Hot Restart Idle

[GLFLSTCI02]

Hello,

I have been working the bugs out of my 1995 FXDS this summer and have it running pretty well at the moment but it does have a couple of odd behaviors. The bike is pretty much stock with 80,000Km on the clock. The motor has an EV13, S&S breather, 2000i ignition running single fire and the round plugs punched out of the stock exhaust. The intake and carb seals are new and solid, the carb has been overhauled and is running a 45 pilot and 180 main and an N65C needle. Total timing is 32 degrees and I am running curve 1.
I did have the CVP "velocity" needle in there and very, very ocasionally it would spit back when leaving a stop, mostly after a period of sustained Hwy speed running. When I put the N65C in there it seems to have solved that and the bike seems to run better and stronger overall, I think it has spit at me 3 times in about 1500Km.
The issue I would like some opinions on is the hot restart behavior. When I restart hot the sucker lights up and idles so low I can't really even tell if it's lit, I give it a bit of throttle and bang, there she is. I hot restart with no throttle or accellerator pump. After it lights it seems to idle low and back to normal shortly after.
Do you think I am still lean?

TIA,
Gene

[Hossamania]

It happens with mine as well, just the nature of carburators.

[smoserx1]

I sort of get that too, especially on a hot day and I leave the bike shut off for a few minutes like a quick trip inside the store.  Sometimes it is hard to start, and sometimes it will flood and usually idles slow for a little time.  I have a theory and it may be 100% wrong but here goes:  When you shut down the engine if the vacuum  petcock and float valve in the carburetor are both working properly, fuel trapped in the hose between these two points has no where to go.  Since this part of the hose goes across the top of the engine it gets hot and the fuel cannot expand and thus pressurizes.  If the engine starts and the carburetor float drops the incoming fuel can be pressurized from the heat and result in a slug of fuel into the carburetor float bowl creating a temporary rich condition that equalizes very soon.  During that brief period  the engine runs poorly.  I got a feeling that a non-vacuum petcock would fix it as long as it was turned on before the engine was started.  Just my theory, may be total BS, I don't know, but it sounds plausible to me.

[Hossamania]

I have a Pingel non-vacuum petcock, and it happens with that one too. But I can get on board with your theory that it's running a bit rich for those moments.

[GLFLSTCI02]

I did change out the petcock for a non-vac operated model, one of the first things I did when I went through the bike getting rid of any potential problems.
It seems as though you guys feel the low idle is caused by a rich condition?

Gene

[Hossamania]

I feel it is caused by a normal condition of hot starts with carburators. If it is caused by a rich condition, which is possible, not sure how you fix that. Just start it, give it some gas to keep it running, and go on with life.
Or convert to efi.

[GLFLSTCI02]

Not my first carbed Harley, I know they don't have start hot like that.

Gene

[Hossamania]

Mine doesn't do it every time, but often enough.
What is your warm/hot idle rpm set at? You could turn it up, that might help.
How was your idle mixture screw adjusted? There is a specific procedure.
Your jetting seems reasonable.

[GLFLSTCI02]

Mine will do that on every hot start. Otherwise hot starts are great, no kickback, no slow grunt. I have my idle set at 1000 on the tach, I should set that with a real tach. I have done the idle mixture every time I made a change and it seems fine @ 2.75 turns out currently.
The carb tuning has been a bit funky, it had all dynojet parts in it so I replaced all that with CVP tube and jets. I had a 45 in there and went to a CVP 46 and wow was that sucker rich, it didn't run well on the road and with the mixture screw all the way in it would still idle. I checked the size of the CVP 46 and a .485 mm drill is the perfect fit, my understanding is that the hole should be about .46 mm on a Keihin jet. I wonder if these CVP jets are different or if I am mistaken regarding the sizing?
The other thing I wonder about is the hole in the slide, mine is drilled for sure. I tried to find out the size of an undrilled hole so I could repair that but this info has proven hard to find.

Gene

[capn]

If your slide is hole is drilled out you can fill it with jb weld and redrill.

[GLFLSTCI02]

If your slide is hole is drilled out you can fill it with jb weld and redrill.

I plan to use brass tubing with a slight flare on the inside of the slide scured with epoxy or JB and then drill it to stock size, I have not done that yet because I cannot find any info on what size the stock hole is. Might just buy a new slide.

Gene

[Hossamania]

If you've got quite few years on the slide, a new one doesn't hurt, the diaphragm gets ready to rip after a while.

You might try turning the idle mixture screw in 1/4 turn, and test, then another 1/4 and test again. There is a specific procedure to adjust it using a tach, turn it in until it slows, turn it out until it slows, adjust to the center of that. If it doesn't slow, time to go up or down on jet. You could try a stock 42 pilot jet to see what happens, or get a 46 from the dealer that is a true Keihen part. 2 3/4 turns out is almost at the acceptable limit of 3 turns out.

[smoserx1]

I have not done that yet because I cannot find any info on what size the stock hole is.

I happen to have an old slide that I put a new diaphragm on.  Anyway I just checked and a 3/32 drill bit will go in the hole but a 7/64 will not.  I don't have anything between those two but the 3/32 did not appear to have any noticeable side play.  Might be 2.5 mm as that would be in between those 2 sizes and since the carburetor is Japanese I suspect the hole would be metric size.  Hope this helps.

[GLFLSTCI02]

If you've got quite few years on the slide, a new one doesn't hurt, the diaphragm gets ready to rip after a while.

You might try turning the idle mixture screw in 1/4 turn, and test, then another 1/4 and test again. There is a specific procedure to adjust it using a tach, turn it in until it slows, turn it out until it slows, adjust to the center of that. If it doesn't slow, time to go up or down on jet. You could try a stock 42 pilot jet to see what happens, or get a 46 from the dealer that is a true Keihen part. 2 3/4 turns out is almost at the acceptable limit of 3 turns out.

I got a 46 jet yesterday and put it in, a test ride seems to indicate that things have improved. I will run like this for a few days to oget a feel for how it runs and how it behaves on the hot and cold starts. This jet is sized right, a .46 mm drill shaft is a perfect fit. I will get the idle mixture set and throw the tach on and get set to an accurate idle speed. The motor seems to have less overall vibration with the 46 jet.

I have not done that yet because I cannot find any info on what size the stock hole is.

I happen to have an old slide that I put a new diaphragm on.  Anyway I just checked and a 3/32 drill bit will go in the hole but a 7/64 will not.  I don't have anything between those two but the 3/32 did not appear to have any noticeable side play.  Might be 2.5 mm as that would be in between those 2 sizes and since the carburetor is Japanese I suspect the hole would be metric size.  Hope this helps.

Hey that is just what I needed to know! I will get this repaired just as soon as I am done evaluating this 46 jet. Thanks for taking the time to measure one up.

Gene