Topic: Fuel Starvation?

[martino1972]

dont you just hate it,when they promise to phone when its in,but then they dont...

ehmmmmm,yeah,you might wanne clean your pretty little carbs out again(you should be really good at doing that by now.. )...
and when your done with yours you can do mine....

it really doesnt take much to plug em up,so yeah,if you dont want your 2 wheeled trip to be a bugger...
hope your riding buddy heals up fast....

[Hush]

A quick possible cure might be to put the bike on it's centre stand and drain the gas from each carb bowl Kits, drain all the bowls and dump what comes out (makes great weedkiller but don't tell Greenpeace ) then let the bowls refill again as per normal.
I ran into a similar problem with my 650 carbs, turned out to be a tilted float, by draining and refilling the carbs the floats should get the chance to reset themselves.
Hey if it doesn't work all it cost you was a cup full of gas.
Not sure about the thread on your petrol cock though, plumbers tape might hold it for a while but I think that gas will eventually eat that stuff.
In saying that I use tape to tighten the threads on my boats gas tanks connections and that hasn't failed me yet.

[mrbreeze]

Do what Hush says.......but now is a good time to check the fuel levels in your bowls. I don't know how the bowls are set up on your bike but on a 75K (probably the same as all early 750's) the bowls are held on by a bale that makes it easy to remove with the carbs mounted. It makes it easy to get up into change mains,tweek floats,etc. The other thing you must have is bowl drains. I put mine on the center stand and run it with the petcock off till it dies.Then I turn the petcock back on and let it do its thing for about 10 minutes. After 10 minutes,everything should be filled back up and you should be able compare fuel levels. I take a small baby food jar and put it under carb #1. Pull the drain plug and mark the fuel level with a sharpy. This is also a good time to see crapola in the fuel....rust,water,etc. Repeat through the rest of the carbs and note any differences. When I did mine...carbs 2 & 4 were spot on with #1 but #3 was a bit lower. Even though I had just rebuilt the carbs and set the floats to spec....1 carb outa 4 wasn't even. Dropped #3 bowl and tweeked the float so that carb would hold the same as the other 3.Problem solved and I still haven't been back into the carbs for that problem (the only time I've been back in was to change from 138.5 mains down to 130's for altitude).

[pelermon]

Maybe helicoil the stripped threads.
Compression check the cylinders.
Start with new plugs.
Spray starting fluid on the block to jugs gaskets, while your checking the boots.
Loose the gas filter until problem is solved. They typically have to be installed to flow only one way.
If the air filter is off, try putting on. But before you do, try shooting starting fluid in each cylinder, to pinpoint the problem cylinder or carb. Its likely only one.

[Frankenkit]

took of the carbs and cleaned the heck out of 'em, sprayed thru cleaner and compressed air, etc, measured the float heights (exactly 1/2")  made sure all the orifices were clean, bench synched (used TT's light method, as opposed to the drill bit method).  I guess I'll see how it works...  I know I need to reset the fast idle, too. 

Mr. Breeze, I'll try what you suggested.  I suspect it's running a bit rich at idle, but I'll have to pull the plugs to see.  The pilot screws were out 3 turns, so I put them in to light seat, then out two, figuring I'll adjust them according to the shop manual.  I'm just not sure (and it doesn't really explain in the manual) whether backing the screws out leans or screwing them in leans.   

Plugs are new, as in rode-with-once.  I ditched the in-line filter and am running only the in-tank filter.  Used gasket-goo to seal any possible cracks, but haven't gotten to test it...  Air filter is on...

[mrbreeze]

Don't worry about if the float is set to spec....worry about if all the bowls are holding the same amount of fuel!!!!!
Before I started fixing that problem,me & CBen from Ausi were going at it about runnin' the inline filter.I took mine out and noticed an improvement.After getting my fuel levels together ....it made a huge difference.The biggest thing after everything else...synch the carbs and it all magically comes together!!!!!

[martino1972]

i'm 99% sure,that the more you screw the idle adjuster in ,the leaner it get's....
cause they are in between the carb and the cylinders,if theyt are between the carb and the airbox it would make em richer when you screw em in....

[Frankenkit]

So you're saying 'hook 'em up, then turn the petcock on enough to fill the float bowls, then drain them to make sure there's the same amt in each'?  ..this'd be on the center stand, right, b/c 1 and 2 (being lowest due to the side stand) had more in them by far than 4...

[mrbreeze]

Yep....gotta have em level....won't cut it on the sidestand.

[TwoTired]

If you are measuring the drainage, the first bowl drained will also have the contents of the fill hoses and won't be representative of the actual fill level of the bowl.

[Frankenkit]

Ideally I should have a clear drain hose on there, bend it around, run it up beside the carb and measure it, making sure the top of the fuel in the tube (as fluid usually finds its own level again...) should be 1/2" below the bottom of the carb (or 1/2 below the top of the float bowl)? 

[mrbreeze]

 You are right Lloyd but how come my carbs are all even and it runs like a bat outa hell?

[martino1972]

Ideally I should have a clear drain hose on there, bend it around, run it up beside the carb and measure it, making sure the top of the fuel in the tube (as fluid usually finds its own level again...) should be 1/2" below the bottom of the carb (or 1/2 below the top of the float bowl)? 

tha measurement might not be completly correct,due to the fact that floats do sink into the fluid abit,but you will be able to tell if all four carbs are equal then....

[Hush]

Er Kits you are starting to scare me, I only understand half of what you say these days?
You are becoming fluent in Honda-speak, an ancient language few truly understand.

[low-side]

I used to run inline fuel lines but quit for two reasons:  1) The paper element filters were too restrictive and can starve you for fuel at the most inopportune times and 2) The free flowing disc types don't filter any better than our sediment bowls (most models).  They are also a pain in the ass to install on these bikes due to space available.  As far as fuel not flowing at all, it was probably just air-locked; you can unplug from the carb end and let fuel flow through them to fix that problem.  BTW, most fuel filters are directional but not normally because of check valves, but because of the shape of the housing and the media and the need to allow adequate flow.  Good luck with it.

[TwoTired]

You are right Lloyd but how come my carbs are all even and it runs like a bat outa hell?

Some maybes...
Because of relative insensitivity to accurate float height, and allowable mixture ratio variation for cylinder firing?  (cylinders will fire with a mixture range of 12 to 1 and 15 to 1, but won't produce best power over the entire range.)
Your inline filter(s) restrict full drain of the feed lines?

Do your spark plugs all show the same deposit patterns?

What is the BHP and Torque curve look like for your bike? 1/4 mile acceleration times?
No offense meant.  But, seat of the pants dyno data is... well ... subjective, wouldn't you agree?

Cheers,

[Frankenkit]

Er Kits you are starting to scare me, I only understand half of what you say these days?
You are becoming fluent in Honda-speak, an ancient language few truly understand.

Oh, that's just in these posts.  In person, I say things like "Well, I'm going to blast cleaner through all these little holes 'til it comes out fast and free, then I'm gonna poke out the float's hinge doohickey with this pin and slide it out until I can lift it and the needle jet thing out, and blast that out with cleaner, too... make sure there's no crap on this thing or the other little moving thingers and that doo-wop.  ...now how do I adjust the pilot things again? Not those, these over here..."  it's a nightmare for anyone to try to understand me unless they're skilled or psychic.

[mrbreeze]

You are right Lloyd but how come my carbs are all even and it runs like a bat outa hell?

Some maybes...
Because of relative insensitivity to accurate float height, and allowable mixture ratio variation for cylinder firing?  (cylinders will fire with a mixture range of 12 to 1 and 15 to 1, but won't produce best power over the entire range.)
Your inline filter(s) restrict full drain of the feed lines?

Do your spark plugs all show the same deposit patterns?

What is the BHP and Torque curve look like for your bike? 1/4 mile acceleration times?
No offense meant.  But, seat of the pants dyno data is... well ... subjective, wouldn't you agree?

Cheers,

Well Lloyd,you threw out alot of high tech words and phrases at me and while it makes sense to you....I'm not really sure I understand WTF you mean. All I was saying is that my bike was having problems after my first carb rebuild. I had to experiment with different jets and needle settings. Cben from Aust. told me his acted up with an inline filter installed so I took mine out and.......better,but still wasn't right.When I tweeked float #3 to supply the same amount of fuel as the other 3 carbs....It fixed it. I'm not saying it is the prefered method but that it worked for me.   ....And what do you mean by this "seat of the pants dyno thing" Hell yeah.....my a$$ gives me dyno data everytime I ride !!!! Quarter mile times?....Hell!!....I dunno......Haven't had it to the track.......Plug chop results?......haven't had a reason to do one since last summer (last time I synched carbs)........And I damn sure haven't had it dynoed yet.......but I'll tell ya Lloyd....this sucker rips!!!!!!

[Frankenkit]

Well here're my plugs- bear in mind, this is mostly just from an hour long ride, then starting 'er up after little work here and there (futzing with the electrics, futzing with the new filter system/removing the inline filter... that's pretty much it. Would've done a plug chop, but I honestly just don't want to ride it too long before I get the carbs figured out and synced, just don't want to do any damage...



If you can't see well enough, 4 looks kind of a coffee brown, 3 has some white under the little arm, but everywhere else is a bit more brown... 2 is shiny black, but not wet.  Where it's not oilish black/brown, it's toasty brown.  1 is black pretty much all over, not necessarily really oily, but not very sooty either.

My theory is that the bike is generally leaning on that left side, so it would stand to reason that if I start it right away after having sat it straight up, it might still be a bit rich on that side... but that doesn't explain the discrepancy between 3 and 4.  Let me know what you think.  It could be missing on 3, because I do hear a "skk, skk..... skk......." sound while she's warming up, like she's missing, then eventually it goes away as the bike warms up.

[TwoTired]

Carb Sync/tune up status?
Are idle screws set to the same position?


Btw, the reason for the dual vs single float in each carb is so the fuel height will be the same when the carbs are tilted.

Cheers,

[Frankenkit]

Don't have a synch tool yet- everything has to go on hold during the work/school week, but Sunday I'll be able to pick one up if Harbor Freight has one... or I can just make one from clear tubing from Home Depot. Carbs are still off.  Their idle screws were all at 3 out, but that was set with the inline filter which was constricting the fuel flow.  I set them to the default 2 1/4 recommended by the manual, they'll go on Sunday as well, when I can set them according to the directions given in the honda shop manual. 

[KingCustomCycles.com]

I have not seen a readily available, inline, fuel filter that was unidirectional in 45 years.  Kuddos to Raul with that picture and comments. 

[Frankenkit]

Well, put my carbs on after cleaning them out and the bike started just p!ssing gas out 1 and 2.  took the float bowl off 1 and used my fingers to push the floats up to test the float valve... the gas just *barely* slowed.  I took out the pin and flipped the needle thinking I had it in backwards... put it all back in and there was no real change.  I think I'm going to end up buying the needle set I showed you, because I haven't actually replaced those yet.  Will  buy new gaskets, too, while I'm at it, because a couple are shot, ironically not at the carbs that were leaking.  All this is unfortunately going to have to wait until after I scrape up money for tuition, so... yay. another effing delay on getting a (second!) ride in on this bike.  The rest of all this is going to my project thread "blah blah 'total newbie'" because this seems to be more about ongoing problems than about the fuel starvation issue anymore.

[mrbreeze]

Don't give up Kit!!...you'll get it.If you can push the float up with your finger and gas still flows......Sounds like you need new needles & seats. They are less expensive in the long run if you get them in complete kits. I don't recall what bike you have but pretty sure it isn't a 750. I am not familiar with anything but a 750 but have heard bad things about Keyster kits.Also OEM Honda kits are expensive. I had real good luck with K&L kits from Dennis Kirk although I was told not to use their needle jets or jet needles. I used everything in the kit but those pieces and had good results. This winter,I plan on buying OEM needle jets & jet needles because I think I may have a problem in that area being that those were old parts and probably have a bit of wear. I also will get new intakes from Z1 ...mine don't leak but they are old and hard. One thing I noticed about the K&L kits....people talk about the bowl gaskets swelling. I haven't had that problem at all.After all the carb rebuilding....be sure and synch em....that makes all the difference.
OK Lloyd.......jump up in there and tell me how full of sh!t I am.....(I know you are following this post(whatever dude!!!)

[GammaFlat]

I spend a lot of time (and too much money) at Harbor Freight and although they have lots of cool "toys", I'm confident they don't have a carb sync tool.  They may have lots of the plumbing that you need to build one but not the tool itself.  There's going to be a "carb syncing party" somewhere west of Chicago tomorrow (the thread is somewhere in the top 20).  I suspect that's not close enough for you Kitsune, although you'd be welcome to attend by all, I'm sure.  I wish I could go. 

My recommendation this week at Harbor Freight is their clamp on Amp Meter (as well as ac/dc volts and ohms of course): http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=95683.  It's on sale for $9.99.  It could be a nice diag tool for electrical issues (of which I have some - crap!). 

Carbs really suck.  Oh, somebody already said that.  I'm anxiously awaiting HondaMan's fuel injection project.  Now wouldn't that be special?  I hope to be in the "early experience program".   

Regards,

John