Topic: I fought my bike and my bike won

[Magilla]

TwoTired should change his name the TheCarbWhisperer.

[iron_worker]

Great info. I enjoyed the read.

IW

[Magilla]

Bad news:  Carb one started to overflow again today.  Just when I thought I had it fix.  For two days it worked fine and today it started to overflow again.  Have I mentioned how much I hate these carbs?  I need an Atkins bike, one with no carbs!!

[TwoTired]

Do you shut the fuel off while it is parked?

Are you parking on the side stand or center stand when it leaks?

Have you checked the bowl stand pipe for cracks?

[Magilla]

Do you shut the fuel off while it is parked?
I always shut the fuel off when its parked or at least when I remember too.

Are you parking on the side stand or center stand when it leaks?
It leaks while on the side stand.  I have yet to see it leak on the center stand.

Have you checked the bowl stand pipe for cracks?

I have not.  Not sure that this would cause such an intermittent issue BUT I will check it out.

[Magilla]

Still fighting with the bike.

It started on the first kick on Wednesday night.  Today I had to kick it about 50 times.  When it started it would barely run.  Then it warmed up and seemed OK.  I am guessing that this may be due to leaning it out and maybe now it will require a choke to start when its cold.

After a few miles and the bike was warm the idle crept up to about 2000.  So i turned it back with the big idle screw.  After a few more miles the RPMs crept up a few hundred and I had to readjust the idle again.  No big deal.

The new problem is that when you let off the throttle it sticks for a few seconds and then drops back down.  Not a good thing.  I am going to check to see if I pinched a cable the last time I put the tank back on.  That seems to be the variable on this trip.

[Roach Carver]

Sluggish return to idle can be an intake rubber leak.

[TwoTired]

Sluggish return to idle can be an intake rubber leak.

..or carbs out of vacuum sync...or

[Magilla]

Sluggish return to idle can be an intake rubber leak.

..or carbs out of vacuum sync...or

Carbs out of vacuum sync?  What is this, how do I check for it and how do I fix it?

[TwoTired]

Sluggish return to idle can be an intake rubber leak.

..or carbs out of vacuum sync...or

Carbs out of vacuum sync?  What is this, how do I check for it and how do I fix it?

See The Honda cb750  shop manual,  Chapter 20 supplement, page 194.

Cheers,

[Magilla]

Unfortunately I don't have a Honda manual.  I have a crappy Cylmers (spelling?) manual.

Everything I think I'm close with this bike it kicks me in the nuts ant lets me know that I'm not close at all.  Very frustrating.

[Roach Carver]

I dont have a " shop manual " or the supplements either. I do have 3 cb 750's that all run well. Like I said. What do the intake boots look like. If they are original, you may want to replace them.  If you want to try and use them a little longer you can try and replace the clamps with a conventional style that you can tighten abit more. Your cable is good right?

[Roach Carver]

Also, you may want to replace that needle and seat. If it stll leaks after that, it can only be 3 things. The float, float height or sediment in the fuel.

[Magilla]

Where do I get a new needle and seat?  I will order it today. Is the "intake boot" the one on the air box side or the motor side of the carb?

Motor side connectors look great.  I tested and they have no leaks.  Air box side connectors are not good.  Rock hard.  I have new ones on order.

[DJ_AX]

Unfortunately I don't have a Honda manual.  I have a crappy Cylmers (spelling?) manual.

Everything I think I'm close with this bike it kicks me in the nuts ant lets me know that I'm not close at all.  Very frustrating.

uhhh... the Honda Manuals.... the first post on this forum. free download.
http://forums.sohc4.net/index.php?topic=17788.0

And chasing the "thing" that will get it running well, is part of it all. You'll know all of those other things  you've fixed and tidied up won't need replacing next... and  while they are not the one "thing" that makes a significantly noticeable difference, collectively they do.

[DJ_AX]

I got needles and seats from PartsNMore.com
good price, selection, and service.

don't get the rubber tipped ones!

[TwoTired]

Unfortunately I don't have a Honda manual.  I have a crappy Cylmers (spelling?) manual.

You can buy a Honda manual at helminc.com.  It's where I bought mine.

Hard to imagine successfully working on an unknown bike without one.   It's possible to fix a bike with random replacement of components and eventually fix the real problem.  Not that I recommend that.  I always figure, if I know how it's supposed to work, I can figure out why it doesn't.  I believe the shop manual helps in that regard.

The Honda manual is the most knowledgeable source I know of.   Better than most "internet experts", imo.

Cheers,

[shinyribs]

I am away from my computer right now ( on phone)  but I can give you a link to a free download in a little while. No need to buy one.

[Magilla]

New intake tubes on order.  New needle and seat on order.

Took the bike for a nice 20 run on Sunday.  I hit a highway, a state road and inner city streets.  The bike ran well for the entire ride.  The throttle stick/vacuum issue is still there but replacement parts should clear that up this week.  I put new plugs in before the ride and check them after the ride.  Here is what I found

Plug one:  slight carbon build up
Plug two:  very slight carbon build up
Plug three: looks good
Plug four: looks good

When riding at low rpms (under 2500) the pipes on the left side sound different then those on the right.  They have a slight sputter to them.  It all goes away above 3000 RPMs.

All in all it was a good test run.  I feel like I am finally pointed in the right direction.

[Magilla]

yep....
http://www.powersportsplus.com/parts/detail/honda/HP-17253-405-300.html

What a pisser.  The new tubes and clamps came in today, after a week of waiting.  They were the wrong size.  I needed 17253-341-300 not the 405s.  My carb inlet is 1.6 inches in diameter.  The old tubes are 1.5 inches in diameter.  The new ones were 1.8 inches in diameter.  That sucked.  Now I have to wait another week for the correct ones to come in.  Another down week.