Hey Guys & Girls, I'm new to this and have done a search, been looking at millions of topics since Wednesday and just need some clarification on some bits. My drive belt snapped on Weds and i have replaced it. but now it seems like it popped a piston ring or something as it was stinking of petrol and low on power with no compression. My specs are: 2007 Gilera runner SP50 (soon to be 70cc) Leo vince TT exhaust 5g Rollers 17.5 Carb (the standard one) So to fix it... I've ordered a Athena MH 70cc kit, and jets 75>98 (i think i have 68 in there now). The bike is on the Standard 17.5 carb but i've been told that is ok if i just upjet it. Going by the bits that are already on the bike. What would i need to change? Have i missed anything? I know i'll need a new spark plug to test if it's running lean/rich. The stuff should be here by tomorrow so i just need some reassurance that i've covered everything. Any help regarding the following would be great! 1 - 17.5 carb jet size for the 70cc/exhaust 2 - Roller weights (do i go up or down?) I'm just after a smooth ride 3 - Any bits that i may have missed regarding the upgrade? Sorry for the long post, I hope someone can help me without being too harsh about it! Thanks in advance Peter
youll need stiffer clutch and torque spring (i think) lighter rollers 21mm carbs arent that expensive and youll get more power/speed
Cheers for the quick reply! I already have blue clutch springs installed and have some others that i'll put in if needs be. I've already spent enough money on the bike so 21mm Carb will have to wait for now. Any ideas of Jet sizes for the 17.5? Cheers
Take a look at this i hope it helps http://www.scootershack.co.uk/newbi...er-carburetor-jetting-guide-t2747.html#p37320
Cheers Cjkt! Hit the nail right on the head lol! So it looks like i have got it right for a change... Maybe the jets i'm getting will be a bit too bit but that's a small issue which i'll work out once the 70 kit is on. Fingers crossed nothing else is broken when i take the engine out later :beg:
http://www.scootershack.co.uk/rollerguide.html Read this. Normally when trying to setup a bike I would advise buying a range of rollers as well as jets.
Ok just worked out i have a 62 jet in the runner. Sparkplug looks black but was dry. My question is.... Will a 75jet be too big for when i stich the 70 kit on? And do i have to change idle jet as well? TIA
Cheers Scott, i've ended up with a 72 in there but i think now my reed valves are not sealing properly as it stutters a lot when trying to get onto the power. It does it with all the different jets/settins ive tried I'm gonna have a look tonight and see if i can fix it, but around 72-76 is almost perfect so far! Once i've sorted this out the bike will be spot on Thanks dude!
stutter may be down to clutch seting, or even something as simple as the idle mixture seting, both of these will cause a delay/stutter when you first jam the throtle fully open.
Yep, i've been playing around with it for a week now setting up the carb with different jets etc. I took the reed valve out as no matter which jet/carb setting I had the stutter was still there. I thought maybe that the reeds wasn't sealing properly, so I inspected them and moved them up a bit to sit more flush inside the housing. IT WORKED! and no more stuttering :cheers: Clutch settings seems to be good with the Malossi Black clutch springs (kicks in properly around 5/6k). On my way to work today I easily got the bike up to 60mph and it was smooth throughout the rev range! it had a bit more to go but i didn't want to push it! I was sooooo happy! I have 5.0g rollers in there right now and it accelerates very quickly. I'm thinking to put my 5.7 in there and see how that feels... Glad the hardest part is now over and it's just minor tweaks like rollers
good m9 pleased for you as i know how much of a pain it is jetting etc lol still need to play about with mine abit, gna maybe get sum new reeds etc as they have been in for ages, and a few sets of rollers to c which work best for my set up
easy way... add roller weight untill the revs drop below the powerband... then drop them a quarter or half a gram. then you know your getting the revs and more importantly the TORQUE out of the engine you make something knowingly incorrect to give you an idea of what correct really is. ie, if you know the extremes of incorrect setting of any parts you can work out a happy medium. experimentation is the best way to prove what you assume is correct
