ATC 70 lacks power. Big time!!

[ClayW]

Ok guys, my buddy bought this 1985 ATC 70 a few weeks ago. I have helped him nurse it back to health. Did not run when he got it. So far we put a new plug, points, condensor, and coil on it. Gets plenty fire. The carb was missing a few key parts but it would run with it. For good measures he bought a new one. Ok this is where it gets strange. It cranks and idles perfect. I might add that it does not smoke at all. It lacks power bigtime. My daughter has an 85 also and I can drive it up our driveway that is pretty steep in 2nd gear with no problem. Keep in mind im 6'3 280 lbs. His can even come close. He is 230lbs and it still can fo 10feet. It also revbrates like hell at high RPMS. What do you guys think. Im thinking that when he put the points and condensor in the timing somehow got off. Not much, but definately off. I also am wondering if the lack of power could be from improperly adjusted valves. What do you guys think.

ClayW

[hondaATCman]

I may be wrong, but to me it sounds like the timing. My 110 was off one tooth (I forgot which way) and it would idle fine and even slowly rev up ok in neutral, but when I got on, man I was lucky to even move on flat ground. Re-timed it and it ran perfect. I would definately check it out.

[kdagenais]

I second the timing and would re-check the gap on the points. If that doesn't work do a compression test on it. Keep us posted.

[TimSr]

If I understand your post, you are saying it revs high but doesnt go anywhere? Does "revbrates" mean vibrates? If that is the case, is not a power issue, but a clutching issue. If you lack power it will bog down and die.

[ClayW]

Sorry about the typo Tim SR. Yeah it revs up in neutral with no problem. It is slow about doing so though. Its even slower to rev up when its in gear. I guess it not real responsive to the throttle. It vibrates like hell when you get the RPMs up in gear or out. I think you just notice it more in Neutral, when you dont have the chain and tire noise. Now it does every now and then jump out of gear. Dont know why. More so on inclines. This could be connected to the above problem, but im not sure. I had a old porshe 944 that jumped time a tooth. Belt lost a tooth and it jumped. The car lacked power, and vibrated like hell because the engine was out of time or ( out of balance as the dealer stated).

ClayW

[ClayW]

Also Tim, with a kid on it, it will go up my steep driveway, but only slowly. But with an adult on it, it just wont hardly go. The engine has never been torn down. The flywheel has been off, to install the points & condensor. Could the timing have gotten off then. Kinda strange.

ClayW

[King44]

My friend has a 300 fourtrax that has no where near the power it should and revs slow, but it will rev high eventually. After looking at it, we found out the cam lobes were worn out, so you may check that if you can.

[TimSr]

Also Tim, with a kid on it, it will go up my steep driveway, but only slowly. But with an adult on it, it just wont hardly go. The engine has never been torn down. The flywheel has been off, to install the points & condensor. Could the timing have gotten off then. Kinda strange.

ClayW

When someone is on it, and its in gear, on an incline and they give it gas, does the motor bog down like ts going to die or does it rev up higher, with the bike not moving as though the clutch is not grabbing?

[hondaATCman]

I would go ahead and just check on the timing. It wouldn't take but a few minutes to do... just line it up on TDC and check to see if the marks line up on the cam and head. My 110 just jumped time out of the blue while I was riding, it took me a while to figure out the problem but had tools and was able to fix it on the trail. Also, sometimes mine will jump out of gear too especially uphill, but it also has 22 years of wear and tear. lol

[ClayW]

when someones one it going up a incline it bogs down to a point and just sits there making a sound like HUUUUUUUUU. Not reving just a steady tone from the motor like its in 5th and doesnt have enought gear/torque to go.

Clay

[hrc200x]

Both of my 70s have problems climbing hills too. One has a clamp on air filter to the end of the carb, cobra pipe, and probably hasn't been jetted, basically the whole top end (cyclinder, head, cam, piston) is all supposed to be brand new from Honda parts.

The other 70 is just rebuild with new rings, stock air box and filter, stock pipe.

I found out with both of them, that when going up a hill or any time you go over 3/4's throttle they both die, flip the choke on and it will pull the hill just fine. Maybe try this with yours and see if it helps?

[kdagenais]

I woul check the timing and compression and let us know what you find out. I had a CT70 and ATC 70 that did the same thing. On the CT70 it was the timing and a never got a chance to figure out the ATC 70 cause my parents sold it.

[42F67N]

hrc200x on the 70 with the cobra pipe move the needle clip richer and it will take away that turning the choke on to get more power problem,i have the cobra pipe and my needle is clipped in the last postion now the 70 runs awesome!