gargravarr
Member
Hi all,
Wonder if anyone here has some experience with quads or carburettors in general. A few years ago we bought (new) a cheap no-name 150cc sports quad off eBay. It's not been particularly wonderful, but with a top speed of 40MPH and some crazy acceleration it's great fun to ride around on our land out in France.
Trouble is it's badly made, and has had a lot of problems since we bought it. Most troublesome, it won't idle. It's gotten progressively worse until recently it will not idle at all. The idle speed is set right, since it only takes a little push of the throttle to engage the transmission (CVT). It's also a pig to start - can take half an hour of intermittent cranking and the entire battery charge before it'll fire. I've had to use Easy Start recently to get it running.
I've had the thing in pieces many times and recently completely stripped and cleaned every part of the carburettor with special solvent, but this hasn't fixed it. My experience, however, lies with fuel-injected engines so I don't know how to go about diagnosing the problem we're having.
Fuel pressure seems to be okay, it's gravity fed but has worked fine in the past. There is no choke, or if there is one, it's automatic - there is some kind of electronic needle valve attached to the carb that my stepdad (very experienced) has drawn a blank on, and we're assuming is some kind of choke. One of the vacuum hoses was spit so I fixed that, but it still won't run smoothly.
It ran okay when we first bought it and has gotten progressively worse. I don't really care about idling at a stop, but since it's nearly impossible to start from cold and not much better when warm, I think I need to find out why. It's also a pain when I decelerate into a turn - as soon as I come off the throttle, it stalls even if I'm still rolling, so if I'm turning around, I have to hope it'll restart!
Symptoms:
-Stalls within 10 seconds of being brought back to idle under all conditions, tries to keep going but eventually runs out of power. Opening the throttle in this condition usually stalls it instantly
-Extremely difficult cold start (unassisted)
-Warm start not much better. Letting it stand between cranks, rocking and shaking seem to help. Most often fires while cranking but won't catch
-Runs reasonably smoothly with the engine above idle, throttle response is okay
-May be surging slightly above 25% throttle
-No unusual smoke or fuel leaks
-Oil fine, air-cooled with fan on crankshaft
-Can sometimes be made to start by cranking with the throttle at half-open. Also, holding throttle open then suddenly releasing usually makes it fire
I've done some reading and advice has included vacuum leaks, faulty accelerator pump, idle speed too low, dirty butterfly valve, stuck choke and ignition timing. The only thing I can actually see that can be adjusted is the idle speed, though - the ignition may be electronic, I'm not sure. I don't know if it's side or overhead valve, but it's single cylinder.
It originally had a remote killswitch fitted, which I have since removed as the remote was destroyed. Not sure if things have gotten worse since then, but the receiver was a battery drain.
I took the quad up the woods in the snow and have not long realised how lucky I was that it restarted when I wanted to come home - could have had to push it a mile down a track! :shock:
So, anyone with any carb experience out there? I know this is the fuel-injected era (and a forum for a fuel-injected car!), but it's worth a shot! I've spent more time working on this thing than I have riding it!
Cheers,
Gargravarr
Wonder if anyone here has some experience with quads or carburettors in general. A few years ago we bought (new) a cheap no-name 150cc sports quad off eBay. It's not been particularly wonderful, but with a top speed of 40MPH and some crazy acceleration it's great fun to ride around on our land out in France.
Trouble is it's badly made, and has had a lot of problems since we bought it. Most troublesome, it won't idle. It's gotten progressively worse until recently it will not idle at all. The idle speed is set right, since it only takes a little push of the throttle to engage the transmission (CVT). It's also a pig to start - can take half an hour of intermittent cranking and the entire battery charge before it'll fire. I've had to use Easy Start recently to get it running.
I've had the thing in pieces many times and recently completely stripped and cleaned every part of the carburettor with special solvent, but this hasn't fixed it. My experience, however, lies with fuel-injected engines so I don't know how to go about diagnosing the problem we're having.
Fuel pressure seems to be okay, it's gravity fed but has worked fine in the past. There is no choke, or if there is one, it's automatic - there is some kind of electronic needle valve attached to the carb that my stepdad (very experienced) has drawn a blank on, and we're assuming is some kind of choke. One of the vacuum hoses was spit so I fixed that, but it still won't run smoothly.
It ran okay when we first bought it and has gotten progressively worse. I don't really care about idling at a stop, but since it's nearly impossible to start from cold and not much better when warm, I think I need to find out why. It's also a pain when I decelerate into a turn - as soon as I come off the throttle, it stalls even if I'm still rolling, so if I'm turning around, I have to hope it'll restart!
Symptoms:
-Stalls within 10 seconds of being brought back to idle under all conditions, tries to keep going but eventually runs out of power. Opening the throttle in this condition usually stalls it instantly
-Extremely difficult cold start (unassisted)
-Warm start not much better. Letting it stand between cranks, rocking and shaking seem to help. Most often fires while cranking but won't catch
-Runs reasonably smoothly with the engine above idle, throttle response is okay
-May be surging slightly above 25% throttle
-No unusual smoke or fuel leaks
-Oil fine, air-cooled with fan on crankshaft
-Can sometimes be made to start by cranking with the throttle at half-open. Also, holding throttle open then suddenly releasing usually makes it fire
I've done some reading and advice has included vacuum leaks, faulty accelerator pump, idle speed too low, dirty butterfly valve, stuck choke and ignition timing. The only thing I can actually see that can be adjusted is the idle speed, though - the ignition may be electronic, I'm not sure. I don't know if it's side or overhead valve, but it's single cylinder.
It originally had a remote killswitch fitted, which I have since removed as the remote was destroyed. Not sure if things have gotten worse since then, but the receiver was a battery drain.
I took the quad up the woods in the snow and have not long realised how lucky I was that it restarted when I wanted to come home - could have had to push it a mile down a track! :shock:
So, anyone with any carb experience out there? I know this is the fuel-injected era (and a forum for a fuel-injected car!), but it's worth a shot! I've spent more time working on this thing than I have riding it!
Cheers,
Gargravarr
