Topic: cl 175 running rough carb tune question

[starkmojo]

so here is what I have done-

Valves checked
(OK why the hell didnt the shop manual mention to drain the oil before pulling off the left crankcase cover? I mean what the hell... oil on floor... messy... #$%*.... cleaned up... moving on)
.002 intake .003 exhaust (manual says .002 both, but the PO had it set at .003 exhaust and it seemed logical to me)

Timing- spot on
new plugs (old ones were rich)
checked points and cond. good
drained gas tank
drained carbs (oops.. shoulda done that before now)
cleaned carbs
changed fuel filter (one was good, one wasnt)
changed oil (well finished draining oil pan after that whole left crankcase cover incident...) fresh 20 50 dino oil
charged battery.

well now it starts... no choke? every other bike I know needs some choke to start... Runs well when you give it some gas (right up to the redline) but peters out when you let go the throttle.

My next guess is the carbs need tuning, but I the procedure in the book is vague (I have the cb 175 Honda shop manual.) How exactly do you get both carbs idling att 1100-1300 rpms at idle when the damn thing wont idle? It doesnt say which way to turn the screw to make it go faster...

anyone with any ideas feel free to sghare

[Staggerlee]

Turning the idle screws in should increase idle speed. 

Have the carbs been apart?  It's pretty easy to get the throttle slides installed backwards; makes tuning a real #$%*.

[starkmojo]

Yeaterday I got back to the 175...

I have to say the tube that runs between the tank halves is a #$%*. The only way I can find to get the tank off without making a godawful mess is to remove the tube from one side, put my finger over the bare outlet whilst putting a #2 philips bit in the hose with my third hand. seems like a shutoff valve would be useful here.

I turned the main throttle stop screw in 1/2 a turn on both sides, and it idled at 2200 RPM, backed them off to get it to idle at 1300 when I realized that adjusting the left carb would change the idle, while adjusting the right carb did nada.... so I blocked the right carb with my hand and nothing changed, while blocking the left carb would kill the engine right quick. assuming that I had a carb issue I removed the float bowl and found some detritis in the bottom of it though no tmuch which was cleaned out with carb cleaner and dried with a paper towel. This did not change things and as the carb was getting fuel, and air, I decided to look at the fire end of the equation. I hadnt thought of this before because the coil looks brand new- supple wires, shiny, new connectors etc. But investigation lead me to discern that while the left plug was getting a bright blue spark, the right was getting nothing.... tried clipping back the wire, checked the boots (by switching them) the boot worked fine, which leaves the spark plug wire or the coil- as they are molded together there isnt much difference.

I have to say that I think molding the coil to the wires is the dumbest idea I have ever seen and a pure case of built in cost I can think of- a coil will last for decades, wires for two to three years before they are shot, so instead of just replacing the wire I have to scramble up a whole coil.

Also why is it that well made coils (ie the kind you install the plug wires onto as opposed to being molded on to the coil) cost twice as much? when I found that out I sounded like a sailor with tourettes syndrome! Bah!

So now I am hoping that I can scramble up a used coil while I save up the bread to buy a decent coil- which I seem to be having a hard time buying one of as they get sold in pairs...

[Staggerlee]

I think I might have a 175 coil kicking around in the garage still; I'll check tonight.

[starkmojo]

you really live in FoPo? I think we migh be neighbors...

[Staggerlee]

Yep, sure do.

Whereabouts are you?

[starkmojo]

My legal address is in South Tabor- but I seem to be hanging  my hat in FoPo a lot lately?

Have you been to Sweetness Bakery on 52nd and Powell yet? Thats my regular coffee stop.

[Staggerlee]

Haven't been there yet, but it's on our short list.

Our regular coffee stop used to be Speedboat, but the guy that just bought from the original owner is a complete douchebag so we stopped going.

[starkmojo]

Sweetness is a great place- Kaye the owner is a 4th generation baker and a friendly person.... just beware the treats lest your ass expand!

[Staggerlee]

All right then; sounds like we found a new coffee joint.

[starkmojo]

Hey... Now that its firing on two cylinders...

So I had a total of three coils (used) and all of them had issues (bad wires, bad leads, getting hotter than holy hell the second i turned the key) so I asked Doc Brown and he pulls out a generic coil for 30$. and it has REMOVABLE PLUG WIRES! 30 bucks is cheap....

so I hook it up and get it running but it seems i messed up the carb idle adjustments to get it running back when i had it on one cylinder. If someone was putting in a new (or rebuilt) carb what would be the starting point for the throttle and air screws?

[Staggerlee]

I'd start with the mixture screws being 1-1/4 turns out. 

Sync the carbs with a 1/8" drill bit; slide it back & forth down the throats and adjust the idle screw until the throttle valves just drag on the shank.  That should get ya running.