yamato ignition timing

[piranah racing]

hello, i was hoping somebody might be able to explain what measurement the ignition timing should be set to and what will change by altering it. I have a dial gauge to set the timing with but i've never tried it before, it seems to be about 6.4mm BTDC at present. If i changed it to 6mm BTDC will this give me more top end power or low down power?

thanks for any help

[seanp3]

The specs from the manual for the 102 and 302 call for .200 to .250 BTC (not metric). The Yamato 80 manual calls for .180 to .200 BTC.

[B Walker]

Advancing the timing gives you more top end, retarding the timing gives you punch.

Just remember "retarded for runabouts".

BW

[ZUL8TR]

timing

The best procedure is to start with the OEM setting and test under different prop, weather, fuel, jetting etc. conditions for performance in acceleration and top end and note results. In this process inspect plug readings and the top of the piston for detonation by viewing thru plug hole for preliminary determination. Here is link on piston failures

http://www.boatracingfacts.com/forum...ead.php?t=5472

Here are links on plugs. In first link read down the page on ignition timing and how to read plugs. Note that the author Gordon Jennings is an expert on 2 cycle engines and has written much on tuning them

http://www.strappe.com/plugs.html

Next link is general info on plugs but it is more involved than this.

http://www.ngksparkplugs.com/tech_su...qs/faqread.asp

Also note that in Japan paramutal boat racing they run the yamato engines at lower rpm than in other boat racing with Yamatos. Therefore Yamato timing setting will be effected by that increase in rpm.

And some engines respond better with less advance, hotter plugs and richer mixtures.

So timing setting is not an easy simple answer but one that testing will reveal.

[piranah racing]

Thanks for the advise guys, it's starting to become a little clearer

[PRO-MOTIONRACING]

15/64= 0.2344= 5.9531mm
1/4= 0.2500= 6.350mm
Looks to me like you would want to be about 6mm