Ideal Jetting

SRX_700

SRX_700

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All,

What is ideal jetting and needle position for a 2000 SRX 700? I currently have 150 PTO, 148.8 Center and Mag (2001 jetting). Pilots are 42.5. Needle is in stock position. Sled and clutching is completely stock. I ride in 5 F - 40 F on trails (agressive) with the odd open field or road. Not WOT for too long. Here is what the plugs look like after riding 1/4 - 1/2 throttle for a couple of hours on trial. Plug to the left is the 150 jetting PTO cylinder.

Bit of an idle bog when I punch it with screws set at 1.5 turns.
 

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you should be good then.2002 SRX has the jetting down..147.5/146.3/146.3 but we do have DCS which helps us.We probably could even jet down 1 more time for a more snappy motor..after all..Snow Goer mag tested the 02 SRX and dropped it 12 jetting sizes and the DCS stopped a burn down...interesting.
Yeah stay with what you are running on the 2000.
 
Reason why I ask is that I am building a spare set of carbs and the mains I have are 156.3 and pilots are 45.
 
bluemonster1 said:
156.3 would be rich on a 0 C day..you'd really be smokin like a Semi Truck going up hill in Golden Bc..lol
Click to expand...

That is why I am asking.
 
check the charts on jetting..usually in the manual and I think you can find it on here.Look for the temps you are riding,your elevation and look at the suggested jetting they give ya.
 
sounds about right..wander if mine are right now..I am sure because noticed they were reversed before.oh well that's life..I have DCS..I am good .lol
 
srx190 said:
mag side cylinder runs hotter from the pipes that is why you jet that one up
Click to expand...


The larger jet on the right only applies to the 98/99's. It got switched with the new ign system I remember reading. The early srx's had waste spark, meaning the coils fire on an uncharged cylinder. Every coil fires every 120 degrees of crank rotation. only the piston at tdc lights the mixture ,the other two spark but do nothing because one is 120 degrees past tdc and the other is at 120degrees btdc.it's called a waste spark ign system for that reason.they changed it on the 2000 and up ones to the ign that only fires each coil when it's piston is at tdc ,this allows for a much hotter spark at the plug because the cdi only powers the coil that needs to spark in sted of having to power all three every 120 degrees
 
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There was some other variables also. Like the airbox dividers,porting,heads, and something else. I cant remember. It wasnt because of the pipes, It had to with the newer 3d ignition.

O.k I remember know, Yamaha jetted the 98/99's fatter on the mag side, yes due to all the pipes on that side. Then realized that the clutch side gets hotter and the left pipe exhausts has further to travel to exit, along with the ign changes. So it got swapped in 00.
 
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motorhead327 said:
There was some other variables also. Like the airbox dividers,porting,heads, and something else. I cant remember. It wasnt because of the pipes, It had to with the newer 3d ignition.

O.k I remember know, Yamaha jetted the 98/99's fatter on the mag side, yes due to all the pipes on that side. Then realized that the clutch side gets hotter and the left pipe exhausts has further to travel to exit, along with the ign changes. So it got swapped in 00.
Click to expand...

If that is the case, then why isn't the pilot jet bigger, needle position richer and fuel screw adjustment richer? Only 3/4 - WOT fuel circuit needs to be richer? I thought most of the fuel circuit uses the needle jet when riding. Besides middle throttle is leanest in the fuel curve.

Now I am confused.
 
Pilot jet provides 3-5% fuel throughout throttle settings. Jet needle / needle jet control mid range fuel delivery and main jet 3/4 throttle position and up... once needle no longer controls fuel flow from main jet. Soooo... my "UNDERSTANDING" would be that the larger main jet controls only 3/4 to WOT and is the reason why clip/washer position on jet needle for mid range tuning is so crucial - varying load on motor while at cruising speed creating more heat, then factor in ignition curve...and now we let the smarter people chime in...LOL!
 
Got the 2001 SRX carbs today. 40 Pilots and 152.5 PTO, 150 Center and 150 Mag. This sounds to rich for the mains. Needle position was in 4, changed it back to 3. Should I go back to 2000 stock and get 147.5 PTO and 146.3 Center and Mag? I have currently 150, 148.8 and 148.8.
 
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