hard starting?

Fenix169motox

Fenix169motox

Location
Northwest Ohio
Hey guys my ski's bein a B****** to start. always has been since i did the carb + exhaust

i've been tuning it and the high end is perfect, but the low end is rich, really rich. and i' can lean out the bottom end scew the whole way and its still rich. is that pop off? i have an sbn 44 and fpp on my 750sx.
120 pilot and main jet. silver pop off spring.
in order to start it i have to push the throttle half way then it finally starts real slow, sputters a LOT then as soon as i get half throttle its all good in the hood. any suggestions on where to start? oh and when i jump it revvvvs a lot. i know if its lean then your idle doesnt return quickly..
 
Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
popoff might be too high... but check compression first... do you have a popoff tester? You have to messure popoff somehow... I have a tester if you want to bring it to lake this weekend, or you can try and fab up something yourself... could do it with a bike pump and a decent pressure gage if you have the motivation...

And if popoff is too high you would be really lean on the bottom (not rich) making it about impossible to start/idle because the manifold pressure would not be high enough to pop the needle off the seat to refill the diaphram... that is until you crack the throttle open and the higher pressure coming through the carb takes over and pops it...
 
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Big Kahuna

Big Kahuna

Administrator
Location
Tuscaloosa, AL
Pro-pulsion said:
You learn something every day, I didn't know 44s ran such a wild set of numbers :scratchchin:
Click to expand...

there is an infinate number of jetting combo's out there. some run smaller jets on bottom and higher on top and vice versa.

You would be shocked to see the different jetting specs on STOCK Class SXR's. Same motors, same carbs but there are so many combo's out there. at one time Farthing, Jetworld, Jazzmotorsports, and several others were spec'ing their own "jet kits"
 
Fenix169motox

Fenix169motox

Location
Northwest Ohio
Pro-pulsion said:
120 pilot? pilots are typically from 60-75 and mains range from 120 and up. Look around the Mikuni site and try to locate the specs on that carb...I can't see the pilot being correct.

http://www.mikuni.com/fs-manuals.html
Click to expand...


according to my mikuni owners manual the jett that my carb should have in it is either a 120 or a 100 pilot, thats right out of my book for the bn 44 so i dunno why a 125 is in there, its etched right into the side of the pilot jet and on the top of the main jet.. both are 125 :( fail lol

where would i get different size pilot jets for that carb anyways?
 
Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
you have to mess with the jetting and popoff... its not as simple as looking up what jets your carb should have from the manual... it would be nice if it was that easy....

you have to test the jetting by running the ski... I'd start by checking your popoff pressure.... I'd get it down to around 32ish... you can try to use the chart in the manual, but that chart is not that accurate from my experience... but it may get you close... you'll have to pull the seat out of the carb to see what size needle/seat you are running... it will be on the side of the needle...

I suppose the needle could be leaking bad too that could cause it to run crappy until open throttle.... might want to replace it if its old
 
Fenix169motox

Fenix169motox

Location
Northwest Ohio
ahhh ok. i'd need a pop off tester thing tho. no has.. but as for the needle its fine, no dents or anything..



AND as for my hard starting,my starter just went out.... need one for e 650sx or 750sx :( the solenoid clicks, the starter just buzzes and its not the bendix.. you can turn the motor over by hand.. gonnna tear it apart today
 
Fenix169motox

Fenix169motox

Location
Northwest Ohio
??? pipe plugs like for threading into something? i was thinking to make a plate out of steel and putting holes in it for the bolts to go over the manifolds. and where would i hook up my pop off tester?
 
SUPERTUNE

SUPERTUNE

Race Gas Rules
Location
Clearwater Fl.
Use blockoff plates with some plumber's rubber from Lowe's or Home Depot.
Keep the sparkplugs in.
Hook up the hose to the Pulse Line fitting in the intake to do a pressure test.
A simple brass 'T' with a cheap gauge to test at about 7-8 psi for 3 minutes.
 
Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
usually you get the pipe plugs that are like rubber circles with a metal top and a butterfly screw thing on the metal so when you put the rubber in the intake or exhaust manifold hole you screw the screw and it expands the rubber to seal it... you can also make one like you said with gaskets... then use the pulse fitting to attach your tester....
 
Ericfox

Ericfox

Do it twice?That's DooDoo
Location
Akron area --> OHIO!
you can get the pipe plugs like Ive used from an auto parts store... they have different sizes that expand a certain amount so make sure if you want to get that kind that you measure your intake and exaust holes before you go to the store and get the size under the hole size you measured....
 
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