av7 phbg question


malossi 62cc


maloss bendy air filter

85 main

45 idle

needle second from leanest

plug looks good on WOT, still a little lean in the idle/mid range.

im trying to retune since putting on the filter. previouesly, with no filter, i was running the followng: 92 main, 2nd from richest needle setting, 50 idle, and it ran perfectly. now, with the filter on, im gtting close, but its doing a few weird things. first, it doesnt seemt o hit the power band hard like it did before, second, the bike has weakis low end and, if i open to full throttle from a stop, it will four-stroke like a MFer, but it wont four-stroke at any other point in the progression at all.

i already leaned out the needle since installing the filter, i feel like i shouldnt lean it out any more, but i dont know what the deal is with that weird four stroke at only one point. any ideas whats up with that?

Re: av7 phbg question

Yo man....sounds like you're real close. Drop the needle all the way! I've done that on my Parma and I have about 800 miles on that thing. Piston and cylinder are as mirror shiny as the day I got it.

Also...I've never run an air filter! I had the same problem as you do, so I just took it off. Kit runs so much better without it.

I would drop the needle all the way, and then run it. If it's still a little weird, mess with the air mixture screw. Screw it all the way in, and then one turn out. Try that.

85 seems about right, but I would also try an 82. That number sticks out in my head, for some reason. I've got a whole range of 80's dellorto jets if you need one.

Don't give up! It's going to run great. You're really, really close.

Re: av7 phbg question

yeah dude with a rear facing carb you will NEVER really need an airfilter. fyi peugeot even developed a racing carb sans airfilter. i wouldnt stress it. BUT if you are determined- it just sounds like you need to downjet yr idle. even with a 45 its super rich with a filter. I can only run a 48 in my 21phbg because i dont use a filter. try a 40. everyone runs rich idle jets with phbgs anyway because they come with rich jets.

also, if you say yr midrange feels lean just richen the needle.

Re: av7 phbg question

i was thinking it was the idle jet too, but the weird thing is that it only frou-strokes when i go from a DEAD stop to WOT. if im going literally 2 mph it doesnt happen. whats more, if if does do the four-stroking thing, i can cure that by just opening the throttle gradually.

anyhow, i pretty much have it all tuned now except for that one thing, so im probably just going to keep running the filter unless it turns into a real hassle.

Re: av7 phbg question

ps with no filter i was running 92 main, 2nd richest on the needle and a 50 idle. ran great, with room for further tuning im sure.

Re: av7 phbg question

Oh - then you're in a pretty good place then. I'm in agreement then....idle jet is too big. I actually think I'm in the same boat, but not quite as bad. I won't four stroke, just bog a _hair_. As soon as it revs, it's fucking hold on for dear life.

You know what my call would be in terms of the air filter, man.....take that shit off and RIP!

Re: av7 phbg question

the biggest frustration I had learning to tune a phbg is it's nearly impossible to tune via spark plug if your idle jet is too rich. So by making it leaner, you'll take care of that problem too.

Re: av7 phbg question

man, annoying. i downjetted to a 42. sounded and felt a little lean at idle. cant tell - i may have picked up a little pep, but the problem still pops up: four strokes like amotherfucker if i open it up ALL THE WAY from a dead stop. but if i open the throttle gradually, i can get into my powerband and rip. i FEAR running a 40. but maybe i'll try it?

right now im at

85 main

2nd leanest on needle

45 idle

malossi filter

im running lean somewhere in there, though it doesnt actually feel lean when riding. but i keep coming back with a little white on my plug.

Re: av7 phbg question

i realized something about my bike. i am never going to be able to set the idle correctly because im using a stock, modded throttle assembly. because it only drags the slide a short distance, i have the cable tightened to open all the way. what this means is that, though top end is great, at idle the slide is opened way more than it needs to be. this is fine in an SHA where the idle progressions passes through the barrel, but in a phbg, the slide can be almost 100% closed and still idle fine through the idle jet. in effect, then, when im adjusting my idle im not really relying on the idle jet at all. im really measuring the output of my needle, which is no good for obvious reasons.

Re: av7 phbg question

get a nice throttle for yourself! im using a treats magura w/ choke lever as a decomp and it works dandy. pulls a lot of cable.

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