Turk/ jetting anyone? SRX big bore

S

snowprophet1

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Joined
May 2, 2003
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120
Location
Waterford, Pa.
Here is my info so far...at ANY steady rpm, it runs like it has a studder box. (This is the first ride on the fresh motor, so I never tached it above 7,000 rpms). At ANY rpm, when opening the throttle for accelerating, it is snappy and clean and right there, as long as you are opening the throttle. EGT's are running high 800*F to 1,000*F. With the fuel screw remote adjusters, I went from 1.5 turns down to .25 turns, and it didn't cure it anywhere. At an idle, you can turn the screws in all the way, and doesn't seem to effect the motor at all. Not much time on it for a readable plug color, but they were not black and wet. Setup right now it 42.5 pilots, needles raised 1 clip up (clip on the forth one down from the top) and mains are 157.5 pto, 156.3 c, 156.3 mag . Stock airbox. 780 big bore, nikasil cylinders, stock transfers, main exh very slightly raised and widened, aux exh ports are raised (but still .080" lower than the main exh port) widened deepened and follow the top of the transfer down at an angle (for more exh duration but probably a little more short circuiting than stock), boost port slightly raised, stock pipes/carbs. Pistons are coated, running .004 piston clearance, squish is .054", and compression stock. Running 93 octane. I don't think it's my porting, because if it was, the "unclean" sounding rpm would probably be a constant. It will sound nice at any rpm as long as you're moving your thumb in the right dirrection. I will probably go richer on the needle, just to try it in the "safe" dirrection, but it sounds gurgly fat. If the egt's weren't up into the 1,000*F range, I'd say it was rich. My guess right now is that it is a fat pilot (because throttle responce is good), but I'm all ears! THANKS!!! :cry:
 
42.5,s is the stock pilot for a 700 srx & they are allmost lean. I think you need larger pilots. Try turning choke 1/2 on & see if that helps a bit.
 
First, if the pilot is too lean, can it still burn up, or can only the needle pos and mains burn it up? My latest info...I used to have a tempaflow on when stock bore, and a cold air kit. In the airbox,I put back the shelf, taped lid where it was cut out, and taped the hood opening for the cold air kit. I strapped on a big (stupid) set and tryed 'er out at a short full throttle blast. It started to pig out down to 6,000 rpms. (rich mains). I pulled the duct tape off the lid of the airbox cutout, and it now started to pull some rpms at full throttle (but still not good). Then I pulled the tape of the cold air hood opening. Now it pulls clean on full throttle (which it consistanly wouldn't before) and the r's jumped up to the 8,400 range. It never had a good range between the needle zone and the mains coming into play. My thoughts are that maybe the needles are a little rich also. The plugs are starting to color, and look black/grey. I was considering putting the tempaflow back in the circuit, which would lean it all out a little (I would first tape everything back up). It's already mounted in the airbox, just disarmed right now (vent hoses open under the hood, and carb top hose plugged on carb). My egts went from a high of 1,000*F to 1100*F. If I decide to carefully test it w/the tempaflow, can it seize up coming off the throttle if the pilot is too small? Also- I just tried a quick flip of the choke part way and it fell right on it's face, and yes I do have about 3 oz of oil added to my tank. Thanks for your input!!
 
Pilot jets will contribute about 5% of the fuel from low end to wot. As i said the stock pilots on a SRX are pretty small for that motor. I am sure going up 1 or 2 sizes will help everything. Tempaflows can make the carbs do some goofy things. I would get the jetting close 1st then start playing with the tempaflow.
 
Try a 50 pilot and needles in the middle. The mains sound okay, but watch the egt's when running down the lake. The burble might just be from port timing and the way the pipe scavanges the exhaust. Use a gutted air box and the cold air kit. Stock reeds or v-force? Put the air screws at stock position (I think 1.5) just to get back to some sort of baseline. Check the air jets (in front of the carbs) and see if they are stock (1.0 I think).
 
Now its getting fun to ride again! It's pretty close now. I got rid of the studder box effect by dropping the needles back down 1/2 step at a time, until in the stock position, dropping to 40 pilots, opening the airbox back up and opening the hood back up to make the cold air kit functionable again, and at the same time, hooking the tempaflow back up! I probably changed jetting combos/airbox openings about a dozen times along w/messing w/the fuel adjuster screws. Currenly 40 pilots, stock clip position, 157.5, 156.3, 156.3, cold air kit (shelf still in), and tempaflow. I will try w/the shelf out next. (by the way, I have stock reeds, no spacers). Lucky for me, I've been using the crap out of my new digatron gauge. If you would run 'er wide open, you'd actually drop rpms for a second (and let off the gas of course), and not know what may have happened otherwise. I download my gauge to the computer, and within .01 seconds, you see the #1 cylinder egt drop like a turd, from it not being able to burn all that gas. Without the tempaflow hooked up, it will loose a plug on WOT. I have a few bugs w/the gauge/computer setups, but boy is this an awesome gauge! I turn the gauge on for the heck of it before I try and start it, and the egts are reading the same 28 degrees F that is on the thermometer in the garage! Talk about accurate! I am very impressed w/the performance and features of this gauge. DT-54= two thumbs up! I may play aroung more w/the pilot but it still seems to be rich on the bottom idle. I'll pick at it a little more every day. I was hoping to see my rpms go through the roof using the same clutching I ran last year before the big bore, but it's only over-revving a little, and the egts are in the 1200s already. I'll have to pick at this a little to get some more power out of it. Thanks for all your pointers guys! I appreciate it!
 
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