1968 CL175 repair and build

Oh man it's been a while. Finally have the time to get into this little engine. I ordered a camshaft today, piston rings, and a whole gasket set. Hopefully next week I'll be able to replace the cam and all the gaskets and my little scooter will be back on track.

Question for anyone interested, I've never replaced the cam in a bike before, anything to watch out for? I'm a little worried it'll be a tooth off or something when I'm done. I'm planning to put the left piston at TDC and just pop the cam out and replace the new one in the same position I guess.

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Engine out! Only one deep wound under the fingernail, calling that a success. Just have to pick up a chain breaker and I'll be at least popping the cylinders off, if not getting everything back together tonight.

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teazer

Active Member
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Please pick that motor up and place it on a table of some sort to keep the dust out of it.

Cam timing is easy and is spelled out pretty well in the service manual. Take the time to check the timing and ask questions if it's not clear - before you bolt it all back together. good luck- and mind your fingers.
 
Well, looks like I'm screwed. I got the rings on and was able to slide the cylinders back down onto the pistons but only about halfway, and now they won't go down any further or come off. Not sure where to go from there.

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teazer

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That's unusual. Daft question, but are you sure that the cam chain or tensioner or something else isn't in the way?

Are both pistons in so that all rings are in the bores? or is it cocked to one side? It's really hard to trouble shoot without seeing it. Can you post a picture or two?
 
The chain and tensioner are out of the way for sure, I can move them around freely right now because the pistons are at TDC. I've been able to see that the right piston moves but the left one is completely stuck.

Also Teazer, I heard you were a 175 expert, can you tell me which cranks will fit? I'm fine with tearing all the way down and replacing the crank, pistons, and cylinder and I'm like 90 percent sure the cylinders are interchangeable.

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teazer

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Any 160, sloper 175 and vert 175 crank will drop straight in. Some have different crank drilling etc for lightness/balance but all will work. CB200 would work but the rods are too long and the drive pinion splines are different, so avoid those. The crank can also be rebuilt with C90 rods IIRC.

Any 160 or 175 barrels will drop straight on. Same height etc. Vert 175 have different fin shapes than the slopers but I doubt that anyone else would notice.

Same with heads. Any head will fit BUT 160 has a tiny combustion chamber, sloper and vert 175 have very different ports. Vert head has ports cast much higher in the head and are arguably a better head but take work to make them work correctly. The best valve guides are CB200 which have modern seals and smoke less.

It sounds almost as if the barrels are on at an angle and have cocked on one piston. Check and see how square they are and lightly tap them up on the low side.
 
Dude you're amazing, I spent hours Googling around and got about half that information haha. There were some fins broken off when I got the bike so I'm going to replace the cylinders anyway. The head is in great shape, and with a little cleaning I think it'll be just fine.

I've found a few cranks with rods on them so I'm going to just take the whole mess out and start fresh, and now I have an excuse to open the whole thing up and clean the 50 years of gunk out.

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teazer

Active Member
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You're welcome. That was the cliff notes version.....

When we built our first CB160/CL175 race bikes I collected every cheap motor I could get my hands on and stripped them and measured parts and even had a couple of heads cut into cross sections to see the differences. Fortunately there are a lot more new parts available now that when we built that first motor.

We even have one with highly modified Wiseco Kawasaki pistons and the cylinder head welded up and machined into a different shape. The one thing I never finished though was a decent blade cam chain tensioner design to control chain whip. One of these days....

Check out what Michael Moore did with his 216 motor or racers like Byron Blend. there's a large pool of knowledge available now on those bikes - including guys on this forum like Zeke and his dad Patrick who have spent many hours inside those motors and trying different things. They even had the Bostrom boys ride one of their bikes right at 100 MPH.
 
I'll have a look for sure! I was able to find cylinders on eBay that came with pistons, and a crank with conrods so those are on their way. In the meantime I've tried to impact every single phillips screw on the case and have basically stripped all of them, so it looks like I'm gonna be drilling them out and replacing them.

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teazer

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That's not unusual. They do tend to be overtightened and then rust in place.

The added issue is that they are not actually Phillips screws but JIS which is slightly different in the cross head. Drill off the heads and remove the cover and the stubs should come out relatively easily
 

jag767

New Member
teazer said:
That's not unusual. They do tend to be overtightened and then rust in place.

The added issue is that they are not actually Phillips screws but JIS which is slightly different in the cross head. Drill off the heads and remove the cover and the stubs should come out relatively easily
Funny, of all the issues I have had, this was never one of them. A good pb blaster spraying, following by going around with an impact screwdriver and they'd almost always come out, there'd be one of two I'd have to easy out, but never had to drill a head off. Sometimes I will put a gritty compound in the head, give it a little more to grab on to actually.
 
jag767 said:
Funny, of all the issues I have had, this was never one of them. A good pb blaster spraying, following by going around with an impact screwdriver and they'd almost always come out, there'd be one of two I'd have to easy out, but never had to drill a head off. Sometimes I will put a gritty compound in the head, give it a little more to grab on to actually.
Man I wish that was the case, I've soaked them and hammered away with my impact driver and they're just stripping at this point. I got one out haha, but the rest are not making it easy.

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teazer

Active Member
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Last summer we were at the races and a buddy was having problems with his shifting and needed to replace the hairpin spring and had no oil, so we laid the bike on its side and pulled the clutch to get to the shifter. Careful to not lose any oil.

Then we pulled the shift shaft out and stood looking at the broken spring ......................................................as the oil poured out of the hole we just left and ran around our boots and everywhere else. We all pull a dumb move from time to time. Stuff happens, so you clean it up and get on with life.

BTW, engines are designed so that however you drain teh oil, there is always enough left lurking inside to make a ridiculous mess at some point in the process. I usually plop the motor into a large baking tray and that way if/when the oil leaks out, it is contained. I must remembr to take one racing this season - just in case my mate has another problem to fix.
 
teazer said:
Last summer we were at the races and a buddy was having problems with his shifting and needed to replace the hairpin spring and had no oil, so we laid the bike on its side and pulled the clutch to get to the shifter. Careful to not lose any oil.

Then we pulled the shift shaft out and stood looking at the broken spring ......................................................as the oil poured out of the hole we just left and ran around our boots and everywhere else. We all pull a dumb move from time to time. Stuff happens, so you clean it up and get on with life.

BTW, engines are designed so that however you drain teh oil, there is always enough left lurking inside to make a ridiculous mess at some point in the process. I usually plop the motor into a large baking tray and that way if/when the oil leaks out, it is contained. I must remembr to take one racing this season - just in case my mate has another problem to fix.
Ha, I don't feel so bad now. It's on an old kitchen table that I sawed the legs off of so it'd be like chair height, it was headed for the dump anyway so I don't really care if it's covered in oil. I got the left side of the case off last night and there's one more bolt to remove on the right, and then I guess the next step is to crack the case open. I don't think I'll be able to get the conrods off the crank that's in there now with the cylinders and pistons stuck on so I'm going to have to tap them out or something, but I just wanna tear down as much as I can and clean it all up.

If I just soaked all of these parts in like a standard degreaser in a bucket for a while would it do them any harm? I'd take out rubber bits of course, but some of this stuff is so gunky that I wanna soak it and then pressure wash it while I have it all apart.

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teazer

Active Member
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If you use degreaser on shafts and gears for example, wash them in hot water and use a can of WD40 to force the water out. Do not do that on teh crank as it will rust. Use cans of carb cleaner from Wally World and then follow up with compressed air and WD40.

An alternative is a bath or kerosene or diesel fuel followed by WD40.
 
I was more talking about the covers, like the left and right engine covers, the head, etc. Unless I find something really concerning on the new crank it's going right in, and I really don't want to mess with any of the transmission stuff.

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teazer

Active Member
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For covers you can spray them with whatever cleaner you want and then scrub them with a sponge and dishwashing soap or liquid hand soap and sprayu them clean.
 

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