bogging at 25/30mph

ive changed my filter airbox to an open air filter & upped my jet to 80 but found out was to big so went dwn to 78 & now 76, ordered a 74 but i had a 70 jet in when had standard airbox on & 70 kit. i do all the tweaks & check spark plug but when go for a ride goes boggy @ 25/30mph
ive got a Gilera Runner SP 50 LC 2004 with polini 70cc sport kit, primaray gear kit, polini exhaust, polini varaitor & polini clutch (polini open air filter)

any help wud be greatful please

 

well would love to no why its bogging & not revving when hitting 25/30mph, like said doing all the tweaks to fuel & air mixture :/ think im gunna have to pop to bike shop on thursday when open & see what they say

 

I'm no mechanic on these scooters,but it does sound like you are running way too small on the main jet,that alone could give you the problems you are having,why not try jetting up to see if it gets rid of the problem for you.

 

well guess i could try upping the jet but i always thought bogging came from the jet being to big ? anit got really any idea about jets really

 

would you guys say i shud get a pack of jets ranging from 80 to 100 ? maybe 120 to be on safe side ?
as i have already got a 80 jet ?

just say a big thanks to everyone who has helped

 

Me thinks thats in the right direction,I am not hot on the best advise,but I would be going for much higher jet than an 80,start at somewhere near that sugested by Jonny (2nd post),or slightly more,& work down from that,go safe side or you can screw up the motor,then you will never get it right as the rings/piston will be in a state of decline,& thats an expensive pain in the pocket,always go large on the jets & work your way down.
If you get a partial siezure by running it hard & too lean you will never get your carb right until you have sorted out the messed up internals.
2 strokes are a superb thing,(and we are stuck with them),but they are liable to engine damage problems if run with not enough fuel to air ratio.

 

Thanks lads, ill grab a set of jets starting at 120 & work my way dwn the jets. Didnt think I wud need to go so high up on jets for just an open filter lol.
Will comment if have any other problems & again thanks lads

 

You have a bit more than an open filter going on here,what with an exhaust,a 70 kit,gear up etc.
The open filter is a big step up from the rest of it,matter of opinion as to if its a good move with the filter.

I wait to be shot down over this,but a modified airbox must surely give better results & consistency regards carburetion on this setup?

 

i no the filter want make any diffrence to performace but i wanted to get a better sound & mate of mine said shud get an open air filter as his aerox sounds nice with his on ( his high end tuned ped ). dnt really mind if lose abit of power as only live in a small town anyway & only work 1 or 2 miles away so all good there
just want a nice sound really

 

Yep, I understand that,but why mess up an already good sorted scoot for the sake of a bit of induction noise (from the carb), I know this, its how your bike performs & lasts that matters most in the long run,if you want to go high end it will take a lot of experience, then do it knowing that it will want a good tuning shop,or a lot of experience with 2 stroke engines to be truly happy with the time & money you have invested.
Doing it wrong will blow your engine mate,& thats a bad place to be for sure!

 

Ah u got me thinking there mate, maybe it will be better to stick with the airbox instead of open air filter.

 

Mine Was A Stuggle To Set Up, Had Someone Put Mine On The Dyno To Get It Done And Checked Propperly
For The Little Increase You Get, It Doesnt Seem Worth It.. But Does Sounds Good

 

mate if i was u i would get round 115 main jet and theck wot your rollers way my mate bought a polini exhaust and went from 65 main jet to 84 got bit better but wos still bogging so got a open air filter and got a lil more betta so got 6 gram rollers and it was fine so check ur rollers