CL175 rebuild

[jtn]

Hi folks, thought I'd share a project that just found me --

Saw this sign on a rusty 1970 honda cl175 on the side of the road in the rain.

Who could pass it up? Engine turns over, but doesn't start. Maybe something to do with missing the battery.


I'm hoping to turn it into something like these:



Any leads on on-line repair manuals for this era? It seems like the CL series shares most parts with the CB's of the same years (except the exhaust headers, side cover . . .) so could I just get cb 175 parts and it'll work? I'll put up more pics as I make progress . . .

[nedodjija]

My understanding is that lots of people like better CB160 than 175s because of the difference in the frame and because 160s have overhang engine. However, you cannot beat the price on that baby. Those bikes look awesome. Please keep us posted.

[jtn]

Pulled the carbs out today, and there was a ton of corrosion. Got them soaking in some gas for a while and hopefully that will help. What do you all think? The throttle body wouldn't even slide up & down, so I don't know if its worth the effort to refurbish the carbs or just find new ones.









Tank is shot, and I'd like to replace it with one that has those knee pads on the sides -- were those for the cb160's? Will they fit a cl175?



Spark plugs and top end didn't look that bad (except for the corrosion on one plug):

[Yad]

Originally Posted by jtn

Pulled the carbs out today, and there was a ton of corrosion. Got them soaking in some gas for a while and hopefully that will help. What do you all think? The throttle body wouldn't even slide up & down, so I don't know if its worth the effort to refurbish the carbs or just find new ones.

gas won't help. There are many ways to clean carbs, do some searching and you will find details.

1. carb dip in a big can (toxic but effective). Not the aerosol stuff, that only works after they're already clean.
2. ultrasonic cleaner (can be expensive unless you already have one)
3. degreaser (e.g. Purple Power) to get rid of gas residue (brown stuff)followed by acid (SHORT exposures, not soaking) to get rid of oxidation (white stuff). I use toilet bowl cleaner and a toothbrush. Just a couple of minutes at a time won't harm the parts, and it really helps nicely with the white stuff. Doesn't help with the brown stuff.

This is one of my favorite jobs in motorcycle refurbishment. Regardless of which method you choose, it's definitely worth trying to salvage them. I have very rarely needed to actually replace carbs, nearly all of them can be saved with thorough cleaning, although you are very likely to need parts (jets, float needle and seat, at least).

Good luck!
dave

[Yad]

P.S. I strongly recommend securing a valid title before you spend any significant time or $. Depends on your location, but in some places it borders on impossible to title a bike like that if you cannot get the previous owner to do it (in that case, it's easy). Do some searches on this. Fair warning.

[EvilClown]

Nice find.

[jtn]

Originally Posted by Yad

P.S. I strongly recommend securing a valid title before you spend any significant time or $. Depends on your location, but in some places it borders on impossible to title a bike like that if you cannot get the previous owner to do it (in that case, it's easy). Do some searches on this. Fair warning.

Thanks for the advice -- I figured if it got close to starting I'd look into getting the title, if not then I'd just give it to someone who has more patience than I do.

That said . . . the current goal is to get the engine to run then I'll worry about the details (brakes, lights, gas tank . . . )

Cleaned the carbs (toilet cleaner followed by spray carb cleaner did the trick!) and reinstalled them:


Drained and replaced the oil (I figured if I got stupid lucky and it actually started I didn't want to mess up anything)


Pulled the key ignition and hotwired it


By the way, this is why you need big guage wire when hooking up the battery


Hooked up a temporary gas line & filled it with gas (there's no tank, just got the float bowls full and used that)


And then gas puked out of one of the carbs -- forgot I stripped the drain thread and found a little hole in the side of the float bowl too. Hot glue to the rescue.

[jtn]

So, the next step was to push the start button. The starter actually turned over, which is better than I expected, but the engine didn't fire up. So I checked the spark by pulling each plug and grounding it and hitting the starter, and both had a spark (not pictured here b'c I don't have three arms)


Then I thought maybe the compression was off, so I put my thumb over the spark plug hole and turned the engine over -- the R cyl had some pressure (I couldn't keep the air from pushing past my thumb), and the L had some but less (I could hold it in with some force). Not enough compression to fire? I'm not sure, but my gut says that wasn't the problem.


Thought I'd test it with my compression guage, but it didn't fit the spark plug hole. Anyone know of an adaptor for this?


So after trying again, I thought maybe the engine is flooding. When I pulled the plug on the L side I noticed that the end was damp


And that there was some gas leaking out the air intake for that carb on the L side too


But the R side seemed fine. I would have thought if 1 side worked and the other didn't as well, the engine would still catch and just run poorly. Maybe not?

So, I got frustrated and just steel wooled the exhaust manifold.


Any ideas? What should I try next? I've got a spark, gas, and air in the cylinders, what else do I need?

[postaldave]

i strongly recommond you take Yad's advise. i've seen dream crushed over a title issue.

Originally Posted by Yad

P.S. I strongly recommend securing a valid title before you spend any significant time or $. Depends on your location, but in some places it borders on impossible to title a bike like that if you cannot get the previous owner to do it (in that case, it's easy). Do some searches on this. Fair warning.

[EvilClown]

Originally Posted by jtn

Any ideas? What should I try next? I've got a spark, gas, and air in the cylinders, what else do I need?

I'd get that carb leak ironed out and throw in a some new plugs - or at least clean the old ones. A match in the cylinder will burn out the gas and your finger tips if it's flooded. One of those long lighters will usually save the fingers.

Once all that is done try starting it by spraying WD40 in the carbs. If it runs on that it'll run.

[Lukengruven]

I've got a '73 cl175, and I'm trying to sort out the left carb. perhaps anyone could lend some advice.
the slide is tight in the tube, I've clean and cleaned it. it slides freely in the right carb, but not the left carb.
does anyone with this bike happen to know or remember the numbers on the slides on the carbs?
mine has a 155/25 in the left and a 156/25 in the right.
I am scouring the internet to see if those are different
part numbers for the left/right, or sizing designations.
If anyone has any input, that would be great, thanks!

[jtn]

Originally Posted by EvilClown

I'd get that carb leak ironed out and throw in a some new plugs - or at least clean the old ones. A match in the cylinder will burn out the gas and your finger tips if it's flooded. One of those long lighters will usually save the fingers.

Once all that is done try starting it by spraying WD40 in the carbs. If it runs on that it'll run.

No luck -- the good news is that the electric start works -- it's turning the engine over but it doesn't catch, even with the new plugs. I'm getting stumped -- any ideas?

[EvilClown]

Originally Posted by jtn

No luck -- the good news is that the electric start works -- it's turning the engine over but it doesn't catch, even with the new plugs. I'm getting stumped -- any ideas?

A couple o questions: Is there a (reconfirmed) spark? What do the plugs look like? How did you go about spraying the WD40 (go into detail)? Have you found that compression gage adapter yet?

[jtn]

Got 25 psi in one cyl, and 40 in the other. Took it as a sign that I should learn to recondition valves & pistons. the rings on one were totally stuck and broke right off (looked like water was sitting in the cyl).



The head looked pretty corroded so I put the valves on a wire wheel and am in the process of lapping them. lots of carbon build up and rust, so I think that's where I was loosing a bunch of compression.


Anyone have thoughts about the cam chain tensioner? looks like the teeth got worn off, but its just a tensioner, so . . .


I'm also getting good at breaking bolts and not extracting them correctly -- time to learn how to use one of those keenserts


And we're down to the crankcase.


Meanwhile I took everything down to the frame and got a new (less rusted) gas tank from Bill's Bonyard


And plan to strip the tank paint (leaving it burnished steel with a clear-coat) and repaint the frame matte black


I honed the cylinders and orders some new rings, so hopefully those will be in soon and I can start the re-build . . .

[Quickv4]

Refirbing a bike (that seems utterly abused and neglected), with NO TITLE.....

Been there done that, wouldnt EVER do that again.

Life is so much nicer when you have a title, regardless of the bike's condition! It gives you a motivation as in- "If I get this thing running and ridable, all I then have to do is skip to the DMV, and shes all kosher, lets ride!!!!)