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Old 12-31-2008, 11:58 AM   #1
dorkpunch OP
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Honda XL: A how-to.

FINALLY got some garage time. I blew the headgasket on my '75 XL350 last January and have been meaning to fix it for a LONG time. Unfortunately, the "extra" bikes have been pretty low on my priority list this year. While I was at it, I figured I would do a couple of "how-to's" for the old gurls.

Tools Needed:

Impact driver with phillips bit
Phillips screw driver
Flat bladed screw driver
Sockets and wrenches:
10mm
12mm
14mm

Step 1

Get the bike ready! It helps a lot if you have a lift.



Cleaning it first helps a TON, but I really didnt feel like dragging it down to the carwash in all the snow. I also have a sneaking suspicion the car was is frozen up, again...

Step 2

Take of the body stuff: flip up the seat, remove the tank, pop off the side covers. Remove anything connecting the engine to the bike, but leave the engine mounts until Step 3.

This would include:

Wire from points to coil
Breather from points
Chain
Electrical connector and Neutral wire
Clutch Cable
Tach Cable
Carburetor
Spark Plug wire
Exhaust Pipe.

Everything detached but the engine mounts:





Step 3

Engine mounts. There are 4 of them- Rear top of engine, rear bottom, front bottom, and front top (at the base of the cylinder). A 12mm and 14mm socket is all you need here. Loosen all the bolts and slide them out. You may need to rock the engine a little to get some of them out. *note*- both sides of the top rear mount bracket need to come off (didnt have the one side off for the picture).

The 4 mounting bolts, top rear, bottom rear, bottom front, top front:



I also like to thread anything back together if I can, so the non-pictured bolts are threaded back into the frame.

Step 4

Take the engine out! You shouldnt need to remove either footpeg, but it might make it a bit easier. It's easiest to sit on the bike to get the engine out (lower the lift if you've got one). Lift the engine straight up as high as it will go, then tip the engine to the left side and while tilting the cyclinder down, continue to spin the cylinder out to the left. The kick start lever makes a pretty good handle. Once the engine is loose, you should be able to pull it out the right side easily.

Engine out:





If you look closely you can see the large chunk of missing headgasket:



Guess thats what I get for using a crappy headgasket and a 12:1 piston...

More to follow!
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Old 12-31-2008, 01:09 PM   #2
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ooookay... Head removal time!

Pretty simple.

Tools Needed:

Sockets and Wrenches:
10mm
12mm
14mm
17mm
Impact driver (phillips head)
Rubber mallet
Long pointy thingy

Step 1

Remove the valve covers and points cover.




Step 2

Remove the top part of the head. The XL has a "2 Piece" head, meaning it splits in half around the cam instead of the cam sliding out of the head. To do this, remove the 4 12mm bolts and 6 10mm bolts. Note the position of the points backing plate. There is an alignment mark at about the 2 o'clock position. Loosen the two screws holding the points backing plate onto the head and remove it. Pull the top of the head off. If it is stuck, you can tap it gently with a rubber mallet to help break it loose.

Walla!



Pile of parts:



While youre at this stage, inspect the rockers, upper cam journals, and cam carefully. I was a little worried because I threw an unknown cam in there when I put the Hicomp piston in. It looks to be hard-faced, and I was worried it was going to eat the rockers, but they look exactly the same as when I put 'em in.

Step 3

Here's where the long pointy thingy comes in to play. Remove the cam! Take the 10mm bolt out of the end of the cam and slide off the points advance mechanism. On the left hand side of the engine behind the cam, there is a 10mm bolt. Remove that- it holds the top of the cam chain tensioner. Take off the outer engine side cover over the stator on the left hand side of the engine to get access to the big bolt on the flywheel. Using a 17mm socket, turn the engine until you can loosen and remove the 2 10mm bolts holding the sprocket on the cam. The cam chain needs to come off the sprocket TOWARDS the spark plug. It takes some jiggling. once the sprocket is off and the chain is off the sprocket, you can lift the cam up and slide it out towards the spark plug. While youre doint that, stick the long pointy thingy in the cam chain so it doesnt fall into the dark abyss!

This is another inspection point- check the lower cam journals carefully. You will notice the two oil ports on each side. Last time I was in here I took my dremel and notched it out a bit to spread the oil over more of the surface. The journals dont look great but they havent changed, so thats good! (notice the long pointy thingy!)



Step 4

Phew! Finally time to pop the head off! Not quite as simple as it looks. There are 4 14mm nuts holding the head on. Simple, right? Dont forget the OTHER 4 nuts on the BOTTOM side! There are 2 12mm nuts front and rear and 2 10mm nuts on the cam chain side, front and rear. Crack them all loose, then remove them all. Now take it off! If your head has never been off, it can take some work to break it free. Again with the gentle rubber mallet and maybe a bit of prying, just be carefull not to break a fin or scratch the head surface! Once you get it loose, you need to move your long pointy thingy down so the head can come all the way off.



Head all the way off:



The head (and a large piece of missing headgasket!):




Wow.




When it popped it looks like it took out this little blue seal. VERY IMPORTANT!!!! Without this seal your top end will go kablooooey, the cam will eat the head, and lots of bad things will happen. The XL pumps oil up that stud to the top end, and without it oil pressure in the top end is null.



Heres what your pile of parts should look like:





Hmmm....

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Old 12-31-2008, 04:07 PM   #3
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Now for putting it all back together!

First step is that new head gasket. Notice the new rubber seal installed on the alignment pin as well.



Step 1

Put the head back on! Be careful with the rear cam tensioner. It lifts out and can fall out of its slot on the bottom. It would be a good idea to pull it out before you drop the head on and make sure you get it in the slot. This will save you some headache later... A wire or something with a hook will come in handy for fishing the cam chain back up through the head. Once the head is seated, install the 4 copper washers, the 4 large head nuts, and the 4 nuts on the underside of the head. Lightly tighten them, then torque them up.

14mm head: 22-26 ft-lbs
12mm head: 13-18 ft-lbs
10mm head: 5-9 ft-lbs

If you find a way to torque the nuts on the underside, well, your better at this than me! (or you've got a way cooler torque wrench).

Step 2

Getting the dang cam back in there. This can be a royal pain unless you take some tension of the cam chain tensioner. Easiest way to to this was while you had the head off- pull the rear one off, stick something down there and push on the spring while you've got the adjuster bolt loose, then tighten it up when its all the way down. Its do-able without messing with it, just not as fun. SO. Getting the cam back in. First put the sprocket in and slide it as far away from the spark plug as it will go. Next, angle the cam down through the chain and sprocket.





The chain will need to go up on the shoulder of the cam in order to get the cam all the way down. It takes some wiggling and patience, but it'll go!

Step 3

Timing the cam. Line up the "T" mark on the flywheel with the pointer on the case. Pointer is kinda hard to see in the pick, but its pointing at the line under the T.




Spin the cam so both lobes are down, and the pin for the points advance mechanisim is pointing up. With the cam set in that position, rotate the cam sprocket until the 2 lines are even with the top of the head. The bolt holes should line up with the sprocket now. Get the chain on the sprocket and lift the sprocket onto the shoulder of the cam.

The lines on the sprocket didnt turn out, but they would be parallel to the top surface of the head.



Loosen the chain tensioner locknut and bolt:




You should hear a "thunk" as the spring pops and pushes the tensioner up. The manual says to do this with the engine warm, so it will get done after we're finished putting the engine back in.

Cam in, chain tight, engine assembly grease applied, and almost ready for the top half of the head:



Step 4

Time to put the top back on! You might notice there is no gasket between the two halves of the head. I use a bit of 1104 gasket goop, basically yamabond, just to be safe. Goop it up however suits you best and drop the top on. The cam must have both lobes pointing down still (engine at TDC) or your going to have issues getting the top on- if the lobes are up, you are going to be trying to compress the valve springs and theyre pretty stiff...

Torque the 8 bolts as follows:

12mm head: 13-18 ft-lbs
10mm head: 5-9 ft-lbs

And keep in mind the aluminum head has the consistency of soft cheese.

Step 5

Points and stuff! Slide the advance mechanism on and be sure it slides over the dowel in the right place. Tighten the bolt on the end of the cam to hold it on. Put the points backing plate in, line up the marks, and tighten the screws. Might be a good idea to check the points while your here. If you are spinning the engine, the points should just start to open at the "F" mark on the flywheel. The points gap should be .012-.016 in.

Step 6

Check the valves! Spin the engine over carefully and listen for any bad noises. If it feels to hard to turn over, it probably is and you need to take it all back apart and see whats wrong. If it spins nice with no clangy-clangy, check the valve clearance.

Intake: .002mm
Exhaust: .003mm




Put the caps back on and the engine is ready to go!



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Old 01-02-2009, 06:04 AM   #4
BIG ED XT FAN
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Did that piston push the head gasket out? Looks from the photos, the piston can push the head right off the barrel! How long do you run that piston before you lost the gasket? Do you run the bike on the street? "High revs" or "Dual-Sport it"?? Thanks ED
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Old 01-02-2009, 09:26 AM   #5
dorkpunch OP
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It ran for quite a while before it popped. I would say 1500 miles? of mostly street and a bit of off road. The piston is a bit of a tight fit... Think the cause was a combination of a couple of things- I still havent gotten the jetting right and it is EXTREEEEEEMLY rich in the midrange. I had also noticed that the gasket was leaking where it blew a day or two before it popped. It was supper cold out and once the bike warmed up it quit leaking. Shoulda checked the torque on the headbolts right when I noticed it, might have averted this whole process.
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Old 01-03-2009, 02:29 PM   #6
crazydrummerdude
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Cool thread!
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Old 01-04-2009, 09:19 AM   #7
MoMan
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a man and his Honda XL, a wonderful thing.
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Old 01-04-2009, 03:14 PM   #8
dorkpunch OP
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Thanks! The bike is back together and seems to run great although I think I got the valves to tight. I'm going to be (re)posting some of my other XL stuff here too cause we havent been having much luck with the XL board at oldrice.com.
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Old 01-04-2009, 09:19 PM   #9
BillsR100
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Awesome thread. I dont even own a Honda but you sure make me want one.
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