If it doesn't need the choke to start cold you have an over rich situation. My take from what you wrote is that you don't have a needle and seat problem. My guess is at worst you have a float out of adjustment.

If your worried about the petcock pull the line off the carbs and put some vacuum on it. It best done with a Mighty Vac or equivalent. I don't think you have a petcock problem.

 

I second that.

 

Is the correct float height spec for a 1998 8mm?

 

Yes.

 

Last night I stripped it down to get access to the carbs. I disconnected both overflow tubes on the carbs and saw no visible fuel coming out yet when I reconnect them I see a drip or two of fuel at the tube under the bike. Also, I never really see fuel dripping down the carb throut yet when the bike sits and I take a flashlight(LED) and look down the carb throut it looks a little damp down there(intake area below the butterfly).

I'll be honest I am confused at this point. When I disassembled the carbs last week I checked the float height and they appeared to be at 8mm. Not sure what direction to take.

 

Running rich


Hi did you ever find the problem cause i have to look at a 1500 this week sounds like it is doing the same thing , also is it hard to remove the two carbs ?

 

What kind carb cleaner did you spray with? There's always the possibility of damaging a seat with the wrong solvent or errosion from high-velocity solvent/air; leading to a seat that wouldn't seal properly at 'float height' leaving you a little rich and or drippy...

With everything clean, did you reset your idle, idle mixture, and rebalance... If the idle mix was set last wih partially or fully fouled passages, and this was set by 'screw turn count' only, you could jsut be dripping outta the idle (which happens anyway, but is more pronounced when the screws are richer)

Personally, I'd suspect the needle and seats (and pray that your solvent didn't harden the slide diaphragms)...

 

Spray



I used the auto parts store brand of carb spray/cleaner. I did not use it on the slides knowing the diaphram would not like it. I cleaned the diaphragm with wd-40.

I think I'm goin to order replacement needles and seats and while apart take a closer look at float height.

Also, both pilot screws are out 2.25 turns. Should I go to 2?

Hope to report back by next week.

 

2.25 or 2.0 won't make a difference. That is just your idle mixture and would not cause your problems.

 

Guys, seems to only do this when the bike is hot. Could fuel be boiling in the carbs?

 

I'd suspect boiling or a clogged vent line. If your idle is lean, you'll run a bit hotter than you would if your idle mix was richer... and any fuel drip that you have (barring mechanical, and/or needle/seat issues) would be dropping from the idle ports (nothing in the 1500 Keihin carbs shut off the idle passage - it'll run whenever the pressure differential is great enough to lift the fuel (high float, pressurized bowl, etc), which is exacurbated by a higher than expected bowl fuel level (float level) or a richer than anticipated idle mix (less restriction to flow).

Interestingly enough, if your carbs do boil, lowering the float bowl levels enough to uncover any of the fuel passages - the passages will vent vapor - not only will this "dry out" the carb passages, but this also places a lot of fuel vapor below the slide into those long intake runners -- this can lead to a rich start on a dry carb.

Just for reference, how well does your accelleator pump discharge? You can "kinda" use that to gauge the fule available in your carbs after a hot shut-down and soak -- if the Accellrator pump is working fine (normoally) and won't recharge for a second pump after a hot shutdown, then your bowls are emptying...

 

Just FYI if the carbs are out replace all the rubber tubes..they do get old and leak..not your current issue but willb e sooner or later with old tubes..do them all...

 

At what RPM does the engine idle at? Boiling gas in the carbs., no. The number of turns out for mixture screws are just a starting point, final adjustment is done through an idle drop procedure covered in manual.

Float settings are done properly when the float tang is just touching needle valve and not compressing the inner plunger spring.

JD

 

Satan, the accellerator pump seems to inject fuel ok when I snap the throttle.
Driverider, the bike idles around 800 rpm.

Last night I pulled one plug from each bank and if anything they look lean. I was expecting them to look dark and sooty but not the case.

So in recap, the bike runs strong and responsive. gets around 40 MPG. Issue only appears when the bike is restarted hot. It takes several seconds of cracking then will start and blow out a rich plum of smoke. When hot I will also get a drop or two of fuel from the carb vent overflow tube under right side of bike.

I'm prepared to pull carbs again and replace the float needles and seats and for good measure rebuild the fuel petcock but I'm doubtful this is related to my issue but want to start eliminating things.

 

Make sure you check the middle plug on the left side. On rare occasions the auto fuel valve will fail in such a way as to leak fuel into the vacuum pick up...and it goes to that spark plug. All other plugs will look normal. I would recommend carefully bench testing the auto fuel valve before going to the trouble of rebuilding it. It's unlikely it would fail in such a way as remain open, and even if it did, your float valve system should keep your carbs from overflowing.

At 40MPG and running well, it seems unlikely that anything is too far off. BTW, if you check your owner's manual I think you will find it is recommended to hold the throttle part way open on warm restart. I've noticed (particularily on the late model 1500's) that sometimes this is necessary or they will start hard.

The fact that you're dripping a bit of fuel now and then out the fuel overflow tubes does point to an issue with the float valve system. Are you sure the drain plugs are nice and tight? I like to 'bench test' the float system by applying fuel with a gravity feed tank for several minutes before I install them back on the bike.

 

snip...
At 40MPG and running well, it seems unlikely that anything is too far off. BTW, if you check your owner's manual I think you will find it is recommended to hold the throttle part way open on warm restart. I've noticed (particularily on the late model 1500's) that sometimes this is necessary or they will start hard.

That is correct. I just checked the owners manual and it says on a warm restart that you should open the throttle slightly when starting the engine. When starting a cold engine you use the choke and no throttle.

 

Dizzy, just pulled the left center plug and it looks dry and if anything, lean looking just like the other plugs I checked.

 

I had a dead spot and hot restart issue when I first got my 2000 1500 along with a few other problems. I"m not sure all symptoms are the same but I traced my issues to the o-ring in the pipe that feeds the little squirters in carb throats.(Sorry for lack of technical term...suffering CRS at the moment)...anyway they can get munched when replacing the base for air cleaner if you had any of that off.

 

Guy,

I got my issue resolved for the most part. My bike now runs perfect but if the ambient temps are hot and the bike is real hot from slow running etc, if I shut if off and let it sit, it will drip a drop or two out the carb overflow. I'm convinced its fuel percolation in the carbs. Gas vapor gets pushed down the carb overflow and as the vapor cools as it runs down the tube it condenses and will eventually drip.

I'm going to experiment next summer when its hot and try to run exclusively on ethanol free gas and see if that resolves it. I suspect the 10% ethanol has something to do with this but I have yet to prove it.

As for removing the carbs, no its not hard. It is a little tedious and time consuming but anyone with patients and some mechanical aptitude can do it following the great instructions found on this forum. Do yourself a favor though, if you've decided your going to go though with pulling the carbs do it once(unlike me) and get Randakks master kit and get new float needles and seats. I tried to cheap out the first carb pull so I ended up pulling 'em a second time. Mind you I'm proficient at it now.

 

Wonder if the fuel smoke is from flooding due to a weak battery? It has happened. Bike doesn't start till you let off the starter switch, meantime, the engine gets a wet start? Just wondering. jimsjinx

 

Looking in the Honda service manual… in the 'FUEL SYSTEM' section…. under the EVAP Carburetor Air Vent Control Valve Inspection it says:

"THE EVAP CAV CONTROL VALVE SHOULD BE INSPECTED IF RESTARTING A WARM ENGINE IS DIFFICULT"

If you don't have a CALIFORNIA model then I would suspect a partially clogged or crushed vent hose going to the carb. Can't tell you which one but it's some where to look.

 

I have rebuilt 1000, and 1100 always have problems with the 1000 but most 1100s seem to be ok after rebuilding if the jets can be removed i dont have any problem Hey where is the warm weather , painting a bike today