Honda Twins banner
1 - 13 of 13 Posts

·
Registered
Joined
·
215 Posts
Discussion Starter · #1 ·
Bought a CL175 in shambles to fix up for my girl. I'm looking for some guidance...

What I've done:
Checked and adjusted valve clearance
Tensioned cam chain
Cleaned fuel system (de-rusted tank, new lines & filters)
Deep cleaned carbs with carb dip, carb cleaner
Compression is 30 PSI on left, 55-60 PSI on right with engine cold
New spark plugs

She started up but it's a little rough. Definitely doesn't purr like my old CB200t did.
After the initial start, I pulled the new plugs and left side a little wet, right side caked with soot.
I adjusted carb a bit and got her to idle but only by unscrewing the throttle cable out of the top of the carb by about 5 turns. Don't know if that's the way to do it...

I want to turn this into a clean, smooth running machine for my lady...

So I'm looking for help:
What would be the best next course of action to stabilize the idle and have better combustion?

Thanks for reading and for any help, and happy New Year!

Pics of spark plugs (Left, then right)

IMG_1283.jpg

IMG_1284.jpg
 

·
Registered
Joined
·
3,154 Posts
The throttle cables need to be adjusted to lift the slides off the bottom at EXACTLY the same time( this is very important). The idle speed is set with the adjustment screws located in the center of the carbs, in line with the center of the slides. With the air cleaners removed, back the idle speed screws out until the slides are all the way down and adjust the cables so that both slides lift at the same time. Then screw the idle screws in evenly until the engine will idle. The other screws (the air screws) are adjusted by running them in LIGHTLY until they bottom out, then back them out evenly. Start about one turn open and adjust them for the best idle, in for richer and out for leaner. Before you mess with the carbs, be sure to adjust the points (.014") and set the static timing to where the points open at the "f" mark on the flywheel. Be sure and check the advancer while you're in there, give the points cam a counter-clockwise twist to see if it moves and snaps back.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #3 ·
Thanks Mike!

I went out and pulled the air filters off, unscrewed the idle speed screws, and adjusted the screws inline with the throttle cable to the carb and made sure both sides open at the same time. Smoothed things out a lot! Still getting a bunch of white smoke out the tail pipe... but I will check the ignition timing and post back.

Also... Saw a bit of oil leakage for the first time - looks to be at the bottom of the crankcase. Running my finger on the inside of the exhaust opening, feels like there might be a little oily substance there too.....

Will check
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #4 ·
I adjusted the points. The spark advancer does snap back but it's a bit loose within its fitting. Is that normal for these smaller bikes? My CB450's spark advancer felt pretty snug.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #5 ·
Don't know if I should create a new thread for this, but: Now that it's idling a bit, it isn't idling steady. The idle is fluctuating a lot-sometimes racing. I tried looking for air leaks by spraying carb cleaner on the outside of the carbs/boots while the engine was running, but the engine didn't respond. Any ideas or things I should try?
 

·
Premium Member
Joined
·
10,203 Posts
Warm it up and repeat your compression test. If the numbers you posted are for real no amount of tuning it up is going to make it a runner.
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #7 ·
Ooooh.....

After warming up for approx 5 minutes, those I still got about 30psi on the left and 55psi on the right.

What would be a practical next course of action? Am I looking at replacing piston rings? Or something more involved?

Thanks for any guidance.
 

·
Premium Member
Joined
·
10,203 Posts
That's certainly worth the effort. You might also do a leakdown test which could tell you if air is getting past the valves. Air leaking into the crankcase could be rings but could also be a blown head gasket.
 

·
Registered
Joined
·
582 Posts

·
Registered
Joined
·
215 Posts
Discussion Starter · #12 ·
OK! So I can happily report that the piston soak has been a complete success. About a month ago, I put a couple of tablespoons of seafoam into both spark plug holes. I let it sit for a week and a half, then fired the bike up. Kicking it to a start, it sure felt like she had more compression but I didn't have a compression gauge to test. Ordered one, and finally got around to checking the compression.

Left cylinder went from 30 to 122 PSI!!!
Right went from 55 to 125 PSI!!!

So the problem was certainly cause by stuck rings from the bike sitting for years. Last tags were from early 90s so, that's a lot of time for the rings to loosen.

I will the oil promptly to remove any seafoam from my crankcase... I have heard some members express worries of it damaging the wet clutch.

55
 

·
Registered
Joined
·
215 Posts
Discussion Starter · #13 ·
When he said he turned over the motor to get the seafoam out of the cylinders? Where does it go?
Put it directly into the spark plug holes. A funnel or tube is necessary to keep from splashing out onto the floor.
 
1 - 13 of 13 Posts
Top