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How long does a valve job last?

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was just curious......how many hours of running time does a valve job last on a xr200?

is it years or months......i know it depends on how much you ride but what are the numbers?

why i ask is......is it worth buying a 200 dollar valve seat tool or to just pay 50 bucks to get it done?

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My '82 made it to 2015.  Not sure if I will still be around for the next time.

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I should post a video, but once the engine is pulled and the head removed doing the valve job is easy. I would inspect the head, and then just lap the valves if the seats look ok. I did this for nearly no money. Even made my own spring compressor out of a 2x4 and a piece of pipe. There are plenty of videos out there on lapping valves. With a new piston and the head cleaned up, new valves and seals, my xr200r really pulls! You can check the length of the springs too, there are specs in the manual for that. This would be a real beast of a motor if they made a 300cc version! lol!

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is the exhaust side suppose to be full of carbon everywhere?....on top of the valve and inside the valve and around the opening of the valve and also the exhaust port is all carboned up too......should i clean that up with a wire brush?

my bike was smoking grayish blue smoke......

the piston did need rings per the manuals wear limits also......

somewhere i heard you shouldnt lap xr200 valves because they have a coating?

im just trying to get the best bang for my buck on redoing this motor that smoked while running.....

the piston still feels tight in the cylinder, when i slide it through air pressure slows it down.....maybe just a ring job and scoring the cylinder is all i need for that part?

and the intake valve side is clean and tight.....

so replace the valve seals, get new rings, score the cylinder, get a new exhaust valve and lap it to the seat and i should be good? cant get past that your not suppose to lap the valves for fear of removing that hardened coating surface they possess...

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On 3/22/2017 at 8:19 AM, ZooR1 said:

I should post a video, but once the engine is pulled and the head removed doing the valve job is easy. I would inspect the head, and then just lap the valves if the seats look ok. I did this for nearly no money. Even made my own spring compressor out of a 2x4 and a piece of pipe. There are plenty of videos out there on lapping valves. With a new piston and the head cleaned up, new valves and seals, my xr200r really pulls! You can check the length of the springs too, there are specs in the manual for that. This would be a real beast of a motor if they made a 300cc version! lol!

300cc's......YEAH!!!!! my friend who rode my bike last year and ive only owned the bike since last year, and yes it did smoke when i bought it, said he thought the bike would of been faster being his wife has a smaller cc bike and hers seemed faster.......i would buy a 300cc version of this bike in a heart beat.....my friend has the xr400 and hes always messing with the motor concerning starting.....i believe hes got it figured out but man make bikes simple.....

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On 3/22/2017 at 8:14 AM, chadzu said:

My '82 made it to 2015.  Not sure if I will still be around for the next time.

i hear ya......the only thing in the dirt will be me......or lets say my carbon based body......lol

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I'm no expert, but I believe the valves on these bikes are all Steel. I would brush it and inspect it. I heard somewhere that easyoff oven cleaner does a miracle on removing carbon??? Keep the same valves if they are not dished out, same with the seats. I wasn't exactly excited at the lapping process as it really just leaves concentric grinding marks, but I was sure I had a seal when the valves were closed. Also there are specs to the wiggle the valves have in their guides, but mine seemed ok. BTW I think the do not lap order is for those pesky Titanium valves. Believe me titanium is a light alloy but it won't take the abrasion that steel does and it doesn't dissipate heat very well. One other thing I picked up somewhere is to blow some air through the oil passage that comes up to the cam. Don't forget the little o-rings that go down that left rear head stud. thats the oil galley.

 

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Honda valves should not be lapped when new, they do have a hard coating.
The intake valve will eventually get a very sharp edge, this is a good indication that new valves are in order. Valves are cheap why risk it?

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2 hours ago, ZooR1 said:

I'm no expert, but I believe the valves on these bikes are all Steel. I would brush it and inspect it. I heard somewhere that easyoff oven cleaner does a miracle on removing carbon??? Keep the same valves if they are not dished out, same with the seats. I wasn't exactly excited at the lapping process as it really just leaves concentric grinding marks, but I was sure I had a seal when the valves were closed. Also there are specs to the wiggle the valves have in their guides, but mine seemed ok. BTW I think the do not lap order is for those pesky Titanium valves. Believe me titanium is a light alloy but it won't take the abrasion that steel does and it doesn't dissipate heat very well. One other thing I picked up somewhere is to blow some air through the oil passage that comes up to the cam. Don't forget the little o-rings that go down that left rear head stud. thats the oil galley.

 

yeah all good points, thank you !!!!!!!!!

i was going to ask about those oil passages and o-rings next.....

i need to get a year specific honda shop manual.....

 

49 minutes ago, chadzu said:

Honda valves should not be lapped when new, they do have a hard coating.
The intake valve will eventually get a very sharp edge, this is a good indication that new valves are in order. Valves are cheap why risk it?

i will check it now more closely......thanks !!!!!!!!!

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if i spend 2 grand total to get the bike i want.....even if its an xr200.....i see it cheaper than buying a new one......

i will soon do a topic on fish oils as per someone asked me to do for my forks.....i saw at harbor freight they have air-tool oil for real cheap for 16 ounces and it looked thin which i like in my 1984 xr350 41mm damper rod forks.....so for under 5 bucks i can play around with oils for forks.....maybe i might stumble onto something or maybe not......

 

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Yeah, If you are going to get new valves, might as well get a machine shop to re-cut the seats. My bike's used valves looked ok, so I just lapped them. I figured if the first set lasted 20yrs and looked that good, then they were probably still ok. The Titanium intake valves on my RMZ looked like hell though, and I just got the whole thing redone. Although next time I'll probably just have the seats recut  and do all the rest myself. I'm still dreaming they'll come out with a 300cc version of this lovely 2 valve motor... lol

 

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i bought bought  1980 xl100s with 18000 on it. still ran and never rebuilt. 1/8th inch ring gap. valves look great but i put new ones in it when i put that head on my xr100 engine 

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On ‎3‎/‎22‎/‎2017 at 5:19 AM, ZooR1 said:

I should post a video, but once the engine is pulled and the head removed doing the valve job is easy. I would inspect the head, and then just lap the valves if the seats look ok. I did this for nearly no money. Even made my own spring compressor out of a 2x4 and a piece of pipe. There are plenty of videos out there on lapping valves. With a new piston and the head cleaned up, new valves and seals, my xr200r really pulls! You can check the length of the springs too, there are specs in the manual for that. This would be a real beast of a motor if they made a 300cc version! lol!

I concur 100% with this. The head is easily removed. Most of the time, the valves can be lapped only (unless the valve is bent or sharp edged). The seats are pretty hard; no need to replace or grind unless really worn. The guides are still available, and can be done by any home mechanic with a work bench, an oven, a freezer and a punch (heat the head, punch out the old guide; freeze the new guides and punch in). While I had the head off, waiting for one valve to come in the mail, I went ahead and did a light porting job with a Dremel tool with a course sanding drum (aluminum grinds away quickly). Lapped the valves, and checked for leaks by putting light oil in the chamber overnight, and then looking into the ports to verify no leak by. Cleaned the head very well with Dawn dishwashing soap, until it passed the "white rag test". I also made a lever style spring compressor from scrap wood and a notched pipe nipple. Once assembled and reinstalled on the engine, the difference in the pulling was night and day. Stronger and crisper all around. Well worth the time.

Edited by HomerDodd

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I check the valve for leaks using paint thinner, you can also remove the valves and check the seats.  A quick test for valve guides is to insert a valve into its guide until the end is flush with the other end of the guide, cover the open end of the guide with a finger and quickly remove the valve. A good pop indicates a tight guide.

Do not lap Honda valves, the compound will cut thru the hard coating on the valves. I paint the seat areas with a felt tip marker and then turn the valve a turn or so against the seat.  One exception to lapping compound is using a fine grade on new valves with about 1/2 turn to check seat fit, but a felt tip marker does the same thing with no risk to the OEM coating. 

I had an 82 XR200R engine that is still on the original valves and a big bore high compression piston installed in the early eighties. I used that bike 10 years for Enduro competition and mountain trail riding, some years riding 1000+ miles.  So it wasn't a garage queen. One of my sons is still riding it. I've built a few other XR200 engines and while I've found lots of problems with the engines I've never needed to replace valves. With proper maintenance these engines have a very long life, without they eat themselves from the inside and keep running until they are junk. I bought a complete 97 engine on ebay and planned to install it in a chassis to see how it would run before deciding if it needed rebuilding, but I procrastinated. Eventually I decided to use it for a Powroll build so I started taking it apart. Bad parts: crank/rod, rockers/shafts, cylinder, Wiseco piston (it had been rebuilt), timing chain/sprockets, timing chain sliders, advancer extension on cam broken off, oil pump.  I also replaced all the bearings and some shifter parts. But the valves were OK, seven years later I'm still using that head. Expensive rebuild! $$$$

 

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