Dual Carb from XR 200 on ATC???

[bigredhead]

A friend of mine called yesterday, he got a killer deal on an 85 XR 200, and he swears it's DUAL CARB !!! First thing that came to mind was " Dual what ? on an XR 200 ??? yeah.. right ".

2nd thing that came to mind after he swore it was true.. was Hey...... " I wonder if this could be adapted to an ATC ?? ".

I imagine it has to be a 4 valve head.. and has the sought after 6 speed tranny... anyone ever check this out before ?

found a good link on google about parts interchanging... XL. XR, atc X etc..


http://www-staff.lboro.ac.uk/~elvpc/bikes.html?http://www-staff.lboro.ac.uk/~elvpc/papers/XR200.html

[jenndnn3]

Goto ATVconnections and do a search on this. You will find your freind is telling the truth. You will also find from what I understand, that it wont work on the 200x. And the gain is not worth the work.

[bigredhead]

http://forums.atvconnection.com/messageview.cfm?catid=15&threadid=427506&highlight_key=y&keyword1=xr200

found it !

[OldSchoolin86]

I've always know the dual setup to be more of a pain then an advantage. As a matter of fact, many builders back then would ditch the dual carb setup and convert them to a single for race applications.

[grundlegrabber]

The dual carb setup (used on the 4 valve heads) consisted of a primary and secondary carb. Although both carbs are identical, one works all the time like a regular carb and one of them doesn't start opening until you're past 1/3 throttle. I have this same setup on my 84 XR350. They changed the XR350 to a sngle carb in 85, so the single carb must work better....

[rob0781]

yeah dual carb is a pain,my friend had an xr250 and what a time tryin to sync the carbs...Hey G did ya get to ride the xr200 i wonder if they work good,i know of a 91 with a parts bike for $500...

[Blown 331]

I've got 2 carbs on my XR500, I kinda like it. I'm not saying it's better or anything but it's kinda cool, something different. I put a pipe on it and ported the air box. Once you get into it it's not that bad to jet, I am a little rich on the bottom end though. It has dual 32mm's on it. It's gonna take big single carb to flow that much air.

What year XR200 had 4-valves? I know someone who has a 2002 XR200 and it's only 2 valve. Never mind on this question, the link posted above answered it. That's kinda crazy they had a RFVC 200. I wonder if could some how get that in a 86-87 200X.

[bigredhead]

could easily me moded to a 250 from what i read... a 250 X. 6 speed would be awsome !

[OldSchoolin86]

It has dual 32mm's on it. It's gonna take big single carb to flow that much air.
A single 44 will flow the same as two 32's. With todays tech that xr500 would do best on something like a single fcr 40.

Some rappys are running a single kit too. FCR and Edelbrock make the kits for those.

[Blown 331]

A single 44 will flow the same as two 32's. With todays tech that xr500 would do best on something like a single fcr 40.

Some rappys are running a single kit too. FCR and Edelbrock make the kits for those.

I dont mean to hijack the thread but I was thinking there is no way my 2 carbs can flow as much as a 44 so I double checked and it actually has 2 28mm carbs. I think that is more like a single 37mm. That is still big for a stock carb. I would say a fcr 40 would be great on that thing! Probably get intake system off an XR600 to go to a single carb. I'm gonna leave it the way it is but it's something to think about.

[OldSchoolin86]

Two 28mm's are the same as 1 39mm so the 40mm would be a nice upgrade considering size and quality.

If they were 32mm carbs and you wanted to know the single size just do a little math.
r*r*3.14=A(area of 1), 16*16*3.14=803.84
A*2=B(area of 2), 803.84*2=1607.68
B/3.14=C, 1607.68/3.14=512
the square root of C is the r of the d of the single carb, ---> 22.62mm
r+r=d, 22.62+22.62=45.25

So you were right, a 44mm was too small. You'd need a 45mm to replace them.