1968 CL175 repair and build

Woah been a while. I had a surprise move and a bunch of traveling to deal with but I'm nearly done here.

Ran into one snag, though. The camshaft I bought looked right, but compared to the one I pulled out there are some differences. Pics attached are all the old cam on the top and the new one on the bottom.

The thing fits in the journals but the advance doesn't slip over the small end of the new cam. I'm tempted to just bore it out with a drill press but I'm sure someone here will save me with a decent solution.

Any ideas?
Thanks!


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Edit: The new cam has R6 cast into one side of it, not sure if that helps anyone, but if anyone knows what it is I'd like to get rid of it haha
 
Well I ordered a new camshaft and it doesn't fit the advance plate either, so now I wondering if maybe I had the wrong cam to begin with, or if it's possible that the 68 cam is somehow different from the later models. Anyone got any insight on that?

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Progress! I got a new advancer and it fits the cam I bought. It looks like this bike had maybe the wrong cam in it when I got it. My understanding is that the 306, 307 etc casted advancer belongs in the 175s and the one I had said CB93 on it so I dunno.

Anyway, just have to sinch everything up and find a tiny bolt to hold the points plate down and we'll be good to go!

Scissor jack from my 88 Supra ftw.


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teazer

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Just got back into town after a week without much internet. Early cams - 160 and sloper 175 had a smaller diameter points cam. Later ones were 1mm larger. 11mm vs 10mm I think.

CB93 was the 125 version of the CB160 and that's what the points assembly were on slopers of all sizes - 125, 160 and 175. Later Honda changed to use the model code 268, 259, 312 or whatever and they use that code in the part number.

You can also use a rev counter on that slotted later cam. You will need the whole cam tower assembly with gears, cable and a suitable tacho.
 
teazer said:
Just got back into town after a week without much internet. Early cams - 160 and sloper 175 had a smaller diameter points cam. Later ones were 1mm larger. 11mm vs 10mm I think.

CB93 was the 125 version of the CB160 and that's what the points assembly were on slopers of all sizes - 125, 160 and 175. Later Honda changed to use the model code 268, 259, 312 or whatever and they use that code in the part number.

You can also use a rev counter on that slotted later cam. You will need the whole cam tower assembly with gears, cable and a suitable tacho.
I'd need the new tower, gears and cable for a tach, but it should work at least to get it running again right? I've got it all back together and it seems to fit just fine so I gonna grab some hardware tonight and see if I can get it started.

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Well, oiled and gassed up and I kicked my guts out but no start. I've got spark from both plugs, checked and double checked the points, played with the choke, and nada.

I tried to do the old finger in the hole compression test and didn't really feel anything, maybe somehow I messed up the rings. I'm also a little worried that my cam is a tooth off or something because it's firing enough for a warm pipe but it won't run.

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Now that I think about it, it'd make more sense that I put the cam in wrong and the valves are open on the compression stroke or something. Guess I'll tear back in there and redo that and the points.

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teazer

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Before you tear it all apart, did you check that spark happens at the T position? Are the carbs getting fuel and are the jets etc all clean?

At TDC, what is the position of the points cam?
 
The spark happens at the right spot for sure, checked that twice. The carbs are clean because I cleaned them when I removed them, and I'm getting a gas smell on the plugs. Since I'm not feeling any compression on the plug hole when rotating I'm assuming the valves are not closed on the compression stroke. I installed the cam with the O at the top but I don't remember checking what stroke I was on and I bet I messed that up haha.

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teazer

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That's odd. The points cam is keyed to the camshaft, so in theory if the ignition timing is right, the valve timing is also right.

The crank is 360 degrees and both pistons rise and fall together. The coil fires both plugs at the same time just before TDC, so if the timing is 180 degrees out it should still be right. At TDC one side whould have both valves open on overlap and the other side should have them both closed at TDC. You might try removing the valve caps and at TDC see that one side there is play and on the other side, both valves should be open.

How did you clean the carbs? Those crabs have a bypass pilot circuit that's a tiny hole on the engine side of the slide and they clog up pretty regularly. Pull the carbs and blast cleaner through that circuit and do it on both carbs to compare sides.
 
Well for giggles I redid the points because I was getting a kick back in the kickstart lever, and that's gone now. I gapped the point to whatever it is, can't remember now, while on the high point in the cam, and rotated the plate so it just breaks at the F mark on compression.

Occasionally I'll get about ten revolutions if I kick it hard, but it won't start all the way up.

I'm gonna have a look at the carbs this weekend but I'm 99% sure they're clean because I pulled them off and cleaned them, and kept them in an empty toolbox drawer while I was rebuilding.

I did actually feel compression with my finger on the left side but I'm gonna test both cylinders this weekend too just to make sure I didn't fail at the rings.

I also charged the battery up and I'm getting spark for sure.

It has to be carbs, rings, or cam timing right?

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By the way Teazer you're a fucking legend dude, thanks for helping me out so much.

I run a screen printing business, so if you send me a good shot of your favorite bike I'll put a white print of it on a shirt for you free of charge, you're saving this bike haha.

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teazer

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At TDC on compression, both are closed and at TDC on the other side, both should be open more or less the same amount. Rock it slighl forwards and if the inlet valve on that side continues to open, it's probably OK. Rotate it another 300 degrees or so and see when the inlet valve cracks open. Should be close to TDC.

Try squirting a small amount of STerter Fluid into the intakes and see if it fires.
 
I just tore down the right side carb and it's squeaky clean. If the tiny pilot jet you're talking about is a little hole behind the seat for the needle, it seems clean and I ran a wire pretty deep into it to check. With a little starting fluid I get a warm pipe from the left side and the left carb is also super clean, but the right side pipe doesn't warm up. I got it to fire a couple times but it won't idle, and dies immediately when I give it any throttle.

I have a few print projects I'm working on so I haven't had a ton of time, but I found the wrench I use to get the tappet covers off so I'm gonna do the valve adjustments and make sure they're doing the right stuff at the right time this week.

I've got a little fantasy of taking this thing to a local bike show in September and I really hope that happens.

End of the day it has to be cam timing, compression (borrowed a compression tester and forgot it at my buddy's house haha), or maybe fuel but it seems like it's getting gas.

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teazer

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sounds like the slow jet circuit is still blocked. Remove both carbs and strip them completely.

Spray WD40 or carb cleaner down the hole that the air adjustment screw was in. it should squirt out at the filter side and out of the hole that teh pilot jet was in. Repeat on the other carb. Do they both flow more or less the same?

Now spray up through the hole that the pilot jet was in and repeat on the second carb and compare. Do NOT poke wire through jets or drillings. It will tend to open them up and we want them stock sizes.

Do the same through each of the air drillings and compare one side to the other.

Also look carefully at the tiny hole on the floor of the bore roughly in line with the front edge of the slide. You should get spray coming out of there. That's where the pilot jet flows out into the airstream.
 
Alright well I don't have a screw in compression tester handy but with the press in one with the rubber funnel I'm getting 60psi on the left side and nothing on the right. I know without screwing in the gauge these numbers are sketchy at best, but nothing at all on the right side probably isn't wrong.

If I could get the tappet covers off of the exhaust side I'd know if the valves were closing, but I'm more inclined to think it's rings at this point.

Gonna pop the engine out again and work my way back to the rings I guess. What's the spec for the inside diameter of the cylinders? And what's a good source for new rings? The ebay ones I got before these were crap.

This will also give me a chance to double check and make sure my cam timing is right on the way back up I guess.

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teazer

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That should be around 120-140psi with throttle wide open, so 60/0 is low for sure - assuming you are using a good compression tester. Some ebay units are total junk and read way low.

When you pull the head off, try the old gas in the combustion chamber trick and see if any seeps out though the ports - one side at a time or with the cam out of course.

Stock bore is 52mm on all 175s. Honda sell rings and they are usually available on ebay. Inspect the rings and pistons as you remove the barrels and see if they are broken or stuck in place.
 
Alright, had some time today to get into this thing. I haven't taken the engine all the way off again but I got the valve cover off, or that whole cast piece I guess. These pictures show the camshaft position at the T mark on compression. Looks pretty good to me? Makes me think it's a piston issue after all.
I still can't get the tappet covers off because I keep forgetting to get a socket big enough, but just touching the rockers at TDC and they're all tight except for the right side intake valve, the rocker there jiggles just a tad. I'm assuming that's a valve lash issue and someday I'll adjust it haha.

Any suggestions?

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