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Old 05-04-2010, 01:44 PM   #31
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CHANGE THE PLUG!!

what engine is it? some run very well at the low temps and some don't, 1.5 gallons it should be broke in fully by now . if you are happy with the power delivery why mess with it ? the runtimes tell me your tune is a little off though
No Offense intended toward psychoB4 at all, but he could be driving on the throttle a little to much too.. I've noticed I loose anywhere from 1-3 minutes depending on how hard I am driving.. Obviously the harder I drive it the lower the run time gets.. Only a few engines like the low 200 range, most are sirio based.. I run a Extech .24 on my truggy and it stays around 200 most of the time, and I get near 12 minutes w/JP6 pipe. But I have run it dry in 8.5minutes before.. I was driving really hard and was upside down more than usual..
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Old 05-04-2010, 04:12 PM   #32
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i was thinking on this last weekend,my jx21 was 189f,i tried to lean it & i end-up 204f (empty tank) it will idle all day long ,i know my hsn is set ,is it fine to lean it more cause i remember the hsn is 2 out turns from close??already
i know some engines tune different, but i can tell you for a fact anything more then 2 turns out on a jx is too lean. I don't care what the humidity or altitude is. 2 turns out MAYBE. but that is still too lean. Mine stays around 2 1/4 most of the time give or take an hour. All my o.s. engines do

the jx runs colder then the vspec. I had the same problem for a long time until i realized it was not a problem. One of the best drivers in my area runs nothing but jx's and he temps about 175 after a main. I think it has something to do with that oversized block or lightened cooling head. I would always try to lean it out to get it hotter, DONT! You will ruin your engine.

If anything go in on your LSN but anything more then 3 1/8 is getting too lean.
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Old 05-04-2010, 04:22 PM   #33
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No Offense intended toward psychoB4 at all, but he could be driving on the throttle a little to much too.. I've noticed I loose anywhere from 1-3 minutes depending on how hard I am driving.. Obviously the harder I drive it the lower the run time gets.. Only a few engines like the low 200 range, most are sirio based.. I run a Extech .24 on my truggy and it stays around 200 most of the time, and I get near 12 minutes w/JP6 pipe. But I have run it dry in 8.5minutes before.. I was driving really hard and was upside down more than usual..

Very true Buddy and NO offense taken. I drive my Buggy hard, and really I try to drift it around most turns. The Losi rear is so light and soft that I can throw the weight around like my drift car. thats how I been driving me buggy hahaha. But If I drove my buggy harder MRC, wouldnt that bring the temps up also??
I have to time myself this weeknd see how many mins Im getting per tank.
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Old 05-04-2010, 04:26 PM   #34
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Can anyone explain Venturi's and why they are used? My Engine has 2 and Id like to know why and what I can do with them. Thank you
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Old 05-04-2010, 04:50 PM   #35
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Can anyone explain Venturi's and why they are used? My Engine has 2 and Id like to know why and what I can do with them. Thank you
the shape of it funnels or streamlines the air through the carb. I guess you could call it the venturi affect or something.

everything is about air flow in these little engines. The silicon ramp, rounding off the bottom of the sleeve, the fangs on the ports etc.
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Old 05-04-2010, 04:52 PM   #36
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the shape of it funnels or streamlines the air through the carb. I guess you could call it the venturi affect or something.

everything is about air flow in these little engines. The silicon ramp, rounding off the bottom of the sleeve, the fangs on the ports etc.
ok so what does me going from 8 to 7 or 7 to 8 etcc do and why does what make what faster and better.
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Old 05-04-2010, 04:55 PM   #37
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ok so what does me going from 8 to 7 or 7 to 8 etcc do and why does what make what faster and better.
one of the more expierienced guys can answer that for you a little better then me. I know the smaller the number the less air it gets, the less air the less fuel it needs = longer run times. But you should always have some sort of insert in there. The carb neck is very rough.

if you have a jx, speed or vspec the 7 is money.
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Old 05-04-2010, 05:05 PM   #38
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Smaller venturi for longer run times is right. Usually get less power too, but your track usually determines what venturi you want to use. Sometimes even makes you faster if you don't control throttle trigger as smooth as you should LOL.
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Old 05-04-2010, 05:21 PM   #39
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Smaller venturi for longer run times is right. Usually get less power too, but your track usually determines what venturi you want to use. Sometimes even makes you faster if you don't control throttle trigger as smooth as you should LOL.
Now if you change the Venturi, do you have to Re-tune the Engine? Since you are drawing more or less air?
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Old 05-04-2010, 06:37 PM   #40
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Now if you change the Venturi, do you have to Re-tune the Engine? Since you are drawing more or less air?
Yes each time you change to a different size carb insert you need to retune.
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Old 05-04-2010, 07:11 PM   #41
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Now if you change the Venturi, do you have to Re-tune the Engine? Since you are drawing more or less air?
Yes you will have to re-tune. That is in fact the purpose of a venturi. Running a smaller venturi will require a leaner setting, thus it will give you better runtime. The smaller the venturi the better the runtime, but the lesser the top end of the engine(bottom end is not affected much). If you find you can sacrifice a bit of top speed, running a smaller venturi will get you more mileage.
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Old 05-04-2010, 07:20 PM   #42
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Yes you will have to re-tune. That is in fact the purpose of a venturi. Running a smaller venturi will require a leaner setting, thus it will give you better runtime. The smaller the venturi the better the runtime, but the lesser the top end of the engine(bottom end is not affected much). If you find you can sacrifice a bit of top speed, running a smaller venturi will get you more mileage.
thank you sir
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Old 05-04-2010, 07:30 PM   #43
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thank you sir
Not a problem. Which engine are you running? What are you running it in? What general size are the tracks you are running on? What pipe are you running?

Edit: Never mind I see you are running the OD engine and JP-4. I would think a 7mm should be plenty in a buggy.
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Old 05-04-2010, 07:31 PM   #44
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Not a problem. Which engine are you running? What are you running it in? What general size are the tracks you are running on? What pipe are you running?
Right now I got the OD SS .21 I think it is Superb. Very Smooth And easy to tune. Love it! 1.5 gallons and runnin strong 200F 206 max so far.
Pipe I have the ofna 086 or the Jp-1, just bought the Dynamite 007ht was told it was the same as the jp-1... Buggy is a losi 2.0 and track size idk normal? 30-40 sec laps
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Old 05-04-2010, 07:38 PM   #45
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Right now I got the OD SS .21 I think it is Superb. Very Smooth And easy to tune. Love it! 1.5 gallons and runnin strong 200F 206 max so far.
Pipe I have the ofna 086 or the Jp-1, just bought the Dynamite 007ht was told it was the same as the jp-1... Buggy is a losi 2.0 and track size idk normal? 30-40 sec laps
The 007 is not the same as the JP-1. Not sure who told you that, but they are far from the same. They are both low end/torque pipes but not the same. I don't know much about the OD engines, but a 7mm should be a good starting place for a venturi.
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