Stock Jet question

[D-Max2012]

Hey guys,
I was wondering if anyone is running stock Main Jets with the setup as stated in the manual.
Carb 1 and 3 Mukini 152.5, Carb 2 and 4 Mukini 150.0
I've been looking at the threads and it seems like people are running the same Jets on all 4 carbs.
I have F.P. Needles shimmed to center position. (Copied from post on needles)
I was just wondering, If your running it like the manual says, how many turns out are you running the idle screws, and are they set slightly different between the different carbs?
I've noticed that carbs 1 and 3 while adjusting the idle screw, the engine will noticeably change RPM (almost cut the engine off), but when you adjust 2 and 4, you don’t hear any change at all. Is this normal?
Sorry if this is V-Max 101 but I just this bike last year, and have been working on getting her running correctly for months now. After all the work I've done, yesterday was the 1st time I actually felt the V-Boost kick in..
OMG!!! What a rush!!!! :biglaugh:
I'm now trying to iron out the idle circuit. When coming off a high rev, I pull the clutch and the RPM drops till it cuts off. I've been playing with the idle screws and now it doesn’t cut off, but it will drop to like 500RPM before getting back up to 1K. It takes about 2-3 seconds. I think I'm on the right track but it’s a pain trying to adjust 4 carbs.

 

[06VMAXIMUS]

Have you sync'd the carbs yet? It will run like poop if you don't sync em.

 

[D-Max2012]

"Have you sync'd the carbs yet? It will run like poop if you don't sync em"
Yup. Synch them up with the Sync master pro (Blue liquid one)..
This is the 4th time I've synched them up.
Not much to it, once you've done it a couple of times..
I was wondering if others have the same experience with the pilot (idle) screws on carbs 1 and 3 (the ones closest to the family jewels)..:biglaugh:

 

[SpecOps13]

I'd heard the bikes came with mixed main jets. Has to do with the rear cylinders running a little hotter I believe.

I have the same number mains in all cylinders of both bikes although the sizes are different between bikes due to different exhaust. I set my Idle Screws to the same number of turns, averaging the settings and don't worry past that.

I also do the sync differently than others. I set the sync with fans running on the radiator and the RPM at 3,000. I don't care where the idle falls. I do care about the sync where the engine spends most of it's time. This has worked well for me on many bikes and over a lot of years.
Good Luck..

 

[D-Max2012]

"I also do the sync differently than others. I set the sync with fans running on the radiator and the RPM at 3,000. I don't care where the idle falls. I do care about the sync where the engine spends most of it's time. This has worked well for me on many bikes and over a lot of years."

Man, I was thinking the same thing last night. Why pay so much attention to where the bike idles and only blip the trottle while synching. I should synch for crusing RPM's, which is around 3-4K. When I blipped the trottle, I did see them go off a bit while synching. I will synch again before the weekend. GREAT POINT!!


So you're running the same mains all around. Well, that makes things a bit easier for setups. I wondered why they would have different mains in the rear set of carbs. It would make sence that they're trying to keep all cyclindars the same temp.


Would'nd that cause a mix-match in power across the front and rear bank of pistons though? Seeing that the flow rate would be 150CC / min vs 152.5 on the same sized piston. Maybe its nothing to worry about.. :hmmm:

 

[Rusty McNeil]

Im just thinking out loud here, so no one shoot me ok? I'm just tuning through my own thought process. Feel free to educate me.

At idle, the range of synch adjustment is pretty much 100% of the total opening at that point. Meaning you could choke it down all the way and cause one cylinder to barely or not at all fire.


That range of synch adjustment is a fixed mechanical amount, regardless of total throttle opening.

As butterflies are opened to a greater degree, that fixed range of synch adjustment becomes a smaller and less significant portion of the total butterfly opening.

I don't see how synch really has much impact on things other than at idle and slightly off idle throttle positions. Once the butterflies are opened very much I don't see how it could. Its such a tiny percentage of the total opening.

I still think synch is to simply get it to run right, and on all four carbs, at very minor butterfly openings.


Thoughts?

 

[Diablotin]

Interesting...

I always wondered why when synching at 1500 rpm I was seeing the carbs slightly unbalanced at 900rpm.

Sent from my GT-I9100 using Tapatalk 2

 

[D-Max2012]

I always wondered why when synching at 1500 rpm I was seeing the carbs slightly unbalanced at 900rpm.

Has anyone else seen where their sync is around 3 or 4K (other than SpecOpts), to see if they're balanced. I know that logically it would make sense that it would be in synch, but logic is always trumped by real world analysis. Scientist said that the common Bumble Bee is not supposed to be able to fly. I guess the Bee didnt get the memo..

 

[D-Max2012]

Synced them up at 4K last weekend.. I did find that they were perfectly in sync at 1K but really off at 4K.. Put the fans on the radiator and synced them up and its running a lot stronger at cruising RPM..

 

[tugla]

What's the rest of your bike set up, exhaust, air box or pods, etc.

I think you shold set a/f screws to 2.25 and put needle on clip two from top and give it a try.....if you have aftermarket pipes.

 

[dannymax]

What's the rest of your bike set up, exhaust, air box or pods, etc.

I think you shold set a/f screws to 2.25 and put needle on clip two from top and give it a try.....if you have aftermarket pipes.

+1 Need the whole picture. If stock pipes run 152.5 mains on all 4 carbs with mixture screws out 2 1/2 turns each. Stock needles also.

 

[D-Max2012]

What's the rest of your bike set up, exhaust, air box or pods, etc.

Modded Stock pipes(Baffles removed from Previous Owner),
Stock Airbox.. Stock Filter
Right now, No Shims on needles.
A/F screws out 3.5 turns
Tank Coated with KBS, carbs and filter, crystal clear.
Brand new carb boots, no leaks on others.
Synced up carbs at 4K

 

[one2dmax]

Install 150 or 147.5 MIKUNI (not dynojet) mains. Shim the "Y" up with a couple of washers (do not remove completely). You may be able to turn in some of the A/F setting unless that is absolutely where it must be to get good throttle response.

This is a water cooled engine. The front and rear cylinders maintain very consistent temps and do not need different jetting from the front to the rear. That was on the air cooled bikes where the front cylinders had a greater cooling effect.

 

[sdt354]

Man, I was thinking the same thing last night. Why pay so much attention to where the bike idles and only blip the trottle while synching. I should synch for crusing RPM's, which is around 3-4K. When I blipped the trottle, I did see them go off a bit while synching. I will synch again before the weekend. GREAT POINT!!


I set sync at a low idle speed (900-1k), then do the idle A/F adjustments. You can hear the engine changes very well this way while adjusting the A/F.
My, final sync I do off idle. Around 1800 rpm for a nice crisp throttle response. Then I reset idle speed to spec. +1 to could care less about idle.
Steve

 

[tugla]

+3 on last three post....
chg needle and air screw settinga and have a happy bike set up. if u needle stock needles I got a set I'd make a deal for your factory pro ones..