ATC 250R Carburator

[Caraholic86]

I pulled the carb apart on my 1983 ATC 250R to clean it and noticed this circular brass piece between my main jet and piece that my main jet screws into. Can some one please tell me what the circular piece is for and if its supposed to be in the position it is in the first pic or like it is in the second pic? Thanks.

[Liquid-Darkness]

Its probably to guide the float maybe?? But probably like the 2nd pic so fuel does not get stuck in the lil lip.

[AbnMike]

See page 2:

http://www.mikuni.com/pdf/vmmanual.pdf

[AbnMike]

Hmm, I guess links aren't allowed here, my bad.

Google Mikuni carb VM Manual You will find a .pdf manual for your carb. Page 2 is an exploded view.

[Bren_downe]

I can't see that well on your pic, there is supposed to be a bowl shape pice between your main jet and needle seat. From what I understand it keeps the fuel directed up towards the main jet. When your riding over rough terrain and the fuel is sloshing around in the bowl it stops the fuel from surging into the main jet.
The carb is a stock Kehin PE30.
You can find the carb diagrams at JetsRus.com

[Caraholic86]

Yea I found that diagram on jetsrus.com but couldn't find my exact same carb. Looks like they have every one but the pe 30. The first pic is how the previous owner had it installed with the bowl facing up so I think I'm gonna put it back like that.

Also he had the clip on the needle on the very top notch. Should this be more toward the middle? I have a 140 main jet and 50 pilot jet in it.

[Caraholic86]

See page 2:

http://www.mikuni.com/pdf/vmmanual.pdf

Thanks for the link! Its kinda hard to make out on there but it looks like they have the bowl facing up. They call it a fuel retaining cup so it makes sense to have it up like a cup.

[Caraholic86]

Anyone have a recommendation on where the needle clip should be. I have a 140 main and 50 pilot jet, no air box lid.

[PittsburghPete]

Depends on whether you are running rich or lean. Your spark plug will tell you. Check out a link on the home page of www.jetsrus.com at the top left corner..FAQs/ Tuning....then click on REJETTING 101- How to rejet. This should help out big time.

[Caraholic86]

Ok thanks.

[barnett468]

.
Howdy!

http://t3.gstatic.com/images?q=tbn:ANd9GcQxr9P5OYMQvRhaWZ5QfBVTS7isj4zCS JQ6Ku1TmxO1HY-ScDvHod7NuYM


Thanks for the link! Its kinda hard to make out on there but it looks like they have the bowl facing up. They call it a fuel retaining cup so it makes sense to have it up like a cup.
The bowl goes down, the main jet goes inside it 110% guaranteed. It is a main jet shield as bren downe implied.




Anyone have a recommendation on where the needle clip should be. I have a 140 main and 50 pilot jet, no air box lid.As pittsburgpete suggested, you need to jet it to your particular bike and elevation. the plug color is a good indicator of jetting.

If it starts easy, idles and runs well, and your spark plug is lite to medium tan, your jetting is close if not ideal.

Below are the stock settings for your bike. Your current main jet is extremely small.

PE30A
air screw - 1 1/2
main jet - 158
float level - 20 mm.
needle position - middle

[Caraholic86]

.
Howdy!

http://t3.gstatic.com/images?q=tbn:ANd9GcQxr9P5OYMQvRhaWZ5QfBVTS7isj4zCS JQ6Ku1TmxO1HY-ScDvHod7NuYM


The bowl goes down, the main jet goes inside it 110% guaranteed. It is a main jet shield as bren downe implied.



As pittsburgpete suggested, you need to jet it to your particular bike and elevation. the plug color is a good indicator of jetting.

If it starts easy, idles and runs well, and your spark plug is lite to medium tan, your jetting is close if not ideal.

Below are the stock settings for your bike. Your current main jet is extremely small.

PE30A
air screw - 1 1/2
main jet - 158
float level - 20 mm.
needle position - middle



Ok so it needs to be like it is in my second picture? The guy that I bought it from had the bowl like it is in the first picture. What would have happend if I left it like that?

Also are you sure it came with a 158 main jet? I have read a few different places that it came with a 130 stock.

[barnett468]

Ok so it needs to be like it is in my second picture?The moderators don;t allow me to view photos the way you have them posted because I'm apparently different than everybody else. One side is deeper than the other, the main goes in the deep part.



Also are you sure it came with a 158 main jet? I have read a few different places that it came with a 130 stock.You have never read in the manual that it came with anything other than a 158 stock. The 130 is for a different year.

Honda manual.

http://www.atcmanuals.info/

:beer

[atc300r]

The stock 83-84 250r came with a 30 mill Keihin carb with a 130 main jet. 50 slow jet.The 158 main jet came in 81 250r stock carb wich is different than the 83-84 250r carb.

[barnett468]

The stock 83-84 250r came with a 30 mill Keihin carb with a 130 main jet. 50 slow jet.The 158 main jet came in 81 250r stock carb wich is different than the 83-84 250r carb.

Yes, I see, pg 18-12 1983 addendum under "High Altitude Adjustment". Nothing like hiding it, lol. Thanks for the correction.

:beer