YAMATO 80 TIMING

[pburgford]

I do not know how to time an Yamato 80, looking for help. I live in Snohomish, Wa . Please feel free to contact me via this post, email or call (425)315-5518. Thank You, Glen

[jeff55v]

This is a good start. Go to the top of the page, select owners manuals- Yamato 80.
I'm sure others will chime in with more help.

[pburgford]

Thanx, Will Check it out! Glen

[ZUL8TR]

What tools/gauges do you have to do the timing? Do you have a buzz box, dial indicator, feeler gauges? At the same site jeff55v noted there is a tech area and here is the timing DIY

http://yamatoracing.com/technical_entry.php?pid=8

See your PM

[dholt]

We won a ton of races at .265 timing the Y-80.

[ZUL8TR]

We won a ton of races at .265 timing the Y-80.

Stock Y80? That is really up there with a lot of piston heat considering max is 0.200 factory, I was told 0.220 from Tom Cronk and about same from Peanut Pinner. What type oil and mix ratio were you using?

[dholt]

6 oz/gallon of synthetic. Probably could have run 5 oz there was always extra carbon on pistons. Never had any issues with cylinder temp.
You have to test with heat gauge and speedo. Each motor may react differently. Whatever is fastest and doesn't burn the piston...that's all that matters. But we had 3 engines...all ran same timing and same speed.

[ZUL8TR]

6 to a gallon is 21.3:1, 5 per gallon is 25.5:1 that is about right on, manual has 25:1. What brand syn are you using and best heat set up speed on the Y80? What rpm?

[ryan_4z]

I may be wrong, but isn't the timing measured as below top dead center? Meaning, the larger the number the lower the timing. Never ran a Y80 but we had 302s that liked to be anywhere from .180 to .255. They ran the same speed but not if you reversed the timing from one to the other.

[Matt Dagostino]

Ryan.........the higher the timing the 'hotter the burn'...............we run at.235-.240 btdc. Hard to argue with Dana. He did win a few titles with the ole reliable Yamato 80. Actually we have never seen much difference from .200-.260btdc as far as performance. The higher timing is important with 18mm heads where the only sparkplugs that are available are NGK-10 which is a cold plug! The higher timing helps from fouling plugs in the cool weather.Maybe what your thinking about Ryan are the spark plug index. NGK spark plugs work opposite from what you may think. The higher the number (NGK-10) the colder the plug. In the old days you could get NGK-9 in a 18mm plug but now only the NGK-10 is available for the bigger head hence the higher timing helps balance out the operating head temp.If you run the 14mm head then NGK-9 plugs are available and no fouling worries at any timing.

[ZUL8TR]

You are right . The timing is the piston position before top dead center (BTDC) in inches (or mm) for the spark to occur. The larger the number the further the piston is BTDC. The timing determines when the coils release their energy and the spark starts and the fuel starts to ignite and the flame front expands in the combustion chamber. Idealy the timing is set so that the fuel mostly is consumed by about 5 degrees ATDC (after top dead center) for the max pressure on the piston to push it down for power stroke. At high rpm this happens very quickly. Timing is rpm specific so one setting can't fit all rpm. Timing on these race engines is set and the magneto is locked for no movement during the race to keep it accurate as set.

[ryan_4z]

Matt, that is what I am getting at. Dana's timing is the lowest mentioned on this thread. Therefore a 'cooler' burn.

[deeougee]

I can back Dana up on the timing. I run 270. Without getting into a longwinded engineered answer, it's all about port timing, among other things.

[ZUL8TR]

Since this is a timing thread would like to hear the long winded answer.

[runabout333]

.245 BTDC.. 3 pints to 4 gallons... VP C-12,, Mercury 2 stroke oil... Never had a problem,,,, but there again,,, I never won the Nationals...

[Top Gun 3-Z]

I just won the nationals with my 80 it was modified but I don't run my timing no where near any one on this thread .So I would say try different timing with different props carb setting etc you'll get different results it's whatever works with your climate pitch prop gas mixture it can get real technical 1/2mph is the difference between me passing you and you passing me lol

[ZUL8TR]

I just won the nationals with my 80 it was modified but I don't run my timing no where near any one on this thread .So I would say try different timing with different props carb setting etc you'll get different results it's whatever works with your climate pitch prop gas mixture it can get real technical 1/2mph is the difference between me passing you and you passing me lol

So what timing(s) have you run on the 80?