ATC 70 Jetting

[surveywaters]

I am in the progress of resto/customizing a 1985 ATC70 that I was givin. I have corresponded and recieved help on many topics so far and I thank you all.
My newest issue is jetting. I got her running strong and smooth but she bogs with out choke. I have cleaned the carb and replaced all servicable parts with oem. It idles fine but dies with throttle. I am running with a pod filter because the factory air box didn't have the end caps. It's a stock rebuild in it with the 38 pilot and a 58 main. The needle is all the way up and it's not helping. Is it a pressure issue due to the lack of an air box or can this thing be jetted to run a pod? If the pod is do-able (I hope so) then what jetting have you guys had luck with.

Thanks,

Jon

[bkm]

Since the carb is clean and it will run with the choke on, thats telling you that it is getting too much air and not enough fuel. The choke is making the mixture rich and is compensating for the lack of an air box and jetting needs to be increased. Try two jet sizes bigger and go from there.

[surveywaters]

Thanks for the quick response!
Just go up on the main, like a 60, and leave the pilot on 38?
Have others run these 70's with a pod with good performance?

Thanks

[bkm]

Start with the pilot and go from there. It sounds like its right off idle so I'd start there.

[CRAZY70MAN]

Thanks for the quick response!
Just go up on the main, like a 60, and leave the pilot on 38?
Have others run these 70's with a pod with good performance?

Thanks

Too much air. In all my 70 endeavors....I have never had to re jet a stock motor even with pod filter. I have had luck with restricting the air on the pod filters with any type of foam wrap, sock, ace bandage etc....... you get the point. You may try that route first before re jetting. My 90cc atc 70 used to bog with a pod filter as you stated till I wrapped it nicely with a rag and zip ties. Also keeps a lot of the mud and water out. Good luck

[Frankencelery]

Ok, I have to ask, I think I know but what's a pod filter? Is it one of those aftermarket filters that just hangs off the back of the carb?

Sometimes running only with the choke on means you've got an air leak somewhere. My 70 runs with the caps off, although not as well.

[surveywaters]

Yes a pod is an aftermarket filter that does not use the airbox.
I hadn't considered an airleak. I haven't removed the intake and it has been set up for a long time, thanks for that thought. I'll yank the intake tomorrow and cut some new gaskets before I order jets.

Crazy70man, I appreciate the tip, and I'm sure that wrapping the filter would cure my lean condition but I won't be in the dirt and mud too much with this little trike, it's more for show, so I'd like to get the jetting right rather than buy a gym sock to match the new paint job ;) jk

Jon

[CRAZY70MAN]

Yes a pod is an aftermarket filter that does not use the airbox.
I hadn't considered an airleak. I haven't removed the intake and it has been set up for a long time, thanks for that thought. I'll yank the intake tomorrow and cut some new gaskets before I order jets.

Crazy70man, I appreciate the tip, and I'm sure that wrapping the filter would cure my lean condition but I won't be in the dirt and mud too much with this little trike, it's more for show, so I'd like to get the jetting right rather than buy a gym sock to match the new paint job ;) jk

Jon

Gotcha.......just thought I would tell ya how to cure it on the cheap!!!......Let me know how that jetting works..............never see many 70's rejetted......good luck.

[surveywaters]

I order a 40 pilot, a 60 and a 62 main. Should fix her up if there's still enough venturi effect, which there ought to be since it's still that itty bitty stock carb. Also went on and ordered new plastics and some other goodies. That DRATV is an awesome one stop shop! This freebie is almost a $250 mint. Thanks guys, and I'll let ya'll know how the jetting works.

[surveywaters]

Okay, quick update for anyone who cares.
Background:
The pod I'm using a a pretty cheap 3" slip on filter.
The bike was idling good with the choke off, and running fine with the choke half on (no the carb didn't just need a cleanin').

Update:
I started with a 40 pilot, but it ran sorry, smelt like fuel, and still needed choke at higher revs.
Replaced the 38 pilot and put a 65 main in, ran her a bit, did alot better but smelt rich. I checked the plug and it confirmed the rich odor.
I have a 62 main now and it is running like it should.

Thanks for the help guys

[bkm]

Good to hear that you got it lined out. Sounds like the two jet sizes were just what the doctor ordered.