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Discussion Starter · #1 ·
would i need to change the fuel screw setting or setup the pilot jet to fix this issue thanks
 

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Discussion Starter · #3 ·
im using a stock needle and i want to say i already shimmed it
 

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Captain Zoom Sand Pirate
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Dead idle- throttle shut = Mixture screw
Idle to 1/8 throttle = pilot jet
1/4 to 3/4 throttle = needle
3/4 to full throttle = main jet
Now there is some grey area but these are the basics. The idle and the mid can be affected by the pilot. The pilot can affect the needle. Those areas take a little time. Once you get a good base tune you can make adjustments much easier for altitude and air temp changes. I usually make sure the main jet is right first then tackle the other aspects.
 

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if u have stock needle and u did the ol flipy washer trick with fat on bottom and skinny on top, u can also run the skinny on bottom to richen it up, u dont need a washer on top anyways,
 

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Discussion Starter · #6 ·
what is the best way to tell if your are at 1/8th or 1/4th thorttle? im not really 100% sure its going lean if you just touch the gas like crushing around slowly


Dead idle- throttle shut = Mixture screw
Idle to 1/8 throttle = pilot jet
1/4 to 3/4 throttle = needle
3/4 to full throttle = main jet
Now there is some grey area but these are the basics. The idle and the mid can be affected by the pilot. The pilot can affect the needle. Those areas take a little time. Once you get a good base tune you can make adjustments much easier for altitude and air temp changes. I usually make sure the main jet is right first then tackle the other aspects.
 

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Discussion Starter · #7 ·
took the stock needle out and i got the fat washer on top and the skinny on bottem so if i understand this right the needle is set as rich as i can with a stock needle?
 

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put the thick washer on the bottom,that will raise the needle,thus make it richer,try that first and see if it helps,try one thing at a time so you know what fixes it.good luck
 

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The correct way to do it is use the larges pilot jet that will yield the correct idle a/f with the idle screw at least one full turn out with the stock needle in the stock position...

Then select the main jet that yields the fastest acceleration from a stop to 300'...

Very simple... works every time... and if you do this and your a/f gauge is accurate you will have an idle a/f of around 12-12.5:1 and a wot during max acceleration a/f of around 13.5:1...and around 13.0:1 at top speed...

Then if you were to put it on a chassis dyno you find that there is nothing left to gain...by jetting or adjusting the needle...or so close to nothing it might as well be nothing...

Our jet kits have exactly what you need to dial in a stock carb for any intake/exhaust motor mods...
 

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Rutting, I ordered a jet kit from you today, and am going to try your method out this time around tuning my 660 (although a little different than how I've done it in the past with different carbs).

My question is, how does your method take in to consideration part throttle operation? It seems its only tuned for idle, and WOT..?
 

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The correct way to do it is use the larges pilot jet that will yield the correct idle a/f with the idle screw at least one full turn out with the stock needle in the stock position...

Then select the main jet that yields the fastest acceleration from a stop to 300'...

Very simple... works every time... and if you do this and your a/f gauge is accurate you will have an idle a/f of around 12-12.5:1 and a wot during max acceleration a/f of around 13.5:1...and around 13.0:1 at top speed...

Then if you were to put it on a chassis dyno you find that there is nothing left to gain...by jetting or adjusting the needle...or so close to nothing it might as well be nothing...

Our jet kits have exactly what you need to dial in a stock carb for any intake/exhaust motor mods...
ya,what he said,you da man craig!!!:banana:
 

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Ben I thought that was you but I didn't want to ask... lol... it already shipped and you might get it Saturday...

Yes I wouldn't say it was that simple for a carb with a cable-controlled slide...it just works out that this carb takes care of itself the rest of the time if you have the right pilot jet and main jet...

The right pilot/main combination with the stock needle in the stock position will give you max power from stop to top...

When you are at part throttle the diaphragm automatically self adjusts according to air flow...

However for the correct amount of fuel to be metered at that point you have to have two things...good air flow...and the correct jets...

If the jets are selected with the needle out of position then you will wind up selecting the wrong jets to compensate for it...

All moving the needle does is skew the curve up/down it doesn't really change it...of course you can get into semantics and absolutes and ague both sides of that till the cows come home but results are what matters...

Fine adjustments to the needle are not a problem for all out perfection once better results cannot be obtained by jetting but at that point it is truly hair splitting at best...

And here it the best part about it...

It is supremely simple...and if you let the stopwatch pick your jets and methodically prove to yourself that you acceleration cannot be any better...and for some reason you are able to make some other adjustment that somehow works better for you for any reason you will not have left anything behind or be compensating for errors made elsewhere...

I thought you abandoned the 660 for a long time ago... ???


THANK YOU MIKE... :)


The a/f gauge should be your friend...but some people are obsessed with it...

When your a/f gauge, stop watch, and spark plug color all tell you its good... you are golden...

The stop watch NEVER lies... but a/f gauges sometimes DO... and if you are not sure your spark plug will help you sort it out...

Again...some people tune by spark plug... IMO... for MOST people... including ME... that is a MISTAKE...
 

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Discussion Starter · #13 ·
i think i have a 50 poilt around 2-2.5 turns out on the fuel screw and a 165 main..with light throttle input like 1/8th or 1/4th not sure the exhuast will glow red after just a few mins of crushing wot is good idle is ok but just off idle goes lean
 

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Thanks for the response Craig! This is my last 660, and I won't have it much longer, but I wanted to dial it in as best as I can before selling it. Its always been a little rich since I got rid of the overly loud Ron Woods exhaust.

Ive never spent much time messing with the stock carb, only the HSR45. That must be the difference, the cable operated slide...
 

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i think i have a 50 poilt around 2-2.5 turns out on the fuel screw and a 165 main..with light throttle input like 1/8th or 1/4th not sure the exhuast will glow red after just a few mins of crushing wot is good idle is ok but just off idle goes lean
It sure sounds like needle adjustment needed as you have some really big jets in there already.
 

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Craigs kit and way of jetting works, he put alot of time and testing into this and i think it has worked for everyone using it. My dad and i both have the kits and they worth it just take your time and it will come out perfect.
 

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i think i have a 50 poilt around 2-2.5 turns out on the fuel screw and a 165 main..with light throttle input like 1/8th or 1/4th not sure the exhuast will glow red after just a few mins of crushing wot is good idle is ok but just off idle goes lean
Something is seriously wrong with that...

Are you sure you don't have the stock 40 pilot jet in it...

2-1/4 turns out on the idle a/f screw would be insanely rich for a 50 pilot jet...

2.5 turns out for stock 40 would be right but the 40 and you can do that but it will run better with at least a 45...
 

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Discussion Starter · #18 ·
im sure its a 50 and yes it was pig rich and never wanted to idle great i played with the needle some today and no more lean also chnaging the washers on the needle let me back the fuel screw down to about 1.5 turns

i think i have a 50 poilt around 2-2.5 turns out on the fuel screw and a 165 main..with light throttle input like 1/8th or 1/4th not sure the exhuast will glow red after just a few mins of crushing wot is good idle is ok but just off idle goes lean
Something is seriously wrong with that...

Are you sure you don't have the stock 40 pilot jet in it...

2-1/4 turns out on the idle a/f screw would be insanely rich for a 50 pilot jet...

2.5 turns out for stock 40 would be right but the 40 and you can do that but it will run better with at least a 45...
 

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Discussion Starter · #20 ·
will do ill back it down about a half a turn tomorrow am and see how it does
 
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