2015 - DesertDuler

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chancer

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So.... Is this why Kelly painted his old helmet for a "real track" this Saturday. Hmmm the 24th.
Sounds like fun.
 

Lucky7

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Desert I just read through this whole thread and that is one badazz kart you made. Do rotary engines make more power than standard 4,2 strokes,etc. I really have no idea how a rotary engine works expect that they sound really mean.
 

Desertduler

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So.... Is this why Kelly painted his old helmet for a "real track" this Saturday. Hmmm the 24th.
Sounds like fun.
Could be chancer! :lolgoku:

---------- Post added at 08:22 PM ---------- Previous post was at 07:56 PM ----------

Desert I just read through this whole thread and that is one badazz kart you made. Do rotary engines make more power than standard 4,2 strokes,etc. I really have no idea how a rotary engine works expect that they sound really mean.
Thanks Lucky! Rotary engines do not have as much bottom end as a four stroke poppet valve engines but they have more top end power than most four stroke poppet valve engines, they are four cycle engines that fire every revolution and all of the cycles are 270 degrees, they have a power band kind of like two and four cycle engines mixed together but without vibration and of course they have no valve train to worry about but they are prone to apex and side seal wear if they are not taken care of and if they are fed cheap oil, this engine is very rare and I have done some mild port work to it and I could do more to it and get more power out of it but there is really no need because it is powerful enough as is, one would have to take it for a spin in real life to see what I mean as the engine is as smooth as an electric motor not the norm by any means, they have their drawbacks but positive things about them too that I like.
This engine is 40 years old and in pristine condition and yes indeed they have their own sound that can not be duplicated.

---------- Post added at 08:26 PM ---------- Previous post was at 08:22 PM ----------

Listen to this Mazda 787B
https://www.youtube.com/watch?v=az39eqLIbyU
 

Lucky7

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Yeh they do sound real nice. I think Mazda made rotary engines in the rx7??? I love the sound. They sound way better than a 2 stroke. I know the design of it. In my mechanics they have a cut-away of a small rotary engine so I can kinda grasp the idea but I have never had it explained in any depth. Thanks for replying.
 

Desertduler

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Yeh they do sound real nice. I think Mazda made rotary engines in the rx7??? I love the sound. They sound way better than a 2 stroke. I know the design of it. In my mechanics they have a cut-away of a small rotary engine so I can kinda grasp the idea but I have never had it explained in any depth. Thanks for replying.
Anytime! Thanks for the interest :thumbsup:
 

machinist@large

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Brett, correct me if I'm in error, but isn't the simplicity of the rotary engine off set by the complexity of it's manufacture? Round holes in a fixed pattern are relatively easy to produce; the semi hour glass shape of the rotor section is a different story.

The same goes for combustion chamber sealing; the swept area of the nine seals is extreme, even before you consider the fact that each one has to do the same job as the most common three stacked piston ring set.

My take? An impressive piece of engineering, but most definitely not for your first time small engine owner. Properly cared for, they're impressive. Hand one to a hack? I pity the poor thing.....
 

Desertduler

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Brett, correct me if I'm in error, but isn't the simplicity of the rotary engine off set by the complexity of it's manufacture? Round holes in a fixed pattern are relatively easy to produce; the semi hour glass shape of the rotor section is a different story.

The same goes for combustion chamber sealing; the swept area of the nine seals is extreme, even before you consider the fact that each one has to do the same job as the most common three stacked piston ring set.

My take? An impressive piece of engineering, but most definitely not for your first time small engine owner. Properly cared for, they're impressive. Hand one to a hack? I pity the poor thing.....
You are correct Pat, one can debate the pros and cons about them but once you have owned one you most likely will think that they are way cool besides that they are the only engine that has been massed produced and used in vehicles other than the reciprocating piston engine, I can't say enough about their lack of vibration, I own more of these engines that I will use in future builds.
 

Desertduler

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Looks like the weather will be perfect tomorrow at the asphalt track, 64 f and sunny, I will have to jet both the karts up about one step on the mains and maybe reset the needles and air screws in order to keep the engines on the safe side and allow for the denser air, as a rule of thumb after I have set a jetting baseline for a certain engine and combination, temperature changes plus or minus twenty degrees and or 1000 ft in elevation deviation the jetting must be changed in order for these changes plus changes in humidity.
Both karts should put out some good power tomorrow.
 

Desertduler

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So I headed out alone this morning and when I arrived it was pretty cool so I unloaded the karts and jetted them one step rich from where I had them at 80 degrees and after taking a few laps on both of them I did a plug reading on both engines and they were good so I proceeded to run the karts all day long with no problems at all, watch the video and you will see one mean little rotary engine with a hot tune up done to it, the kart handles excellent on the asphalt, a fun day indeed! With this 32 mm Mikuni carburetor on this engine it will turn a little over 8500 RPM which I have noted when I tested this set up with this engine on my kart before, I am really happy with this kart.
https://www.youtube.com/watch?v=ot4SnrDAtFQ
 

Desertduler

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Looks and sounds awesome. What was your approximate top speed?
Thank you, 50 mph and change at least for sure, enough to get you killed or life flighted away if you mess up. I will have to GPS it to get a better estimate, this is not a toy! :lolgoku:
 

chancer

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That is a cool video. Looks like fun. How long is the track. Does your red kart go as well as the new one?
 

Desertduler

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That is a cool video. Looks like fun. How long is the track. Does your red kart go as well as the new one?
You know I did not have a way to measure the track other than if I drove my truck around it and checked the distance with my odometer, maybe a little over a half a mile. This kart handles better than my red kart and I think this one would spank my red one on a short tight course for sure, the power delivery is different between these two engines but if you drove the two one after the other the red one vibrates and feels different than the yellow one to a degree, the videos do not give one the sensation of the real on board feel of any kart for sure and one cannot relate to the G forces that are induced in the corners, to be honest about these two different engines I would take the rotary over the two stroke powerhouse just because it is so smooth and the powerband is more predictable and less violent than the Rotax 277 even with the reed valve installation, you would have to drive them both to see what I mean but they both rip, just different. One has to remember these engines are snowmobile engines and not small utility engines and they are very powerful and high revving engines that can get you in trouble real fast if you are not careful.

---------- Post added at 10:28 PM ---------- Previous post was at 10:25 PM ----------

Holy **** that is fast.
The thing is Lucky, there is always something faster. :thumbsup:
 

dwcopple

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Cool vid for sure! I just wish you had some third person views by someone filming the driver in the kart instead of cockpit view only.
 

Desertduler

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Cool vid for sure! I just wish you had some third person views by someone filming the driver in the kart instead of cockpit view only.
Thanks, I couldn't get anyone else to go with me to do any filming.
My wife was going to go with me until her plans were changed by one of our kids.
 

chancer

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Well since "you would have to drive them both to see the difference" I will have to stop by if I am ever in Utah, Plus it sounds like you need a camera man.:lolgoku:
 

Desertduler

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Well since "you would have to drive them both to see the difference" I will have to stop by if I am ever in Utah, Plus it sounds like you need a camera man.:lolgoku:
If you do come to Utah let me know and I promise I will let you drive them both out on the lake bed, we will make a day of it. :thumbsup:
 

chancer

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Thank you. But unfortunately other than go karts I cant think of any reason that I would ever be in Utah. LOL
 
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