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Discussion Starter · #1 ·
Hey guys! I am currently resurrecting a 1972 Honda CB175, I started by ultrasonic cleaning the carbs and jets. Got 90% of that old caked on grime and gunk. I then used some really small sewing needles and of course some carb cleaner/CLR to get off all of the lime and the gunk that was really stuck in the jets preventing flow. I also replaced the O-rings on the intake of the carbs because it was creating a vacuum leak because of how flat the O-ring was. Also I am using a "Bottle" for the fuel so I don't have to worry about and anything from the tank while I am tuning the carbs and what not. So basically I noticed it has somewhat of a rough idle (not bad) but also it WILL NOT run off of the choke at all. I know it is not in the carbs because I have inspected everything multiple times and cleaned them multiple times. But as soon as you turn the choke off the bike dies instantly. Brand new Spark plugs, battery, perfect fuel, float height is good and needle is functioning perfectly, and the both cylinders are firing (They weren't before when I had the Vacuum leak). But I was wondering if anybody could please help me and if any of you had ideas! Thanks!

Sorry for the lengthy post, just wanted to give as much information that would be needed for you guys to know! :)
 

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Running only with the choke on is an indication of too much air or not enough fuel. Either would also explain the rough idle. It would be a good idea to dismantle the carb (completely) and let it soak overnight in cleaner and then reassemble with a carb overhaul kit.

Also check that your carb flange and mounting surface are flat and free of scratches.
 

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Vintage Rider
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Most likely you still have plugged idle jets. Use a small single strand of copper wire from an 18 ga wire and make sure you can get it completely through the jets.
I use a wire jet cleaning kit to do mine. I you can't see a tiny round hole of light through it it's not clean.
 

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Discussion Starter · #5 ·
Most likely you still have plugged idle jets. Use a small single strand of copper wire and make sure you can get it completely through the jets.
I use a wire jet cleaning kit to do mine. I you can't see a tiny round hole of light through it it's not clean.
The weird thing is that I have done that and can see perfectly through the hole like you described, that is why I am so flustered.
 

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Vintage Rider
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The weird thing is that I have done that and can see perfectly through the hole like you described, that is why I am so flustered.
Then your float level is incorrect. Reduce the height a couple of millimeters at a time until the idle jets are in the fuel. The main jets are lower in the bowl and are picking up fuel but the idle jets aren't.
 

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Sounds complicated! I just bought a 1971 cb175 that was sitting in a garage for almost two years. It was rusted up but I've been working on that steadily and it looks better. It only kick started and ran when i bought it a few weeks back but the thing just died on me! Something electrical or the relay...I don't know anything about bikes or cars. I really want to get it working but not sure about towing it to a shop and having to pay a ton of money (the one shop that says they can work on something this old charges $90 per hour for assessment and then the same for labor plus parts). Plus I just got screwed by a "mobile mechanic"

My wish list is to get it started and running obviously, fully tuned up and lubed and repair the electric starter. Any idea what all that would cost in a fair shop? Thanks!
 

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I don't know anything about bikes or cars.
I'm guessing this means you have few tools. It may be prudent to have a shop give you an assessment, then decide if you want to start buying tools, including finding a shop manual, and learn as you go, or have an experienced mechanic do the work. But first, ask around for a shop that can/has worked on a bike of similar age. IMO, having an older bike means working on bikes.
 
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Rule #1 of troubleshooting, do the easiest thing first, so try playing around with the air adjustment screws until you get a more rich mixture.
 
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