One Of Boostinjdm's Toys

[boostinjdm]

Here is one of my toys. It is a tinker toy compared to most builds on this site, but you gotta start somewhere and at this point I would rather spend money on equipment than a big budget build. It is almost completely built out of scrap. The rear, as it sits, has about 6" of travel and the front about 8". I was going to put an SR 500 engine in it, but that got removed and then wedged into my Blaster. Now it is going to get this 13hp honda clone with a 40 series torque converter. The rear swing arm is attached via 3/4" heim joints for alignment and lenght adjustments, and the front is double A-arm with heims everywhere. It is very light, and the way it is in the pics two guys can pick it up and put it on my 30" tall stand I built. The last buggy ran across the scale at 320#s without driver and this one is quite a bit lighter. I am expecting under 300#s when all said and done. Right now there is one question I am trying to answer. Should I rubber mount this engine or not. It is a big one lunger and in my lawn mower vibrated pretty good. Driven shaft will be solid mounted in line with my rear swing arm pivots to eliminate the chain length changes through travel. Will rubber mounting the engine greatly affect the torque converter operation? I have never used a torque converter before so this is new to me. With the gearing I have chosen, and tire size, this will top out at 49mph. The ratio from crankshaft to axle is 10.91 on the low side and 4.78 on the high. I also have ordered gears for 12.73 on the low and 5.58 high. From past projects this gearing seems about right, but I guess time will tell. I will mostly be running on flat ground with a hill once and a while, jumps and whoops don't really excite me. Mike

[WelderPat]

It kind of looks like this.

[boostinjdm]

I kinda like the way dwarf cars look so that's what inspired the shape.

[boostinjdm]

Another question... I would like to get rid of the stock carb on this motor and put a round slide carb on it for ease of tuning and throttle linkage. If I do this then I lose the governer. Will I have a prob with the engine over revving if I floor it? In my racing kart the rpms are limited by gear selection on a given track but in this situation if I put the pedal to the floor and run in a straight line for a long time won't the engine over rev? Like I said I am new to this cvt thing. I would prefer to keep the engine governed if I could. Any one got an idea for a rev limiter? Possibly electronic?

[TutTech]

I am no good with motor questions so hopefully someone can help you out there but
I like the project and I agree a good project is priceless.
It does not have to be expensive to keep you busy and happy.

Keep up the cool build and as long as its safe, fun and you enjoy it
then keep on doing it.
It looks like your doing a good job from the photos.
Keep us posted.

[masternate]

it looks like your own COOL version of the Sidewinder!!


*if you havent seen the sidewinder....

The EDGE Products - The Sidewinder


or was that your inspiration?

COOL BUILD!

[boostinjdm]

I looked at sidewinders a long time ago. I just don't like them. Too many sharp points and square tube. Plus the swing arm just looks goofy.

[nutz4sand]

Originally Posted by boostinjdm

Another question... I would like to get rid of the stock carb on this motor and put a round slide carb on it for ease of tuning and throttle linkage. If I do this then I lose the governer. Will I have a prob with the engine over revving if I floor it? In my racing kart the rpms are limited by gear selection on a given track but in this situation if I put the pedal to the floor and run in a straight line for a long time won't the engine over rev? Like I said I am new to this cvt thing. I would prefer to keep the engine governed if I could. Any one got an idea for a rev limiter? Possibly electronic?

As the CVT shifts out it will be tough for the motor to over rev scince you are pushing a little bit of weight and unless the gearings real deep but it is possible.

The governor is a mechanical lever that pulls the carbs butterfly valve back correct? You could attach that lever to a simple switch that cuts (grounds out) the coil thus looses spark. You might be able use the spring on it that the governor lever fights now IF you do not change the lever length. (Otherwise you will be searching for that "just right tension" spring. Put the spring on a threaded (adjustable) mounting point on the "fixed" end (The one not attached to the governor lever) and you should be able to use it to limit the top end revs if the CVT does not hold it down by itself.

I have not seen one but I would bet the briggs guys who run go karts have a electronic governor of some kind to keep those built briggs from overrevving. Bill

[masternate]

i was talking about how you sit next to the engine...and yes i do agree that they are too pointy!

[boostinjdm]

The briggs guys don't run governors. The Animal and World formula engines are limited by track condition and gearing choices. If you choose the wrong gear you over rev.