ATC-110 Engine questions...

[Vantage]

Hi all!

Okay, '79 ATC110 basket case, pulled it all down and did major full maintenance, lube/adjust/repair all. Bored out cylinder, had corrosion to .020 so I took it out something like .075, can't remember. New piston & rings, valve job, a little porting "While I'm in here...". Has a DG pipe, painted & polished stuff up, built some custom fenders out of thin aluminum diamond plate on 3/4" square tube frame, made a custom seat [needs better upholstery]. Bought new inner tubes for tires, ready to rock.

Naw, it would only roll > no spark! Bought all new ignition, installed & tested all, built new looms, tested more, narrowed problem to stator. Got used one off Ebay, he saw me coming. No spark. Bought 2nd used stator from a forum member, no spark. Posted to ask questions for more info on loss-less ignition, not accuse or even mention seller's name. Unfortunately everything went nuts when seller insisted forcefully that stator was good, therefore identifying himself, which I wasn't going to do. Several forum members piled on, quickly convinced that I was a complete idiot and liar, stator was good, I was half witted and should go and... well, you know. I didn't come back.

I'd spent all I had, around $150 for 2 used stators and $400+ in other new parts. Fully broke on my meager fixed income so left it dead & parked ever since. By chance a neighbor had a trashed 110 engine complete, mine for 20 bucks, tore it apart and got stator. Installed it in my bike a few days ago and super bright spark! Great, plus everyting else is new. Carb is leaky but now fixing carb petcock, may be running tonite!!

So, this spare engine had a carb but way different from mine, a Kei Hin that's stamped 'KF' on one edge of flange, '660A' on the opposing edge. Engine-side bore is 24mm, air cleaner horn is 32.6mm. Mounted on SUDCO manifold, with sharper angle out to side for better clearance. Set up with thumb throttle. Has a steel lever about 1/4" by about 3" long, flat on end, for choke lever, similar to my [long gone] XL-100.

Any ideas on what carb this is or what it's off of?

Checked head and one valve is about 27mm diameter, other about 23mm. Head may be mildly ported. Are those stock measurements for 110 valves, or oversized valves?

Cam casting is cast-marked '53'. I can't imagine how to measure the profile on it, not sure of what reference points to use and only have a digital caliper to measure with. Any suggestions to figure out if this is a hard-faced regrind by measuring somehow? Is that the right cam number for stock 110?

I'm thinking this spare engine might be highly modifed with that fat carb and custom intake, trying to discover just what I've got.

Thanks, any information is appreciated.

[Vealmonkey]

Not sure if your engine is modified or not. And intake and a bigger carb doesn't mean that there are any internal differences. Of course it doesn't mean that it isn't modified either. It's hard to say wether the cam is a different grind without more info. You may have to take your old cam out and compare. You might want to measure the piston bore and compare with what you have too. Since you have all the parts at your disposal, you have way better access to what you have then we do here behind our computers. You will probably just have to take some things apart and compare bits side by side. Sorry I can't help you more. There were so many places at one time that sold different cams and such it's pretty hard to keep track of all the statistics. Heck, you could have a cam out of a cl90 or sl90 and they would be a different grind than an atc90 or atc110 cam, and those are from stock honda bikes. Some of the first atc performance cams were older honda bike cam copies. So get in there and and take some pictures and compare bits side by side and let us know what you have.

[Vantage]

Not sure if your engine is modified or not. And intake and a bigger carb doesn't mean that there are any internal differences. Of course it doesn't mean that it isn't modified either. It's hard to say wether the cam is a different grind without more info. You may have to take your old cam out and compare. You might want to measure the piston bore and compare with what you have too. Since you have all the parts at your disposal, you have way better access to what you have then we do here behind our computers. You will probably just have to take some things apart and compare bits side by side. Sorry I can't help you more. There were so many places at one time that sold different cams and such it's pretty hard to keep track of all the statistics. Heck, you could have a cam out of a cl90 or sl90 and they would be a different grind than an atc90 or atc110 cam, and those are from stock honda bikes. Some of the first atc performance cams were older honda bike cam copies. So get in there and and take some pictures and compare bits side by side and let us know what you have.

Thanks for your reply. Yeah, it's a mystery motor for sure, no history on it at all. As mentioned I got to thinking that with a carb that much larger than stock, plus an oversized [internally] and short-ram intake mainfold it could be a strong indication that it was hotted up inside as well. I don't think a bone stock engine would run worth a hoot with that large a carb?

The bore is way far gone, very deeply pitted. Possibility of a max overbore saving it, dunno. It's a 105 cc barrel by casting #, current diameter looks like 52mm. Can't recall what stock bore is.

I may be inside my good engine again, will compare cams. Hopefully someone will post with some further info on how to get some kinda measurement for now, because cam is still useable. Wondered about casting number '53', if that's the usual number found on cams.

Also hoping someone knows what carb by the letters & numbers, or something close.

Thanks!

[Vealmonkey]

It's a kehin carb. Sounds like you have all the info though. I'm sure it's a round slide carb, not a flat side or the newer "cv" style of kehin. Shouldn't be to hard to get parts for if you wanted to rebuild it. The real tale would be to see what jets it has in it. You can run a big carb, but the jetting is real critical. A big carb means it's more for high end. Who knows where or why a previous owner got that carb and intake. Maybe the old stock carb was worn out and someone gave him the carb and intake. I've seen it happen before. Then the trike runs worse than it did before since it is now over carbed and the trike is retired to a corner. The stories on old trikes never cease to amaze me sometimes.

[Vantage]

Thanks, and yes, it's a Kei Hin, apparently a model KF #660A. Problem is I can't find info on it regarding exact specs, application, parts. Checked on several search engines etc. and came up with a screamin zero. Kei Hin's website was no help at all. I cannot even find any reference to a KF series, let alone a 660A, just a dead end. Looks just like the carb on my XL-100 but no idea if it's actually the same model etc.

If this build progesses I'd need to know more about it and what's available for it for jets & metering rod.

I figure if those are stock specs on bore and valve size on that engine then it's maybe that somebody had carb jetted for a specific use, but it's still pretty big for a stock 110. However if the valves are oversize I may want to swap heads & cam with current setup, plus use that carb as I already have decent exhaust etc.

[Vantage]

Found the Sudco website, maybe I can find info there. On dialup it will take a while.

http://www.sudco.com/Carburetor01.html

Too bad Keihin doesn't offer much Technical Support or Customer Support. Fine, Keihin > > > Mikuni's are far better anyway so that's where I'll take my business!