Low RPM ignition issue???

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Skyguyz
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Joined: Sat Jun 01, 2019 6:53 pm
Location: Las Vegas, NV. USA

Low RPM ignition issue???

Post by Skyguyz »

My 75 GT750 had been running great until it recently developed over a slow period of time a cutting out of ignition at low RPM. It runs great above about 2500 RPM but when it goes back to idle you can tell it is cutting out ignition wise, It's not fuel because it's like a light switch on/off cutout. It seems to be on 1 or 2 cylinders. It could be something as easy as spark plugs or worn points; I have not investigated yet. It could be a slight grounding of something? But it runs spot on when you "Give er the beans." So before I unessasarly tear into this, is it a common problem that I am unaware of? Thoughts?


Thanks in advance as always,


Sky





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PaulD738
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Joined: Thu Sep 25, 2014 6:57 pm
Location: Warrington Cheshire

Re: Low RPM ignition issue???

Post by PaulD738 »

My T500 has recently had a similar problem which turned out to be one set of points closing up. I reset them and checked the timing and all’s back to normal.
They're rubbish them Jap bikes lad they won't last five minutes! you want to get yourself a nice Royal Enfield!
A quote from my old dad 8-)

I started out with nothing and I’ve got most of it left!
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Low RPM ignition issue???

Post by Alan H »

Check the battery voltage and voltage at the orange wire at the coils.
You get poor sparks if the voltage to the coils is low and that will cause poor running especially at low revs.
Proof that four strokes are over complicated
Skyguyz
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Joined: Sat Jun 01, 2019 6:53 pm
Location: Las Vegas, NV. USA

Re: Low RPM ignition issue???

Post by Skyguyz »

PaulD738 wrote: Fri Sep 18, 2020 7:13 pm My T500 has recently had a similar problem which turned out to be one set of points closing up. I reset them and checked the timing and all’s back to normal.
Well that solved it!

Thanks so much for the advice. The left points were not opening. Strange that this would happen. But problem solved!

Thanks again,


Sky



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PaulD738
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Re: Low RPM ignition issue???

Post by PaulD738 »

If you’ve fitted new points to the bike the heel of the moving side that runs on the cam tends to wear until it work hardens. Original Suzuki contact sets seem to be better in that respect than the pattern ones available now. Glad you sorted it 8-)
They're rubbish them Jap bikes lad they won't last five minutes! you want to get yourself a nice Royal Enfield!
A quote from my old dad 8-)

I started out with nothing and I’ve got most of it left!
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mizzytheman
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Joined: Tue Dec 28, 2010 1:17 pm
Location: Knowsley, Liverpool

Re: Low RPM ignition issue???

Post by mizzytheman »

PaulD738 wrote: Sat Sep 19, 2020 8:56 am If you’ve fitted new points to the bike the heel of the moving side that runs on the cam tends to wear until it work hardens. Original Suzuki contact sets seem to be better in that respect than the pattern ones available now. Glad you sorted it 8-)
I always put a little smear of grease on the points cam and a few drops of oil on the felt pad. I do this every year when the bike goes back on the road after winter. Haven’t had to adjust the points for over 5 years.
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Alan H
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Location: Wombwell, Republic of South Yorkshire

Re: Low RPM ignition issue???

Post by Alan H »

Probably gets someone else to do it.
Proof that four strokes are over complicated
julian
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Joined: Wed May 11, 2011 8:12 pm
Location: milton keynes

Re: Low RPM ignition issue???

Post by julian »

Hi had exactly same problem on centre cylinder on my kettle points not opening ,found points spring strap gone soft could bend it with my fingers fitted new points been fine ever since .
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