SuzukiSavage.com /cgi-bin/YaBB.pl General Category >> Rubber Side Down! >> How do I know if I have the correct jets installed /cgi-bin/YaBB.pl?num=1341881522 Message started by Greg on 07/09/12 at 17:52:01

Title: How do I know if I have the correct jets installed Post by Greg on 07/09/12 at 17:52:01 My jet kit came in over the weekend and I installed the 152.5 main jet and left the pilot jet alone. I only had a chance to ride it for 10 miles or so. When cold, low speed is much better. When warmed up, sometimes I get pops when letting off the throttle to shift, sometimes I don't. I get an occasional pop on hard decel. I bumped up my idle and some of the pops seemed to have lessened, but I could be imagining things. I read about the test for the pilot jet, to run WOT and back off 1/4 turn to see if it speeds up, but don't remember anything for testing the main jet. I have a HD muffler with a 1/2 hole drilled in the baffle. Stock filter (which needs replaced) and no other real or imagined go-fast things.

Title: Re: How do I know if I have the correct jets insta Post by Serowbot on 07/09/12 at 18:07:05 Read it again, Greg... It's a lot to absorb... Quote: run WOT and back off 1/4 turn to see if it speeds up That is the main jet test... only an 1/8th  though... ;)... Main jet change, shouldn't affect low speed much at all... Serowbot's carb tuning tips for beginners... (http://suzukisavage.com/cgi-bin/YaBB.pl?num=1309246277) Try to do any jetting adjustments on an average day... weather wise... Weather makes a big difference... particularly humidity... ;)...

Title: Re: How do I know if I have the correct jets insta Post by Greg on 07/09/12 at 18:17:38 So I guess I am pretty confused. I got the test backwards. Is there a test for the pilot jet? The big one in the middle is the main, right? That is the one I changed and I didn't need to use my choke to get out of my neighborhood without revving the engine. But you said that shouldn't affect that. Please put my head on straight!

Title: Re: How do I know if I have the correct jets insta Post by Serowbot on 07/09/12 at 18:25:18 Quote: A good indicator of overall jetting is the weather...if popping/backfiring increases on humid days, or at higher elevation, that indicates rich....less popping at those times indicates lean. Drill out the brass plug on the idle mix screw... adjust for smooth and steady idle... if it needs more than 3 turns out, go one step larger on the pilot jet. The pilot jet will have an effect on MPG's... If you want good gas mileage, don't get carried away there... CW, in, is going leaner,... CCW, out, is going richer... The needle jet is adjusted by varying the spacer thickness under the plate that mounts the needle to the slide... this has the biggest effect on acceleration and in the midrange area... Say 60+ mph cruising, and half throttle acceleration... To test the main, accelerate from 30 or 40 mph, in 4th or 5th gear at full throttle for several seconds, then reduce throttle by about 1/8,...if power increases for a second, you are lean on the main jet.  Go up one jet size and test again. Jets are incrementally additive.... starting with the idle mix, then pilot, then needle, then main...  Each jet adds it's volume to the next in line...  Wide open throttle is accessing all of them, so changes in one, adds to next and the next.. I start at the bottom, and work my way up.... idle, pilot, needle, then main...

Title: Re: How do I know if I have the correct jets insta Post by Greg on 07/09/12 at 18:30:15 I read that. It doesn't say how to test the pilot jet. Unless I am missing something.

Title: Re: How do I know if I have the correct jets insta Post by Greg on 07/09/12 at 18:30:58 Unless I need to go out more than 3 turns. I actually had to go in 1/2 turn when I put in the main.

Title: Re: How do I know if I have the correct jets insta Post by Serowbot on 07/09/12 at 22:40:10 Jetting without a dyno and proper air/fuel testing stuff, is a guessing game... Experience,.. seat of pants testing,.. and inference... You can get the main right with the 1/8th throttle drop... keep testing with bigger jets 'till the up-surge is gone... Adjust your needle jet in relation to that,... roughly... if you go up a step or two on the main... reduce the spacer for the slide to 2/3... if you need more main,.. reduce the spacer more... Adjust the pilot with that in mind also,.. but... the pilot is less critical, because you aren't stressing the engine at those rpm's... so, ere on the side of smaller with the pilot, as long as you can still adjust idle with less than 3 turns from full closed... This will help with gas mileage and won't hurt the engine or performance... Maybe I should add this to the tuning post I did?.. :-?... (I'm actually just realising that I contradict myself, somewhat)... You should do jetting from bottom to top,.. because each step affects the next... idle mix, pilot, needle, main... additively... ...but, to get a base point.. I'm testing the main, with the throttle drop test... then adjusting everything below from there... ... but, once you make those changes, you need to test the main again... Because, the pilot and needle have affected the WFO total... I will make some changes to the tuning post... I was stating proper procedure, as I have been taught... but, I realise now,.. that's not really what I do... I say,..  :-?... test the main, then adjust the other circuits proportionally... then retest the main... It ain't easy... ... and I judge my work, by observing how the bike behaves in humid weather, or at higher elevation... in those circumstances a well tuned bike, should start to pop just a little.. that's a lean pop.... and your well tuned bike should start to pop a bit when it's overly humid, or when you elevate more than 5k... I'm sure I add more confusion than clarity.... Sorry... Jetting is tricky... it's never right,.. just pretty good... even with pro equipment.. because the elements change day to day, and ride to ride... :-?...

Title: Re: How do I know if I have the correct jets insta Post by Greg on 07/10/12 at 05:48:31 I believe that explanation is pretty clear. Thank you.

Title: Re: How do I know if I have the correct jets insta Post by RanDaMan on 07/12/12 at 06:59:54 7C6A7D60786D607B0F0 wrote: Quote: Drill out the brass plug on the idle mix screw... adjust for smooth and steady idle... if it needs more than 3 turns out, go one step larger on the pilot jet. .... "as long as you can still adjust idle with less than 3 turns from full closed... This will help with gas mileage and won't hurt the engine or performance..." when i adjust the idle mix screw it seems to makes no changes to the idle at all? at least not as drastic of a change as the actual idle adjustment on the other side of the carb. and 3 turns from full close? :o I thought it was three turns out from factory settings?  :-?

Title: Re: How do I know if I have the correct jets insta Post by ZAR on 07/12/12 at 07:54:40 RanDaMan as I was taught and understand it.....all carb settings,from a lawnmower to motorcycle to a full-on race engine, you always start from a fully screwed in(gently,as in just when the needle touches bottom) position. Same as describing problems your mechanic...you call left and right from the driving position. Strange how many folks have never figured that one out :o

Title: Re: How do I know if I have the correct jets insta Post by RanDaMan on 07/12/12 at 08:13:06 OH, thanks for the heads up! ive been at three turns out from stock position for the past couple of days now  :o i hope that wont cause any problems with my carb!  :'(

Title: Re: How do I know if I have the correct jets insta Post by ZAR on 07/12/12 at 08:16:03 5A69664C69456966080 wrote: OH, thanks for the heads up! ive been at three turns out from stock position for the past couple of days now  :o i hope that wont cause any problems with my carb!  :'( You should be OK!

Title: Re: How do I know if I have the correct jets insta Post by RanDaMan on 07/12/12 at 08:24:17 FEW! (wipes forehead)  :D i thought i might of accidentally opened up a can of worms there!

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