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3Wheel_Hunter
01-15-2014, 11:16 PM
Hi all, new to posting but not new to the site. Looking for some help with a recent build. I just rebuilt the top end of a 85 ATC110 and got everything back together. Everything was done according to the manual; cam timing set, ignition timing set, carb rebuilt, gas tank cleaned, and new plug.

I was excited when it started on the first pull. I ran it around a little bit, nothing too rough; 1 and 2 gear at half throttle. I turned it off, changed the oil, cleaned the filter and the carbon on the clutch. Now that it's back together again, I can't get it to start. I have good compression; 125 - 130, fuel and spark. I've switch out the ignition coil without any luck.

Looking for help, hoping it's something simple I've overlooked. Hate to have to tear the top end apart again.

tri again
01-15-2014, 11:32 PM
Top rebuild?
Hasn't run in a while before that?
I'd bet on stuck advance plate.
Should be under the cover that says "CDI"
Plate should rotate a little and 2 teeny tiny springs to return it to zero.

If you revved it a little it may have rotated to advance and never returned.

Hope it's something that simple.
Happens to mine if I let them sit over the winter.
Blow out the rust, and oil or grease as necessary.
PLEASE let us know what you find.

Does the pull rope seem a little harder to pull? like it wants to snap out of your hand like it's too far advanced?
Can you check IG timing with a light?

3Wheel_Hunter
01-15-2014, 11:35 PM
Yes, it was just a top end rebuild. It lost compression a few months back and I just got around to rebuilding it.

It's not the advance plate; this was the first thing I looked at. I check the ignition and cam timing again, but still not luck.

I'm hoping it's something simple that I might've missed.

tri again
01-15-2014, 11:45 PM
Valve adjustment still ok?
spark, fuel air, what else do they need?
Any chance the mice built a nest in the muffler?
Air box and air filter ok? They seem to run good without filter as a diagnostic move.

How's about a spritz of gas or start fluid just to rule out fuel issue?

3Wheel_Hunter
01-15-2014, 11:48 PM
Haven't check the valves yet; it was fine after I put it back together. No nest anywhere; I cleaned and painted the exhaust and put on a new filter.

Starting fluid into the spark plug chamber didn't do anything.

tri again
01-15-2014, 11:57 PM
I'll keep thinking.
I'm trying to keep, let's see, 1,2,3,4,5,6,7,+ a couple more alive year round so I
believe I've run into almost every problem and even created a few for myself.
Lots of 90/110 and 250 but no 1985 models.
Let's start over.

1985 110
Does it have a key switch like the 125m?
Does it have any sort of neutral safety switch?
so it won't start in gear?

Any chance it has a decompression lever? prob not since you have good compression.
I HAVE seen perfect looking spark plugs mess me up for days, maybe even weeks.
Throw great spark tested outside on the engine until you put them under load.
Also last tiny bit of plug wire gets corroded so nip off a little so the spark plug cap has fresh copper to bite into.

3Wheel_Hunter
01-16-2014, 12:00 AM
Thanks for the help!

No key switch, pull start only. No safety switch; it'll start in gear. I put a new plug in with another coil, and still no luck.

tri again
01-16-2014, 12:14 AM
Thanks for the help!

No key switch, pull start only. No safety switch; it'll start in gear. I put a new plug in with another coil, and still no luck.

Dang, yer gonna get a trophy for figuring this one out.
Had good spark but you tried new coil and plug anyway?
sounds like something I'd do.

There comes a time when it goes beyond diagnosis and back to
a point of process of elimination.
You can feel compression with your thumb?
Will it suck on your hand if you cover the carb intake?..just getting back to serious basics.

NO doubt about spark.?
aaaaargh...
it ran and now it doesn't want to run and for no good reason,
and nothing makes sense.

Sounds like it might be related to my ex.

3Wheel_Hunter
01-16-2014, 12:17 AM
That's funny!

Yep, it had a spark but wanted to eliminate the possibility of plug and coil. It has good compression, I did the test with a compression tool.

This is going to be a pain in the rear for sure.

tri again
01-16-2014, 12:33 AM
Maybe we take a lesson from the mindboggling nonsensical ex, walk away, pretend you don't care
and maybe it will come a runnin'.

Oh, the search key has done wonders for me in times like this.
Not sure of keywords to use but I usually read all posts on a particular topic, even if it's not the machine I'm working on.
Time consuming but when I'm going nowhere, at least makes me feel like I'm doing something productive.

Stator ohms out and you can SEE spark?
I've seen one stator throw spark like 10 times and then fade out, spin it again and NO spark.
Spin it again and 10 sparks that fade but the engine is slowing down anyway, right?
BAD stator on that one.

A cdi can do that too. but dearGod you think it would at least spit in your face trying to start right?

I'm thinking we should start a special 'impossible thread' for situations like this one, separate category with an actual prize for who(m)ever gets it.

tri again
01-16-2014, 01:01 AM
Since we're on the topic of bizzarre oddities, I had a 200x driving me kaRazy.

Apparently, the kill switch ground is ALSO the ground that makes the cdi WORK.
...so to make sure the KILL switch ground was working properly, actually made it RUN.

Talk about a double negative and 2 wrongs making a right.

3Wheel_Hunter
01-16-2014, 08:31 AM
Thanks for sticking with it. I've searched the site but can't find anything related to what I'm doing.

3Wheel_Hunter
01-16-2014, 10:16 AM
try again - thanks for hanging around last night; seems that the carb was flooded last night. I went out this morning and it started on the first pull.

tri again
01-16-2014, 03:22 PM
YaY
so?
you walked away, pretending to give up and it chased you screaming
and wanting to try again.

Carb float needle valve?
Fuel shut offs don't always shut off.
Had one leak gas into the engine diluting the oil.

3Wheel_Hunter
01-16-2014, 06:20 PM
Yep!! Seems like a total carb rebuild is in the near future.