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Old 01-30-2016, 01:24 PM   #1
GB500guy
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1975 XL250 build thread

My 1975 XL250K2 build

A couple of my riding buddies have dual sports and do some combination pavement/dirt or gravel road rides. So I've been thinking that direction and in keeping with my interest in vintage bikes I decided to look for an XL250. I worked on many of them back in the day wrenching at a Honda shop, so they are familiar and I always found them to be an all around agreeable bike to work on and ride.

After looking at some real beaters on craigslist (supposedly in "great original condition", yeah right) I finally found a keeper, and 1975 K2 model with 8,600 miles showing on the odometer. It was not nearly as nice as it appears in these pictures but mostly appeared to need cosmetic and minor mechanical work. There were several small dents in the tank, minor rust on many parts, a couple of broken spokes, worn chain and sprockets, various minor oil leaks, and a couple of electrical bugs among other things. I paid a premium price but around here these old XL's sell high even in unrestorable condition, so I went ahead and paid market price for a decent one. Initially I wasn't sure how far I would go with it, whether to strip down to the frame and go all out or just do a 3/4 job. I started by fixing a few things and riding it a bit to get a feel for its condition.

Here is how she looked after purchase. Looks great at first glance, but like most 41 year old bikes it had many problems as I soon discovered.



So I rode the bike a bit and it seemed mechanically sound as I expected. I did some minor service like lubing cables, checking valve clearance, cam chain tension and timing, spoke tensioning, etc. then pulled engine covers for a better look inside. The bike ran fine and had great compression, and sounded good with no death rattles or other warning signs, so I assumed I'd be mostly dealing with cosmetics and fixing some oil leaks as far as the engine was concerned. So, eager to repaint the unique greenish-silver metallic engine side covers I pulled them off and discovered the cavity for the clutch actuating mechanism had severe corrosion. The Xl250 side covers are magnesium, and apparently magnesium does not like water! This is the plunger that pushes against the end of the clutch rod, and the hole in the case it rides in, totally corroded:



And the hole in the case that the clutch actuation shaft/lever rides in was totally corroded and worn badly oval. Here is the bottom end of the clutch actuation lever sitting in the corroded remains of its hole:



OK, no problem, this will make a fun little project! Fix this problem and I'll have this bike on the road in a week or two! (ha ha!) I'll make brass bushings and epoxy them in place to repair the damage. First step was to machine a Delrin bushing, press it into the case and use it as a drill guide to prepare the first hole for a brass bushing:



Then back to the lathe to make the bushing:



Then epoxy the bushing in place and one of the two problem holes is fixed:



To fit a brass bushing for the lower end of the clutch actuation lever I first needed to use a reamer to machine the corroded oval hole so the new bushing would be in the right position. Again I machined a Delrin bushing on the lathe, but this one needed to have three steps to fit the stepped hole in the case:



Then to hold the case vertically while reaming I clamped the case to a right angle fence:



Machined the second bushing and epoxied it in place:



And viola, the clutch lifter mechanism is repaired. The lever rides in a new needle bearing and seal at the top end, and the bottom end in a brass bushing. Both new bushings are drilled for passageways to the grease fitting on the case:



Here is the completed side cover, painted and with new needle bearing, seal, and clutch shaft to replace the corroded parts on the right. The original rubber cap for the adjustment hole is tough to find, so I just made one on the lathe from Delrin. I even found a brand new Honda grease fitting in my old parts bin.



That problem was solved, but the same corrosion that attacked the case also damaged the clutch push rod and the clutch rod oil seal. And on this bike you have to split the crankcases to replace the clutch rod seal (and the countershaft seal, which has a locating tab inside the cases):



I could just pull the lower crankcase off and replace the seals without disturbing the head and cylinder, but I figured I should at least pull the head cover and make sure the cam and rockers looked good. Uh oh, more problems! The intake rocker didn't look so good, and the cam lobes showed some pitting:



Also, using Plastigage the cam/head bearing journals measured out on the loose side at around 0.003":



Measuring the cam, it seemed most of the wear was in the cam and not the head bearings, so I went for a NO$ camshaft. I found a NOS intake rocker arm for cheap, and an almost new cam chain. OK, I'll get these parts installed and be on the trail soon!

Things were looking good, but a nagging thought told me that as long as I was this far into the engine I should at least pull the head and take a peek at the cylinder walls. Uh oh, again more problems! Apparently the bike had sat with water in the cylinder and there was too much pitting to ignore. So off came the cylinder. Should have expected this after seeing evidence of water damage in the carb float bowl:



So after scoring a .5mm over piston on eBay and sending the cylinder out for boring, I continued checking for problems. With fingers crossed I checked the connecting rod small end/wrist pin clearance. Using a feeler gauge cut from brass shim stock I found a new wrist pin had a snug .002" clearance. I'd rather have less, but this will work.



Back to splitting the crankcases, I took a good look at the transmission and found the 4th/5th gear shift fork had unacceptable wear:



OK, by now I was in too far in to turn back, so I ordered the shift fork and began working on theories to justify all the money I was pouring into this bike. But truthfully, the reason I bought the bike was that I needed a new shop project, and from that standpoint I've gotten my money's worth. Having the chance to revive a machine that I worked on in my younger days as a Honda mechanic was great fun. Hitting the trails could wait until the bike was really ready.

While waiting for engine parts and a cylinder bore I started cleaning, polishing and painting. Initially I assumed I would just touch up the frame paint but after buffing and clear coating nuts and bolts, removing rust and repainting every little bracket it was obvious the frame needed at least a complete repaint job. I probably should have sent it out for powder coating, but trying to keep to my mantra "It's a dirt bike, don't gold plate it" I compromised and glass bead blasted the frame and primed/sanded and enameled it with spray cans. I'm going for a mechanically sound machine and a cosmetically nice overall effect, not building a show bike, so here's my approach.

I used to do piano restoration and built this plywood glass bead blasting cabinet to refurbish large wood and metal piano parts. It's ideal for prepping any type of part for painting, and is big enough to hold the Xl250 frame. It has nylon windbreaker sleeves for the arm holes and is connected to a dust collector port to extract dust and create negative pressure inside to prevent harmful dust entering the shop (and my lungs!)





After blasting I applied rattle can black primer, sanded lightly, then put on three coats of black enamel. Here the paint is curing above the shop wood heater which also serves as a dog lounge on cold winter days.



-Bill

Last edited by GB500guy; 07-08-2017 at 10:02 AM..
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Old 01-30-2016, 01:27 PM   #2
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The wheel hubs and brake panels were originally painted a dull silver color. I may eventually re-spoke with Buchanan spokes but for now decided to just clean up the old spokes and hubs. For the brake panels I found that spraying with Dupli-Color DE1650 Aluminum paint followed by Eastwood catalyzed matte clear coat is a perfect match for the original color on these parts. The two-part catalyzed clear uses a special can where you press a button on the bottom of the can to puncture the catalyst chamber, and then have only a few days to use the product before the can sets up. It comes in matte and gloss. I've used it on several parts that just need a clear coat but something more durable than normal clear enamel, plus oil and fuel resistance. Below are the brake panels and crankcases after this treatment.



While waiting for some engine parts I completed refurbing the suspension, wheel and frame components. So after days of cleaning, repairing, de-rusting, buffing and painting, I had the fun payback of assembling clean and serviced parts and was able to stand back and imagine the finished product!

One sore spot on the bike was the side stand. How does someone completely grind through the side stand tip unless they are deliberately holding it down against the road to make sparks?? I don't get it.



I cut off the worn out stand foot, made a new one from 1/8" plate and welded it on.



Also, the pivot bolt hole in the frame bracket was badly worn so the side stand was really sloppy. This might sound compulsive but I can't stand a floppy loose side stand, it just makes the whole bike scream "worn out!" So after a quick trip to the lathe I bored the bracket for a brass bushing and now the side stand swings up and down with quiet precision. A bit of brass and 10 minutes time well spent. A small metal lathe is a beautiful thing.



Meantime more refurbed parts went back onto the frame.



The rear wheel had two broken spokes, so I replaced them, did a Scotch Brite pad polish on the spokes and trued & balanced both wheels for now. I may re-lace both wheels with new SS Buchannan spokes in the future, but for now we're rolling straight and true.



Steering stem bearings and races were fine, so just cleaned, repainted and greased everything up front. The fork lowers are refinished and fork seals replaced.



All fasteners have been blasted or buffed and clear coated.





Engine parts arrived so I assembled the engine and put it back in the bike. One of it's multiple oil leaks was familiar to me from long ago, namely leakage from the stator wire grommet where the wires exit the left side case. Back in the 1960's I ran into lots of CB/CL 160's with oil leaks from the countershaft cover area. Customers came in asking for a new counter shaft oil seal or clutch rod seal, but the culprit was actually the multi-wire stator grommet, leaking both between the grommet and the case and between the four wires and the grommet. At the time I was a big fan of silicone seal, to me a miracle fix-all sealant. So I used contact cleaner on the wires and grommet, sliding the grommet back and forth along the wires, re-spraying and blasting with compressed air. I then applied silicone seal to the wires, slid the grommet back and forth to get the sealer into the wire holes, put some more around the outside of the grommet and assembled. The fix was always successful, but I've since sworn off silicone seal for internal engine parts because of the tendency of the squeeze-out to come loose and float around inside the engine. But the basic repair is sound, I would just use Gasgacinch or equivalent case sealant which stays put. I don't recall seeing the problem as much on later models beyond the 160, but here it was plain as day on this '75 XL250. I could easily slide the grommet back and forth on the wires, proving a leaky pathway for oil. Here is the grommet cleaned and sealed as described above except using Gasgacinch for a sealant.



Originally Honda painted the upper carnkcase silver but left the lower one unpainted. The mismatch looked odd to me so I went ahead and painted the lower case to match using the Dupli-Color Aluminum paint followed by the Eastwood catalyzed flat clear coat described earlier. I like it, looks nice and tidy.



More pretty parts went back on.



Next up were two thorny issues: the speedo and tach mounts and the chain guard. This bike has the instruments sitting in soft foam rubber-lined chrome rings. The foam rubber mounts were totally shriveled and petrified, leaving the instruments flopping around with little protection from vibration. The rubber rings are discontinued, but I was able to do a workaround using self-adhesive foam weather stripping. Below is the remains of the original rubber part, lower right. And lower left is the chrome ring with a 3/8" x 5/16" medium density weatherstrip stuck around the bottom, and a 3/16" x 3/8" low density foam around the sides. It's not original, but functionally it works great. The instruments are nestled in soft foam and hopefully will have a happy life free of damaging vibration.



The original foam had cut-outs for the instrument mounting studs and wiring harness, so I heated a nail with a torch to singe the foam.



Happy instruments in their cushy holders:



-Bill

Last edited by GB500guy; 07-08-2017 at 10:18 AM..
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Old 01-30-2016, 01:29 PM   #3
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The XL250's plastic chain guard is a weak point. Every one I've seen on eBay has cracked mountings. So I had two options: make a new one from sheet metal, or try to repair mine. I did the repair, not sure how it will hold up but for now I'm optimistic.

The broken front mounting hole:



And a missing rear section, looks like someone chopped it off:



I decided to try a thermal weld job using a soldering iron. I've done a bit of plastic welding in the past and have worked with high density polyethylene (HDPE) for many years. The chain guard appears to be HDPE so I gave it a try. First I fused the inside of the crack over its total length with a flat blade type soldering tip, using a small scrap of HDPE as a filler. Like any welding, you have to make sure there is good penetration, so the idea is to melt the base material together, then melt a filler into the gap:



Then the front side:



Next I took some scrap black HDPE, planed it to thickness, and cut it to fit the missing piece:



Then welded it in place front and back:



And after trimming to shape, grinding out the bolt hole, and wet sanding the surface to a reasonable appearance this is how it ended up. To hopefully give the repair the best chance of success I enlarged the hole to accept a shoulder bolt with rubber sleeve and rubber washers with a loose fit to allow some movement of the parts as the XL250 Motosport bounds over bumpy trails in the future. EDIT: I later went ahead and added a thin steel liner inside from the front mounting bolt up to the top of the guard and riveted it in place. This should make it bullet proof.



I welded in a new piece of HDPE to fix the rear section:



These repairs are not perfect by any means but for now they'll do. Add a coating of trail dust and back up a few feet and the chain guard looks pretty decent!



-Bill

Last edited by GB500guy; 07-08-2017 at 10:25 AM..
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Old 01-30-2016, 01:30 PM   #4
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For the plastic fenders I ended up sanding out the scratches and painting them and am happy with the result. The front fender was the worst, photo below:



After sanding, I tried buffing but the plastic was not cooperating, so I went ahead and painted with the Krylon Fusion paint for plastic. The original XL's had silver painted fenders so I felt paint would work OK. I sprayed on 7-8 coats, but wet sanded several times between coats to reduce orange peel and small pits, so final paint thickness is minimal. Here's that front fender after painting:



The rear fender got the same treatment. Both fenders have steel liners inside, fastened to the plastic with aluminum rivets. To allow sanding I had drilled out the original rivets before refinishing. I found a close match to the originals locally and was able to re-rivet the parts for a similar appearance to original, rather than using screws. Finally, I ended up rubbing out the gloss black fender paint to a semi-gloss to give them that slight patina of age, and to disguise small imperfections.



Next the original frame stickers got applied, they even included the DID rim stickers.



My painter friend just completed the tank and am delighted with the result. It still needs to age a few weeks before final rub out, but I'm totally impressed with the work. The painter chose to save the original wing decals, skilfully working around them even though there were dents very close to the decals. There were at least a dozen dents in all, now completely repaired, and the tank is repainted in exact original colors.





I took her on a couple of short rides to cure the high-temp exhaust paint, and the bike ran great. Here are a few more details of the refurb job:

I've gone through the electrical system, cleaning and lubricating all switch contacts and connectors. I reamed all female bullet connectors with the appropriate drill bit (running in reverse to avoid grabbing the connector) and wire brushing the males. All females were then tightened and given a dose of WD40 to repel water and corrosion. All ignition wiring was cleaned and got a coating of dielectric grease at all junctions.



Everything else is polished, painted, lubed and adjusted to the "stare at it and try to find something more to fix" state.











So the bike is just about where I want it. I ended up taking it much closer to an actual restoration than I first planned, so will not be doing any slogging through mud. But I look forward to many fun filled miles of paved back roads, gravel or dry dirt roads. Ride reports to come later.



-Bill

Last edited by GB500guy; 07-08-2017 at 10:39 AM..
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Old 01-30-2016, 01:51 PM   #5
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Nice job .

At any point did you consider installing a single sided swingarm?
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Old 01-30-2016, 02:14 PM   #6
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That bike is lucky to have you as the owner.

Really nice work.
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Old 01-30-2016, 02:29 PM   #7
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A bit of brass and 10 minutes time well spent. A small metal lathe is a beautiful thing.

Wow, that XL found a good home ...
you are an artist ... great thread!
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Old 01-30-2016, 04:35 PM   #8
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Nice job .

At any point did you consider installing a single sided swingarm?
No, I was going for an original as possible rebuild. Those old bikes could certainly benefit from some modern upgrades. But on the other hand, being 66 years old and only back into motorcycling after a 35 year absence, these "vintage" bikes make me happy just as I remember them!
-Bill
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Old 01-30-2016, 05:19 PM   #9
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Old 01-31-2016, 08:25 AM   #10
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Great build and nice outcome. You should enjoy the bike for years.
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Old 01-31-2016, 08:54 AM   #11
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Does it still have a breaker point ignition? I used to hate that crap. (Filing pits with a tungsten file, setting gap, dwell & timing) CDI is so much simpler and reliable.
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Old 01-31-2016, 09:33 AM   #12
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Wow!
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Old 01-31-2016, 09:37 AM   #13
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No, I was going for an original as possible rebuild. Those old bikes could certainly benefit from some modern upgrades.
That wasn't really a serious question. I'm not a fan of the single sided swingarm mod.

As mentioned by WFO getting rid of the breaker points is a mod I'd make unless going for a totally stock rebuild.
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Old 01-31-2016, 10:17 AM   #14
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Does it still have a breaker point ignition? I used to hate that crap. (Filing pits with a tungsten file, setting gap, dwell & timing) CDI is so much simpler and reliable.
CDI ignition is certainly simpler and lower maintenance, but in my experience properly maintained points ignitions perform every bit as well. I've worked on engines with points all my life and never felt they were a problem to maintain. So from my viewpoint a CDI conversion is a solution looking for a problem. To each his own.

-Bill
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Old 01-31-2016, 10:18 AM   #15
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That wasn't really a serious question. I'm not a fan of the single sided swingarm mod.
I figured that might be the case.

-Bill
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