaneer]

Maxxers will either install Dynojet Stage 1 (DJS1), DJS3, DJS7, or Morley Muscle Jet Kit (MMJK). DJS7 is easy to spot--tube running from oil-fill port back into crankcase and four individual pods (no airbox). Morley Jet Kit is just as easy--tube running from oil-fill port back into crankcase and a panel filter embedded into the top of stock air box. Identifying a DJS1 requires a little more work--spotting a flowy filter in the airbox like a K&N and aggressively tapered needles (like what you have pictured) and somewhat small-sized main jets (DJ90 with stock exhaust or DJ94 with slipons or full-up exhaust, for example). DJS3 installations are very very rare. IDing DJS3 is similar to IDing DJS1 except that the MJs are a bigger--DJ126 and DJ130, respectively.

My guess is that you have a DJS1. Guys who graduate from DJS1 typically go to DJS7. Other guys simply jump right into MMJK or the DJS7. It really boils down to a dollar issue and DJS3 falls through the bang-for-buck crack.

 

[vmaxrooky]

Jetted like this is that what is destroying my fuel mileage? 20-22 seems really low? Or can the carbs not being sync'd be the culprit? Rand5107 has the marks and stock jetting he's 15 min away from me and he's getting 40-45 mpg he said he went to Canada and recorded a 48 mpg once... I want at least to be able to go more than 70 miles on one tank...

 

[NHVmaxpower]

I just went through this. My mj were 170s switched to 150s I am 1000ft above sea level. The jets on top of Carb under air box are 90s . I took out the stage 1 and put stock needles back in.

 

[tothemax93]

I have marks 4-1, with stock carbs, factory needles that are shimmed .30. I'm getting around 35 mpg. Depending on your goals as far as performance. Go back to stock needles, stock mains, I believe 152.2 mikuni and shim the needles approx .30. make adjustments from there. If your looking for more performance, and still get mid to upper 30's for milage. get a muscle jet kit from Morley muscle AKA Sean morley.

 

[NHVmaxpower]

These are the needels I removed.

 

[06VMAXIMUS]

I think your best bet is to do some research in the carb thread to identify stock jet numbers and locations. That will give you a baseline to compare with what you have. Your needles are adjustable, so they are not stock.

 

[dannymax]

Bob, Canadian needles are adjustable also....not sure of the taper tho.

Rooky....I'd start by cleaning/inspecting the carbs, adjust the floats and sync 'em....then see what you have for performance/mileage/etc. Depending on mileage you may want to check valve lash also.

 

[AtlasMax]

Looks like stage 1 needles. You will need to pop the carb rack off, split the carbs and check the main jetting. I am guessing they are simply too fat.

Adjust your idle screws to 2.5 turns and see how it runs, if the brass idle screw plugs are missing.

 

[AtlasMax]

What do your plugs look like?

 

[vmaxrooky]

The plugs are out of the shifter side one on left is front cyl one on the right is the rear cyl...

 

[vmaxrooky]

Ya I had 65fury look at her today and he said she's running way rich said go back to stock and start from there. Ya the mixture screws were 4 1/2 out dropped them down to 2 3/4 now but she's still rich as hell... Love the bike just want better fuel mileage shoot my 2004 3/4 gmc crew cab gets 21MPG @55MPH... 25MPG behind a big rig drafting lol...

 

[ninjaneer]

looks overly rich. was this a plug chop off of full throttle pulls, or after pulling into the garage?

 

[DMAN999]

They should look like this:

 

[vmaxrooky]

Dang dman999 that looks really lean I like mine brown... I get paranoid so I run my stuff a hair rich but my max is overboard lol... Heard perfect was like a light tan? Like mine brown.. Lol ya 65 fury smelled my exhaust and said ya man she's runnin fat so I'm gunna fix that.. So stock mains are 152.5 so with marks pipes people are saying run 150's isn't that to lean?? Thought that from yamaha most bikes come lean here in Cali? So shouldn't I run like a 155? The jets in the diaphragm are 170 seems to be stock and the jets under the air box are 100 and should be 90? Right? Gunna pick up some stock needles how do I get the .30 shims/spacers? Who has them?

 

[vmaxrooky]

Ah looked at your plug again looks pretty dam close to perfect.