ATC 110 Shoots Gas From Carb, Low on Power

[KI4UJO]

I had a thread on jetting a while back, but I think starting a new one is more appropriate for these problems.

Today, I had the rear plastics off and was going to wash my 110. It was in my barn, so I started it up and rode it out. However, since I also had the filter off, I noticed gas being shot from the carb every time I pulled it over. Also, when I pull it over, I normally have to pull it over slowly with the kill switch off to avoid having my arm pulled from its socket. When it does get going, I can only get to 23 MPH (GPS Verified). I should point out that I have been having these issues for a while, but hadn't thought about it much until today. Also, when idling, it gradually begins to idle slower, until sputtering out and dying.

Only mods from stock: 125m exhaust, No Airbox

It also has a 9 Month old .20 Over bore/Piston, and the carb was throughly cleaned and rebuilt in January

Any ideas here?

[barnett468]

Hello k14ujo

Sorry to hear about your troubles. The following are a few of the potential causes I can think of, others will have good suggestions also. First a couple questions that may help determine your problem.

You say you "normally" have to pull it hard to start, is tgis still the case or does it still offer the same resistance now that it was before you had the problem?

Bent intake valve caused by either

1. something getting into motor through intake tract

2. cam chain jumping a tooth causing improper cam timing and/or a bent valve

3. the intake valve getting stuck from using old gas or new gas being used in a tank that had old gas dry up in it leaving a tar like residue in the bottom.

[barnett468]

Hello

Sorry I accidentally sent my first post before it was complete and can’t edit it.


Sorry to hear about your troubles. The following are a few of the potential causes I can think of, others will have good suggestions also. First a couple questions that may help determine your problem.


You say you "normally" have to pull it hard to start, is this still the case or does it now offer less resistance than it did before you had the problem?


A low resistance “pull” feel along with the fact that you say it now blows fuel back out the intake suggests the following possibilities to me however if it idles then if the valve is bent it not too bad and is leaking very little. A bike won’t typically idle with a bent valve.


Bent intake valves are typically caused by either


1. something getting into motor through intake tract and getting stuck in intake valve.


2. cam chain jumping a tooth causing improper cam timing and/or a bent valve


3. the intake valve getting stuck open from using old gas or new gas being used in a tank that had old gas dry up in it leaving a tar like residue in the bottom.


4. intake valve adjusted too tight [no valve/rocker clearance] however the clearance should not change unless the adjuster nut/screw is loose.


You can easily check the valve clearance and cam timing and also do a compression test.If the compression is lower than around 115 in your case you probably have a leaking valve for one reason or another.


Hoe this info helps.

[shovelryder]

1....get an airbox on it.....2....Is the exhaust opened up, like muffler gutted? May need some restriction.......3....Check yer timing.....4....Clean and adjust the carb......Welcome!

[CRAZY70MAN]

x2 on the airbox. You do have a pod filter on it or some type of filter hopefully? They are picky on the airflow..... Carb removal and complete cleaning would be my next step. And the 3rd step would be a valve adjustment.... Always makes for a hard cold start with valves out of adjustment. Good luck

[KI4UJO]

To answer everyone's questions

Every time I start it, cold or not, it is hard to pull. It feels as if something is dragging or hitting something. A bent valve is definitely possible. I will run a compression test and report back.

Exhaust is not opened up, it is just a standard 125m exhaust. What I have is a 1985 125m frame that I bought for the hitch, which has a 1983 110 motor in it.

I have a UNI filter as of right now. I don't have the tube that goes from the airbox to the carb, but I do have the airbox.

[KI4UJO]

Well, I got 75 Pounds. It's time for the head to come off. At lease I have 2 other heads setting on the bench that are known good. Head issues would explain the idle and lack of power ; I just went through this with a chinese GY6 for a buggy. Time to do it again.

[barnett468]

Hello

Glad you figered it out, kinda what I thought but it seemed strange it was still hard to pull but now that you say it has 70 lbs that explains it however with 70 lbs the valve shouldn'd be stuck or bent much. Maybe carbon holdinng it open slightly.

I would suggest to shoot some carb cleaner down intake then ex ports on the other heads. If it weeps by valves they are leaking. May need lapping or repair.

Keep us posted as to what problem was


Hope this info helps

[Yamaha_Rules69]

before you take the head off be sure to check the valve clearamce on both sides. rocker arms that are adjusted too tigjt can cause this. it takes about 10 minutes to check them with a feeler guage.

[fabiodriven]

Yeah, a valve adjustment takes 10 minutes and could very well be your problem. I'd highly suggest doing that before tearing it down.

As far as the machine taking jabs at you, your timing is probably off.

[KI4UJO]

From what I could tell, the valve is slightly warped. I'm not going to strip it down though, as I have another head ready to go. As of now, I am waiting on exhaust studs so that I can get it back together.

As for the timing, the flywheel key has taken some damage in the past; I'll be replacing it as well. I think that when I timed it, the messed up key threw me off a tooth, causing the grabbing when starting it.