cold running problem

bigbore2 · November 02, 2013, 07:35:04 PM

84-1100 Bike runs fine everywhere except at low RPM's when cold. Runs fine as soon as my RPM's get to 2100 when cold but under that it is real doggy. I have run it with the choke on full, partial and off and does not seem to matter. Once bike is warm low RPM is fine. Probably due for a carb synch. as have put 8000 mi. since last one. These engines seem to take a while to warm up. 40 degrees F here in the morning

Pat Conlon · November 02, 2013, 08:00:48 PM

Check the choke for full activation: Pull the tank, look at the carbs, now roll your choke on and off...see the choke slider rod the top of the carbs move back and forth? Full range of motion?
If so, then look at cleaning out your choke circuit and idle circuit, might as well do a complete carb cleaning.

andyb · November 02, 2013, 09:33:23 PM

...and ensure that all four of the choke plungers are properly connected to the rod, while you're watching it.

bigbore2 · November 02, 2013, 10:21:28 PM

I know choke works cause cold starts need full choke. Carbs completely cleaned and rebuilt 2 years ago [9000 mi.] But I don't know if choke is fully working cause carbs have been off several times for tuning. I will check for full activation of choke rod. Thanx

FJ_Hooligan · November 03, 2013, 12:07:16 AM

Quote from: bigbore2 on November 02, 2013, 07:35:04 PM
These engines seem to take a while to warm up.

Mine doesn't. Fires right up and only need choke for about 90 sec then it's ready to ride off. Something's not right. Sounds like choke circuit is not getting enough fuel. Make sure the orifices in the float bowls are clear.

ELIMINATOR · November 03, 2013, 11:12:32 AM

I start mine with about 1/4 throttle and no choke. As soon as I let go of the choke it closes itself anyway!

1200 3cv, and yes, mine takes a while to warm up and reach normal idle speed.

Bike seems very fussy about how much choke I give it, when I have tried to use it.

My other bikes are not so fussy.

Len Redmond · November 12, 2013, 10:02:17 PM

Bike is notoriously slow to warm up, especially in cold weather. Full choke to start, reduced to ½ after 30 seconds where it remains 'till warm. My previous two and current FJ110s required this technique.

~JM~ · November 13, 2013, 09:56:53 AM

My '89 FJ is also the most cold blooded bike of the bunch. Of course it is also the biggest bike of the bunch also. I just figured it needs more time to come up to operating temperature than my other bikes that are half the size or smaller in displacement. I don't commute with it so it's not much of a problem. I just let it run at around 1/2 choke & 2500 RPM for several minutes to warm up before riding it.

~JM~

simi_ed · November 13, 2013, 10:28:18 AM

Try putting some #40 pilot jets in. That'll solve your cold blooded problem and make your FJ run a whole lot better. BTDT.

FJmonkey · November 13, 2013, 10:52:39 AM

After putting #40 pilots in my 86' it spends way less time with the choke on and idle seems smoother as well.

andyb · November 14, 2013, 02:35:49 AM

Cold blooded is another way of saying "I don't understand how to jet things properly".

30s on choke, off you go.

~JM~ · November 14, 2013, 09:31:04 AM

Quote from: andyb on November 14, 2013, 02:35:49 AMCold blooded is another way of saying "I don't understand how to jet things properly".

30s on choke, off you go.

Hadn't considered it a problem after reading several posts from others that the FJ was a bit on the cold blooded side. Like I said... It's much larger than my 500cc & 400cc bikes, so it only stands to reason that it may take a bit longer to warm up. Somewhat like my Dodge/Cummins pick-up truck vs. the little womans Saturn. I don't believe in trying to force an engine to perform that has just been started & hasn't come up to normal operating temperature yet. A few minutes warming up seems a lot easier than re-jetting 4 carbs.

What size is the OEM pilot jet on an '89? Does up-jetting to size #40 change MPG ratings any? My bike seems fairly thirsty to begin with, but I do ride on the fast side.

Thanks
~JM~

simi_ed · November 14, 2013, 10:41:16 AM

The original pilot in the '89 is a #37.5. Upsizing one to #40 made no real difference in fuel mileage, but a HUGE improvement in driveibility. I noticed a big improvment in throttle response from idle to 5-6k rpm! Cold blooded feel was gone too.
I was typically in the low 40s before, same after. Beside, you can always change 'em back if you don't like the results. I never did.

~JM~ · November 15, 2013, 09:07:11 AM

How difficult of a job is it? Is there access to the float bowls, or do the carbs need to be removed?

I have never worked on a 4-cylinder bike & haven't had my bike for very long. Were is a good place to purchase the jets?

Is there any other work that I should consider doing while I'm at it?

Thanks
~JM~

Pat Conlon · November 15, 2013, 05:44:51 PM

Don't worry about it until the time comes when you have to clean your carbs....or replace leaking float seat O rings...it will happen sooner or later.....only then replace the pilots and along with that, invest in RPM's stainless steel screw kits for your carbs.

All necessary parts are available from RPM.

For right now, if all is well, just ride the bike......consider it a honeymoon.

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cold running problem