jr dragster T
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Yeah he asked the same thing on another post
The 6.5 HP Engine on Harbor Freight???
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Yeah he asked the same thing on another post
Jerryburger
Admiral Annoy
engine rpm
Russ suggested an item called the "Tiny Tach"... its about $28 on ebay, and it hooks up very easily to most engines. That would help you dial in the proper rpm on your kart.... It has a kinda slow response time, but once you know what 5000 rpm sounds like, the ol' seat-of-the-pants takes over, anyway. Or reverse engineer the whole thing. If you know your tire diameter, gear ratio and the speeds you're hitting, you can figure your rpm that way. This is off the intended subject, though. Sorry.
Russ suggested an item called the "Tiny Tach"... its about $28 on ebay, and it hooks up very easily to most engines. That would help you dial in the proper rpm on your kart.... It has a kinda slow response time, but once you know what 5000 rpm sounds like, the ol' seat-of-the-pants takes over, anyway. Or reverse engineer the whole thing. If you know your tire diameter, gear ratio and the speeds you're hitting, you can figure your rpm that way. This is off the intended subject, though. Sorry.
Yeah, a tach is the most accurate way... And probably the only way. I've heard of people making them theirselves... but I can tell you it ain't easy.
Oh... here's something:
5300RPM - Valves Float
5900-6000 - Expect the rod to go through... (that isn't good)
Oh... here's something:
5300RPM - Valves Float
5900-6000 - Expect the rod to go through... (that isn't good)
How do you identify when the valves float???
Jerryburger
Admiral Annoy
With the present gearing on my lowrider, I should be "safe" up to 52mph (5000 rpm)... I'm off the next couple of days, so I'm going to attempt a top speed run on the thing, just to see what one of these motors will do. I'll time it with the GPS and report back. The motor will be completely stock.
Russ2251
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Usually engine will surge up and down at the point when valves start floating. Almost resembles a high speed lean out. It's unlikely you will experience this if engine is running under a load unless you and kart are very light in weight.
Russ2251
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It has been my experience that any engine (not just clones) will 'blow up' if over revved without a load.
Loads tend to smooth out combustion pulses which, among other things, causes rods and crankshafts to flex and bend. Take away the load and engine won't live very long.
This is one of the reasons that horizontal shaft engines have heavy flywheels.
Loads tend to smooth out combustion pulses which, among other things, causes rods and crankshafts to flex and bend. Take away the load and engine won't live very long.
This is one of the reasons that horizontal shaft engines have heavy flywheels.
Jerryburger
Admiral Annoy
Just changed the oil on the lowrider to synthetic after about 3 hours of break-in on regular oil. Came out clean and hardly any discoloration. These motors are amazing. Quite the far cry from the old 2- 3hp B/S engines I grew up with! Between these motors and the 2-stroke snowblower engines Russ found, I don't think a person can go wrong.
It's basically when the valve springs do not retract the valves fast enough... and then the piston hits it...
When will u post ur results? Soon?
Jerryburger
Admiral Annoy
Today, hopefully. It should be a "go".... I can do GPS or video, and I promise to post the results. It has new tires and a new seat on it, so it should be a fun run!
Jerryburger
Admiral Annoy
Okay- finished a couple of runs.... it hit 47 in one direction and 49 the other, so we'll call it 48mph with my fat butt on it. Nothing weird happened, but I figure the motor didn't hit over 4700rpm, either. Posted a video under the Photo-Galleries section. Now I've got a few chores to take care of!
Russ2251
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Hits what? A valve? This would be a really nasty design flaw and is not correct. Valve float actually prevents this from happening.
Russ2251
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Could you please post link where you saw this? Would appreciate it. I'll take up my argument with them. Thanx
Could you please post link where you saw this? Would appreciate it. I'll take up my argument with them. Thanx
Problem is, I read it around 4 months ago. Heck, I don't even remember the title name (seriously)...
I was just browsing through looking for mods (I didn't know squat back then)...
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