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zebvance
01-18-2023, 02:10 PM
I'm planning on doing some upgrades on my 83 atc 200 and have a few questions.

I'm looking to upgrade the carb to a 28 mm (link: http://www.nichecycle.com/ncs/mikuni/carburetors/mikuni-vm28-round-slide-28mm-carburetor.html ) I was told it would work but I would need some sort of intake manifold adaptor. Can anyone help point me in the direction of getting this? Also would there be any other additional parts needed?

At the same time, I will be upgrading the exhaust (link: https://www.ebay.com/itm/334578707999 )

And lastly, the head is going to be pulled for leaking head gaskets and I saw this on aftermarket head and piston kit and am considering it.

(link: https://www.ebay.com/itm/255723614691 )



Any issues with this build? Am I overlooking anything? Please give me your opnions.

350for350
01-18-2023, 09:46 PM
Going by what your link says, I think that you'll be running pretty rich with that carb. Those seem like pretty large jets for a 200cc engine. It lists a 200 main and a 60 pilot. Another question is why are you wanting to use a 28mm carb? Your stock carb was a 22mm and a 200X uses a 24mm. A XR200 uses a 26mm. I'm not really trying to say that you're wrong for wanting a 28mm carb, I'm just asking out of curiosity.

patriot1
01-18-2023, 11:41 PM
The best and possibly the cheapest upgrade is to find a 200x roller for that engine

TrikeKid
01-19-2023, 12:43 AM
What's your reasoning behind going so big on the carb? Without a cam and head work you won't be likely to turn the RPM needed to make use of that much carburetor and you'll give up response and low RPM performance in the process.

zebvance
01-19-2023, 10:21 AM
Going by what your link says, I think that you'll be running pretty rich with that carb. Those seem like pretty large jets for a 200cc engine. It lists a 200 main and a 60 pilot. Another question is why are you wanting to use a 28mm carb? Your stock carb was a 22mm and a 200X uses a 24mm. A XR200 uses a 26mm. I'm not really trying to say that you're wrong for wanting a 28mm carb, I'm just asking out of curiosity.

This is what I was recommended and with the upgraded head and larger piston size I thought it would be ok. Definitely open to other suggestions.

zebvance
01-19-2023, 10:22 AM
What's your reasoning behind going so big on the carb? Without a cam and head work you won't be likely to turn the RPM needed to make use of that much carburetor and you'll give up response and low RPM performance in the process.

It was recommended to me and thought it would be a good match with the upgraded head and piston size. Open to other suggestions!

Footy
01-19-2023, 04:17 PM
Could you let us know which 1983 ATC200 you are working on? There are 3 1983 ATC200 models. A plain 200, a 200E and a 200X. Which of these are you working on?

zebvance
01-19-2023, 05:24 PM
Could you let us know which 1983 ATC200 you are working on? There are 3 1983 ATC200 models. A plain 200, a 200E and a 200X. Which of these are you working on?

Just a plain ATC 200. No electric start and not a 2 stroke.

zebvance
01-20-2023, 10:55 AM
Any help on this would be greatly appreciated. Suggestions on a upgraded/bigger carb and opinions on the head and piston kit?

shortline10
01-20-2023, 12:34 PM
Can call or message four stroke tech , they sell the parts your looking for .
https://m.facebook.com/100054606602640/

zebvance
01-23-2023, 10:20 AM
Can call or message four stroke tech , they sell the parts your looking for .
https://m.facebook.com/100054606602640/

Thanks for the recommendation. Contacted them and they suggested a 30mm bolt up carb that they use. Ordered and hopefully shipping this week.

Homeless Dave
01-23-2023, 02:24 PM
A few mods I’ve done with great results are:
Xr200 cam
Xr200 carb
Good aftermarket exhaust

Those will yield a good bit of difference, but still have great reliability.


Sent from my iPhone using Tapatalk

Scootertrash
01-23-2023, 04:38 PM
A few mods I’ve done with great results are:
Xr200 cam
Xr200 carb
Good aftermarket exhaust

Those will yield a good bit of difference, but still have great reliability.


Sent from my iPhone using Tapatalk

I can second this suggestion. Mine runs great.....when I get the time to ride it.:rolleyes: