Advanced Tuning Dudez and Ladies Help Please!

I started tuning my e50/polini/casematched/4-reed/race crank/dellorto 19 this weekend and I have a couple of questions for you rad tuner dudes.

1) Put bike up on stand, warmed engine up, set idle highish, and then set my mixture screw. Seems best at about half a turn out. Does this mean I need a smaller idle jet so that my mixture screw can come out another half turn or more?

2) At any jet that I tried from 103-118, my engine would sputter and run real rough when I tried to go past half throttle. I left the 118 in and started playing with the needle settings and the only way I could get up close to full throttle was with the needle (a W7) set in the leanest position. Still sputters now from about 7/8ths-throttle to WOT but I figure that might be due to the 118. Does this mean I need to try a different needle? I was thinking I might need to get a slightly fatter needle. W8 has a taper 3mm shorter than a W7 or else the W10 needle which has a 3mm shorter taper also, but in additon to that the tip has a diameter of 1.8mm compared to the 1.4mm tip that the W7 has. Does that sound right to you guys?

I haven't plug chopped yet cuz I can't WOT, but my plug is starting to look a little better over-all with the 118. I might even want to go richer, but I'm not sure if that roughness at near WOT is because of the big jet or the fact that it still wants a leaner needle.

Advanced-tuning advice greatly appreciated here.

Thanks!

Re: Advanced Tuning Dudez and Ladies Help Please!

Oh yeah when I said I think I might need to get a "slightly fatter needle" I meant fatter as in leaner-running, not fatter as in richer-running.

Re: Advanced Tuning Dudez and Ladies Help Please!

I would set the needle in the middle with whatever needle came with the carb, then work on getting the main jet right first. If your stuttering at WOT it is probably a main jet issue, I would adjust the main jet until you run smooth at WOT then start to work with the other adjustments.

When I put the 19mm dellorto on the G3 choppyness at WOT was due to too large of a main jet.

Re: Advanced Tuning Dudez and Ladies Help Please!

ok so to sum it up:

19mm phbg

118 main

w7 needle leanest setting i.e. the clip is in the highest position.

50 pilot? brass screw 1/2 turn out.

My 1st assessment would be to go with the 8 needle and try it in the one of the middle clip positions. In attempt to install a needle that isn't in one of the farthest clip positions.

I would not go with the fatter tips #10 just to be on the safe side for now (we all know how finicky polini is). One thing at a time, maybe if there is no difference between the 7 and 8 try the 10.

try to get the bike to run as it is now with the w8 with out needing to put it into the leanest clip position (ideally the richer mid slot)

now the bike hopefully feels good up to 7/8th throttle then it 4strokes. lower the main jet one or 2 numbers at a time till the 4 stoke goes away and the motor revs up to max rpms at WOT.

Be careful here tho there is a point where the motor will not respond any differently from 7/8 to wot (or still a bit faster at 7/8). This means your tuned up well but on the rich side, if you try to tune out this you might find yourself seized. I always leave my bikes a bit on the rich side, when u run hard the motor will heat up and be able to burn this extra fuel more efficiently after riding for a while.

as for the idle jet I like it a bit rich too, you don't want to drop the throttle too fast downhill and sieze cuz ur carb can't supply enough mix to lube up the kit at high RPMS when the slip is closed.

Overall take it slow and keep it lubed, only down jet more when you feel confident in the motor, you can still hit 60 at 7/8th throttle. Also watch out leaning the needle positions with a leaner needle, I have experienced a hard seize from a single needle clip movement.

Re: Advanced Tuning Dudez and Ladies Help Please!

I got a 106 jet in the same set up and Im rich at wot. So try to get that main jet in the neighborhood first.

Re: Advanced Tuning Dudez and Ladies Help Please!

Yeah, thats what I figured, too. Get the main right first. The problem was that I was running pretty lean with the 103 and I couldn't get up past 1/2 throttle at all without the engine wanting to die. So I started going up in jet sizes and my plug started looking a little better each time but I still couldn't get past 1/2 throttle. So when I reached 118, I thought I'd lean the needle one notch and then I was finally able to get to abot 3/4 throttle. Then I leaned it all the way and I was able to get to 7/8ths before the bike started getting rough and wanting to die. Thats what is leading me to believe that the problem is with the needle selection.

Re: Advanced Tuning Dudez and Ladies Help Please!

Radness. Thats what my plan was... put in the W8 at the 2nd richest clip setting with everything else the same, readjust my idle and mix screws up on the stand and see how it feels after that. maybe lower one clip position to the 2nd leanest if I absolutely have to and then mess around with the main jet again if it still doesn't feel right.

One more question about the pilot jet... couldn't a small pilot jet with the mixture screw turned out like say 1-1.5 turns run richer than a bigger pilot jet with the mixture screw at half a turn out? It kind of scares me to have to turn in the mixture screw to just half a turn out.

Thanks for the great advice elliot!

Re: Advanced Tuning Dudez and Ladies Help Please!

oh yeah and you were right, 50 pilot...

Re: Advanced Tuning Dudez and Ladies Help Please!

hmm. what needle is in your 19? Not sure if Chicago atmospheric conditions could play a part it that equation? I know that MattW has run similar setups here in Cincinnati with up to a 118/120.

Re: Advanced Tuning Dudez and Ladies Help Please!

it is possible to run the mix screw a bit more out with a smaller idle I suppose but unless its really a big issue I'd just turn the mix screw out another 1/2 turn keep it a bit poppy and call it a day.

I'm gonna stick with keep it rich at least till after a couple hundred miles or so.

Also the mix screw and pilot jet do in fact effect wot and all positions to there given it might only be by a jet number or 1/2 of one it has an effect. keep that in mind if you decide to change the jet etc.

most ppl who jump into the PHBG game don't understand that the needle jet is very important and effects alot more than the main. its important to make sure its not running too lean.

Re: Advanced Tuning Dudez and Ladies Help Please!

How's your ignition set? Are your points clean, are they set to 0.35mm? Makes a pretty big difference in wanting to rev or not wanting to rev.

And about the carb, the order is: Main jet, air screw, idle screw, needle and then idle jet. Don't do it the other way around, you'll get suicidal way before you get it running right. :P

So find the correct jet and screw settings and then start thinking about a fatter needle. And you might need some stiffer reeds, those can help prevent mid-rev stutter too.

Re: Advanced Tuning Dudez and Ladies Help Please!

I cleaned and set my points to the high end of the service manual specifications which is 0.018in (0.45mm). I started out with a 103 main jet. I'm kind of afraid to go any leaner than that. I mean, I could set my needle back to the 2nd richest clip setting and try to keep going down jet sizes until I can get past half throttle, but don't you think that 103 is already kind of lean for this setup?

Re: Advanced Tuning Dudez and Ladies Help Please!

So I have 2 choices then.

1) Put in a W8 needle on 2nd richest clip setting and a 118 main jet and see how it runs.

2) Leave the stock W7 needle in, put it back to the 2nd richest clip setting and go back to a 103 main and start working down in jet sizes from there.

Re: Advanced Tuning Dudez and Ladies Help Please!

I didn't say that you need to go down 103. Where the hell did you find a 103 anyway? Here Dell'orto jets only come in even numbers.

What I did say is that you need to find the correct jet. Go by feeling, throttle response and plug color.

If the plug is brown with jet 103, you can easily go down 3 sizes to a 100 and see what it does then :P

Experiment. Don't let it get too hot tho when trying out new jets.

Re: Advanced Tuning Dudez and Ladies Help Please!

yeah, i know what you're saying. the problem is that I haven't been able to get to wide open throttle at all without the engine wanting to die. The closest I've gotten is 3/4 throttle with a 118 main and the needle on the leanest setting. even then the plug is just starting to get tan colored. If I have the needle set on anything except the leanest setting with any jet between 103 and 118 I can't get past 1/2 throttle or the engine will die.

Re: Advanced Tuning Dudez and Ladies Help Please!

your tuning issues are in the needle, not the main.

Re: Advanced Tuning Dudez and Ladies Help Please!

Hmm, try a fatter needle then.

Pretty strange situation, never had a needle that was so thin it couldn't make the engine run anywhere near proper.

Re: Advanced Tuning Dudez and Ladies Help Please!

smaller jets is all i think is necessary

Re: Advanced Tuning Dudez and Ladies Help Please!

yeah. i'm waiting on some stuff from dellorto direct and then i'll be able to experiment. thanks again for the help guys. i'll update soon.

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