XL350 Honda conversion

I have known this bike for about the past three years when a friend first purchased it for his 16-year-old daughter. This is a very early version first registered in 1973. The engine note immediately put me in mind of the Norton Manx bikes I used to drool over at the local road racing track. I know it will never be anything like one of those, but that was my inspiration.
Eventually he decided that the bike just wasn't really suitable his girl and mentioned that he wanted to sell it. He also mentioned that somehow the kickstarter no longer seemed to work and asked me if I would have a go at repairing it. Well, it turned out that there wasn't anything wrong at all with the starter, but when the engine was opened about a cup of water poured out. Turned out the bike had been left outside during a hard rain storm, water had entered the engine through the large exposed air filter and the engine itself had seized. Trying to keep the cost of repairs low for him, I did manage to free up the engine and after cleaning the old fuel and gook out of the carburetor, I managed to get it running again. That got my head spinning...I decided to make him an offer and after discussing it with his 'finical adviser' he came back with a deal that was too good to turn down....it never left my shop. My plan is to convert it into something that will handle and stop better than the stock while retaining the reliability that Honda is famous for...and look good too. Here's what I'm starting with......

very nice ! those engines will run forever if maintained and that is the key they have the same type centrifugal oil filter trap as a 350 twin but on those singles they rarely get serviced because you gotta pull the whole clutch cover to do so..

if you didnt yet it should be done because the only issue that really kills them is the cam in head seizing from oil starvation, no bearings can be replaced up there its a one shot deal
oh and that exhaust system is worth a pretty penny, enough to help finance a custom buildup

Oh yeah...cleaned the centrifugal filter/ trap when I was freeing up the engine. Not much in it. Took the engine out of the machine for a complete rebuild as I want to know the extent of any damage done by the seizure before I start on anything else. Luckily the engine hadn't run with the water in the oil, so no worries about trying to clean out a mess of emulsified/ milky gunk out of it every nook and cranny.
Unfortunately, although the head pipe is still in pretty good shape (despite the rusty exterior), the muffler is full of holes and not worth much to anybody.

I have one of these broken down to roller and still waiting for a decent head to show up on eBay, Like XB says... yer lucky someone had the foresight to clean the trap, My cams and head are toast.

This what a bad deal looks like


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Yikes. Is that oil or hashish?

Love an XL350. There are a lot of go fast offerings, if you are so inclined...

deviant said:

Yikes. Is that oil or hashish?

Love an XL350. There are a lot of go fast offerings, if you are so inclined...

Click to expand...

Heavy Metal Play Dough... would of been good grease for covered wagon wheels, I'm gonna smash it into a chunk out of an old cotton mop and make a small torch, should burn a good while with an occasional spark from magnesium chunks?? haha!

Got the head and barrel off the engine...there is some etching on the cylinder from the water that got in there. Will have to see if most of the damage will hone out...if not, then it's a re-bore for this old girl.

Yeah, probably not.

I'm going to follow this

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I'm in. Great engines!

Success! Got some time between jobs to take the hone to that ugly cylinder and it cleaned up much better than I thought it would...still some mild etch marks, but nothing that would stop me from using it as is. Found a Canadian supplier for rings, gaskets and seals, so the wait time for getting this thing back together should be fairly short.

sweet
while yer in there stick the best end of the gudgeon pin in the rod,check for slop ,its not uncommon
it would suck to get it all together ,then,knockin' ....well that makes more of a TACK TACK TACK noise ;D

Haah I could twist mine and see a full 0.30 shine EW :-\

Thanks for the advice guys...there is pretty low mileage on the bike, but I'll give everything a good thorough going over while it's apart. I would like to polish up those magnesium casings, but I know they won't stay that way for long...any advice on keeping them looking good, or should I just paint them?

Stripped and polished those magnesium engine covers...came out pretty good. I'll have another go at them before I apply the clear coat; too damp for that today anyhow. Hopefully when I do, it will keep them from corroding all to hell. Still waiting for engine parts...maybe tomorrow.

Those polished up pretty well.

What are you clear coating them with. Im in the process of polishing up some aluminum parts on mycb350 and am worried about them corroding again in the future.

Going to try some of that Duplicolor engine clear...it's cheap and I have had some pretty good luck with it before. I know this magnesium is going to be troublesome in terms of keeping it shiny unless I put something on it. I don't usually clear coat my own stuff when it comes to aluminum...it tends to stay pretty clean unless you are out in the rain a lot.Besides, I enjoy sitting beside the machines on a rainy Sunday afternoon with some polish and an old chammy in hand...Therapeutic in a sick sort of way, I guess.

Ok the parts came in and I had time to do a little tinkering for myself. Engine is all back in one piece, new rings, seals and gaskets. Valves cleaned and lapped and fitted with new seals. In the process of reassembly, I discovered that the ignition advance was stuck in the retarded position...it's a wonder the machine worked as well as it did, must have been loosing a heck of a lot of power at the mid range and beyond. Had some new clutch plates left over from another job, so they went in as well and I decided to replace the bushing in the kicker gear too, as it also serves to drive the oil pump and turns constantly while the engine is running. I have loosely set the engine back in the frame for now...better than cluttering up the bench. Went hunting for a shorter front end and smaller front wheel...waiting for those to show up for now.