Author Topic: magneto  (Read 3502 times)

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Offline Okie-Chopper

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magneto
« on: September 23, 2007, 09:51:25 am »
I'm new here and I have a question about a magneto.  I have had trouble starting the engine for years on my 16.5 briggs OHV and at times when I would turn it off I would get a small back-fire. I also have a new mower with a 17.5 Hp, they seem like good engines,  my old one is 10 years old and up to spring of this year, it always ran great, then it quit running. The last time I got it started it ran for about 2 mins. and died.  I noticed it had a little water in the gas, but anyway, I have had to always roll it to top dead center before starting it and even sometimes I also had to have a charger hooked up as well to get it started. I would get it spining then chock it and it would start. It would always run great after it was started.  I had to put on a new starter ring gear and a new gear in the starter drive as well.  I decided to fix this one up and build something kinda sorta in a racing tractor. Anyway I tried to start it and again I had to roll it to TDC again.  After scratching a hole in my head over what it was doing ( it ran slow back-fired out the exhaust pipe and the carb as well, and the muffler got redhot and while it was running it shot out a nice blue flame while running about six inches from the tip of the exhaust pipe.)  I tested the spark and it was orange and sometimes you would see a slight blue spark ( more orange than blue tho ) so now I'm going to put on a magneto,  but what is the air-gap to be set at?  And do you think I might have another problem with this 16.5 OVH that I have not seen yet?  Someone said it might be the cam,  but it did run very well when I did get it started. Thanks for your time I just hope someone can shead a little light on this small problem.

Offline George Herrin

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Re: magneto
« Reply #1 on: September 23, 2007, 10:01:57 am »
.012 on air gap. The compression relase mechanism is bad on the caM (MEANING YOU NEDD A NEW CAM) a common problem with oem ohv's in that era.
George Herrin #6
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Offline Okie-Chopper

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Re: magneto
« Reply #2 on: September 23, 2007, 01:23:17 pm »
Ok next question: what do the valves set at  cold and hot?
I found what might be the settings   it says .005/.007 intake and .009/.011 on exhaust........but hot or cold,  can you not set it by turning the flywheel 1/4 turn after the power stroke?

Offline Squidd

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Re: magneto
« Reply #3 on: September 23, 2007, 03:56:02 pm »
Set them cold...
Randy Stys
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Offline Okie-Chopper

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Re: magneto
« Reply #4 on: September 24, 2007, 06:24:24 pm »
Thanks for all of the help, The mower is running better than when it was new.  the hard start problem is gone as well.  Now i just need to figure where to go from here.  I have not checked out how big the mower sport is here in Oklahoma yet, I just hope the people here are as nice as the few i met on this site are.  Now I guess I'll go check out a few races here sometime ( or go get my feet wet ).  I hope to be putting a few pics of my mower on here in the next few days.   And again  BIG thanks.  BP

Offline redrocket

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Re: magneto
« Reply #5 on: September 28, 2007, 12:13:44 pm »
What part of Oklahoma are you in?

Offline Okie-Chopper

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Re: magneto
« Reply #6 on: September 28, 2007, 04:25:17 pm »
I'm in moore, 7 miles south of Okc

 

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