Hard to start...

Bike is hard to start cold, starts right up when hot.

It's not very hard to bump start it, so to be easy on the starter and battery, I generally end up doing this.

Carbs cleaned, float levels set (it's intentionally low a little on #4 because I had set it correctly and later got an overflow problem, fixing it later, but it can't be the cause of this alone I'm sure), vacuum sync, idles very smoothly at 1k when warm or with choke when colder.

I can feel the difference of the vacuum sync, but I would feel it no matter what I'm sure because my bench sync really left something to be desired. In spite of the bike feeling amazing now in general, being at a loss of other theories, I'm wondering if there's a chance the guy forgot to use the YICS tool (only thing I didn't do myself, because at materials and time to build my own YICS and bottle set-up and learn how to do it myself, it would be hard to beat the $37.50 my trustworthy mechanic charges).

If he didn't use the YICS tool to sync, would it have been possible to get it to look sync'd on the gauges and get it to behave much better than a poor bench sync, but still be hard to start? Or am I barking up the wrong tree, and it might be something else?

(I'll call the guy and ask him tomorrow if he did or not--it'd the apprentice of my mechanic. It's the kind of thing he might forget but the older guy who runs the place would know to do. I'm sure they'll redo it if they forgot, and they won't bullshit me. Sold me a spare TCI for my trip for $75, too.)

The more I think about it, the less likely that theory sounds. What are the possible causes of a hard start? It almost just sounds like not enough gas is getting there. If nothing else presents itself, I can check the bowl enrichment circuit again and make sure some of the silicone grease I used on the fuel rail didn't make it into a bowl and clog it up (I used way too much at first, but I'm fairly certain I cleaned it all up).

Any ideas besides those, or support for either of those?

 

If that carb overflowed, then the float needle didn't seat. It might be dirty, or damaged, or the pieces might not have lined up right. When I first got my carbs together after a thorough cleaning and rebuild, I had one that poured gas because the needle "hook" caught on to the float "tab" wrong and stuck open. Simply piddling with it fixed the issue. Setting the fuel level lower doesn't really "fix" the problem, but maybe the piddling did (And you should go back and set it correctly).

YICS tool takes the vacuum generated by the other cylinders out of the measurement you are taking, otherwise, you are measuring the vacuum of that cylinder + varying contributing vacuums from the other 3. It is *possible* to MEASURE a similar vacuum at idle between the ports, but have each cylinder be pulling different vacuum (really just like solving a non-linear system of equations). However, not using the YICS tool tends to lead more to frustration when syncing, if the final measured sync is good, it's likely fine, but it doesn't hurt to ask.

An otto engine needs 3 things to run, compression, fuel, and spark, all at the same time. Confirm (again) each of these.

I'd say that if it's the enrichment circuit, it wouldn't bump start cold any easier. The only thing bump starting takes out of the mix is the starter...pointing to either the battery (I know you changed it) or enough resistance drop in your harness that you aren't getting spark with the starter is turning. Have you cleaned and greased all of your connectors?

Take out the float needle valve assembly and clean the "beanie" screen too. If any of that grease got into the fuel rail, it might be clumped up there.

One final question: How did you set your idle mixture screws?

 

The float level should be very carefully set. Watch for the floats hanging on the sides of the bowl cover. Set idle set screws out 2.5 turns to start. Set bench sync. I used a paper clip to bench mine.

 

I removed all my beanie screens; they are just extra fuel filters, but since I have installed my own and I only had 3 and they were in rough shape, I pulled them. (It was recommended by an experienced mechanic nearby.)

Perhaps some grease stuck in such a way as to hold open the needle there?

Mixture screws are about 3 turns out.

Electrical system overhaul is next, once all of this is good. I've never had spark problems before, though.

I feel like it's necessary to mention as I'm getting to know it in its current state of tune, though, that there are some peculiarities I'm noticing...

1. The choke doesn't make the engine race when it's all the way engaged, it doesn't feel like it adds much.

2. The choke cable, when I turn the choke lever to its fully off position, wants to stick out a bit and be slack instead of inserting into its housing. Is this normal to some extent?

3. The idle seems to be a bit variable depending on engine temp, I guess? This is always true, I guess, but I feel like the bike doesn't warm up fast enough and cools down too fast, if that makes any sense... Certainly confuses me. It will always idle at 1000, but I have to play with the idle adjust screw to get it where it has to be to make that happen. (Which is kind of like playing with the choke in a way, perhaps, and compensating for a possible weak choke?) I'm really confused by all of this.

4. The big one: I rode the bike hard for 30 minutes across town and parked somewhere for 30 minutes, VERY hot day outside and it was in the sun. When I came back to it, though, it wouldn't just start up when I pressed the starter. I have to pull back on the throttle half way, and it acts like it is still barely getting enough gas and slowly pulls up to running. Then the bike runs well, though the idle is too low at that temp and the choke doesn't do enough, so I have to keep a little throttle to keep it running. I've experienced this a couple times. This leads me to believe that not enough fuel is getting in, and that is being exacerbated (but cannot be fully explained) by the choke not seeming to fully function. But maybe someone else can make something of this. And why wouldn't it be getting enough fuel?

Dirty passages? It should be clean, and I never had hard start problems before.

Swapped Jets? I feel very confident that I didn't, but I can check this--but wouldn't it run poorly altogether if that was the case?

Float levels way off? I set them, but I can check them again... Would this be a symptom of low fuel levels or what?

And what's up with the choke? Is it different on different bikes? If you pull the choke all the way on and the bike is hot, shouldn't it make the RPM's race to like 5k or more or something?

I know that I hear all of this and I'd immediately say it sounds like the carbs aren't cleaned, but the problem is that when the bike is running, it idles really sweet and slow, performs great all around, and the bike bump starts really easily when cold.

That, then, makes me think starter or electrical (just like bender suggested), but battery is new, I hear it pulling really hard, and it's an AGM--ETX15L, too, so it should be better than the lead-acid one I had.

I guess I'll go look at spark strength and finally get around to looking at my plugs and seeing what color they're at. In spite of my boot rehab, I still am getting a leak on cylinder 1 from it, so I may have to replace it.

Could this all just be bad mixture settings? Just haven't done those yet since the vacuum sync yesterday.

 

Ha! Hard starting fixed; the little bracket on the carbs that sits on top of carb #4 and holds the choke line wasn't tightened down enough, so the cable wasn't engaging the choke--just pulling the line through the hole. With the choke working, it starts right up.

I've just never had it tuned properly so that it requires a little choke to start.

Also, I was running lean--not 3 turns out, somehow most were closer to two turns. I went ahead and put them at 3, will be checking them tomorrow morning to see how what went.

 

The "choke" isn't a choke, it's an enrichment circuit-- the lever lifts the plungers which then dump extra fuel into the carbs.

If you suddenly enagage the "choke" on a fully warmed-up engine it won't race, it will sputter and die. Too much fuel, throttles not open.

If your idle varies a lot depending on how "hot" the motor is then your float levels aren't set correctly and/or your sync is off. This could be caused by something as simple as not having the bike fully warmed up when the sync was done; or your float levels aren't set correctly, or a combination of the two.

 

Right, I'm aware, that mention about racing RPM's came for three reasons:

1. Some memory of an article talking about another 80's bike that would have racing RPM's if the choke was left on and discussing how it almost seemed intentional so you couldn't leave it on on accident

2. My friend's ninja 600 '95 does this, and he was helping me and mentioned that his bike shoots up. His bike has true 'choke' though, I am almost sure I remember now, so that makes sense.

3. Mine wasn't working at all and I almost never needed it before, so I realized I wasn't sure what it was supposed to do on this bike when properly functioning.

I think the varying a lot might have been just the fact that I was trying to use the idle adjustment rod in place of choke. Give me a day or two with a functioning choke and I'll see how it's doing.

 

So that definitely was the bulk of the problem, but today I started it up cold--tried to put on half choke, no dice, put on full choke, and it slowly pulled into a running state. Was able to take off almost all choke after a couple minutes, but still needed a little to idle stable at 1k. It was hot and happy to idle at 1k after 6 miles of highway riding without question.

Still wanted a bit of throttle even with full choke to start, though; should I tighten my idle adjustment rod just a little to help that?

And I guess that one low float level can't help.

 

Set the idle knob so the bike will idle at 1050~1100 and see how it does then.

It will be varying kinds of goofy with one out-of-whack float level.