any performance gains using a XR head on 200X?

[3Wheelers4Life]

would their be any performance gain if i were to use a XR200 head on an 84 200x? or are the 200X and XR heads identical (the years that interchange)? also, what year XR heads will interchange with the 83-85 200X? thanks!

[thefox]

If your just talking about the head then no, no performance difference (the difference is in the cam). You can use all non RFVC XR200 or XR200R heads (1981-1983, 1986-on).

Honda switched engine design for 2 years in 84 and 85 (duel carb setup is the easy sign of this RFVC engine). Parts from that motor do not fit.

[oldred95]

Well the heads appear to be identical but the topends as a whole have some differences. The 83-85 200X's were a 192cc bore if I remember correctly. The 1981 XR200 engine I have in pieces stock was 195cc. The XR also had a bigger cam and carb, and in the case of the one I've got, a 29mm mikuni rather then a stock appearing kehein. As far as the heads flow wise I doubt there is much if any difference.

[Bigbore]

No differences in the head.

But... most XR 200 rides their big performance swaps are to run the 200X cylinder because the increased size of the cooling fins.

The only advantage of the XR for a 200X is the tranny. If you have a XR motor, swap the 6 speed into the 200X. Do a rebuild with a 10.5 / 1 piston and a mid range cam. Mild port work makes a big difference.

[oldred95]

No differences in the head.

But... most XR 200 rides their big performance swaps are to run the 200X cylinder because the increased size of the cooling fins.

The only advantage of the XR for a 200X is the tranny. If you have a XR motor, swap the 6 speed into the 200X. Do a rebuild with a 10.5 / 1 piston and a mid range cam. Mild port work makes a big difference.

What about the rearward kick on the XR200?

[jenndnn3]

There is a difference in the heads,,,
the xr has decompresion
Which affects the rockers..

[OldSchoolin86]

There is a difference in the heads,,,
the xr has decompresion
Which affects the rockers..Isn't that more to do with the valve cover?

[3Wheelers4Life]

ok, so xr and 200x heads are the same. i was hoping the xr would have been a performance mod. oh well. maybe ill get my x head ported if i get enough cash. thanks guys.

[oldred95]

You can do a port job pretty easy. The head on my 200x had some very obvious imperfections in it that I took care of. One of the biggest being on the back side of the valve seat on the intake there was a nice little ledge where the seat and casting met. Anything like that in the intake will catch fuel and cause it to form droplets. Gas droplets don't burn very well compared to vapor. I knocked down the ledge the valve seat was causing, sized the throat of the port equally all the way around, cleaned up a little casting flash and moved to the exhaust port. I found the same sort of ledge on the exhaust side and although it wouldn't be able to trap anything it was still bottle necking the throat of the port so I opened it up a little, cleaned up some casting flash and matched the head pipe to the head using the exhaust donut seal. I never rode it before doing the port work but for being pretty well stock and not rejetted it runs very well.

[Bigbore]

What about the rearward kick on the XR200?

What do you mean? I didn't say use the bottom end, just the gear set from the XR.

[oldred95]

What do you mean? I didn't say use the bottom end, just the gear set from the XR.

You're saying you can take the gear set out of the XR bottom end and put it into the 200X bottom end? Is it really that simple? If it is I may have to do this to my 200X since the crank is trashed on the XR engine.

[lndy650]

maybe its just me but i prefer 5 gears. 6 gears just makes acceleration slower if you have the power to pull 5 at the same top speed ratio

[3Wheelers4Life]

yea, would the xr200 6-speed trans be a direct swap into a 200X with no mods? i may also have to look into this if its a direct swap. correct me if im wrong, but i think i heard somewhere that the xr200 gears are weaker then the 200X? now if only you could get reverse, that would be nice. thanks.

[hrc200x]

I'd think a person could just use the xr bottom end and bolt the 200x right side cover and kick start shafts onto that bottom end.

From comparing I've done in manuals it showed the lobe size the same, but the degrees the cam is at when it opens and closes the valves was different.

Here are the main difference I've come up with:

compression bumped up like .6 or .4. So instead of a 200x being 9.4:1 a xr is 10:1
Larger bore
cam degree openeing
larger carb on xr
6 speed xr

I am not sure how they got a little more compression. Maybe with a larger bore and keeping the same cc sized head?

[Dirtcrasher]

Nope, you must use the 200X lower end but the XR gears are a direct swap. Jenndnn3 has done it.....

[oldred95]

Nope, you must use the 200X lower end but the XR gears are a direct swap. Jenndnn3 has done it.....

I PM'd her about it a few hours ago on .org but haven't gotten a reply yet. You use the entire 200X bottom end right, inner case, outer covers both left and right, same kicker and everything right just the XR200 gear set?

[3Wheelers4Life]

DC, your sure about this right? i am thinking about doing this. will any year xr trans swap, or will only certain ones? what all would you need, just the gears? is the picture below all you would need? ignore the xl200 paper. also i have heard that the xr200 gears are weaker then the 200X, is this true? thanks!


http://i21.ebayimg.com/04/i/000/e1/dc/1008_1.JPG

[oldred95]

There is only two reasons I can think of that they would be weaker. One the existing gears physically had to be made a little smaller to have room for the 6th gear, or two that Honda never intended the gears to only have to turn one wheel and didn't see the need to harden them more or less or whatever the case might be. But stock for stock the XR200 produces more power then the 200X so would it not need gears equally as strong to handle the extra power?

[Dirtcrasher]

IDK what year XR200 you must use or if thrust washers change etc etc, but from what I have read it is a direct and fairly easy swap with no machining at all.

Give it a bit of time JENN will chime in and it will all get figured out. I'm not gonna "pretend" to know whats up like most unguided postwhore morons do.....

EDIT - as far as weaker gears go.... How many of you guys have EVER broke a gear? I'm 25 years deep as a rider and have owned about 50 machines, beat the snot out of every one of them and never broke a gear..............................................

[oldred95]

The XR engine I have is from a 1981 and other then rearward kicker and a slightly different shaped right side outer case the engines physically are almost identical in appearance. I think it was 1984 they changed the engine design of the XR200. Somewhere around in there they came out with the XR200R which was a different animal.

[thefox]

If your just talking about the head then no, no performance difference (the difference is in the cam). You can use all non RFVC XR200 or XR200R heads (1981-1983, 1986-on).

Honda switched engine design for 2 years in 84 and 85 (duel carb setup is the easy sign of this RFVC engine). Parts from that motor do not fit.

It can also say engines... the 81-83 and 86-on (both XR200 and XR200R) are all nearly the same engine. Stay away from the RFVC, they look very different so it should be easy to spot them.

As far as weaker gears, the only time I have heard of the XR gears being weaker is when using the powroll stroker and the engine built to the max.... I would not worry about the gears being weak.

[oldred95]

It can also say engines... the 81-83 and 86-on (both XR200 and XR200R) are all nearly the same engine. Stay away from the RFVC, they look very different so it should be easy to spot them.

As far as weaker gears, the only time I have heard of the XR gears being weaker is when using the powroll stroker and the engine built to the max.... I would not worry about the gears being weak.

Sounds good. Now to get Jenn to confirm the details of the gear swap.

[3Wheelers4Life]

are the 1,2,3,4,5 gears on the xr200 the same ratio as the 200X, and 6th gear just ads more top end? is a xr200 geared lower then the 200x? or is the 200X geared lower then the xr200? thanks.