Hi all, I have a Malaguti Firefox F15, I bought it a few months ago and got it pretty cheap as it needed a new water pump. I fixed the pump but It just isnt running right. The power just disappears every now and again (very frequently like every couple of minutes), you can be doing 40mph with the throttle open and the revs just drop, next thing you are doing like 18mph up the ring road with a que of cars behind you and then it picks up and off you go again (leaving the que of cars thinking you were doing it on purpose, and are therefore some kind of stroker). I took it to a local scooter specialist who to be honest seemed very good and after a few days he phoned and told me that it needed a new piston and rebore. I paid for this to be done and now have got the scooter back (it also had a new top set fitted and exhaust gasket seal), the compression is better, but the problem remains. I had been thinking it could be something to do with the fuel mix so I bought an induction tach meter and tuned the carb to get the best engine speed, the scooter runs better for it, but the same problem remains. The drive belt is apparently fine, I have checked it myself and the garage I took it to confirmed this. I have had the rollers out and checked for flat spots and they seem fine, I have drained and emptied the fuel tank, and checked the fuel filter for blockages, the bike has a spanking new plug in it, the carb is clean, I also cleaned the air filter and checked that the variator isnt sticking open. I am currently toying with the idea that it could possibly be a vaccum leak causing the fuel not to be drawn through properly, but that doesnt explain what sometimes its goes ok and then sometimes it just sort of sags away to nothing. I have read what other posts I could find regarding similar problems and the common causes seem to be carb jets and clutch springs. Would the wrong clutch springs actually cause the engine revs to drop? Or would it, as I am thinking, just rev high and go nowhere? Its my engine that is bogging and as this is my first bike and I have almost none existant mechanical experience im kinda stuck so any help would be really appreciated. I would really like to be ably to fix it myself as I quite enjoy working on the bike. and also not paying mechanics £200 is always quite pleasant. Above is an artists impression of what my bike might of looked like before the little toe rag who had it before me beat the living c@#p out of it.
lol so you paid a mechanic to fix your bike and he dident even fix it... go get your 200 quid back and tell him to re-fit the old bore and actually FIX the problem not just replace parts..
Hmm I will pop down my bike shop tommorrow and try to pick up some lighter rollers, how much lighter do you think I should go? im sure the standards are 6.5g or there abouts. I am also planning to up the jetting and give that a try, for the sake for 50p per jet its got to be worth a go. The jet in the carb at the moment is a size 64 which seems pretty small given that the bike has a leo vinci TT exhaust fitted. Would love to go to the mechanic and complain, but he has gone on holiday :banghead: LoL, tbh the piston and rebore was needed though, the bike had bad compression. And I do want to restore the bike and get everything it needs done anyway so i'm not too sore about it. And I can understand why he thought that was the problem given the state of the old piston.
Well I took the rollers out today and took them to a shop that buys gold, I got the bloke to weigh them on his electronic scales and they weighed in at 4.29g each. (well 4 did and the remaining two weighed in at 4.39g which is a bit wierd as I would expect even wear on them, although if they were cheap rollers this .1 of a gram difference may well have been there when they were fitted). I went to my local bike shop but the lightest they have is 6.5g. I just ordered a set of pollini 3g rollers from adrenaline, so hopefully when they turn up I can put my bike back together and it will work! Will update when done, Thanks for the help.
couple of things spring to mind... first it could be fuel starvation...faulty tap maybe. It would allow the fuel to catch up and then the revs would pick up again or its maybe nipping up due to lack of oil/too much air. The piston rings would expand...the engine slows for a split second or two cooling to barrel. the extra fuel lubes the bore and its off again. Could also be why the old piston and barrel needed a bore job My old 375 LC would do the same but that was coz the twat that rebuilt the crank didn't get it aligned correct making the firing out and it would temp nip up like you describe...the revs dropped, things cooled off and off it went again....fookin thing. Was glad to see the back of that one
Ok I got the 3g polini rollers in the post this morning, I fired them in and went for a nip about. First thing I noticed to my relief, is that there was no bogging whatsoever, and I had to slow down for a 40mph speed camera on an uphill stretch where the bike was doing 18mph before, so I'm pretty sure the problem was just the roller weight. However, its now really sluggish on the take off now, and as it gets to around 40 mph it starts making a "rah rah rah rah" noise like the variator is struggling to stay out. I think that by going from 4.3g rollers down to 3g I have overshot the mark a bit, I am planning on ordering a set of 3.5g and hopefully that will be the end of it.
sounds like the bike wasnt properly setup for the pipe in the first place check how its running you might need to go up a bit but im not sure on the stock size. you could buy a roller box which has weights and rollers so you can mess around finding the right weight then buy a set at the required weight.
Well... I know that the weight i need is in between 3g (too light) and 4.3g (too heavy) so im planning on getting malossi rollers this time, they are a bit more expensive but are available in more weights, im going to try 3.5g and if thats still too light i'll get the 3.7g ones. Since I know roughly the right weight I need now, its probably going to be cheaper for me to just buy the rollers themselves.
