Since I've had my 599, idle speed has been a touchy subject for me that I'd like some clarification on. I don't think my dealer is being completely up front with me. By completely, I mean "they are full of crap."

The manual says the two following things:

1. When starting the bike, operate the choke to keep fast idle at 2500 - 3000 RPM. (assuming not-hot temps)

2. After riding stop and go for about 15 minutes, engine idle speed should be 1400 +/- 100.


My dealer said the two following things when I complained on their setup:

1. Startup idle speed with the choke open is irrelevant. Barely topping 2000 RPM is no big deal.

2. Idle speed around 1000 is really ideal. To appease me, they upped it up to about 1100 and said, "changing conditions will make it go even higher, so this is perfect."

Any thoughts?

SECOND TOPIC!

My bike had been down for two weeks. Egads, I know, but I was out of town and it's been raining every day since I've been back. Anyways, after starting up it was idling very low and it had a very strange throttle issue. If I gave it a bit of gas, say up to 2000RPM, it would sputter and start to drop. The lights dimmed considerably, so I figured it was a battery issue.

After a good ride and tweaked idle speed, low throttle response was still acting up. The bike wasn't threatening suicide anymore, but it was very grabby - it'd loom at 2000RPM for a second or two and then jump up to 3500-4000 without me making any extra twist.

That spot is not a huge deal to me except when I start from a stop - if I forget and go for more throttle, it'll grab hard. I've been careful about it by just modulating the clutch a bit extra in first gear. Should I have it looked at or should I be going for a higher RPM from a stop anyways?

Sounds like a dirty/partially clogged j...

actually it sounds like your idling too high. Drop it down a little, lol. A high idle will cause the bike to hang up momentarily at certain RPM's.

Idle is partially determined by air density... meaning you'd want a lower idle at a lower altitude.

Never choke for longer then you have too... my bike chokes at 1500 while cold, but will up to 3000 if I forget to turn to off :oops:! I back the bike out of the garage, run inside, press the door button, run out, get on, turn off the coke (almost every time)and go. *mileage may vary depending on where you live*.

High idle?? 1100 is not a high idle - it's rather low. That jerkiness off idle is very odd behavior. I have no idea why your carbs would be doing that, though.

I did not read the manual about idle but for what it's worth I rarely let mine get over 2000 on choke. Of course it rarely gets under 55 down here, but even in the winter during the few days when I started it in the 40s I had no difficulty idling my bike at under 2000 while it warmed up. It did not take any 15 minutes, either. More like five at the most.

High idle?? 1100 is not a high idle - it's rather low. That jerkiness off idle is very odd behavior. I have no idea why your carbs would be doing that, though.

I know of three things that commonly will cause the bike to hang up when the throttle is closed.

1) High idle - easy to fix, turn the idle down
2) Clogged jets - pull the carbs off and clean them
3) A vacuum leak - bloody tough to find without resorting to a cheap trick that potentially damages the boots in the long run.

Which would you check first? Turn the idle down a touch, rev it up, see if it hangs at 2grand on the way down if, so turn it down a little more, and try again.

Or pull the seat, tank, airbox, and then the carbs. Take them to a dealer and have them soaked... or clean them yourselves with brake clean, compressed air, and a ton of luck. Reinstall everything, then pray the problem is solved.

They had the sucker set at like 850 when I originally took it home. Talk about a fun time trying to get going. Weehaw!

The carbs were cleaned out about a month and a half ago and the throttle response issue has always been there - both after purchase and after cleaning. Everything else is completely smooth.

Sev - I'm not sure how I'd be idling too high when I consider what the manual says. I upped the slow idle so it'd be at about 1300-1400, which is the bottom end of specification.

As far as fast idle (choked), I fire it up, close the garage door, put on my helmet and gloves and go. It hits the top of it's RPM (about 2000) by that time and does not go higher, even if I leave it open for awhile.

Sachi - The 15 minutes I gave it was just 'cause of the manual. I'm a mechanical retard, so that manual is my bible for the bike. It probably didn't need much time at all.

Not offering a solution but rather some information. The choke increases the amount of gas going into the mixture without increasing the amount of air to make combustion easier for a cold bike. You really only want to keep the choke open for 20-30 seconds when you start the bike and then close it completely. The bike should be idling just fine after that. If you leave it open too much you will start to foul your spark plugs.

Let the BIKE be your guide. Will it run without the choke? Let it!

My recommendation is to get OUT of the city and onto a freeway or other unrestricted motorway, such as highway 395 in California. Burn off a tank of gas at 80. Refill the tank. Ride home. See if the problem is resolved (or at least lessened.)

If the carbs were just cleaned it's possible that you need to sync them, or start checking for a vacuum leak.

If the carbs were just cleaned it's possible that you need to sync them, or start checking for a vacuum leak.

The particular problem is the same as it was before they were cleaned. But maybe things are a bit gunked up again. Maybe a fuel cleaner additive to the gas would help out? If so, is there a particular one that is best?

So far, I'm gathering that:

1. Choke/fast idle is not important, long as she runs.
2. Slow idle is important.
3. Throttle response issue could be a serious problem if it doesn't go away.

Yeah, just get it started and adjust the choke for fastest idle...it isn't too critical. Shouldn't take more than a minute or two to get her to run w/o any choke.

Can’t believe the carbs are dirty unless there are extenuating circumstances. I'd be leaning toward air leak in a hose OR some hose hooked up wrong...

SEV - doesn't this bike have some air injection thing for when you shut off the throttle to help burn unused gas in the exhaust? Could messed up hose connection there cause these issues?


FWIW here is my routine for starting the bike...

I open the choke all the way then back it off by about ¼ to 1/3 THEN press the starter while giving the throttle a little twist, some times it takes two or three for her to catch (the key is the little bit of throttle). BUT I got to keep the throttle open just a bit for a few seconds, maybe around 2-2.5k RPM... after 5 seconds or so I let go of the throttle then adjust the choke for fastest RPM. Put helmet on, put gloves on, back out of garage. Blip the throttle then close the choke. Indicated idle RPM is around 1.2 to 1.4k (the needle moves around). Seems a bit low to me because I get this Brap Brap Barp kinda idle instead of a nice purr but that is the way she has always been and no issues so far so why change things?

That's cool, rnd. I'm not too worried about the fast idle because that, in and of itself, hasn't been an issue. As far as idle goes, I was mostly curious about normal slow idle speeds and why the heck a dealer would contradict the bike specs so much. Just lazy?

1.3-1.5k RPM = smooth idle sound
1k RPM = angry idle sound
800 RPM = almost a Harley

My greater concern is that strange spot around 2k RPM. I'm going to fiddle with it this weekend - by which I mean ride and hope it's happy. I'm planning a route that goes directly past my dealer so if the issue doesn't go away after a tank or so on the highway, I can just stop in and kick them in the nuts.

SEV - doesn't this bike have some air injection thing for when you shut off the throttle to help burn unused gas in the exhaust? Could messed up hose connection there cause these issues?

Yeah, that's the PAIR. Basically what it does is dump a SMALL shot of air into the cylinder head just after the exhaust valve. This causes any unburnt fuel to detonate in the exhaust itself. I cannot see how it'd be causing any problems with normal combustion.



I'm going to go through things again to make sure that I've got everything "clear" in my head.

Your carbs have been cleaned.
When the bike is cold it starts to sputter a bit if you attempt to give it gas - sounds like it's trying to die? choke choke weeze cough sputter?

When you give it throttle after the bike has warmed up it will slowly rise in RPM to 2000... then jump to 3 or 4k all of a sudden?




It really really sounds like either dirty carbs, or a vacuum leak to me.

A partially plugged idle/pilot jet would limit the amount of fuel going into the carb up to about 3000rpm, at which point the needlejet takes over and you'll get a sudden shot of correctly metered gas through the clean jet. It would also explain the lugging shortly after a start because you wouldn't be getting enough fuel when you try to gas it.

A vacuum leak is the opposite.. it means extra air is getting into the.... :O I wonder if the float heights are set correctly in your bike. If they were too low that would mean you weren't getting enough fuel at any given time...

Anyways, a vacuum leak would mean there is a break in the seal between the carbs and the cylinder. Extra air is getting in and leaning out the system... This usually leads to a really weird idle and throttle response though. I don't think this is the problem, but if you want to check for it - start the bike, and get a little arosol starter fluid, spray it at the boots around the carbs (bits between the carbs and the engine). If the idle suddenly picks up you have a leak. Seal the leak and your problem would be solved. Spraying this stuff on your boots can dry them out and cause them to crack, do not use this method excessively.

GRRRRR, I hate stuff like this over the net. It'd be a lot easier if I could fiddle with it :( sorry.

Your carbs have been cleaned.
When the bike is cold it starts to sputter a bit if you attempt to give it gas - sounds like it's trying to die? choke choke weeze cough sputter?

When you give it throttle after the bike has warmed up it will slowly rise in RPM to 2000... then jump to 3 or 4k all of a sudden?

Carbs were cleaned by the dealer about two months ago and the bike has sat for no longer than two weeks in that timeframe.

When it starts cold, just after I've closed the choke and am sitting in neutral, I give it a bit of gas and it goes up to about 2k RPM and sputters. If I don't let out on the gas or grab the clutch, it dies.

After the bike has warmed up, if I give it the same amount of throttle to about 2k RPM, it'll quickly get there, hesitate for a moment, then jump up to 3-4k.

I'll grab a video of it if I can just to illustrate it.

Sev the floats in our carbs are plastic but are they adjustable? I wondered about that ....ive been in there many times and never really investigated wether or not they can be

Sev the floats in our carbs are plastic but are they adjustable? I wondered about that ....ive been in there many times and never really investigated wether or not they can be

The plastic floaty bits themselves cannot be changed... but you bend the metal part they attach too (gently) to set the float height. Yes, it's a highly technical process, which involves great skill and dexterity... LOL. Or you crack them open, measure, bend a little, measure again. Repeat until it works.

:idea: OK was just in my carbs again today and my floats definitely are not adjustable .... the tab/stop that you normally bend on traditional tin/metal floats is plastic on my floats .... also found in the dyno jet paper work where they give you float height and drop measurements to check if they are off or not , if they are floats need to be replaced wich usually come with new valve and seat also. Just an FYI for anyone who wants to know :thumbsup

After a (relatively) long ride last night, the throttle issue seems to be gone. I'll update if it continues, but maybe it just has something to do with the bike having been down for two weeks.

It's irritating being so non-mechanical sometimes. I feel like my relatives must feel when they're coming to me for help with their computers.

Unrelated choke question: How long does an engine stay warm after you've been riding?

I rode for about an hour to hang out with some relatives - started up with choke as normal. I was at their place for about three hours. When I got out to leave, the bike refused to start with choke and, if I opened the choke at all, it'd immediately die. It was only about 80 outside.

Is it just trial and error or is there a general guideline?
Should I try to start sans choke if possible, or choke first?

Maybe I should rename this to "Help Transient Figure Out Which Way Is Up."

Not sure if this is right... there are more knowledgeable people here but...

Morning starts, I open the choke on all the way and slowly close it as it warms up. Daytime starts when it's warm, I start it with half choke or none but blip the throttle. If there is a delay or it stutters, I add more choke until she's warm!

Not very scientific, I know! :shock:

Is it just trial and error or is there a general guideline?
Should I try to start sans choke if possible, or choke first?

eeee. I feel your pain. I have the same problems! Even after all my years riding and miles on this bike, I can't always guess what it wants. I usually try without choke if it's hot out, and with choke if it is cold. I'll adjust if it doesn't fire. That's about all I can suggest . . . :?

Well, I'm glad it's not a scientific thing. I always have this initial reaction of "OH GOD I BROKE SOMETHING" if something doesn't do what it's supposed to. My cousins were just laughing at me tonight. It's so tough to look like a motorcycle stud when you have that panic lighting up your eyes. :roll:

I live in relatively warm climate but have ridden my 599 in the low 40's. I usually use the choke if cold. I try not use choke if warm outside. I thinks the owners manual says do not use it if ambient temp is >90. I have had lots of 80-88 degree days lately and always try initially without choke but usuallly end up using choke for a few seconds. On my old cb 350 f in 30 degree weather I never have used the choke for more than 5 mins and usually less than 2 mins. I think the less choke the better...but I am not a mechanic just my experience.

...when you have that panic lighting up your eyes. :roll:
Every other minute of my waking life... :lol:

I find if the bike has been warm within 0-6 hours during the day, no choke needed... when I get out of work 9-11 hours, I start her just like in the morning...off the choke within a minute.

Do y'all that ride from sea level up into the mountains notice any difference in how your bike runs?

I ride up to about 6k feet and I have not noticed any difference.

I rode my former Guzzi V65 SP from Seattle (sea level) up to the top of the Beartooth pass (11,000 feet) and didn't notice any problems with that either. If a crappy old 1984 Guzzi can handle an 11,000 foot differential, a Honda certainly can! :)

Yea I had the same problem after a long store. You just need to run her hot for a while. Don't mess with the idle screw too much because it will cause exactly what you described.

Just a heads up - a few hundred miles later and I'm still experiencing the odd behavior from a cold start.

It's been in the 90's lately and the bike will not start with choke. However, starting without choke is around 500RPM and the sucker is sputtering badly. If I try to give it any throttle, it'll barely rev before dying completely. If I give it any choke, it'll barely rev before dying completely.

If I let it run like that for a minute or so, it'll gradually crawl over 1000. Once I take off, it's a rough departure - like trying to con the bike into not dying.

Even after a half hour, most starts from a stop are rough. I'll try to give it more gas, I'll try to let the clutch out more gradually, but it still hesitates a bit. Once we're going, it's all good, but damn does it hate being stopped.

I'm going to pick up some overpants so I can ride to work during the week more often and really amp up the number of miles that I put on, but I'm not convinced it's an issue of more mileage.

As far as the starting issue. I've had some of the same problems. From what I've heard (I'm also not very mechanically inclined) you should avoid using choke if it's warm. Lately in warm weather I've had trouble starting it. I find opening and holding the throttle slightly and then starting it seems to get it going okay. That's without any choke. Sorry if someone has already mentioned this.

I appreciate the suggestion and those folks are absolutely right. It will not start with choke of any sort once it's in the 90s. However, I also can't really give it throttle, as that kills it, too. That's the quirk. Something's going on down low. Which probably just means having the dealer go through it.

Does it die immediately if you hold the throttle open a bit before pressing the starter or does it die if you try giving it throttle after you've pressed the starter?

After, once it's started up. Jesus, does that make a difference?

sounds to me like you still have to learn the quirks of your bike...every bike especially carb bikes will have starting quirks unique to themselves

but you should set the idle to what honda specifies, do it after 15min of riding....I had some idle issues too when I just got my bike but adjusted the idle to specs and now it is fine under any conditions (hot/cold or low/high elevation). When warm or if motor is still warm then no choke other wise I'll choke it for about 5-30 seconds depending on how cold it is.

Maybe so. I just don't recall the old Interceptor hesitating so much.

Headed into the dealer for scheduled maintenance this weekend. After having a few riders observe the issue, their guesses were either incorrect carb adjustment (maybe flooding?) or an idle air control valve issue.

Hell if I know if the bike even has an IACV, but screw it. I like going to the dealer like some nightmarish hospital patient after an all-nighter on web-md.com.

Dropped the bike off yesterday and explained the issue to the dealer. "It starts extremely rough, on the brink of dying. Once running, it idles rough. There's a dead zone somewhere between 1000-2000 RPM where the engine's just not there."

At first, the rep seemed to think it wasn't a big deal. Maybe I'm just crazy. When I explained that the bike dies when revved (before warm) he turned serious and seemed to acknowledge the issue.

From what research I've done, I'm guessing it's a problem with the pilot jet. We'll see when I get the bike back.

Hopping back in the frickin' Elantra is miserable.

Hopping back in the frickin' Elantra is miserable.
As my neighbor used to say..."Da worstest kinda ridin' beats the bestest kinda walkin'."

Let us know what they find.

The mechanic who worked on it apparently didn't take any notes as to what was actually done. When I asked, the service rep just said that it was taken for a few test rides after whatever work was done and everything checked out just fine.

That said, the bike's running great now. It irritates me a bit not knowing what the issue was, but at least we're together again.