new ESR 310 build jetting check?

[jfwyatt1]

ESR 310 PV cylinder pump gas dome, trx7 porting, 38 a/s, trx5 pipe, oem ignition, B8es plug, 4gal 93 non eth pump mixed with 1 gal sunoco 112 36/1 lucas 2500 ft got everything installed and did my heat cycles sat. got it out and rode it around the feild makin sure to lug it some let it cool off then did it again for about half a tank then started dailing in the jetting some as it was way too rich spooge out of silencer bad now ive worked my way down to a a 48 pilot  3/4 turns out, DDJ needle clip in 4th slot now started in 2nd, down to a 178 MJ started with 185. it seems to run good on low end and top end midrange has a slight stutter. also not sure if its the jetting or the PV (this is my first PV) plug is dark chocolate color so i know im still a little rich. i havent done a plug chop yet but will this weekend after i ride another tank thru it . should i lower the needle again or go to a DGH to see if that clears up the stutter? ive never had to lower a needle all the way before and i know the dgH needle is a bit leaner than the ddj. also havent checked compression yet after breakin was 175 before heat cycles.also should i drop down to a smaller pilot jet since im only 3/4 turns out?

[hontrx265r]

Ddj is a pretty rich needle go back to second clip. May need a leaner needle. Dej would be your next step then dgj. If your happy with bottom and top. Needles are cheap on amazon. Try a few so you can learn how they change the bike. I think the second clip on ddj is the same as 4th on dej. But dont hold me to it. My 310 is running 50/178/dej on 3rd lrd exhaust. But location bike combos change alot. Im in phoenix.

[Bowtie316]

If you are only 3/4 turn out on the air screw, then the 48 pilot is too small.

[Jerry Hall]

If you are only 3/4 turn out on the air screw, then the 48 pilot is too small.

.................or may need to go from a "J" diameter needle to a "H" diameter on the needle to richen the idle mixture and help the throttle response  


Unfortunately all carburetors do not respond according to the theory presented in the Keihin tuning manual.  


I would not base ANY carburetor settings upon how much oil is coming out of the exhaust flange or silencer.  How easy you are riding has a huge effect on how much spluge comes out of the silencer.

[Bowtie316]

.................or may need to go from a "J" diameter needle to a "H" diameter on the needle to richen the idle mixture and help the throttle response


Unfortunately all carburetors do not respond according to the theory presented in the Keihin tuning manual.

I'm sure your correct Jerry, but unfortunately thats all many of us have to go on. I wish I could send you all my stuff for fine tuning but it's just not in the cards.

[jfwyatt1]

i changed out the DDJ needle for a DGH and had to turn the air screw back out a bit more than half a turn to get it to smooth back out so im going to play with that needle some tommorrow i have the clip in the middle position now and it seems to be at least the same if not better from 1/4- 3/4 throttle still have a stutter but i think its a bit better than it was. im safe and rich with it rideable so ill put another tank thru her before i get real picky just to make sure the rings are seated good. thanks Jerry for the info . i have a 50 pilot i will try if i have any more issues with the low end response but right now i think im good air screw is just under 1 3/4 turns out. thanks for clearing that up Bowtie. ive read over this stuff so much i think i got confused on the pilot jet

[jfwyatt1]

ok sat. i ran another tank thru it and so today i ran it a bit harder with some full throttle moments and it is running great the wot throttle chop was white with a dark brown smoke ring looking at it with a light down toward the base of the porcelin. i did another 2/3 throttle chop and the plug was white so i think im still lean on the needle right now im in the 4th (from the top) slot on a DGH needle should i go back to the DDJ needle or should i drop another slot with the Dgh needle? im real rusty with my jetting skills and dont want to burn this topend up like the last 1. it runs beyond great compared to the previous oem cylinder. throttle response is real crisp

[Jerry Hall]

Be very careful trying to adjust the needle or main jet based solely upon what the spark plug looks like.  Tune it to where it runs good and monitor the spark plug and the top of the piston for the onset of detonation!!!!!!!!!!


We have to remember that the color of the porcelain is ONLY an indicator of the temperature of the Porcelain insulator and is not an indicator if the current jet is making optimum power or if the current jet will be a safe setting.  

Richen the main jet up 2 or 3 steps and make another wide open throttle chop.  I think that your will find that the look of the spark plug and smoke ring will not change very much if any but it will be richer and may start having a rich miss-fire at high RPM.

[jfwyatt1]

Be very careful trying to adjust the needle or main jet based solely upon what the spark plug looks like.  Tune it to where it runs good and monitor the spark plug and the top of the piston for the onset of detonation!!!!!!!!!!


We have to remember that the color of the porcelain is ONLY an indicator of the temperature of the Porcelain insulator and is not an indicator if the current jet is making optimum power or if the current jet will be a safe setting.  

Richen the main jet up 2 or 3 steps and make another wide open throttle chop.  I think that your will find that the look of the spark plug and smoke ring will not change very much if any but it will be richer and may start having a rich miss-fire at high RPM.

i went up 2 sizes on the main to a 182 still runs  great but has a very slight miss just before wot which im fine with it as i very rarely ever run past 3/4 throttle in the woods. i looked at the piston with a snap-on  borescope and it looked fine with no signs of detenation.  i did find 1 other issue the idle adjustment screw is broke off i did have to screwit just about all the way in to get a nice idle but evidentally i went too far. is there a brass alternative to the plastic idle screw? that is if i can get whats left in there out. thanks Jerry for all the input                                                           ( just spent an hour trying to get the broke idle screw out any tricks guys?