c4dude
08-23-2010, 09:01 PM
New to the board - I've learned a ton just reading stuff here - nice job guys. I was afraid I was all alone owning a 3 wheeler - boy was I wrong!
I have a '78 ATC90. Had it for several years now, rebuilt the top end, cylinder, rings, valve job, etc. Ran great for awhile then I lost interest (boating!). Decided to get it back to running shape. Had carb trouble - decided to go with a new replacement carb. So far so good. Fires up fine, idles fine but after about 15 - 20 minutes, right after it heats up, it stalls. Plug is wet and dark in color. So I dropped the e-clip one notch (now in 2nd down from top, instead of middle) thinking it's running too rich. Now it run only on the choke, no matter where I set the mixture screw and throttle stop. So that reinforces ignition trouble in my mind. I've checked the points with an ohmeter, adjusted both advance and gap, still the same symptom.
It's tough to get it to fire so I've been suspecting a coil or stator problem. I pulled the coil (no small task as it's mounted inside the frame) and checked it with an ohmeter. It appears to be OK to me, but I'm not sure. Maybe a heat problem? I checked the condensor using by reversing the polarity of the ohmeter leads and it charged then went to infinity, both directions so from what I recall of capacitors, that's OK as a basic test to make sure it hasn't shorted or opened.
I checked the output voltage at the yellow and black wire coming off the stator. I got 24VAC between the black lead and ground, 2.6VAC between Yellow and ground, and 24VAC between the Yellow and Black wires.
I haven't seen anything that tells me what type of voltage I should see at the stator leads so I'm hoping someone either knows or has a running 90 and would be so kind as to take a voltage reading for me.
By way of comparison, I just picked up a little Honda Trail 70 project - CT70 I guess it's called. I pulled the plug on that as a comparison to see how much spark I see and that thing gets a lot more pops and a much brighter looking spark than the 90 is throwing.
I'm guessing I need a coil & condensor, but that's a pretty pricey part, especially if I guess wrong.
Can someone help a newbie out?
Thanks!
I have a '78 ATC90. Had it for several years now, rebuilt the top end, cylinder, rings, valve job, etc. Ran great for awhile then I lost interest (boating!). Decided to get it back to running shape. Had carb trouble - decided to go with a new replacement carb. So far so good. Fires up fine, idles fine but after about 15 - 20 minutes, right after it heats up, it stalls. Plug is wet and dark in color. So I dropped the e-clip one notch (now in 2nd down from top, instead of middle) thinking it's running too rich. Now it run only on the choke, no matter where I set the mixture screw and throttle stop. So that reinforces ignition trouble in my mind. I've checked the points with an ohmeter, adjusted both advance and gap, still the same symptom.
It's tough to get it to fire so I've been suspecting a coil or stator problem. I pulled the coil (no small task as it's mounted inside the frame) and checked it with an ohmeter. It appears to be OK to me, but I'm not sure. Maybe a heat problem? I checked the condensor using by reversing the polarity of the ohmeter leads and it charged then went to infinity, both directions so from what I recall of capacitors, that's OK as a basic test to make sure it hasn't shorted or opened.
I checked the output voltage at the yellow and black wire coming off the stator. I got 24VAC between the black lead and ground, 2.6VAC between Yellow and ground, and 24VAC between the Yellow and Black wires.
I haven't seen anything that tells me what type of voltage I should see at the stator leads so I'm hoping someone either knows or has a running 90 and would be so kind as to take a voltage reading for me.
By way of comparison, I just picked up a little Honda Trail 70 project - CT70 I guess it's called. I pulled the plug on that as a comparison to see how much spark I see and that thing gets a lot more pops and a much brighter looking spark than the 90 is throwing.
I'm guessing I need a coil & condensor, but that's a pretty pricey part, especially if I guess wrong.
Can someone help a newbie out?
Thanks!