i have just completed my first 4 mill stroker motor, and i was wondering wut i should run for timing. i have the cometic 1.0mm spacer under the jug so u guys kno. im lookin to get around 165-180 for compression i will update u tonite on how much psi my motor has. im just lookin for a ballpark range and im gonna do half race gas half 93octane. and just incase u guys need to kno i have a fmf fatty with a custom fmf silencer i made thats about 6in long, carbon 2 stage reeds, .040 over, ported jugg, 3/8 reed spacer, bored carb in my lathe to 27.5mm(untill i get a bigger carb), adjustable timing plate and theres prolly stuff im forgetting. thx for ur time!
blaster 4mm stroker timing question
- Thread starter jreds4mill
- Start date
12.25 compression ratio, 180 psi will require an octane ratio of greater than 100.
11.25 compression ratio, 165 psi will require an octane ratio of about 97.
If my information on compression ratio vs octane rating is correct, I would be sticking at stock timing to avoid detonation.
Its been a while since I broached the subject, so my info could be a little marred and I am open to correction from ones who know better.
To obtain compression ratio divide psi by 14.7
11.25 compression ratio, 165 psi will require an octane ratio of about 97.
If my information on compression ratio vs octane rating is correct, I would be sticking at stock timing to avoid detonation.
Its been a while since I broached the subject, so my info could be a little marred and I am open to correction from ones who know better.
To obtain compression ratio divide psi by 14.7
the head was milled .010 to clean up and i polished the dome thats it eventually im gonna rechamber the head in my lathe at work(cnc) i got all the dimension's just gotta write up my program and yes the cases r trenched and have plenty of clearance for the rod&swing i circle interpulated the cases in a cnc mill at work. thank u for all the replies
yeah, not sure with just a "shaved head"
better get a properly re-chambered head before you start playing with timing.
who knows what compression thats going to give you, and the squish/chamber shape are way off.
I am led to believe that a re chambered head requires stock advance, due to advanced combustion properties.
I don't run any of my bikes on stock timing. They are all advanced quite a bit with a rechambered head on all of them. Nothing wrong with advancing the timing. If you know how to read a plug it will never be an issue.
ya so do i and thats wut i always said wether its a atv snomobile car/truck if its tuned right u wont have ne problems. and u gotta read how far down or up the strap the brown stops to see hopw far advanced it is correct?
Looks nice,great job!! I would suggest throwing 2-4 degrees advance at it,read the plug and adjust accordingly. IMO it's free power. You shouldn't need any more than +4 at most with your setup.
