Stupid ATC 110 Cylinder Head Question

[derrick81787]

Hi everyone,

So I've been missing with my 1980 ATC 110 trying to fix what I thought was an air leak around my intake manifold gasket. I finally fixed that, was sure it was going to work, and then seemingly nothing changed. The 110 idles okay and does okay at really slow speeds, but it completely craps out when I give it any throttle.

Then I was looking at the intake manifold are and saw what look like a hole in my cylinder head that I've somehow never noticed before. I've attached pictures so that you can see what I mean.

Is that what I think it is? Do I just have some huge hole in my cylinder head somehow? I think that I probably know the answer to this, but there's not supposed to be anything like this there, is there?

[Mackus84]

I could be completely wrong due to limited knowledge on the 110's, but no. Lol. Absolutely not supposed to be a hole in the head like that. Looks like its busted through somehow

[1979atc]

It is supposed to be like that. Air goes thru there while riding, and cools the head. Aircooled... I think your timing maybe off due to the way your bike is running. Bad points, points plate not in correct spot, valve adjustment, could be also carb. These are just examples of what could be wrong, something else could be wrong but would be a good idea to check these.

[Mackus84]

Wow. Thats crazy. Ive never seen that. Guess ill have to check when i get home, i just picked up a 110 a cpl days ago. Tore it apart but didnt notice that. New to me. Glad this questions been answered already before i did notice it!!!. Thanks guys

[derrick81787]

Thanks guys. I haven't had this ATC for long and am just starting out with this maintenance stuff. I was looking at the intake manifold, saw that, and had a moment where I thought "have I seen that before?" It looked kind of out of place, but I wasn't sure. I'm relieved to know that I don't have a major problem on my hands. I don't really know what I'm doing, but I will look up how to adjust the timing, points, valves, etc and see how it goes. Thanks for the help.

[Mackus84]

Well I'll be damned. It IS there. Here i am saying definitely didnt think it should be, and i have one in the garage! Sure enough. Its there. (In my defense, i just got the bike. And was at work when i answered haha.

[ps2fixer]

I was about to chime in and offer up an ATC110 head... but it probably has that hole too lol!

[derrick81787]

It's a real jagged hole too. It definitely looks like something that broke, not something that's supposed to be there. Oh well. At least I can feel better knowing that it's probably just my timing or points or something. I recently had the valves replaced, so I'm hoping they are okay. And I did have an air leak on my intake manifold that is fixed now, but I guess that just wasn't the main culprit here.

[yaegerb]

have you cleaned and rebuilt the carb yet?

[atc300r]

Try a new coil or different coil.The one under the gas tank.How old is your spark plug.Fouled plug could cause your problems aswell.

[derrick81787]

Yeah, I also fixed the stripped holes with a Helicoil and have the manifold bolted down tight with a new gasket. Overall, I'm feeling pretty good about the carb now. It did run a little bit better this last time around and it idles perfectly, but it's still having trouble when I give it a lot of gas. I'm kind of thinking that it has to be the timing or points or something now because there's not really anything more left to do with the carb or intake manifold.

I have the service manual and have been reading about adjusting the timing. I was nervous about it (which is why I did the carb first, hoping that would fix it), but it really doesn't look too bad. It looks like something that can be done while the engine is mounted in the frame and fully assembled, other than removing the starter and the valve cover. I guess that I just need to get a spark plug tester and go at it. Hopefully when I get it opened up I will see that it is out of timing, and that will that. I've got a 7 1/2 month old baby, and the wife thinks I'm spending too much time working on this, haha.

Edit: Spark plug is brand new. This last test ride was the very first time that plug has been used, but the problem was still there. Does this sound more like a coil problem or a timing problem? I don't really know. At this point I'm pretty much doing what you people tell me, haha.

[atc300r]

My 85 250r started,idled and ran fine up to half throttle with a bad coil. I know mine is 2 stroke and your is 4 stroke but it sounds like it very well could be coil. or stator. In my opinion if you clean the carb put in a new plug have fresh gas and your machine still runs crappy. Its time to look elsewhere for trouble. Just my opinion though.Iv been around trikes and small engines since I was a teen . I also went to trade school for small engine repair and was the top of my class. Not bragging just saying and Im still learning new stuff everyday.

[Mackus84]

I've got a 7 1/2 month old baby, and the wife thinks I'm spending too much time working on this, haha.

Haha. Funny, my wife loves when im out working on mine, because im not in there bugging her lol we have an 8 month old son

[mendoAu]

Did you check the fuel tank for crapage. I just picked up a 110 and the tank was full of rust. Fuel would still flow to the carb but not enough at higher RPMs. If you have an air compressor blow some air thru the gas line into the tank (disconnect from the carb) and make sure it's clear.

[derrick81787]

Haha. Funny, my wife loves when im out working on mine, because im not in there bugging her lol we have an 8 month old son

I wish. My wife stays home with him during the day and is ready to hand him off by the time I get home from work, haha. He has been a little bit more of a handful lately than usual, though.

My gas tank was full of rust when I got it, but since then it's been cleaned out. The fuel lines have been replaced and now have inline fuel filters, and the filters look clean. I'm going to look at the timing and the points as soon as I can. I need to replace my starter rope anyway. It was rotten and broke one day when I was trying to start it. I've been getting by with the rope being shorter than normal, but I might as well replace the rope and check on the timing and points all at the same time.

I had a guy replace the piston and rings for me back in December. He said that he fixed the timing then, but then again I didn't have the best experience with him so he might have screwed it up. He didn't say anything at all about the points.

It is significantly better since fixing the carb and the intake manifold, but it's still not where it should be. If I slowly accelerate then I am okay most of the time, but for some reason it really craps out when I attempt a sudden acceleration. I'm going to replace the starter rope because it's really annoying me, and then I'm going to take a look at the points and timing. Hopefully there's some adjustment I can do there that will help out.