Honda Headscratching

If it's like the CB750's , that cam runs in bare aluminum in the head . Not sure how they recondition them .

I rebuilt a 125 some years ago and the cam was loose in the head. Bored it out and bronze bushed both sides. Lasted as long as I had the bike.

Cheers,

Bruce (bruceinbangkokatgmaildotcom)

Plain aluminum bearings...with that much slop....Crom sob....

I guess Im going to have to pull the valve cover tommorow and see what kind of damage is in there. Ive been searching the net for any info..and not turning up much other than hip slick and cool new racing camshafts with needle bearings, which apparently need a $150 line boring job to install The bike isnt worth putting $300 in camshaft stuff....shit.

That much play means the journal is likely to be egg shaped. I just found a picture of the exposed guts of a head on Ebay...and yup..no bearings in there.

Now the big question is how to repair the existing head, reweld the egg shape and clamp the head an angle plate and rebore it on the mill? Mill the hole round and make up a steel split bearing to go in the larger hole and hone it to size? Pin the split bearing in place in the cover and head? With the appropriate oiler hole? Shit..this is getting more complicated as time goes on.

Maybe Ill try to find a used head..though its gonna be tough unless the '74-75 heads were used on later bikes

Still dont know if thats connected to the running problem. Maybe try to find a 38mm Mikuni carb like the racers use, or a used carby

Labor (mine) I can afford...buying stuff...thats not in the budget.

Maybe its time to change over to the BMW and get her on the road....

Sigh

Gunner

"Upon Roosevelt's death in 1945, H. L. Mencken predicted in his diary that Roosevelt would be remembered as a great president, "maybe even alongside Washington and Lincoln," opining that Roosevelt "had every quality that morons esteem in their heroes.""

Was it a one-piece head? They had cut-outs for the cam lobes so you could put it in from the side - but it meant that there was a lot less meat for the cam journal to run in.

All (as far as I know) SOHC fours have the cams run run in the aluminium; when the cam in what I had lost luberication and seized it was time for a new head (first time) and new engine (second time). Small metal bits in the oil-restrictors plugged the feed to the rockers and cam end-bearings - after that I started oil and filter changes on a much more frequent schedule and epoxied a magnet in a hole bored in the sump plug.

Certainly a cam that's that scruddy would account for a lot of trouble, although the fact that the thing has _no_ response to the idle adjustment or choke doesn't sound good.

I like Bruce's suggestion of bronze bearings better than steel, although as you said there's a lot of work to it. You'll want to take a look at the condition of the camshaft before you decide anything else.

Welding up the bearings and machining down isn't bad in principle, but were I doing that I'd be concerned with ever so slight warping and I'd have the whole thing re-machined (at least at my current level of expertise I'd _have_ it re-machined -- maybe if I get better I could do it myself).

On the XL185, the end opposite the cam chain runs in a steel bushing that is pinned to prevent rotation. The 185 head splits horizontally at the cam centerline. Not sure how your head is configured, this may or may not be an option for you. It would be the simplest fix, assuming the cam journal surface is still in good enough shape. But with that much wear up top and the shade tree idle jet you found, I think you've got to start wondering how well this bike was maintained and what other surprises lurk... I see those XL's show up now and then fairly cheap. I just missed one by minutes at a yard sale for $100. Buyer had to come back with a truck, that's why I got to check it out and talk to the seller. It was really clean, guy said it needed a brand new cylinder sleeve, piston, and bore job, over $500 worth of parts and work. I would have just set it in the back yard and waited for a good cylinder to show on ebay. Either cut your losses now or start looking for a deal on a better one and use this one for parts. That BMW will be a much better freeway ride anyway....

Jon

Well, there should be a bearing in the "distributor". I think it is a separate component and the shaft keys into the end of the camshaft. I got rid of my engine a couple years ago. (Only had the engine out of a wreck, I was trying to mod it to use in a hybrid car project.) It may have had the exact same problem, it ran VERY rough, too.

Jon

Are you SURE the carbs are originals and have the proper main jet? The carbs off of a 400 are the same but have different mains. They would cause rich running.

Wrong jet in there someplace.

Plain aluminum on both ends. The usual repair is to grind the cam then align bore the heads/saddles to fit bronze bearing inserts. You could also do it the other way. Grind the bearing surfaces true then weld up and grind down the head surface and the clamps as well.

As I've gotten older I think my "BAIL-BAIL-BAIL" point has moved. I see my short remaining time on the Earth as being more valuable and I have become very selective with what projects I will take on. I have started to consider where my time is most valuably spent and what kind of return on that investment is forthcoming. I no longer think I have to conquer every demon or catch every ball that is thrown at me. The danger I see is that I won't do anything challenging anymore or not do something that is extremely satisfying because I can't justify it. Just an observation.

Did you make bronze split bearings, or just round bushing? How did you you keep them from spinning in the journals? Drill and put in a pin in the bore and a matching hole in the bushing?

This does sound like something possible for me to do with materials on hand.

What would the best bronze type to use this application? Aluminum bronze? Silicon bronze?

Thanks

Gunner

"Upon Roosevelt's death in 1945, H. L. Mencken predicted in his diary that Roosevelt would be remembered as a great president, "maybe even alongside Washington and Lincoln," opining that Roosevelt "had every quality that morons esteem in their heroes.""

Gap somewhat OK, but have you gotten a timing light on it?

Is the centrifugal advance working?

If you do decide to pass on this bike, it does have enough of a following you can find a willing victim for it fairly easily.

Dave

None of my timing lights works on 6vts.

Having that variable point gap has to be wrecking havoc with the dwell.

No idea. It is free and appears to be in good shape.

Ive been told that one of my strengths (and weaknesses) is that Im Mission Oriented...ie stubborn as hell. I tend to pursue a problem until it and I are a bloody mess, with me standing in victory above it...chuckle. I cant throw money at most things, so tend to have to find other alternatives. I may put it aside for a bit, but I always come back ..sometimes many times, until Ive resolved it. Sometimes with horrendous amounts of time expended. Shrug...charector flaw perhaps. Dont know when to quit.

I might wind up selling this thing off to someone who needs a parts bike, but it wont be for a while.

Gunner

"Upon Roosevelt's death in 1945, H. L. Mencken predicted in his diary that Roosevelt would be remembered as a great president, "maybe even alongside Washington and Lincoln," opining that Roosevelt "had every quality that morons esteem in their heroes.""

Make certain that the gas is fresh. The ethanol blends that are sold today go bad very fast. Everyone that I ride with has started using fuel stabilizer. The mechanic at the local Kawasaki shop claims that he had fuel go bad as quickly as 2-3 weeks. The symptoms you are describing sound exactly like you have bad fuel.

The timing light powers off +12V but triggers off the spark lead- you should be able to: connect a +12V battery's (-) lead to the bikes chassis, the (-) lead of the timing light to (-) on the bike, the (+) lead of the timing light to +12 on the 12V battery, and the timing light sensor to the plug lead.

The common ground reference probably isn't even required.

The 'closing' end of the dwell isn't critical, but if its all over the place on the opening end, yeah, the timing will be all over the place.

Hey, if it runs, that thing will get almost 100mpg... its a free survival bike.

Dave

Oh, and:

In article , Gunner Asch writes

How did you clean it? These carbs are a maze of twisty passages (all alike) and they are *buggers* to get properly clean.

Ultrasonic cleaning seems to be the only way to do a proper job.

My money is on some old gas gumming up a passage or two somewhere. Can you remember what the carb smelt like when you first got it? Old paint thinners, and it's *definitely* gummed up.

A used carb will likely have the same problems.

New carbs can be surprisingly cheap. Or eye-wateringly expensive... ;^)

I agree with that bad fuel idea. I had a problem with my Arctic Cat 4 wheeler this summer. After I cleaned the carb and changed the plug and it still ran rough at an idle and wouldn't rev up I dumped the gas for some fresh stuff and it perked right up. The gas in the machine was only 3-4 weeks old. Steve

It runs on bare AL . change the oil, put in something heavy, like STP and drive it till it dies. Its not hard to pull the engine, but why bother. If you try to pull the head you will need to split the timing change. gary

Gunner Asch formulated on Monday :

What's your impetus for getting this bike going, other than you have it? Does it have sentimental value? I can see where it would be good for local trips. But it really isn't any good for off road or highway use.

Try posting your questions on rec . motorcycles . dirt or

Wayne D.