Topic: CB750 K3 running poor at low gears

[Lars]

Last summer I was making a CB750 1973 model roadworthy for a friend of mine, living in another city.

New fluids and filters, carbs off and properly cleaned, new gasket set and new slow jets. New rubber boots airboks to carbs and carbs to cylinder. New points plate ass, new coils and new spark advancer. All adjusted and carbs synched. Engine ran nice last summer, but owner says taking the bike out from a cold shed winterstorage, it does not run nice anymore. Engine is not pulling - like suffocating on giving throttle 1. and 2. gears, runs well on the rest of the gears when you get up in speed.

Any tip before I drive out and visit him? Slow jets? Air/fuel mix needle screws?

Lars

[iron_worker]

Since pretty much everything is new my money is on clogged idle jets.

IW

[Duke McDukiedook]

Since pretty much everything is new my money is on clogged idle jets.

IW

+1.

[DJ_AX]

Since pretty much everything is new my money is on clogged idle jets.

IW

+1.

+ another one

[flybox1]

+ another.  some carb cleaning needs to be done.
....and tell him to drain the carbs of gas befor he winterizes his bike    it might save you a service trip next spring  ...or dont if his wife is a good cook and he drinks good scotch.

[iron_worker]

What I have found to at least keep my bike in roughly the same condition over the harsh canadian winters:

-Fill the tank right up with premium fuel
-Add the correct amount of good fuel stabilizer (slosh it around if you can)
-Shut off the petcock
-Drain the fuel lines, fuel bowls, filters, etc

I had tried dumping the tank too but that usually lets it rust due to moisture. Not good!

You could try pulling the bowls and pilot jets out of the bike with a stubby screw driver and give them a good cleaning. That's probably all it needs.  If you're enthusiastic you could pull the carbs and clean em up good again... better yet: teach him how to clean the carbs. ha

IW

[lucky]

Quote:
"but owner says taking the bike out from a cold shed winterstorage, it does not run nice anymore."

There is your clue.

[HondaMan]

If your friend is not a mechanic-type, or a sedate rider, it might just be fouled sparkplugs. Maybe get a set of the ND X24ES-U plugs instead of the D8EA type, as they tend to stay cleaner. Also, chekc the resistance of his sparkplug caps: they must not be more than 8500 ohms (if original), and must be within 500 ohms on any one coil. Replace with modern 5000 ohm types, if needed, in pairs.

The K3 often came with #110 mainjets, and tended to foul sparkplugs if not ridden stoutly. If this appears to be the problem, consider dropping the jet size to #108 or even #105, and ask him to use a lower-octane fuel. These things will help keep the plugs cleaner.

[Lars]

OK, thanks guys, I will visit him today and check it all out. I will take new spark plugs with me and test the bike, if that does not solve it i will drop the float bowls and take out the idle jets for another cleaning. Will also check the resistance of the Spark plugg caps.
Warm and sunny over here in Norway, great riding conditions!

Will be at the Mid Ohio Swap Meet in July, anyone else joining?

Lars

[chewbacca5000]

Hi Lars,

I'd be up for Mid Ohio I got a bunch of time off this summer and that sounds like a good time.  Who knows I might even ride out there on my 750

[bjatwood]

That is exactly the way things roll with people/friends/customerswhen you get their old Honda running perfect for them. They store them wrong and then call every spring and tell you that they have a problem with their bike. It almost feels like you can't get away from a bike if anything EVER goes wrong with it. The phone call goes like this, Hey my bike is doing this.........what do you think is wrong with it. You tell them, then comes the "can you fix it"?  I'll help ya comes next with the assumption that them watching you is going to make it a freebie! LOL

[robvangulik]

All good tips, don't forget to check the airfilter, if the original housing is used; lots of small animals like spiders, mice, squirrels etc. know there's no better hiding place in winter than the ole Honda air filter next door