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July 4, 2012 at 2:18 pm #101626
Just inherited some sort of chinese 50 for the kids on loan. Apparently it is a rip off of the Honda QR 50. Anyway when we picked it up on the weekend it would not run properly. Inspection of the carby indicated that water had been sitting in there for a long period and everything was rusted up. Gave everything a good clean and all is well now.
However in the process of cleaning my mate removed the air screw (or is it a fuel screw). It is just in front of the idle screw. What is the correct setting for this. Is it normally 1.5 turns from full in. At the moment the thing starts and idles well but takes some encouragement to rev out. Not sure what the current setting is though.
Thanks
July 4, 2012 at 3:39 pm #225530Yeah Bundy, I am thinking 1.5 turns from full in.
It is a Fuel screw when it is on the engine side of the carby and the air screw is on the filter side as a rule.
Is it pre mix or oil injected?
Not revving out can be caused by the air screw, lifting up the needle by one notch is something to try if dicking with the airscrew doesn’t work. Blocked air filter is something obvious that you would have already checked?
July 5, 2012 at 1:53 pm #225533Thanks Mick. I’ve now had time to do a bit more investigation since the first post. Whoever told my mate it is a rip off of a QR 50 didn’t know too much as this bike is 4T not 2T. Going on photos I looked at on bikesales it looks a similar shape to the xr50.
The screw is a fuel screw as it is on the engine side. Haven’t had a chance yet to play with it or check the air cleaner. This bike hasn’t had a lot of maintenance I don’t think. I’ll give everything the once over on the weekend.
After that I’ve just got to get thekids to use the brake to stop. They back off the throttle but just put their feet down. Works in first but won’t work when they go faster.
July 5, 2012 at 1:59 pm #225583If it is 4T and it is a honda knock off, I am betting that the air box is full of grass. Moose has a CRF70 that plays up a treat when the airbox sucks in a heap of grass. The air intake is near the rear wheel, which allows it to pick up crap when used on grass tracks.
July 5, 2012 at 2:48 pm #225584I wouldn’t call it an air box. It has a plastic air horn looking thing that clamps straight onto the carby. Doesn’t attach anywhere else. It does however point straight at the rear wheel. One of the reasons I haven’t been game to check yet is I was worried that as soon as I disturb it the air filter will disintegrate (because it has never been changed before) and I am then left with 2 despondent kids and an air filter that I don’t know where to get a replacement.
Oh well, will have to do it and if push comes to shove can always get a bit of foam to fit in there.
Haven’t changed the oil yet either but I’m just hoping it doesn’t come out in lumps. It’s not my bike but I feel sorry for this little thing already. I’ve also got a feeling that the bloke lent it to me so that it would get some TLC as well. Small price to pay for the kids enjoyment.
July 8, 2012 at 2:51 pm #225586Finally got a chance to get into it on the weekend. I cleaned air filter (wasn’t too bad), changed oil, set fuel screw. Still not reving out. Pulled carby apart. In our rush to beat diminishing daylight it appears we may have only completed a bodgey job of this the weekend before. It was filthy. Cleaned it all out. Blew out the little jets so I could see daylight through them.
Put it back together and gave it a go. It needed choke to start (had never needed this before even when cold) so I took that as a good sign. Anyway it is much better. Revs right out now. A little bog but not enough to worry the kids.
It is still a little odd though. The choke has two locking spots. One for full on and one for what I assume was off. It will not run at all in the “off” lock position. If I leave just forward of the slot where it locks (will sit there all day no worries) it runs fine. It may be a coincidence but this position just happens to be where the butterfly valve marked on the lever is in the horizontal position. (It goes vertical in the choke on position).
I’m assuming that maybe the butterfly has moved on the mechanism and when I lock it in the off position it starts to put the choke back on again. Don’t know.
As an aside I pulled the spark plug out when I was mucking around with it and it was really black. I assume this means rich. The kids rode it all arvo with no worries and I haven’t checked it since so it may have changed. I had been playing with the fuel screw and choke for 10 minutes before I checked it was black.
Other things that may be of note. It was blowing a bit of smoke to start with but I never noticed this again once the kids were riding it. It also seemed to rev out best when I had the fuel screw around 2 turns from full in but there wasn’t a huge difference between 1.5 through to 2.5 turns.
The exhaust also gets pretty hot. The muffler is too hot to touch, is this normal.
Thanks again.
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