General XR200 Information.

Please note: The bulk of this information has been collected from various sources around the internet and may contain errors.  Before acting on any of this info confirm it with your qualified bike mechanic or Honda dealer.

1998 XR200R

2000 XR200R

Miscellaneous XR200 Info:
Things to consider if you are buying an XR200:
1981 XR200R was the first year of the Pro-Link Shock and Chassis which was a great improvement in handling over twin shock models
1984 and later Full cradle chassis had geometry and rigidity improvements
1984 & 1985 RFVC 4 valve motors were heavier but provided more power.  Can be troublesome if not maintained and are harder to get parts for.
1986 to 1991 Thought by many to be the best years of these bikes with the Full cradle chassis, 2 valve engine and full travel suspension.
1993 to 1999 A shock without adjusters and reduced suspension travel hurt the handling of these models.  This did reduce seat height which may suit some.
2000 allegedly another reduction in suspension (not sure how much) This also is claimed to have reduced seat height which again may suit some.
Check the Known Issues List.

Basic Tuning & Maintenance Info

Stock Jetting:
Model / Year 79 XR185 XR200 (not XR200R) XR200R (81-83 only) XR200R (84-85 RFVC ) XR200R (1986) XR200R (1987 to 2002) Californian 1998 and later
Main Jet 115 102 138 ? 112 110 102
Pilot Jet n/a 35 None * ? 38 (35) (98 and later CA only) 38 35
Needle Position
(from top down)
4th groove 3rd groove 3rd grove ** ? 2nd groove?? 3rd Groove 3rd
Pilot screw setting 2 1/4 turns out 1 3/4 turns out 2 1/2 turns out ? 1 1/8 turns out 1 1/8 turns out 1 7/8 turns out
Float Level ? 12.5mm
Carb (Keihin) PD31A PD32 PD28A ? PD97A PD97A PD97

* Alternate sources suggest the PD28A did have interchangeable pilot jetting
**  Honda manual is said to suggest 4th groove

Keihin PD97A Information
Standard Alternate No.
Pilot Jet Type Keihin N242-21
Overall length: 28mm
Thread diamter: 5.9mm
Head diameter: 4.9mm
Main Jet Type Keihin 99101-357-xxxx
Overall length: 16.5mm
Thread diameter: 4.9mm
Keihin 99113-GHB-xxxx (may supercede 99101-357 jets)
Needle Jet

Basic HOP UP & reliability mods info:

Popular 2 valve engine mods:

Easiest mods:

    1/  Replace the standard filter with a free flowing Uni-Filter, No Toil, Twin Air or similar foam filter.

    2/  Remove the Induction Cap (item 11 in image on the right hand side), leaving the Induction Duct (item 10) in place.
                                                   It may be possible to sensibly modify the Induction Duct (item 10), but keep in mind
                                                   that it performs a important function in helping to keep dust, mud, water and other
                                                   debris from entering the airbox.

    3/  Rejet - Presuming that all other motor/intake/exhaust components are stock
going up 1 jet size on the Pilot and Main Jet from standard  seems to
                     be the accepted ballpark rejetting required.

    4/  Exhaust - There are a few different aftermarket pipes and header pipes available, but for the cheapest and easiest
                        change grind the weld off the inside of the header where it connects to the head and remove the cap on
                        the rear ( by removing 2 x 8mm bolts )  As with most exhaust modifications, it usually makes the bike
                        Obnoxiously loud or illegal bikes can hurt the sport / passtime.
                        The baffle out of an ATC250R (years?) is meant to be less restrictive and bolts straight in.



             Extensive "race level" porting is something that most agree be left to the experienced guys that have been there done that and lunched numerous heads while determining what works and the casting limitations.  However many people online seem to have done some basic cleanup and port matching successfully.  I've collected some online info ( here )

Lift Lobe
Lift Lobe
Powroll 12701N Torque Measured 23 42 245 0.369 102 44 17 241 0.365 104 103 40
Powroll 1214N Track 18 43 241 0.355 103 41 20 241 0.355 100.5 101.5 38
Powroll P714 measured 20 52 252 0.365 106 49 23 252 0.361 103 104.5 43
XR200R measured 14 46 240 0.321 106 43 21 244 0.299 101 103.5 35
TLR200 measured 5 32 217 0.276 104 31 6 217 0.245 90 96.75 11
Stock (ATC200X) 8 37 225? 0.318 104.5 40 8 228 0.308 106 105.25 16 ATC200X Camshaft
Specs from Megacycle
Stock (ATC185C) 6 36 222 0.288 105 35 6 221 0.270 104.5 104.75 12 ATC185  Camshaft
Specs from Megacycle
Megacycle 143-00 17 46 243 0.365 104.5 46 17 243 0.365 105 104.5 34 OK with stock piston and springs.  Increases
mid-range power and torque.  Smooth Idle
Megacycle 143-20 34 59 273 0.370 102.5 59 34 273 0.370 102.5 102.5 68 Use modified piston and springs.  Best all
around cam.  Great mid-range and added
Megacycle 143-40 30 62 272 0.435 106 62 30 272 0.435 106 106 60 Full race cam.  Use racing piston and springs.
Maximum mid-range and top-end power.
Must cut cylinder head for lobe clearance. Use E/D228-H valve spring kit
5 30 215 35 5 220 10
All timing is quoted at 0.040"                                 LSA and Overlap calculator:

Cam Intake Exhaust Notes
Duration Duration
@ .050"
Lift Duration Duration
@ .050"
Webcam 40b 266° 237° 0.340 266° 237° 0.340 Good mid and upper end performance for stock engines
Webcam 89a 270° 240° 0.362 270° 240° 0.362 Good mid and upper end performance.  Requires exhaust system, high compression piston and performance valve springs
Webcam 214 280° 250° 0.375 280° 250° 0.375 Broad power range for high compression racing engines.  Requires exhaust system, high compression piston and performance valve spring kit.
Webcam 172 288° 262° 0.395 288° 262° 0.395 Broad power range for high compression racing engines.  Requires exhaust system, high compression piston, and performance valve spring kit.  Check ALL clearances!
Webcam 232/172 288° 262° 0.435 288° 262° 0.395 Racing cam designed to take advantage of larger valves and the latest port flow technology.  Requires exhaust system, high compression piston and performance valve spring kit.  Check ALL clearances.

Awesome post on camshaft/valetrain theory: =

Suspension Mods

For 93 & later:
*  Fork Swap or internals from an 84-85 (RFVC engine) or 86 to 91 (2valve) XR200R to get longest factory travel available from the 200R, and a shock from the same bikes which also has longer travel and is adjustable.
*  Race Tech cartridge emulators.  These are said to make a big difference to the original damper rod forks ( )
*  Fork & triples & wheel swap:  Late XR250(e.g. 1997) forks and triple clamps can be fitted with an "AllBalls" conversion bearing set.  It is said to make a huge difference.  It also has the advantage of the front disc.  This will require the longer travel shock and will be a far more involved modification.


Forum post ( on a clutch modification.  "XR200's DIIY 6-clutch-pack ultimate enhancement"  I Haven't tried this or read it in detail,  be sure to run it by your engineer / mechanic If you are considering it.  I think I would try performance frictions and springs first.

Misc. Bulletproofing::
* Drill a wire hole in the oil drain plug and wire up to avoid it being bumped and rattling out then losing it and your oil on a ride.  (Picture anyone? Contact Justxr )
* OSA Tensioner Mod
* Late ('87 and on) kickstart conversion for earlier models ( Thumper Talk Forum Post )

Tools & Tips:
* 24mm socket for the crank gear and clutch hub retainer nuts
* Flywheel puller - You can buy these (e.g. motion pro) but apparently at a pinch the rear axle (or a 16mm x 1.5 pitch bolt) will work. The "Bikeservice Magneto Flywheel Puller 0 Ext. M16 x 1.5 RH -BS2402 ( GasWeld , Supercheap Auto )
* Oil Filter Rotor Lock Nut / Clutch Hub Nut tool - OEM 07716-0020100.  I suspect (but have not tried) that the Bikeservice Counter Balancer & Clutch Hub Socket BS2501  available from Gasweld to be the equivalent. ( here )

Misc. Teardown / Build information:
*  It is worthwhile to flush the oil galleries, resevoirs, cavities and metering orifices while disasembled.
*  There are several orifices in the Right Hand cover that meter oil to: the top end, the crank and to the transmission.  Ensure these are in place and galleries are clean.

*  You may be able to upgrade early 6Volt XRs by changing to a 12Volt AC regulator and swapping bulbs.

Motor information Links:
* Chuck @ Thumpertalk's 218 build page (Fantastic post, a must read)

Micro Fiche's:
So'Cal XR's Parts Fiche online  -

XR185/200/200R parts compatibility:
From what I have read on the www the two valve engines from 80 through to 02 are quite similar.  Double check with dealer / mechanic prior to purchasing.

2 Valve cylinder heads:
All XR185/200/R Cylinder heads will fit interchangably between the two valve motors.  There are some difference in the frame mount though.
79-84 twin shock XR200's have a different width top motor mount (~42mm wide) than the 86-02 XR200R's (~36mm wide)
 (81 to 83 XR200R's width??)
79-84 twin shock XR200's also have a different intake manifold than the 86 and on pro link models  (81 to 83 XR200R's as well??)
83-84 XL200R heads are also claimed to be the same as an early XR200 (80-84) head.
ATC185-200 heads may also be interchangeable, check using accurate parts fiche's first.
Some heads may not have a decompressor setup, running without this may lead to kickstarter mechanism problems.

2 Valve Motor Cylinder Heads
Top mount
79 80 81 82 83 84 85 86 87 88 90 91 93 94 95 96 97 98 99 00 01 02
12000-427-305 42mm? XR185









12000-KA2-305 ??mm



12000-KTO-305 36mm? XR200R XR200R
12000-KT0-306 36mm? XR200R XR200R XR200R
12000-KT0-307 36mm? XR200R XR200R XR200R XR200R XR200R XR200R XR200R XR200R XR200R
1200-KT0-712 36mm? XR200R XR200R
12002-965-505 ??mm ATC200X** ATC200X** ATC200X**
                                                        * Manual Decompressor                    ** No Decompression                               Checked on Partzilla, CMSNL & megazip

Cylinders compatibility and information:
* 80-83 & 86-02 appear to all bolt up and share same bore sizes, height and oil passages
             * 94 and on have 2 dowels rather than 3 of the earlier models.
* 194cc cylinders are OEM, be carefull of chinese cylinders online
* Apparently almost any of the 185-200 2 valve cylinders from XL/XR/ATC will fit and even the 185cc cylinders will bore to 65.5 but may require two passes.
            * XR185 has 180cm3 on the rear of the cylinder
            * Early XR200R has 195cm2 on the rear of the cylinder
            * 86-87 XR200R cylinder marking unknown
            * 88-02 XR200R has 194cm3 on the cylinder
            * ATC200 has 192cm3 on cylinder for big and small fin models
                    * The 83-85 ATC200 cylinder are said to fit and some (apparently not all) have larger cooling fins, but the 86 and on changed and wont fit.
* Over 66mm the sleeve starts to get thin and is questionable for high performance, the sleeves have been known to fail on bores over 66.
* Oil leaking/weeping is a common problem on the two valve bikes on the right rear cylinder stud as it is part of the oil feed to the head.
            *  Evidently there are o-ring and non o-ring (close fit around dowel) base gaskets availalbe.  Sealant may be required.

2 Valve Cylinder Heads and associated parts  (No 2 valves in 85,89 & 92)
79 80 81 82 83 84 86 87 88 90 91 93 94 95 96 97 98 99 00 01 02
12100-427-010 185(1)
12100-446-772 200(1) 200(1) 200(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1)


1200-KT0-000 200R(1) 200R(1)
12251-427-P00 185(1)







200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1) 200R(1)
12191-KT0-711 185(1)

















12191-KT0-710 200R(1) 200R(1)
Dowell (10x20)

















O-Ring (10x1.6)







Table checked using partzila and                        Items in red are superceded and replaced by item in black

Crankshaft timing Chain Sprocket:
* Engines up to and including 1988 use a 20mm ID crankshaft timing chain sprocket (88: 14311-958-000)
* Engines 1990 and after use a 22mm ID crankshaft timing chain sprocket  (90: 14311-KJ2-300)
Note: There is some conflicting information online as to whether the breakpoint for this change was on the introduction of the 1990 or 1994 model
          I haven't been able to find any part number changes on the crank between the 88 and 90 models but I have found fiches that confirm
          the change despite there being no corresponding crank part number changes.  For this reason I think it is also believed that the change
          occured in 1994 when the crank / bearing fit was changed.

Kickstart Mechanism:

* In approx 86 the kicker shaft and lever changed (Kickstart bolt changed from 6x22 to 8x25)
* In approx 87 the kicker gear ratios chandged and were widened (Gears changed from 30/28/19T to 21/19/14T)
* A late kicker can be modified to suit an earlier bike.


* Early side cases (pre 86) were painted black inside and out
* 86 and on side cases were painted silver outside.
* 86 Center case part numbers changed, left case cover changed for new stator.
* Early Right hand side cases may not fit on 86 and on motors due to clearance issues (possible with kickstart mechanisms)
* 94 RH crank case changed.  This was related to the Right Hand main bearing and crank change. Serial 5705049 (or 5708410??) & on. First 94=Ser.No.5704992
                                               Right hand side sidecover appears to have stayed the same (11330-KT0-830)
                                               RH Crankcase, RH Crank, RH bearing and cam sprocket all changed.

Frame / Drive:
* The 86 and up XR200R's have a longer countershaft (~ 1/4") and the frames don't have the footpeg bosses.  This may affect motor swaps between years.

* In 86 the motor was painted silver instead of black.

CDI & Rotor:
* In 86 the electical system went to 12 volts and the alternator output double to 100watts (this may differ on AU models)
* In 86 the CDI system also changed.  CDI parts are said not to be interchangeable between pre and post 86 bikes.
* Stick to the correct XR200 ignition modules ( 'KTO' in part number) other modules may be troublesome or not work.
* The 86 and later rotor is 10oz (283.5g) heavier.  To use this an 86 and later Left Hand sidecover, CDI module, harness, and coil need to be used.
* On non AU models when the headlight and tail light were dropped the lighting coil was left on the stator.
* In the 90's ('94?) the lighting section of the stator was changed to a two wire output system which simplifies having a DC system, no rotor and cover change though.
             * AU fiches indicate 31120-KT0-831 was used from 1993 to 2001, but it is possible AU models had this all along?

Fork Leg Sizes (diameter):
80-84 XR200 - 31mm
81-83 XR200R - 35mm
84-02 XR200R - 36mm
* from - requires checking

2 Valve Motor Identification:

Early motors are painted black inside and out.
The left case near the center (by the oil drain) has the engine serial number, the first four characters are the model code. The numbers under this are the serial number.

Two valve Model motor codes:
MD02 - XL185S B-D (USA / Canada)
MD06 - XL200R D-E
MD09 - TLR 200 D-H
MD10 - XL200 FMD (New Zealand)
ME02 - XR185 Z / XR 200 B-E 79-84
ME04 - XR200R B-D 81-83
ME05 - XR200R E-J + L-P (84-88,90-93 to #5705049)
ME05 - XR200R R-2 (94-02 #5705049 and on)
TB01 - ATC185 A / S B-D
TB05 - ATC200 B-D /E C-D / X D-H /S E-G /M E-F /ES E-F
TD05 - ATC200E C-E /ES E-F /X D-H
TD05 - ATC200E C-E /ES E-F /X D-H
TE03 - TRX200E /SX F-J
TE17 - TRX200 L-M Fourtrax / D M-P Fourtrax

To identify the model year, Honda has added some logic to their model names. The last character refers to the year, also tenth character in the VIN.

Z = 1979 H = 1987 S = 1995 3 = 2003
A = 1980 J = 1988 T = 1996 4 = 2004
B = 1981 K = 1989 V = 1997 5 = 2005
C = 1982 L = 1990 W = 1998 6 = 2006
D = 1983 M = 1991 X = 1999 7 = 2007
E = 1984 N = 1992 Y = 2000 8 = 2008
F = 1985 P = 1993 1 = 2001 9 = 2009
G = 1986 R = 1994 2 = 2002

Redbook guide for ME05E models:

5000001~ =84 5500001~ =90 5714097~ =96
5100001~ =85 5600001~ =91 5719334~ =97
5200001~ =86 5700001~ =93 5800001~ =98
5300001~ =87 5704992~ =94 58119xx is 2000
5400001~ =88 5708833~ =95

XR200 Parts Links & Info

Honda Part Numbers Explanation Powroll FACEBOOK page
Kibblewhite Precision Machining Sudco - carburettor sales EBC Brakes Hagon Shocks  (Portuguese)

Changing 2 valve XR200 Crank timing chain sprockets

Getting the Clutch cover back onto your 2 Valve XR200

XR200 Wheel Bearings

Item. XR200R 81-2002 *
Rear left bearing Sealed 6303  (47mm OD x 17mm ID x 14mm Wide)
Rear right bearing Sealed 6203 ( 40mm OD x 17mm ID x 12mm Wide)
Rear Dust Seal Oil Seal 25x40x7
Front left bearing Sealed 6202 (15x35x11)
Front right bearing Sealed 6202 (15x35x11)
Rear Dust Seal Oil Seal 20x35x7 (Arai)

* Years 1993, 2000, 2001 Checked on Honda Microfiches (AU)

Tip: Aluminium ring in front of bearing on the real wheel is a screwed retainer and needs to be unscrewed, not driven out.

XR200R Suspension Parts


79-83 XR185/200/R's used Kayaba 35mm damper rod forks.
84-02 XR200R forks are all Kayaba 36mm damper rod forks, they varied in design as shown by the table below.  

Year Travel Damper Rod
(Pipe, Seat)
(Pipe Comp Front Fork)
R Slider
(Case Comp RH)
L Slider
(Case Comp LH)
(Spring Front Cushion)
Rebound Springs Spacers
84 10.0" 51440-KK0-004 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KK0-004 & 51402-KK0-004
(two springs each leg)
51411-KK0-004 N/A
85 10.0" 51440-KK0-004 51410-KK0-004 51420-KK0-004 51520-KK0-004 51411-KK0-004 N/A
86 10.0" 51440-KT0-671 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KT0-671
single two rate springs each leg
51411-KK0-004 N/A
87 10.0" 51440-KT0-671 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KT0-671
single two rate springs each leg
51411-KK0-004 N/A
88 10.0" 51440-KT0-671 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KT0-671
single two rate springs each leg
51411-KK0-004 N/A
Not Made ------ ------ ------ ------ ------ ------- ------- ------
90 10.0" 51440-KT0-671 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KT0-831 51411-KK0-004 N/A
91 10.0" 51440-KT0-671 51410-KK0-004 51420-KK0-004 51520-KK0-004 51401-KT0-831 51411-KK0-004 N/A
Not Made ------ ------ ------ ------ ------ ------ ------ ------
93 8.2" All: 51440-KT0-671
U: 51440-KT0-691
All: 51410-KT0-004
U:  51410-KT0-691
51420-KK0-004 515420-KK0-004 All: 51401-KT0-831
U: 51401-KT0-691
51411-KK0-004 51402-ML0-004
94 8.2" U & All: 51440-KT0-691 U & All: 51410-KT0-691 51420-KK0-004 515420-KK0-004 U & All: 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
95 8.2" U & All: 51440-KT0-691 U & All: 51410-KT0-691 51420-KK0-014 51520-KK0-014 U & All: 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
96 8.2" U & All: 51440-KT0-691 U & All: 51410-KT0-691 51420-KK0-014 51520-KK0-014 U & All: 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
97 8.2" 51440-KT0-691 51410-KT0-691 51420-KK0-014 51520-KK0-014 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
98 8.2" 51440-KT0-691 51410-KT0-691 51420-KK0-014 51520-KK0-014 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
99 8.2" 51440-KT0-691 51410-KT0-691 51420-KK0-014 51520-KK0-014 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
00 ? 51440-KT0-691 51410-KT0-691 51420-KK0-014 51520-KK0-014 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
01 ? 51440-KT0-691 51410-KT0-691 51420-KK0-014 51520-KK0-014 51401-KT0-691 51411-KK0-004 U & All: 51402-ML0-004
02 ? 51440-KT0-691 51510-KT0-691 51420-KK0-014 51520-KK0-014 51401_KT0-691 51411-KK0-004 U & All: 51402-ML0-004

U: Australia
Table compiled from info at  & Various other resources  (Green is checked with AU Honda Fiches)  (checked with online fiches)

Fork Fluid type and levels
Year Fluid Nominal level Min Level Max Level
86-91 350cc (11.8oz) of ATF 150mm (5.9") 170mm (6.7") 140mm (5.5")
93-99 377cc (12.8oz) of ATF 116mm (4.6") 159mm (6.3") 108mm (4.3")

81 ? 52410-KA2-681
82 ?
83 ?
84 ? 52410-KK0-014
85 ?
86 52401-KT0-671 52410-KT0-771 (Replaces -671)
88 52401-KT0-681ZA (R119 red)
52410-KT0-682 (Replaces -681)
93 52401-KT0-691 52410-KT0-691
95 52401-KT0-761
96 52401-KT0-A01

Old School Al's (OSA) Cam chain tensioner mod:

I've recently been working on a 2000 XR200R that had a slipped camchain resulting in bent valves.  I can only assume this bike was again the victim of the XR200R's reliability and ridden mercilessly until it finally stopped.

During this project I've learn't alot about these little XR's, much of which is from reading posts on thumpertalk by Chuck, Old School Al and several others that post over there.  They are, and there is a wealth of knowledge over there on these great little bikes.

During the process for obvious reasons I went over the entire camchain/sprocket and tensioner assemblies.  The chain had been slapping around and had chewed the camchain cavity in the cylinder some and both gears were clearly worn and required replacing.  After reading a bunch on how to tension the chain it became apparent that over time  the tensioner set bar (6) and or spring (5) can get worn or lose tension respectively.  Upon inspection the tensioner set bar (6) it was found to have a number of  sharp gouges/marks in it that appeared to have been caused by the collars (10).

Old School Al came up with a suggestion that I'm going to try. (Refer to this post at thumpertalk)

He removed the two collars/wedges (10) using a magnet to get the top one and a shop vacuum cleaner to get the second lower one.  Please note that he used a piece of wire poked in the threaded M3 hole in the top of the tensioner set bar (6) and bent to the side to try and capture it as it got sucked out.  As Al mentiones in his post it may also pay to empty the vacuum bag beforehand just in case it ends up in there.  I had the sidecover, flywheel and camchain off mine so I carefully used some mechanics picks to get them out.

Once you have the collars (10) out, use a dremel or similar to smooth out and radius the sharp chamfered edges of the hole on the angled side of the locks cleaning them up with a small sanding disc or emery paper afterwards, don't go crazy just get rid or the sharp edges.  This should stop them damaging the tensioner set bar (6) when they are tightened/clamped to the correct torque spec. (19NM / 14fl/lb ???)

On mine the one shown I will either clean the damage up on the tensioner set bar (6) pictured below, or possible even replace it with a new unit.  Some of the Damage is highlighted with a red circle.

Note: There is an M3 threaded hole in the end of the tensioner set bar (10).  The M6x10 bolt and washer (15 & 13) can be removed and a M3 (length?) bolt can be wound in to allow manual adjustment if the assembly is sticky.  I'm more in favour of getting the adjuster working as intended for my project.

Tensioner Collars (10)

Tensioner set bar (6) - Click to enlarge

Porting Info:

General consensus on basic DIY porting seems to be as follows:

    Clean up and casting marks or dags left over from the casting process
    Port match intake manifold/insulator with the head (Install the manifold mark where there metal protrudes, remove then match and blend)
    Don't polish the intake, the rough finish / dimples ecourages fuel deposited on the port walls to evaporate quickly and can alter flow something akin to dimples on a golf ball.
    The intake port to the right shows examples of casting marks and a runner that can be cleaned and blended.

    Clean up port casting marks or dags
    Port match exhaust port to the header pipe
    Polishing (smooth finishing) is considered a good thing with the exhaust ports because of the dry gas flow and helping to minimise by product build up.
    Using around 400grit paper and a light buff is considered by some as "near optimal" for smooth finishing.
    Around 80 to 120grit appears to be the consensus for intake port finishing.

    The surface in a combustion chamber should be smooth to promote heat retention in the chamber and prevent detonation hot spots from shar edges and rough surfaces.

Polishing theory:

Australian ADR compliant models (Fully Registerable)
Year XR200 XR200R
1980 ?
1981 ? ? *
1982 ? Yes
1983 ? ? *
1984 ? Yes
1985 Yes
1986 Yes
1987 no
1988 no

* I have seen a Compliance plate for a 1982 XR200R, ME04-51003**, and presume that the '81 and '83 are also ADR compliant bikes, but have not seen compliance plates to verify this yet.

Known Issues:

*   2001 XR200R models are said to have a problem where the crank slips out of alignment due to a fit problem from the factory, causing the lower sprocket to "wobble" causing the camchain to start "slapping" which eventually results in the tensioner breaking at the bottom.  Old School Al over at Thumpertalk has seen this happen and heard or several others doing the same thing.  On this model it has been suggested that it is worthwhile to ensure the end of the crank is running true.  Rotate the crankshaft and watch the flywheel, if it's bent enough to break tensioner / guide it should be evident by eye.

* Pre '97 in models in particular are known to have kickstart gear failures.  It is important to keep the anti decompression mechanism operating and adjusted correctly to minimise stress on the gears during starting.

The majority of this XR200 information has been pieced together from many online and some offline resources.
If you have anything to add or correct your input would be appreciated: