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Cold start/choke issue.

Started by 4everFJ, September 08, 2015, 07:51:36 AM

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4everFJ

Here goes... My cold start 'procedure'.

1. Choke to starting position (this is a FJ1100)
2. Push starter without throttle (as per User Manual...) -> It won't start.
3. Open throttle a little and push start -> Now it starts and idles rough at <1000 rpm (i.e. as if the choke wasn't on).
4. Blip throttle and idle will go up to 3000 rpm and stay there.
5. Push choke to warm up position -> Engine dies.
6. Push choke to starting position and push start. -> Engine will start but can't idle/dies.
7. Push start again with throttle a little open and play back and forth with choke position and throttle until it idles at approx. 2000 rpm.

It is crazy how sensitive cold start is to choke position and throttle and it is a nightmare to get it to idle good for the warm up.

Also, warm up time seems excessive. After 5 minutes warm up time, the engine still dies if the choke is closed. Once warmed up, no problems.

On other bikes I have owned, it was just a matter of starting with choke on, adjusting choke to 1000-1500 rpm and of you go.

Any suggestions, or is this just how the FJ is when cold?

Thank you :good2:
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

FJmonkey

My '86 was a real pig on cold starts with the original pilot jets. I would let it high idle for a few min while I finished putting my helmet and jacket on. Once on the bike and ready to go, back the choke off a little and ride off. I take it easy during the 1.25 miles to the freeway. By then the choke is full off and ready for higher RPMs. Now that I have #40 jets it almost does not need the choke, and not for more than a min. It helps that Southern California does not get as cold as other parts of the country or world.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

4everFJ

Quote from: FJmonkey on September 08, 2015, 08:15:51 AM
My '86 was a real pig on cold starts with the original pilot jets. I would let it high idle for a few min while I finished putting my helmet and jacket on. Once on the bike and ready to go, back the choke off a little and ride off. I take it easy during the 1.25 miles to the freeway. By then the choke is full off and ready for higher RPMs. Now that I have #40 jets it almost does not need the choke, and not for more than a min. It helps that Southern California does not get as cold as other parts of the country or world.

Mine has the #40 jets as standard (European model).

Problem is that I can only back off the choke so that it idles at 2000 rpm. Trying to back it off more - even slightly - and the engine dies.
I am not really happy putting it in 1st gear when idling at 2000 rpm (BIG clonk)...  :nea:

Also, when I back off the choke too much so that idle drops, and then quickly activates the choke again, to stop it from dying, the choke has no effect whatsover on the idle and it just dies.
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

FJmonkey

Quote from: 4everFJ on September 08, 2015, 08:24:13 AM

Also, when I back off the choke too much so that idle drops, and then quickly activates the choke again, to stop it from dying, the choke has no effect whatsover on the idle and it just dies.

Try bringing the idle back up with the throttle before bringing the choke back on. Or give it more time to warm up.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

FJ_Hooligan

Sounds like the choke fuel orifices in the float bowls of one or more carbs may be plugged.

When was the last time you cleaned that carbs?  If recently, did you verify these orifices are clear?
DavidR.

4everFJ

Quote from: FJ_Hooligan on September 08, 2015, 10:58:44 AM
Sounds like the choke fuel orifices in the float bowls of one or more carbs may be plugged.

When was the last time you cleaned that carbs?  If recently, did you verify these orifices are clear?

That could be a possibility.

Could you please explain why plugged orifices would result in the symptoms I describe? I want to learn  :yes:
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

FJmonkey

Quote from: 4everFJ on September 08, 2015, 11:04:32 AM
That could be a possibility.

Could you please explain why plugged orifices would result in the symptoms I describe? I want to learn  :yes:

If the pilot jets are clogged or obstructed then off choke they will not allow enough fuel through to idle properly. The choke circuit allows additional fuel through to run when cold.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

4everFJ

Quote from: FJmonkey on September 08, 2015, 11:54:47 AM
Quote from: 4everFJ on September 08, 2015, 11:04:32 AM
That could be a possibility.

Could you please explain why plugged orifices would result in the symptoms I describe? I want to learn  :yes:

If the pilot jets are clogged or obstructed then off choke they will not allow enough fuel through to idle properly. The choke circuit allows additional fuel through to run when cold.

But, it idles fine when warmed up and off choke? Wouldn't that indicate that they aren't clogged, according to what you write.
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

red

Quote from: 4everFJ on September 08, 2015, 08:24:13 AMMine has the #40 jets as standard (European model).  Problem is that I can only back off the choke so that it idles at 2000 rpm. Trying to back it off more - even slightly - and the engine dies.
I am not really happy putting it in 1st gear when idling at 2000 rpm (BIG clonk)...  :nea:
Also, when I back off the choke too much so that idle drops, and then quickly activates the choke again, to stop it from dying, the choke has no effect whatsover on the idle and it just dies.
4ever,

A good carb cleaner may be all you need, mixed with the gasoline.  In the USA, my choice is SeaFoam, but ask riders in your area what they would recommend.

To avoid that big CLONK into first gear, pull the clutch lever fully and increase/decrease the RPMs a few times, smartly but not very abruptly.  This causes the clutch plates to separate, using their inertia, rather than hammering on your gears.  At low RPM again, engaging first gear should be much less noisy, then.  Old clutch plates may become somewhat sticky, especially when cold.  Then, they may benefit from a plate cleaning and a "clutch-soak" process, but an oil change may also be enough, there.

Cheers,
Red
Cheers,
Red

P.S. Life is too short, and health is too valuable, to ride on cheap parade-duty tires.

4everFJ

Thanks, I will try some carb cleaner in the tank. Can't hurt and if it helps, I can wait until winter to disassemble and do a full clean of the carbs.

I have ridden bikes for more than 20 years, and never thought about doing the rev thing before putting it in 1st. You learn every day  :good2:
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

FJmonkey

Quote from: 4everFJ on September 08, 2015, 12:13:05 PM
But, it idles fine when warmed up and off choke? Wouldn't that indicate that they aren't clogged, according to what you write.

If it idles fine when warm then your pilots should be fine. Give her more time to warm up.

Has it always been like this? Or is this something new?
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

4everFJ

Quote from: FJmonkey on September 08, 2015, 02:12:00 PM
Quote from: 4everFJ on September 08, 2015, 12:13:05 PM
But, it idles fine when warmed up and off choke? Wouldn't that indicate that they aren't clogged, according to what you write.

If it idles fine when warm then your pilots should be fine. Give her more time to warm up.

Has it always been like this? Or is this something new?

Well, I got the FJ about 4 weeks ago, so for me it has always been like this  :smile:
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)

FJmonkey

Quote from: 4everFJ on September 08, 2015, 02:23:53 PM
Well, I got the FJ about 4 weeks ago, so for me it has always been like this  :smile:

Got it.... I have had my FJ for so long the warm up time is normal for me. Start her up a few more minutes earlier than normal, remember to keep the front turned to the side so the heat from the headers don't warp the back side of your front fender.
The glass is not half full, it was engineered with a 2X safety factor.

'86 Ambulance - Bent frame, cracked case, due for an overhaul
'89 Stormy Blue - Suits my Dark Side

FJ_Hooligan

Quote from: 4everFJ on September 08, 2015, 11:04:32 AM
Quote from: FJ_Hooligan on September 08, 2015, 10:58:44 AM
Sounds like the choke fuel orifices in the float bowls of one or more carbs may be plugged.

When was the last time you cleaned that carbs?  If recently, did you verify these orifices are clear?

That could be a possibility.

Could you please explain why plugged orifices would result in the symptoms I describe? I want to learn  :yes:

The choke circuit pulls its fuel through these orifices in the float bowl.  Since they are near the bottom of the float bowl, they get obstructed easily with dried fuel gunk or other debris (they are tiny).  When this happens, the choke circuit starves for fuel.  Therefore, when you apply the choke you're actually adding more lean mixture (basically just extra air) to an already too lean mixture on a cold engine.  The result is WORSE starting when using the choke to start a cold engine.  Once you get it started and it warms up the problem goes away.
DavidR.

4everFJ

This morning I have put som Fuel Service Cleaner in the tank.

I will let you know how it turns out.

Thanks for all the feedback. Great forum  :good2:
1985 - Yamaha FJ1100 36Y
1978 - Yamaha SR500
1983 - Kawasaki GPZ550 (sold)
1977 - Kawasaki Z400 (sold)