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xl600 cylinder head wear

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I pulled the engine out of my recently aquired '83 xl600 earlier. It had oil all over the top of the engine which i suspect is the valve cover gasket leaking. I removed the valve cover and discovered the center cam journal is galded/ground up. I am sort of confused at how it happened as it looks like all of the load should be on the outside bearings and that there shouldnt be much contact on the center journal? would this just be an oiling problem?

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The center journal bearing is there because the cam flexes in the middle from the force of the rockers pushing down. Generally that bearing gets scored/damaged/galled from oil starvation. Usually the rockers and cam lobes are damaged as well.

The most common cause of starvation I see is the operator running the engine out of oil, but there are others like blocked oil system screens. There is one in the case under the clutch cover and there is one in the frame downtube under the drain plug with an oil hose connected to it.

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Thanks for the reply, I will check the oiling system and possibly run a larger line to the head. Its looking like i am goin to have to run the bike like it is for a little while, i started pricing parts and by the time i was done i was gonna be a thousand dollars in on the engine, however it would be a brand new engine, might be able to find a spare over the summer to rebuild or atleast find a head and cam.

Also when i took the valve cover off i discovered the thin metal flapper that covers the hole above the left intake runner was broken off, what does it do exactly? takin a guess backfire check valve maybe?

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Also when i took the valve cover off i discovered the thin metal flapper that covers the hole above the left intake runner was broken off, what does it do exactly? takin a guess backfire check valve maybe?

That's the reed valve and it's there to allow some fuel and air to reach the intake valve behind the secondary carb when the carb is closed. The XR600's bypass was simply a port in the carb boots that bridged both sides.

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discovered the center cam journal is galded/ground up. I am sort of confused at how it happened as it looks like all of the load should be on the outside bearings and that there shouldnt be much contact on the center journal? would this just be an oiling problem?

Here's how it was explained to me quite a few years ago by a guy who was an XR expert. When the cylinder head gets really hot, (and these engines did run pretty darn hot), the head tends to distort somewhat and the center of the head buckles upward a few thousands. The cam jounal contacts the cam and the galling results. I have worked on quite a number of XRs with the journals galled a little. I smooth the galling out with crocus cloth and put 'er back together, have not had a problem yet.

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+1 for above.

it's like they put it there for fun.

if your cam lobes are not brown/puple/black and rockers are not worn, just do what he said, and/or ignore it.

search my posting of the HONDA XL600R CARB MANUAL.

and go up a few sizes on the jets. stock jets are NEVER the right size for anyone..

a cheap fix to make the bike run GREAT. ( less than $10 )

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OK, i read your original post again.

lots of oil leaking from the cover gasket is a good thing... you have lots of oil up there!

is there any "RTV" on that gasket? get a new gasket and put 'er back together....

--AFTER-- you put "helicoils" in just about every hole you can find. they like to strip threads, and you can't fix that while the motor is in the frame.

I had to do 90% of my holes when I took it apart.

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I've only seen the reed bypass on 500 heads. The 600s I've seen only have the boot crossover. You can throw the reed away and forget about it, they aren't needed and were eliminated completely on later heads.

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About that leaky top end. If the oil is coming out of the rocker cover gasket, the bolts probably just needed to be re-torqued.

But since you have it apart... That gasket is solid metal and as long as you don't kink it, it can be cleaned and re-used over and over. A very thin coat of RTV is all you should need to get a good seal.

As for heli-coils, you usually only need them when you make a mistake on the tightening torque. If you use a torque wrench (1/4" drive for the small stuff) you really shouldn't be stripping threads.

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True, but there is a good chance that someone who meddled with the engine prior already messed up the threads.

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I've seen plenty of Hondas that the threads came out with the bolt the first time they were disassembled.

Edited by valvesrule

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Thanks for all the replies, and thats good to hear about the cam, I would love to be able rebuild the engine top to bottom but unless i get rid of some of my other bikes and collected parts it probably wont happen for a while, I'm a freshman at NC State goin for engineerin so its the first time in 5 years i havent had a job, and worse yet first tme since i can remember that i havent had a bike i could ride every day. I would like to see the look on my roommates face though if he walked into our dorm room and saw that big thumper engine torn apart on my desk.

About the helicoils....unfortunately its actully gonna need one or two atleast

The metal gasket did have that nice pretty orange silicone globbed everywhere as well..but the gasket is probably fine

Also thanks for the carb manual....What size jets do you suggest? I will definately be building a new exhaust, thinkin about dual crf250r cans (2 of the earlier cans when they were single exhaust), also i will probably be just running clamp on filters, no dirt...this is being motarded...got a cbr f3 rear i will hopefully get on over Christmas break and find a front somewhere...somethin about a 160 cross section rear tire on a dirtbike =)

Eventually I am WANTING to do USD forks off of a crf450

build a fuel tank out of fiberglass or carbon fiber to fit crf fairings

chop off the rear frame section and weld on mounting points and either use a crf subframe or fab my own so i can use the crf seat, fender, and side plates

And go completely through the engine

Yes i know i have high expectations for this 26 yr old bike but i love the look of the newer bikes and i doubt i could shoehorn that engine into a 450 frame

After all that, maybe just maybe EFI!!!

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Wow, your list of goals sounds just like mine. I have an '83 xl600 and I've laced up a supermoto front wheel and gotten a 320mm brake rotor, made my own relocation bracket, and now the bike is sitting at home while I am at school because I hacked off the rear subframe and reattached it a bit higher so I could fit a crf450 seat, but I couldn't wrap up all the odds and ends before I left. I'm going with a crf450r exhaust because it was free to me, and I think I'm going to use the stock tank with the crf radiator shrouds, but I'll be doing a bit of cutting and welding beforehand (and expanding, because I'm switching to E85 so I need a bit more capacity). Oh, and I just bought a set of cr250 forks for a swap. Haha, my winter break is about a month long, so I'm hoping to have it mostly done by the end. Good luck with your bike.

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haha Dang SuperSingle i thought i was gonna be different, but that sounds like a nice bike your building, i didnt want to mess w/ relacing wheels, however i prefer the look of spokes, i'v built several engines but lacing wheels i'v never done, so i am going cast using cbr f3 wheels 5"rear & 3.5" front should stick to the blacktop....ought to be able to keep campus police on their toes...what model cr250 front are you using? if its the newer style are you going with the emig stem, makin your own, or just using bushings?

If you can post pictures i would love to see the progress.....my last exam is friday and i will be out for a month myself however i will be working on this, an xl100/tlr200 hybrid, and putting a mustang computer in my 93 f150 4x4....lots to keep my mind off of school

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blueovala460, I like your username. :cheers: Good luck with your XL build. :banghead:

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blueovala460, here are some pictures from from before the semester started. Last time I was home I added some gusseting to the subframe. I am also well aware that the gap between the seat and the tank is hideous and needs to be covered by plastics; that's also the area where I plan to expand the tank. Oh, and the most recent parts I got aren't on there yet, like the crf exhaust (which is easy to use because it has the same diameter tubing as the xl header) or the CR250 forks (I went with Showa's from a 97; not too worried about the internals, because they have almost 15 extra years of technology on my bike, and they are 45mm USDs vs the 38mm conventionals I have now).

P8220364_safe.jpg

P8220363_safe.jpg

Here is the obligatory track pic.

IMG_3396.jpg

Good to hear your finals are almost over. I have my first one on saturday.

Edit: I don't plan on buying an Emig stem because I'm really cheap. I'm hoping I can just turn down the old stem. I have two friends with lathes so maybe I can fab one up otherwise.

Edited by SuperSingle

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zrxer, haha blueoval-A-460, you gotta love the big block fords- I just used my name off of my ford forums, the extra "A" was a typo, i set up my thumper talk account with my blackberry while i was at a college football game, shows what sport i'm most interested, If we had a road racing team or mx team i would be all over it...we do have a mini formula 1 team i'm thinkin about gettin in on next year however... this year they used a cbr6 engine

supersingle, i imagine thats gonna be a slick machine once you get all the gaps filled in and get some plastic on there, good luck w/ the exams

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Thanks for all the replies, and thats good to hear about the cam, I would love to be able rebuild the engine top to bottom but unless i get rid of some of my other bikes and collected parts it probably wont happen for a while, I'm a freshman at NC State goin for engineerin so its the first time in 5 years i havent had a job, and worse yet first tme since i can remember that i havent had a bike i could ride every day. I would like to see the look on my roommates face though if he walked into our dorm room and saw that big thumper engine torn apart on my desk.

About the helicoils....unfortunately its actully gonna need one or two atleast

do 'em all while you have it apart.

The metal gasket did have that nice pretty orange silicone globbed everywhere as well..but the gasket is probably fine

get a new one, and skip the rtv.

Also thanks for the carb manual....What size jets do you suggest? I will definately be building a new exhaust, thinkin about dual crf250r cans (2 of the earlier cans when they were single exhaust), also i will probably be just running clamp on filters, no dirt...this is being motarded...got a cbr f3 rear i will hopefully get on over Christmas break and find a front somewhere...somethin about a 160 cross section rear tire on a dirtbike =)

Eventually I am WANTING to do USD forks off of a crf450

build a fuel tank out of fiberglass or carbon fiber to fit crf fairings

chop off the rear frame section and weld on mounting points and either use a crf subframe or fab my own so i can use the crf seat, fender, and side plates

And go completely through the engine

Yes i know i have high expectations for this 26 yr old bike but i love the look of the newer bikes and i doubt i could shoehorn that engine into a 450 frame

After all that, maybe just maybe EFI!!!

with all those changes you are doing, no one can tell you what jets to use.

any of those mods could require a re-jetting party.

go to local guy, and buy the next 3 larger sizes of pilot, and 5 sizes of mains.

they should be $3 each.. or less. Good luck !

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Thanks, I believe i will be makin a few trips to the honda dealer over winter break i'll have to grab a few jets while im there, I'll have to bring dad along, there runnin 08 cbr1K rr's for 7500, might can get him talked into it...ok thats just me dreamin but i'll get some jets atleast.

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I have a XL600R. Lack of oil has destroyed the rockers, cam and center head journal. I have found a used head and rocker cover. Where exactly are these screens? Does anyone have a camshaft for a 1985 XL600R?

Bike only has 4000 miles. Bike was bought in and auction and don't know the history

I plan on putting the wiseco piston in as well

:banghead:

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