Hi guys, I have been off work all week so I decided this would be a good chance to order a iron 70kit and spend some time fitting it, and getting the zip running. I brought my a/c polini sport 70 kit yesterday from a shop brand new with all the gubbings to fit. Spent yesterday afternoon carefully removing the engine from my zip50. And then spent all day today fitting the new kit and getting the bike setup properly. Good news for a start, it runs and it runs like a scalderd cat from the local chinese takeaway. Absolutley no flatspots or bogging through the entire rev range, it takes off very quickly, and accelerates very well midrange and topspeed is obviously way off the clock (about 55-60mph or so), plug is showing its running slightly rich, dark brown and damp but bare in mind I lubed up the new kit with 2t before fitting. I am very proud of myself as this is the first time I've fitted a 70kit and actually made it work without breaking anything (searching these forums helps a bloody lot IDK why people dont search before posting lol) But the ONLY problem is cold starts, this thing is a BITCH to start from cold using both eleccy start and kicker. Once I eventually get it started it will stay running and start first time, and as above it runs almost perfect asif it was piaggios own engine. It starts much better from cold when I remove my airfilter and cover the carb with my hand,starts in 2-3 kicks like that, or a few seconds on the eleccy start.. so this made me think the auto choke is somewhat not working at all so I disconnected it, and obviously made no difference. Can anyone reccomend something that will help my cold starts?? I was thinking of getting a manual choke but Im sure a good engine will start cold with no choke, started many engines without chokes first kick/pull. Heres my setup incase im missing something: polini sport 70 leo vince zx 5.2g rollers Stock vari & clutch, stock clutch springs. 17.5 stock dellorto upjetted to 78main jet and moved the needle up 1 notch. Open airfilter, wire mesh type from my minimoto. Running premix 40:1mix with fully synthetic Silkoline racing oil for premix engines, blocked off oil pipe on carb.
I was kinda hoping to be using no choke at all apart from using my hand lol.. Ditched the auto choke as I already knew it wasent working, never worked with the standard 50 but it still started easy. I will get a manual choke, but I was just a little worried why it takes forever to start with the 70kit, Im sure I fitted it correctly, it runs mint! Just a bugger to start from cold without covering the carb with my hand. Are all 70cc peds like this with no choke?
I've had a play with the idle mix and put the needle to the top notch, and now it starts much easyier without covering the carb with my hand, like 5-6kicks instead of 40. Im happy with this now and im not going to order a manual choke yet, just waiting for a really cold morning to test it on now before I decide to get a choke.
can you even get a manual choke for a standard carb?? didnt think u could. you should buy a 21 it would go well with 1 of them *hint hint*
my sons 70 kit was a bitch to start from cold. Exact same symptoms as you....cover the end of the carb (less air, more fuel...in theory making the mixture richer) and it'd fire straight away. He wunt be said that it wasn't running rich enough so I let him struggle to the point where he was ready to set fire to the thing. I took it into the workshop whilst he went to Modified Nationals for the weekend and stripped it. The manual choke cable had been bodged by previous owner. When you flipped the lever,....it was just taking the slack out the cable and not richening up the mixture at all. I fitted a new cable and reassembled.....starts second kick now the chokes doing what its supposed to do :good: as the man says...get yourself a 21...you wont be sorry
Dellorto 21mm carb ordered with manual choke and quick throttle ... Now im skint again Cant wait for that to arrive, Got a bunch of jets too and some more rollers to play around with. The zip cut out on me today, put a fresh plug in and it started straight away. Obviously Ive mixed the oil and petrol too rich, whats the best ratio is it 50:1? Im running 40:1 right now. I was going to down jet the carb but it seems to be running rich at tickover-low throttle. If ive been riding the plug is dark brown, if I let it tick over/lightly rev it for 5 mins, the plug goes black and wet. So should I lean out the idle mix a bit? Next time I got abit of doe im gonna order a new variator and clutch just to get the best out of the transmission. I was quite supprised at the difference in performance for a £100 kit lol. Revs higher than I expected
"i cant set my strock carb up so ill buy one thats even harder to do" poor tunning practice.. but anyway. needle should be on top notch with the airbox and stock carb (running onun moded box with stock carb on my ported t6 engine just fine) the choke is always a pain and does sound like its plain not working. leave it in place but unplug it for noiw, not having one fitted is BAD for your engine. idle mix should be setup with the engine up to teperature... if it wont start cold with ether choke on it needs a different choke jet. as for the "rich" running.. make sure the ROLLERS are correct as this will obscure correct carb jetting. always start rich, set the transmission up then trim the carb settings. sounds like you got it under control ether way.
Yeah its pretty good at the moment just not perfect and ya know I think its because im running a open filter thats causing most of the trouble with starting, choke is unplugged i havent taken it off but Im thinking about putting my "modded" airbox on and seeing if it helps. Eitherway I will pick up a new airbox at some point, I personally dont like that intake noise you get with open filters, plus I will gain alot in bottom end performance and maybe even be easyier to start. I have only made carb adjustments on a hot engine, as I said above I've made it easyier to start by adjusting the idle mix and putting the needle to the top, starts in under 10 kicks now so that problem is pretty much sorted Im guessing all I need is a choke and airbox to make it even easyier to start. So would you say my 5.2g rollers are a little heavy? Ive got a set of 4.9g and 5.5g.. But I was thinking stiffer clutch springs? Im happy with how it takes off with stock springs tbh.. Also the only little problem I have now is my engine is eating spark plugs, I've mixed my petrol & oil to 40:1 , plug turns out dark brown but dry at full throttle, but if I ride between idle and 1/4 throttle for a few mins the plug turns out black and wet, and eventually the plug fails. So yeah, running abit rich all over the rpm range especially low end revs, constantly got blue smoke from the exhaust even with a hot engine, not loads but the same amount when your warming up a cold 2 smoke.. I was thinking of running 50:1 to lean it out abit sorry for the long esssays lol any help is greatly appreciated
if you have remnoved your airbox it will need EVERY jet in the carb changed to get it running right.. better off wiht the airbox on as its impossible to set the hot mix on idle to start wiht the choke cold.. eating plugs is usually from being really rich (people often richen the carb to fuck in a vein attempt to compensate for the filter altho its usually down to rollers... can sling in the lightest rollers you have (it will rev and not really move) but you will have a better chance of setting the carb up this way.. then add weight to the rollers to bring the speed back while keeping the revs up id honestly put the airbox back on with the 17.5.. im running one on my own, un modded (well, snorkle tube is removed) the box creates a negative charge (vacumm inside the box) wich helps to lower the air pressure in the carb, this basicly means more fuel comes out for the same air passing.. this effect is lost so it runs over rich, lean at mid then rich as fuck... makes it a nightmare to jet the thing (not just main jet) hope this cleard a few things up for ya.
Thanks alot minor yes that helped alot! I've put the modded airbox back on and that seems to have made the engine run abit richer so I've down jetted several sizes and had to adjust the idle mix again because it would not tickover at all this time. But got it going fine now, still running abit rich low-end (dark brown plug but its not soaking wet & black anymore) but getting a nice choco brown plug at full throttle. I blocked off the extra intake I made on my modded airbox, idle mix is set around 2 + 1/2 turns out and the engine seems to like that (on a hot engine of corse). Infact, i havent needed to change the spark plug yet!! Happy days! Actually runs alot better now with the airbox I should have tried this in the first place, I've taken apart the auto choke and it was all gummed up with oil, I got it back together now and it actually works! starts 1-2 kicks and almost instantly on the eleccy start from cold Im not going to fit the 21mm carb kit untill Ive got all the transmission goodies I need so then I can set it up properly
well, your best bet is throw the transmission in at the same time as the carb.. it will only need resetting once setup for one size carb to another. idle mix is around 1/34 up to 2 and 1/4 turns really.... so the lesson for today is, bikes work better with airbox's
Yeah airfilters are just a plain waste.. I've brought a new airbox off ebay thats totally un-modified and the only thing I would do is use a malossi red spounge. Anyways, the 21mm carb has arrived along with the manual choke and quick throttle! Since im not actually using the scooter this week ive fitted the carb (got week off work) I've not really mucked about with it just fitted the new carb, it seems to start very good with the manual choke and im loving the quick throttle! Just on Scooterattack now ordering a polini variator, new belt and some more rollers.. But I want to order my clutch at the same time and im not sure which clutch to buy. I was thinking the polini 2G clutch? As this should work good with the variator right? Thanks minor for all your help! I sorta 90% knew what I was doing but just had a few minor problems to sought and it seems sorted now I was thinking about mixing the next tank of fuel at a 50:1 ratio?? As ive had a search and it seems 50:1 is popular with pre-mix. I mixed 40:1 for this tank beacuse I wanted to be sure there was enough oil in the engine for its first tank.
Im only using a sport iron kit mate, could probably afford to go leaner than an MHR rep without going bang. might stick to 40:1 it seems to like it.
