1968 CL175 repair and build

adventurco

Nick Ol' Eye
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Sounds like your pilot circuit is clogged still. Find a parts fiche for the carbs from any Honda dealers website it will tell you exactly what every part is.


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Alright, so I've disassembled and cleaned the carbs for the second time now, put everything back together, installed it on the bike, balanced the throttle slides, and I can sometimes get the bike to start. It bogs under heavy throttle input, and will not start without the choke at about 90% and a goose from the throttle, and even then not every time. Both cylinders are getting warm at the exhaust, but the right side is a bit cooler so I'm guessing it's running leaner than the left cylinder. I don't really know how to adjust carbs so I'm going to have to read up on it, but at least it's something.
 

teazer

Active Member
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Did you spray through the tiny holes into the bore that the pilot jet discharges from. They are tiny and they block easily
 
teazer said:
Did you spray through the tiny holes into the bore that the pilot jet discharges from. They are tiny and they block easily
I can see daylight through all of the jets, and the carb housing and everything is super clean. There are tiny little holes inside the opening of the carb in front of the slide, do they go straight through or are they just cast in? I honestly can't find anything else to clean because I've done both a number of times now. I'm thinking I should try swapping the carbs and starting to see if that works at all.

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Edit: When I get it started if I cover the right side carb the bike revs way up. I don't know if that's helpful, or if because the right side isn't running in basically just plugging a vacuum leak.
 
Well I was able to ride this little thing today for about ten minutes. It starts alright with no choke, but I'm still getting a much cooler exhaust pipe on the right side. The bike also bogs pretty heavily under throttle and then will catch up, which I'm thinking means it's running rich. If I tip the bike to the left it'll idle up a bit which is weird, and it really doesn't like moving forward haha. I'm getting some white smoke from the exhaust now, so I don't really know where to go from here.

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teazer

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medicalmechanica said:
I can see daylight through all of the jets, and the carb housing and everything is super clean. There are tiny little holes inside the opening of the carb in front of the slide, do they go straight through or are they just cast in? I honestly can't find anything else to clean because I've done both a number of times now. I'm thinking I should try swapping the carbs and starting to see if that works at all.
Those super tiny holes are above the pilot jets and it's hard/impossible to see through them. The trick is to fire carb cleaner up through the pilot jet and look to see that it sprays out of the holes - wear goggles and do that outside or with lots of ventilation.

Much cooler exhaust suggests that the pilot jet is still blocked on that side. And yes, they are a PIA design that clogs so easily and is so hard to get clean.
 
Well I swapped the carbs for kicks and my cold cylinder is now my hot cylinder. This tells me that there's for sure something up with the right side carb, but I took it apart and I can't find a single spot that's clogged. Per Teazer's suggestion I blew through the tiny hole in the top of the intake side of the carb and air moves freely through that jet. The needle jet and jet needle are functioning correctly, and I know that fuel is moving through the fuel lines. I'm thinking about trying to track down another stock carb and see where that takes me.

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Learned two things today!

Thing one, I'm retarded.
Thing two, I have a 180 main jet and a 98 main jet. My suspicion that the right side carb was too rich is true, the carb on that side had like twice as much fuel going to it. Ordered a rebuild kit and I'm confident that two 98s will do it haha. Now all I need is to find a good cam and I'll have a perfect little bike, fingers crossed.

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teazer

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FYI, 180 main jet in a keihin carb 1.8mm diameter and that will flow 4 x as much fuel as a #90. Or did it have a minkuni jet in that carb?

Go on line or contact your dealer and see if you can get two good new Keihin main jets for that carb. Early and late Honda's use different threads - same diameter but different pitch. I can't remember which pitch the 175 used and what that is compatible with but can check it over the weekend if you need.
 
teazer said:
FYI, 180 main jet in a keihin carb 1.8mm diameter and that will flow 4 x as much fuel as a #90. Or did it have a minkuni jet in that carb?

Go on line or contact your dealer and see if you can get two good new Keihin main jets for that carb. Early and late Honda's use different threads - same diameter but different pitch. I can't remember which pitch the 175 used and what that is compatible with but can check it over the weekend if you need.
I have Keihin carbs, and I read somewhere that a 98 and a 38 are the way to go. I ordered a rebuild kit that meets the specs for the threads I have so I think it'll be good to go, but if not it was only like 19 bucks so I won't have to take out a loan or anything if I ordered too hastily.

Should I keep the needle in the 3rd notch and go from there?

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Aaaaaaaand I'm stumped. Both carbs are set up the same, same jets, same float bowl heights, same fuel filters which are known to work, same air filters, same needle positions, same fuel screw settings, and I'm still getting a cold pipe.

Does anyone know what operating temps I should be seeing? My left pipe is like 400 degrees and my right pipe is in the 110s.

I know I have spark. I know I have compression because I checked, and because swapping the carbs reverses the problem. I know there's fuel for that same reason. It has to be something carb related but I would eat off of both of them, and even though I have new jets I cleaned them AGAIN and ran a tiny wire through all of the ports to be safe.

Help? Thanks!

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adventurco

Nick Ol' Eye
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Ha! Good catch. I've had that happen to me before, but it just ended up with fuel spilling all over the driveway. Glad you got it figured out.


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teazer

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Cool. One thing I try to do now is to set FUEL level and not FLOAT level. That way, any float problems are obvious and it's what we are actually trying to do when we set the float level.

Doing it "wet" where possible is more accurate.

A simple test for floats is to stick one into a cup of really hot water and watch for a stream of bubbles. No bubbles is good, any bubbles is bad.
 
Yeah, that's how I found the hole once I realized what was happening.

I'm having a great time riding this thing but it's leaking oil so I should probably stop. I'm seeing oil on the kickstand and the little chain cover is impossible to get off because the PO demolished the screws, so I can't tell where the leak is.

I'll probably tinker around until my gaskets arrive and then I'm gonna just refresh everything, grab a brat seat and some clubmans and call it done.

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HerrDeacon

Active Member
teazer said:
Cool. One thing I try to do now is to set FUEL level and not FLOAT level. That way, any float problems are obvious and it's what we are actually trying to do when we set the float level.

Doing it "wet" where possible is more accurate.
That's the way Kawi does it and it works great. I found it real strange when I got my first Honda and they set them the other way. Way too much margin for error if you ask me.
 
All three of them are destroyed haha, gonna grab an extractor kit and see if that works, and if not I guess I'll have to drill them out and cut new threads in, which I hate doing.

In an earlier post I showed a picture of my camshaft end on the points side and how chewed up it was, and before I order a new cam I have a question.

If I were to cut the scoring out of the cam, would I be able to run a smaller gasket in the cam journal to make a seal? The seal is leaking a few drops into the points housing, and I'm thinking if I can find a gasket with a smaller ID and flatten out that surface it'd work fine.

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adventurco

Nick Ol' Eye
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Get a drill bit that's just a hair bigger than the 6mm bolt shaft, and drill through the head of the screws until they pop off. Take the cover off, and I'll bet the rest of the screw will come out by hand. If not, vice grips.


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advCo said:
Get a drill bit that's just a hair bigger than the 6mm bolt shaft, and drill through the head of the screws until they pop off. Take the cover off, and I'll bet the rest of the screw will come out by hand. If not, vice grips.


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That's the plan! Hopefully I'll get enough of one out without destroying it that I can take it to the hardware store and get some nice new black hex hardware.

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