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General Category => Yamaha FJ1100 / FJ1200 Running Problems => Topic started by: PeteC on November 07, 2015, 10:11:33 AM

Title: Hard to start cold, starts good when hot
Post by: PeteC on November 07, 2015, 10:11:33 AM
Hi,
I have rebuilt the carbs, new fuel pump, new valve shims.
Bike starts very hard when cold, have to use starting fluid, once hot runs great and starts great
Have changed the boost sensor, no help.
When running have experienced it will rev up on it own
Should I be looking at electrical or something else.
Have check compression, good, redone all gas lines.
It is acting like it starves for gas when cold, does the DI have anything to do with that?
any help appreciated
1989 FJ1200

Thanks in advance,
Pete
Title: Re: Hard to start cold, starts good when hot
Post by: FJ1100mjk on November 07, 2015, 10:48:22 AM
Sounds like the carbs' enrichment area is suspect.

1. Are you sure the enrichment plungers are pulling out as far as they should be when the choke knob is pulled out as far as it's supposed to be?

2. Are you certain that the fuel path/passages in the float bowls (the ones that the small brass tube pulls from) were clear? If no/little fuel can be pulled up those brass tubes, you'll get none in the enrichment circuit up through the plungers to start a cold engine.

Good luck!
Title: Re: Hard to start cold, starts good when hot
Post by: simi_ed on November 07, 2015, 11:00:35 AM
Pete, you didn't mention where you are, but I'd guess you're in the U.S., somewhere. I would replace the oem pilots with #40s, instead of the 37.5s that are probably installed.  It seems that theses bikes were pretty cold blooded as new and get worse with time.  I know mine sure did!  The ethanol in our 'fuel' has effectively made the mixture leaner, and it is most noticeable when cold at part throttle.

My 2¢


Ed
Title: Re: Hard to start cold, starts good when hot
Post by: FJ_Hooligan on November 07, 2015, 06:36:56 PM
What Marty said!

Sounds like the tiny orifices in the float bowls are plugged up.
Title: Re: Hard to start cold, starts good when hot
Post by: PeteC on November 08, 2015, 09:37:45 AM
Quote from: simi_ed on November 07, 2015, 11:00:35 AM
Pete, you didn't mention where you are, but I'd guess you're in the U.S., somewhere. I would replace the oem pilots with #40s, instead of the 37.5s that are probably installed.  It seems that theses bikes were pretty cold blooded as new and get worse with time.  I know mine sure did!  The ethanol in our 'fuel' has effectively made the mixture leaner, and it is most noticeable when cold at part throttle.

My 2¢


Ed
Quote from: simi_ed on November 07, 2015, 11:00:35 AM
Pete, you didn't mention where you are, but I'd guess you're in the U.S., somewhere. I would replace the oem pilots with #40s, instead of the 37.5s that are probably installed.  It seems that theses bikes were pretty cold blooded as new and get worse with time.  I know mine sure did!  The ethanol in our 'fuel' has effectively made the mixture leaner, and it is most noticeable when cold at part throttle.

My 2¢


Ed

I am in South Fl
Bike is a Ca model, got the bike with most of the emissions removed.
Thanks for your reply
Title: Re: Hard to start cold, starts good when hot
Post by: ELIMINATOR on February 11, 2016, 07:01:17 AM
I assume you are pulling the choke all the way out & not partially? Mine is crap with only half choke from cold.