Topic: First Time Cleaning Carbs - Help!

[Imago]

1978 CB750F. I had a hard time getting the slow jets out, and marred the side of each jet in doing so with the pliers in the attached photo. Cloth and leather just wouldn't hold and I was marring the top of the first jet by it slipping/sliding by, so I decided just to go without and just use the jaws. Will this damage be a problem after the reinstall? The tiny hole through the slow jets were plugged, the main jets weren't bad at all. The high E string cut from excess on its tuning peg on my electric guitar was just the right size. Anything else I should do before the reinstall?

It's a beautiful 20 degrees Celsius here today (that's 70 Fahrenheit for you Stateside or 293 Kelvin if on Pluto)!

[scondon]

Since you have the slow jets out it would be a good idea to give the entire slow circuit a good clean. Referring to your bottom picture with slow jet/E string:

The adjustment screw below your slow jet can be removed(all 4 carbs). Be careful when doing this as there is a small metal washer, spring, and 0-ring in there which you don't want to lose while removing. Spray copious amounts of carb cleaner down the adjuster passage, the slow jet passage, and even the air jet(located in throat of carb intake). Blow dry with compressed air before assembly. Stock setting for the adjustment screws are 1 3/4 turns out. I tend to run a bit richer at 2- 2 1/4 turns out

Also, in the same pic you will notice a round brass fitting on the float bowl mating surface(top of pic). There's a small o-ring that goes there. Don't forget to put it in place before reinstalling the float bowl(#2 carb only) or your accelerator pump will spray gas out the back.

[Imago]

Thanks Scondon... great advice. The marred slow jets didn't seem to make any difference.  It idled great, albeit a bit high @ 1500 RPM so...
 
...took it for my first spin... woo hoo!!!!

When I got home, the idle was quite high, nearly 2000 RPM... hmmmm, have to look into that.

[Imago]

Hope I haven't opened the orifice in the slow jets with my guitar string, or that a slow jet has fallen out and that's what's causing my high idle. Is that likely with them being a press in fit? I recall someone said they used Locktite on theirs.

Also, are the mixture screws (which are turned out when stock 1 3/4 turns) the ones you adjust when using a manometer?

I ask because the PO threw an old manometer in on the deal, and I thought it might be a good idea to synch the 4 carbs.

[trueblue]

Wind your idle speed back a little there should be a big knob on the side of the carbs for adjusting this, and only adjust when the engine is warm or you will be chasing it all over the shop.  The screws you use to sync the carbs are under the top cover held with a lock nut, before you use the manometer connect all the hoses to one vacuum point to ensure they're all reading the same.

[F16Mech]

For future carb cleanings; i have found that carb cleaner and compressed air is all it takes to clean out the jets.  instead of running guitar string through them.  If it is really gummed up in there, try soaking them in kerosene for 20 minutes or so (no o-rings in Kerosene!!!), then compressed air and carb cleaner.

[Bootlegger56]

If its within your budget and you have access to a compressor go to Harbor Freight and get you one of those hopper fed spot blaster guns for @ 20.00.  I just blasted my PD22's with one and it is "da bomb"!  Regular baking soda...no expensive blast media, washes off with water and made my 37 year old carbs look brand new.  I can save my expensive carb cleaner for flushing out the passages and jets.  I would not have beleived it.  If you dont want to go that "expensive" of a route there is a FAQ post on making your own with tubing and an air nozzle.  I did that first but Ive got to say the cheapo hopper fed blaster was a significant improvement.  A one pound box will do a carb with some to spare....thats a whopping .39 cents per carb and no bad chemicals!  Cant wait to try it on my engine and other components as well!

[TwoTired]

Marring the outside of the pilot jets is no big deal.
The big idle knob is set for idle when the engine is at operating temperature.

The choke has a separate fast idle cam that increases idle with choke application, and it has its own adjustment screw to set rpm when choke is needed.  It will need *some* choke until it warms up, if the carbs are clean and adjusted correctly.

The idle mixture screw is NOT used to vacuum balance carbs.  The balance adjusters are under the top caps (#1, #3, & #4), as described in the Honda shop manual.
The idle mixture screw settings are in the manual too, but the settings won't be relevant unless you also have the stock air filter and exhaust system.  (I didn't see a description of those for your bike.)

If the pilot jets were gummed up, I'd expect the accelerator pump system to be gummed up too, which would affect the throttle twist response.