Base line tach reading question??
06-03-2003 | 11:23 PM
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From: Richmond, VA
Base line tach reading question??
How do you know what the best RPM/Tach reading is for your engine regardless of prop???
Do you basically still have to go by ear with the engine screaming leaned out to the max and then back it off? Or is there a base line standardized tach reading for each engine?
Or do you go with the Practical rpm range: 2000-20,000 lean it out until you hit 20,000 RPM?
I just about burned up my OS 50 SX By running it lean trying to get as much power out of it... at the time I did not have a tach to see what it was turning.
I think some have been turning 12X4 props at around 17,000 RPM? How do you know when the 17,000 is as high as you can go without burning the engine up?
Do you basically still have to go by ear with the engine screaming leaned out to the max and then back it off? Or is there a base line standardized tach reading for each engine?
Or do you go with the Practical rpm range: 2000-20,000 lean it out until you hit 20,000 RPM?
I just about burned up my OS 50 SX By running it lean trying to get as much power out of it... at the time I did not have a tach to see what it was turning.
I think some have been turning 12X4 props at around 17,000 RPM? How do you know when the 17,000 is as high as you can go without burning the engine up?
06-23-2003 | 11:48 AM
#2
Base line tach reading question??
Every engine is has different specs, I would stay with what the Manufacturer has recommended for both the rpm range, and the prop range. Just check your engine documentation, if you don't have documentation with the engine, I'd go to there website, and find out what the specs are. Then set them up from there.
Once you know what the proper size prop is, setup so that you're running a few hundred rpm off of peak for that prop. (on the rich side), The best way to do that is by the use of a tach, some people can "hear" the rpm drop, but I'm a numbers guy, I like to know what numbers I'm really running! I'd recommend getting a tach then you can tell when you have leaned your engine almost immediately.
Start out rich, then SLOWLY lean it out, the numbers on the tach should start to rise, once the numbers start to drop off you are now running lean!!! Back out the needle to run a few hundred from max before the lean out, and you should be good to go!
Engine break-in will have some influence on the numbers also, if an engine, is brand new you will not get top end numbers out of the engine either, I have heard of some of the big gasser engines needing 6-10 gallons of fuel ran in them before they get top numbers.
Hope this helps!!
Have fun, and be safe!
Specs for the 50sx
SPECIFICATIONS:
Stock Number: OSMG0550
Displacement: 0.499 cu in (8.17cc)
Bore: 0.866 in (22mm)
Stroke: 0.847 in (21.5mm)
Output: 1.8 ps @ 17,000 rpm
Practical rpm range: 2000-20,000
Weight: 13.8 oz (390g)
Recommended Props: 10x8, 11x7
Once you know what the proper size prop is, setup so that you're running a few hundred rpm off of peak for that prop. (on the rich side), The best way to do that is by the use of a tach, some people can "hear" the rpm drop, but I'm a numbers guy, I like to know what numbers I'm really running! I'd recommend getting a tach then you can tell when you have leaned your engine almost immediately.
Start out rich, then SLOWLY lean it out, the numbers on the tach should start to rise, once the numbers start to drop off you are now running lean!!! Back out the needle to run a few hundred from max before the lean out, and you should be good to go!
Engine break-in will have some influence on the numbers also, if an engine, is brand new you will not get top end numbers out of the engine either, I have heard of some of the big gasser engines needing 6-10 gallons of fuel ran in them before they get top numbers.
Hope this helps!!
Have fun, and be safe!
Specs for the 50sx
SPECIFICATIONS:
Stock Number: OSMG0550
Displacement: 0.499 cu in (8.17cc)
Bore: 0.866 in (22mm)
Stroke: 0.847 in (21.5mm)
Output: 1.8 ps @ 17,000 rpm
Practical rpm range: 2000-20,000
Weight: 13.8 oz (390g)
Recommended Props: 10x8, 11x7
