will not run below 4000 rpms
Moderators: rztom, silverstrom
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- Posts: 58
- Joined: Sun Feb 21, 2016 6:53 pm
- Location: Gilbert, az
will not run below 4000 rpms
It starts and has good spark when kicked over and will start. but it will not idle. It will die when the rpm drop below 4K. If I open the throttle it will speed up again but as soon as it drops again I will have to increase the throttle.
I have checked the low speed coil and it checks out. I have also replaced the stator assy twice with the same result.
The carbs are clean and the petcock also. If it is not getting enough fuel at idle that it cannot get enought for higher rpms so the fuel system is not the problem.
Amy suggestions????
I have checked the low speed coil and it checks out. I have also replaced the stator assy twice with the same result.
The carbs are clean and the petcock also. If it is not getting enough fuel at idle that it cannot get enought for higher rpms so the fuel system is not the problem.
Amy suggestions????
1982 RD350J aka RD350LC Canadian
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
Re: will not run below 4000 rpms
Compression?
Slides and floatbowls on the correct carbs/direction?
Slides and floatbowls on the correct carbs/direction?
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- Posts: 58
- Joined: Sun Feb 21, 2016 6:53 pm
- Location: Gilbert, az
Re: will not run below 4000 rpms
It ran fine the last 800 miles and then on a ride it started to not run below 4K.
It feels like it electrical. But I have traded out the CDI unit for one that I know is good and have traded out the stator assy twice for known good units. I am at a loss
It feels like it electrical. But I have traded out the CDI unit for one that I know is good and have traded out the stator assy twice for known good units. I am at a loss
1982 RD350J aka RD350LC Canadian
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
Re: will not run below 4000 rpms
Clean and reset the carbs.
'82 RD350LC in '81 colours, OEM pipes, UNI filters
'85 FZ750
'85 FZ750
Re: will not run below 4000 rpms
Plugged pilot jets. Even with clean carbs. Bad fuel or contamination from the tank is all it needs to plug up. Ask me if I've had to clean out pilot jets multiple times on the same bike.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
Re: will not run below 4000 rpms
I run an in-line fuel filter in all my bikes. Helps prevent crap in the carbs.
'82 RD350LC in '81 colours, OEM pipes, UNI filters
'85 FZ750
'85 FZ750
Re: will not run below 4000 rpms
check the PVs are working. Easy to do, pull off the cover and check they move when you switch on the ign.
cold also be the air corrector jets, behind the balls.
cold also be the air corrector jets, behind the balls.
80 XT500 Supermoto!
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid
Like Watches? www.PloProf.com & www.DeskDivers.com
81 RD350LC Resto
82 RD421LC Hybrid
82 RD350LC decapitation project
82 RD250LC JDM '251LC' YPVS
83 RZ350 Resto
84 RZ500 Resto
85 RZ350 F1 Resto
86 RZ350 F2 Resto
86 RZ350 F2 Hybrid
Like Watches? www.PloProf.com & www.DeskDivers.com
Re: will not run below 4000 rpms
Have you by chance had any rust issues at all with your fuel tank?
tuned to Paris Hilton specs............rich and retarded!
Re: will not run below 4000 rpms
That's a must do. I do as well. Good insurance.Hooligan wrote:I run an in-line fuel filter in all my bikes. Helps prevent crap in the carbs.
Rory
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
2 1984 RZ350s
1985 RZ350
9 1986-1990 RZ350s
2000 ST2
2005 749
2005 749 with 999 engine
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- Posts: 58
- Joined: Sun Feb 21, 2016 6:53 pm
- Location: Gilbert, az
Re: will not run below 4000 rpms
Well I finality got around to sorting this out. Took off the carbs, they were very clean, put them back on and scoped out the low and high sped coils, both were good but there could be a broken wire somewhere. I replaced it with one I checked all the wires and and all the specks are good. I fired it up and all was good. Took it for about 8 mile low speed ride and entered to the garage. At about sundown I pulled part of the way out of the garage to time it. Less light better timing light. I fired it up and the same problem was there. While standing on the footpegs to start it I was looking at the tach and noticed that the lights went out when the engine cut out. That points to a short in the wiring harness somewhere.
The wiring harness was not very good to begin with - the water temp gauge would go to the hot end when the key was turned on, I disconnected that, the high beam wasn't getting power, and the front turn signals didn't work.
Now I need a wiring harness. Any suggestions???
The wiring harness was not very good to begin with - the water temp gauge would go to the hot end when the key was turned on, I disconnected that, the high beam wasn't getting power, and the front turn signals didn't work.
Now I need a wiring harness. Any suggestions???
1982 RD350J aka RD350LC Canadian
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
Re: will not run below 4000 rpms
https://www.ebay.com/itm/1983-1984-Yama ... rk:26:pf:0" onclick="window.open(this.href);return false;
Ebay is your friend. The above is probably the most expensive way to go. You will probably find a used one for around $100.
Ebay is your friend. The above is probably the most expensive way to go. You will probably find a used one for around $100.
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Re: will not run below 4000 rpms
1982 RD350LC
https://www.ebay.com/itm/Yamaha-RD350lc ... ctupt=true" onclick="window.open(this.href);return false;
https://www.ebay.com/itm/Yamaha-RD350lc ... ctupt=true" onclick="window.open(this.href);return false;
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- Posts: 58
- Joined: Sun Feb 21, 2016 6:53 pm
- Location: Gilbert, az
Re: will not run below 4000 rpms
UP DATE: I replaced the main wiring harness and it now runs the way it should. idle well and all the problems have gone away
Thanks for all the input. It was all helpful!!
Thanks for all the input. It was all helpful!!
1982 RD350J aka RD350LC Canadian
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
Re: will not run below 4000 rpms
Don't throw that old harness away, always handy to have one around to rob connectors from.
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- Posts: 58
- Joined: Sun Feb 21, 2016 6:53 pm
- Location: Gilbert, az
Re: will not run below 4000 rpms
Now I have two that I can take connectors from. I had to do that to get the current harness to work.
If you have a RD350LC, throw nothing away!!!
Thanks for all your help and encouragement!
If you have a RD350LC, throw nothing away!!!
Thanks for all your help and encouragement!
1982 RD350J aka RD350LC Canadian
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.
1971 Kawasaki F5a Big Horn
2013 NC700X
Judge people by what they do and not what they say they will do.