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Old 11-04-2016, 01:56 PM
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Default briggs timing...firing before tdc??

A couple pics of when engine is firing.(I'm thinking). Does the offset woodruf bring closer to tdc for more combustion? The exhaust burn on cylinder looks to me its firing early....? Last pic is jussst before tdc. And flywheel is way past.But, when is spark released?? As both coil legs it the magnet? Help appreciated.
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Last edited by scratchbuilder; 11-04-2016 at 02:11 PM. Reason: add pic
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Old 11-04-2016, 03:55 PM
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Default Re: briggs timing...firing before tdc??

Looks right to me. Typical firing happens around 30deg BTDC. Advancing timing around 6* really boosted my motor a bit in the higher RPMS. I have my 212 advanced 4*, thinkin of doing more.
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Old 11-04-2016, 06:26 PM
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Default Re: briggs timing...firing before tdc??

Thx 01, how did you advance yours?
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Old 11-04-2016, 10:47 PM
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Default Re: briggs timing...firing before tdc??

I just cut the key. I can send you my key if you want, but if you want it now you can do it easily enough with a good enough caliper or 1" micrometer; stock key is .186" wide and every .0055" you cut into a step is one degree, so I cut a ~.035" wide by .075"dp step, then found a .030" shim to put on the other side. When you tighten the flywheel using whatever trick (I use rope in the cylinder BTDC) clock the flywheel forward so it seats on the face of the step and tighten it up. Make sure those tapers are super clean.
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Last edited by Tony01; 01-05-2017 at 02:37 AM.
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Old 11-04-2016, 10:51 PM
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Default Re: briggs timing...firing before tdc??

Here's how it should look. Pm me your address if ya want this key. Is that a Briggs 3.5? You want a high compression head for it too?
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Last edited by Tony01; 01-05-2017 at 02:37 AM.
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Old 11-05-2016, 03:37 AM
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Default Re: briggs timing...firing before tdc??

Great advice from Tony01.
Changing the timing does not raise compression.
You might also consider doing a simple "eyebrow" porting job like this:
https://www.youtube.com/watch?v=s-Li-mwjvlg

Last edited by Springfieldscooter; 11-05-2016 at 03:40 AM.
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Old 11-05-2016, 09:13 AM
curtisfox curtisfox is offline
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Default Re: briggs timing...firing before tdc??

AWESOME Simple tech , thanks for sharing ..............Curt
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Old 11-05-2016, 09:34 AM
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Default Re: briggs timing...firing before tdc??

Ok guys, at first look I thought the black on the cyl. by exhaust was because it was firing at that point, 3/16 before reaching total compression. Looking again I understand that the top ring is 3/16(the 3\16 is just eyeballing it for discussion)down from top of piston, thus creating a gap between cyl.&piston for the exhaust gases to blacken that area. True??? Yeah 01, I would like the hc head...but this is an engine I got in a 5 bundle deal...it has no mag. I've been swap meet hunting for one. This is a learning work in process... Hey I just watched that eyebrow vid the other day. I will be doing that. I'll try key cutting also. Do you just file it? Yeah 3.5

Last edited by scratchbuilder; 11-05-2016 at 09:42 AM. Reason: add thoght
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Old 11-05-2016, 09:51 AM
curtisfox curtisfox is offline
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Default Re: briggs timing...firing before tdc??

Not to sure but think you can by offset keyways, try AGK.............Curt
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Old 11-05-2016, 10:47 AM
curtisfox curtisfox is offline
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Default Re: briggs timing...firing before tdc??

Another take on timing .....Curt

http://motorbicycling.com/showthread...570#post639570
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