pistons

coreybang

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Dec 19, 2012
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wabush
Hey guy's can someone tell me how these pistons look?
 

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The jetting is not stock either i am running with 40's and a 150 and two 148.8's at 1850ft. Am i asking for trouble or is that ok?
 

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I think they look pretty good like Tony says, you could likely use a 42.5 pilot in the srx, as I always changed out the 2001 to the 42.5's with aggressive clutching. usually have the fuel screws at 1 5/8 out with the 42.5's

you could "nit pick" the center one as it is a hair dryer and less carbon then the other 2 but its awfull dang close, a larger pilot would likely make ya perfect

OR.... if you want a tad more safety and do alot of wide open long running 1 size up on the mains. 152.5,150,150. If you dont do a alot of wide open runs then just add the 42.5 pilots.

(a pilot jet does still flow fuel even at wide open its still 2-3% flow even at wide open)
 
thanks so if i go with the 42.5 and the 152.5,150,150 will that make her faster or slower because i do go wide open pretty often. I also have a 51/43 helix with a www and a green spring. 4.5g in both holes.
 
coreybang said:
thanks so if i go with the 42.5 and the 152.5,150,150 will that make her faster or slower because i do go wide open pretty often. I also have a 51/43 helix with a www and a green spring. 4.5g in both holes.

it wont slow it down any but it will make it "safer", less chance of detonation starting on a longer pull and with todays crap gas, its cheap insurance for sure.


it will get a little bit better topend if youd use like a 51/45 helix, 43 finish is shallow for a srx and doesnt load the engine as hard.
with your current helix it likely over revs on topend some, so going up to a 45 finish with the rest of your primary set up should put you closer to the peak which is 8500rpm
 
Mrviper that seems really rich to turn the fuel screw to 1 5/8. In the manual it says 1 1/8. I really dont know what im at so can u voice ur opinion on why to go 1 5/8? Thanks
 
Cause 1-1/8 is too lean with todays crap gas and they usually have a idle hang. Having the fuel screws at 1-5/8 helps get rid of the idle hang. I had to set my buddies at 1-3/4 to cure his idle hang and bog.
 
coreybang said:
Mrviper that seems really rich to turn the fuel screw to 1 5/8. In the manual it says 1 1/8. I really dont know what im at so can u voice ur opinion on why to go 1 5/8? Thanks

I run mine (all 3 of em) 1.5-1.75 no problems. Figure out where yours are and then go from there. Cant really jump to "manual says" when you very well may already be at 1 5/8. Seems I read on here if you need to go out more than 2 you may want to adjust clips/needle position and start over....That may only apply to vipers though...not 100% sure.
 
coreybang said:
Mrviper with the 51/45 helix do i still set it at 70 degrees.

70 is good as long as it doesnt suck the belt, the looser the sec spring the faster the sled will go, but if your trail riding the backshift will be slower, 70-80 is good for snow.

try it and see where your at.
 
hey guys i installed the 51/45 helix and set it at both 70 and 80 degrees and when i take off it she goes to 8500 and drops back to 7500rpm. I haven't changed my jets to the 42's yet im still running 40's. Any ideas or what is my trouble.... Thanks
 
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coreybang said:
hey guys i installed the 51/45 helix and set it at both 70 and 80 degrees and when i take off it she goes to 8500 and drops back to 7500rpm. I haven't changed my jets to the 42's yet im still running 40's. Any ideas or what is my trouble.... Thanks

its more then likely overshifting, so you need to find out why, its either super good traction, not enough belt pressure in the rear clutch or the front clutch is getting in front of the engine power curve to uphold the load applied.

possible fixes:
1.) go to a firmer sec spring, silver sec is the next stiffest one if you cant hold it with the green dot one, but you would need to be getting serious traction on take off.

((You do have the green dot spring and not the red dot stock sec spring right?))

2.) put in a slightly stiffer front primary spring, use the stock srx yellow/white/yellow primary spring, it wont upshift as fast as raise the rpm slightly.
 
Yes I have a black spring with a green dot on the secondary. With the 51/43 she would stick around 8000. The snow is hard packed but I'm not running studs.
 
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coreybang said:
Yes I have a black spring with a green dot on the secondary. With the 51/43 she would stick around 8000. The snow is hard packed but I'm not running studs.

you need more front primary spring pressure then or remove some weight from the arms, i would just change out the primary to stock and see where your at, the w/w/w is 45/119kg and stock is 45/128kg. you could go to that and possibly add 1 or 2 spring shims and be spot on with the 51/45
 
Changed the primary spring to stock and still the same goes up to 8500 for a sec and then drops back to 7500. Would the power valves have anything to do with this? Also i checked the compression and im around 105 on all three cylinders. That seems a bit low to me... what do you think?
 
Low reading could be the gauge. Most important is they are within 5%. I had similar issue as yours and troubled shoot it for 3 years. Turns out my #1 plug fouls easier than the rest but if I run it hard, it holds 8,500. If I putt around and then pin it, it does what yours is doing. What does your plugs look like? Pics?
 


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