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Whozaa

XR200 teardown advice

19 posts in this topic

Hi all,

 

I just bought an 83 XR200 with a bad motor as a project. The guy I bought it from said that it ran and then quit (incredibly helpful I know). He pulled the oil drain plug and the oil was full of metal shavings and that's where he left it. I'm planning to tear the motor completely down to see what went wrong and figure out if its salvageable. I found a copy of the Honda service manual for the 86-02 models and they seem to be similar enough in the motor section to use as a guide.

 

My current ride is a '79 CB750F that I rebuilt nearly from the ground up so I'm no stranger to bike mechanics. But this is my first dirt bike and I'm looking for any advice that you all might have in regards to the motor teardown/rebuild.

 

Thanks,

Whozaa

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the engines are basically the same through the years so your manual should be good. the best advice I can give is bag and tag parts / bolts for ease of assembly. welcome to the 200 2 valve club :thumbsup:

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the trx200 is basically the same motor, and there's free service manuals floating around for it

 

the cams are what typically seize up first it'll be obvious real quick what you need to do

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Well I've already torn into the motor now and yes the main cause of death is a seized cam bushing. I found where the cam chain had tried to saw its way through the bottom left side case. That's why there's metal shavings everywhere. To me it looks like the chain wasn't kept tight and all the shavings it generated plugged the oil pickup screen. That must have starved the top end of oil. Both valves are bent as well and I haven't taken the springs off yet to see if the guides are ok.

 

The bottom end looks ok though. The oil pump seems to have made it through without any huge gouges which kind of surprised me. With a good flushing the bottom end should be good to go.

 

Forgive my ignorance here, but what years and models will cross with this one? I'm searching for XR200 parts, but there doesn't seem to be a whole lot of options for an '83. Even used stuff seems stupidly expensive. People on eBay are asking $100 for a cam when you can still order a new one from Service Honda for $73. Considering all the damage to the top end is it better (or easier) to just swap the whole head out with a used one?

Edited by Whozaa

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If the can journals are bad then I would swap the head I don't think that is any easy or cheap fix

ATV head probably swaps on too

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i can confirm tat the atv head will swap over. (how i built mine) the cylinder will also swap over but if you want to keep the stock xr bore size you will have to get it bored .5mm.

 

as for year cross over most of the 2 valve 185 or 200 cc engines from the early 80's to the early 2000's should swap over.

 

my bottom end (transmission, crank etc..) is a 87 xl185, connecting rod is for an 83 185, cylinder, head and cam from an 84 atc200s and the piston is for an 83 atc 200x (200x has flat top 200s has dished piston) cam chain for a 79-85 xl 185, oil seal kit for a 81-02 xr200r. this is just a list to show you that things will swap over without issue

 

i used ebay for everything minus the crank bearings.

Edited by steve_1987

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Thanks for the interchange info, definitely helpful!

 

I took the valves out of the head and confirmed that they are both bent, the intake worse than the exhaust. The seats look ok though, as do the guides. The cam journals are also ok. The "plain" one in front just shows the normal wiping type pattern, it's not galled or heat discolored. The rear journal where the bushing sits is also ok. I was initially worried that the seized bushing tried to spin, but apparently it didn't (which is good).

 

So at this point I have a fairly decent shopping list, but if I go with aftermarket parts I should be under $250. This includes a new OEM Honda cam, and then aftermarket bushing, intake and exhaust valves, cam chain, chain tensioner and slipper, gasket set and oil seal set.

 

I have a plan to try and rescue the cam. If it's successful, then I can knock $75 off the list.

 

I've pretty much decided to go ahead with the rebuild and start buying parts. I doubt I could get another motor for $250. And even if I did it wouldn't have a new top end, chain, and tensioners in it.

Edited by Whozaa

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Unfortunately, the cam rescue was unsuccessful. I was able to remove the seized bushing, but the journal was scarred much deeper than the service limit would allow. I have a line on another used one with bushing though I've asked the guy to mic the journals and lobes for me first.

 

How well do the cams generally hold up in these motors (assuming regular maintenance)? Do they tend to wear heavily? Is it ok to take a chance on a used one? Just for grins I checked the lobes and journal on mine and everything was well under the service limit. If that's typical, it seems that taking a chance on a used one is the way to go.

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aslong as these engines are properly maintained and they aren't run out of oil they are pretty well un-stoppable. I dbout you will have any issues with a used cam. I would personally try to get the rocker arms that the cam is "worn" to, just to try and keep everything matched up to ensure good service life

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The rear cam bushing failure is normal for these engines when they are abused by running low on and poor quality (to start with) very contaminated oil.  While your oil intake screen had lots of debris on it, if it were plugged you would have rocker/lobe and front journal damage also.  The rear bushing is the weak I tend to feel because being small there isn't much load carrying bearing area, and the steel bushing isn't a ideal bearing material. Steel doesn't retain oil well as it's not porous, and being hard, has poor what is called..........imbedibility.

 

Whatever you do on a cyl head, make sure and retain the auto decompression mechanism or you'll invite kick starter problems.

 

:thumbsup:.................on the 79 CB750F.  I have a pristine silver one myself I've owned since about 85.............just picked up a rough early SOHC 750F.

 

Old School Al

Edited by Old School Al
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Thanks for the info Old School Al.  The bike came with the decompression mech and cable and I'll be sure to retain it. As I was looking over the transmission yesterday I realized that the kicker idler gear is missing a tooth. It will get replaced of course.
 
 
It's always nice to see somebody who appreciates an F bike. I bought mine as a $200 parts bike and over a period of a couple years resurrected it. It's not pristine by a long shot, but it's turned into a good reliable daily driver (or is that rider?).
 
th_100_0433.jpg

Edited by Whozaa

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It's common for the engagement teeth on the K/S ratchet get worn and slip also.  May want to check them over good.

 

I've always liked this family also.  I have a pretty nice CB1100F and two rough CBX's as well as the CB750F.  Some years ago had a CB900F for awhile.  Yep, you've done a lot of work to bring this one back.  If you can go though one of those, you're not going to have any problem with the XR......! :thumbsup:

 

Old School Al

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After closer inspection I think I'll need to replace all 3 gears related to the kicker. Both the idler on the trans output shaft, and the one on the kick shaft have missing teeth. The smaller one that drives the clutch isn't missing any, but there are a couple that are chipped. I'm watching eBay to try and get as much of this in one assembly as possible as buying them seperately will rack the bill up quickly.

 

The ratchet itself seems to be ok though. None of the ramped teeth are broken or badly worn.

 

I'm having some trouble interpreting the fiche though. My bike seems to be missing parts 12 and 14. Part 12 isn't shown on the parts list and part 14 is listed as discontinued. (I used ServiceHonda's fiche). I looked at a later year fiche and it has a slightly different arrangement where part 14 is deleted and they only use part 12. The inside of the case is a little chewed up from gear 2 rubbing against it. This makes me think that part 12 is necessary to act as a spacer to keep gear 2 from rubbing the case. Does this sound correct?

 

Also, since the later years have part 14 deleted, do you think it's ok to run without it? I think it goes on the outside of the main case. Possibly to keep spring 11 from catching the case surface?

 

E14446A13.gif

Edited by Whozaa

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Hey There. 

 

This is a vid I did a while back on the Xr 200 kickstart. Have a look through my Youtube as there is a bit of stuff here on XR 200 rebuilds.

 

 

OSA is correct about the decomp lever. If it's not working properly is will stuff the pinion and ratchet gear on the kick start. 

It wears and the wear is not usally visable. I have found it a must to replace both the ratchet and the pinion as the cases have to be split to carry out a rebuild on the kick start. 

 

Good luck.

Edited by GEOF

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My son just recently ran his '02 XR200 out of oil so we tried different parts from different years.

Off hand, the jug from the '02, from an '83 or '84 trike and from an '83 XR all have a different bore.

The trike had a dished piston.

The jug from the '83 XR didn't have the hole drilled through for the long bolt that goes through the head down to the cases (just outside the timing chain)

All 3 heads looked the same. I didn't find any difference there.

The jounals on the crank of the '83 were smaller than the ones from the '02.

So even though they may look the same at a glance things did change over the years.

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My son just recently ran his '02 XR200 out of oil so we tried different parts from different years.

Off hand, the jug from the '02, from an '83 or '84 trike and from an '83 XR all have a different bore.

The trike had a dished piston.

The jug from the '83 XR didn't have the hole drilled through for the long bolt that goes through the head down to the cases (just outside the timing chain)

All 3 heads looked the same. I didn't find any difference there.

The jounals on the crank of the '83 were smaller than the ones from the '02.

So even though they may look the same at a glance things did change over the years.

Good job on comparing parts.

 

To my knowledge all of the XR/ATC heads flow basically the same with some variations that seem to be foundry related, so for a trail bike any of the XR/XL/ATC/185/200 heads should be OK (the TLR has smaller valves).  All 79-02 XR185/200 cams are the same, all of the other model cams are milder. To be on the safe side use XR valve springs with the XR cam (or do some part number searches on valve springs).

 

The bolt is a 6x116mm and used on all of the common large 2 valve motors including the 83 XR200R, so the head you have must be from something different. I have several ATC heads and they all have the bolt hole.

 

The nominal displacement of the engines is cast into the rear of the cylinder, I use that to ID cylinders but the bore size differences among the XR/ATC/XL/TLR/185/200 are just that, the liners have the same OD so you can rebore to suit your needs, but some machine shops charge more if they need to bore out more than one oversize.  Stock bore for all of the XR200s is 65.5mm, ATC200s are 65mm and XR185s are 63mm.  I've bored a 63mm XR185 cylinder to 66mm for use on a XR200R. The clue is they all use the same base gasket. The XRs use a 10:1 piston. Once upon a time Honda use to list oversize pistons in increments smaller than 0.5mm but it seems cheaper and easier to use 3rd party forged pistons in 0.5mm increments, rather than Honda cast pistons. Although for trail riding I doubt if it makes any difference in engine life.

 

The only difference in crank journals that are obvious between early/late XL/XRs should be the timing chain sprocket, in 90 the crank sprocket ID changed to 22mm ID from 20mm. Most of the ATC cranks have a long right shaft for an auto clutch so they won't work. The XL/XR bearing journals should be the same except for a change in fit for the right side that occurred in 94, so right crank/bearing/case need to be compatible.

 

There were also some differences in the left end taper on other 2 valve motors to suit different rotors, but the XR185/200 left cranks seem to be the same.  I've mixed early/late rotors and cranks, rotor bolt needs to match the rotor. The 86+ rotor is 12 oz heavier than the early rotors, but you also need the stator/cover and electrics.

 

To the OP; IMO the 86+ Service manual is better because my 81-83 XR200R manual has some bad torque values for the engine, my 86-99 Honda manual is correct!    Any 79-84 XR185/200 or 81-83 XR200R motor will just bolt into your chassis, just use your electrics and carb. Even a XL motor will fit but it will have less compression, only five speeds, and a milder cam, but you can run street lights.

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The XR cam is the most aggressive of the 185/200cc two valve cams.

Without the seller publishing specs for lift and duration there is no way of knowing what you'll get.

Edited by Chuck.

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Thanks Chuck.

 

I was going to ask if the XR cams were interchangeable with other models, say from an ATC. There seem to be more of those available and at better prices. But then I saw the line in your previous post "All 79-02 XR185/200 cams are the same, all of the other model cams are milder." which answered that question before I asked it. :)

 

So I'll be buying a new XR cam from Honda.

Edited by Whozaa

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