Idle Speed Question

I'm a new owner of a 98 (fifth bike tho) and that's what she looked like on the day I picked her up. 20150 on the odo.

Anyway, I apologize if this has been asked before, but I couldn't find it. How rough is too rough on the idle? Mine is about +/- 75 rpm at idle once it's warmed up. Normal? I do need to dump some of the oil off. I'm used to my monster where you check the dip stick with the bike on side stand.

 

What is the idle currently set at?

 

1250rpm roughly at 180F

 

Regular operating temperature usually runs about 200F to max about 225 if stuck in bad traffic, not 180.


First check the plugs on any new bike just to see what the colors show, from chalk to chocolate to soot ? Dirty carbs, low compression gotta check? Best done b4 purchase as insurance. Where to begin if it's not running 100%. Clean off plugs' deposits, regap and reinstall or replace with new. Recheck plugs again after some riding. Sure, it's a pia 3 beer job on that bike just to get the front plugs out, but would u rather be watching TV ?

Almost always, most proppa-running bikes show a fine, tasty Cadbury light milk chocolate glow on the tip.........


Plugs should show consistant color if carbs are clean, fuel levels are the same, idle mixture screws adjusted right and the compression is adequate.

 

Don't mind the Squirrelman. He's been sniffing the carb cleaner again.

There are no carbs on your '98. Checking the plugs and air filter and adding some injector cleaner, would be a good place to start.

Checking the output of the R/R wouldn't hurt, either.

 

Plugs... That's what i forgot. I'll check those tonight. The air filter is clean, but it's a K&N filter. No other mods.

As far as temperature, 180 is as hot as it's got for me. Course, it's been cold as balls. Lol.

Charging system puts out the right voltage across the board. Tops out at 15.2VDC at about 7k.

 

Your problems are at idle, so you need to know the RR output at idle. Sometimes the voltage is too low to keep a steady RPM at idle and it needs to be brought up a little bit.

 

So I just checked the spark plugs and the gaps were obviously not set when they were installed (they look like 2mm or more). Also, they were barely hand tight... Waiting on my wife to get back home, she agreed to get a gap gauge for me.

As far as I remember, (I can't start it now, the plugs are out. lol) the voltage at idle was at 13vdc roughly. Maybe 12.8-12.9. At the time my battery was dead. Metered it at 11 something, the bike just barely caught, then ran at 12.8 or so. I put it on the tender and I haven't had problems since.

I'm starting to get the idea that the PO had no idea what he was doing. The chain was way loose, the brand new battery wasn't charged properly, the oil was overfilled (I checked that when I picked it up, but didn't know you checked it on the center stand), now the spark plugs were new, but loose and the gaps weren't set. I know they shouldn't be too tight, but they felt like I could loosen some without the wrench and just a nut driver.

Geez. I'll volt the system out again as soon as I get the plugs back in.

 

Not sure on the 5th. gen but the 6th. runs iridium plugs with the gap set at the factory. We are told not to try and set gap because it will wreck the iridium electrode.

My idle is around 1300 and it is sometimes a little rough. Kick it up a notch and see what happens. I think this is normal.

Your thermostat opens at approx. 175F. If it is real cold your radiator will keep the bike cool without the bike moving once the thermostat is open. Easy thermostat test. From stone cold start the bike and watch the temp gauge. The temp will climb until the thermostat opens (Approx. 175 to 185). When it opens you will see the gauge tumble until the thermostat closes and the heat starts to rise again. It may do this 2 or 3 times until the coolant in the radiator heats up enough to keep the thermostat open. Heat then contiues to rise until the fan switch kicks in about 220 deg. F.

 

Well, I've never heard that about iridium plugs, but that doesn't mean it isn't true. At any rate, the NGK number didn't come out to an iridium plug, and the gaps were anywhere from 0.4mm to 1.3mm so now they're all between 0.8-0.9 like the service manual says.

The bike seems to warm up fine, and climbs quickly to 170F. I did finally get it to reach 220F and set the idle there at about 1400. Seems to me there is no change. I did notice that while letting the "choke" or whatever is, stay open that the rough stumbling is all over the rev range. Kind of like a lope with +/- 50RPM or so. That might be normal (my old katana did it), but it seemed to do it when held at an RPM with throttle as well (it didn't do that). Also occasionally while holding steady at any RPM, it seems to... idk, stall for a half second or so. It'll drop 2-300 RPMs and then jump right back up to speed. I had noticed it a few times while riding, but it happens so infrequently and it's so fast I was berating myself for poor throttle control. But just sitting and watching the tach it's noticeable.

Voltage at idle is 13.2VDC. Voltage seemed to peak at 14.6VDC now at around 5k. Part of me wonders if there isn't some problem with the PAIR valve. Like for some reason the vacuum that holds the door up isn't steady for some reason. I have no idea at this point. Still pulls hard. She'll pull the front wheel up with a quick throttle grab. All the plugs were a nice tan, with #4 looking just a hair black.

 

Alot sounds like problems with throttlebody plate synch, but i already screwed up on this thread once..........!

with FI there can always be sensor or computer issues, unlike carbs.:redface: so maybe it's that ?

 

Well, it happens squirrelman. Honestly, carb sync was my first thought, but the bike doesn't have carbs. lol. I didn't know you had to sync fuel injected throttle bodies too. Although, now that I think about it, it does make sense on a FI too.

Looks like the starter valve synchronization on page 5-67. Although, I'm fresh out of manometers, and the valves aren't adjusted evenly so a homemade kludge won't work.

#1 - not adjustable
#2 - equal to #1 +/- 5mmHg
#3 - 20mmHg below #1 +/-5
#4 - 10mmHg below #1 +/-5

Crud. Someone got a manometer I can borrow?

 

If the PO over oiled the K&N, the sensors and throttlebody parts can get messed up. Check the MAP and IAT and maybe try some Seafoam.

 

Alright, so I tore the airbox apart, and the temp sensor was fine. Tested in tolerance. The MAP sensor, however, wasn't even connected. The hose that should connect to it was pinched and not on the sensor. So I took the airbox off to test it. Tested okay. About 0.2ohms at atmosphere and jumped around when I blew in the tube. Speaking of, the other end of the tube wasn't connected either. And the first "t" was connected incorrectly. The PAIR system and the MAP system were all mixed up.

Geez.

So I straightened all that out and got the bastard all reconnected, and the surges and stumbles are gone now after it warms up. Just a steady lope that swings about as wide as one of the tach marks. At this point I don't think it's anything to worry about. Put some FI cleaner in it the next time I fill up, and be done with it.

I did notice the "secondary air valve" (that little flapper thingy) isn't working. Tested out to be the solenoid, which is $160 or so. Didn't seem to affect idle when I manually operated it. It is just some emissions thing?

 

Good detective tinkering. Sounds like you are good to go. Be careful on the cold tires and keep the shiny side up!
John

 

Yeah. 30F when I left the house this morning. :smow: Geez, I thought this was Houston, TX...