View Full Version : Protolite MXT 22hp Predator 670 engine

02-18-2016, 10:04 AM
Just finished putting a Predator 670 engine in one of our MXT kids buggies for a customer.
electric start , CV-tech cvt clutch setup.

have not tested it outside the shop yet, but it really has low end power inside the shop [smilie=ext_doc.gif] [smilie=rockout3.gi:

8:1 gear reduction, should have a top speed 55-58mph
20" tires

hope to get some video Saturday,,, snow is melting here

My son is chomping at the bit to test drive it on our snow covered track

here are some pics

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02-18-2016, 10:48 AM
Awesome! Why wait for the snow to melt...get on it!

02-18-2016, 11:12 AM
Awesome! Why wait for the snow to melt...get on it!

lol, my test driver is at school then basketball game
I asked wife if I could go get him from school to test drive for me,,,,,,,nope [smilie=dunno.gif]

02-18-2016, 11:54 AM
lol, my test driver is at school then basketball game
I asked wife if I could go get him from school to test drive for me,,,,,,,nope [smilie=dunno.gif]

man up buttercup... go get your son if you want to.

just kidding. my wife is the boss too. :D looking forward to hearing about the test drive.

02-18-2016, 09:38 PM
Looking forward to how this one runs.... Love that MXT frame.

02-18-2016, 10:05 PM
Time to change the stickers to mxt 670!

herman pahls
02-18-2016, 10:54 PM
Looking forward to the test results.
I am curious why this build only gets 8-1 reduction and the Vegas buggies got 13-1 in the reversing box.
Are the rear tires that much different in diameter or am I missing an important detail like you are not limiting the top speed to 40 mph?
What size and quality of chain are you using.
I am curious how you adjust those 2 chains.
The rear axle and driven shaft appear to non adjustable.
Does that idler shaft somehow adjust up and down and forward and backward to adjust both chains at the same time?

02-19-2016, 07:01 AM
Thanks guys, yes time to change the stickers to 670 :D

motor adjusts on the motor plate to the first shaft which is fixed / welded to the motor plate. Motor adjustment on the plate is for belt tension

motor plate slides and adjusts on the swing arm to which the rear axle is fixed
this allows for chain tension adjustment on one chain

2nd shaft / bearing assembly is on the bottom of the motor plate and moves with the motor plate and it has adjustment bolts to slide forward or back independent on the motor plate and then lock into place

this allows for independent adjustment of each chain separately

Vegas buggy has 13:1 because it is heavier and 2 person and needed to limit top speed to 45mph

MXT buggy has smaller tires , lighter, single seat and do not need to limit top speed to 45
These are for kids who bracket race sand drags at silver lake
so I set the top speed at 55-58 mph

with the dual jack shaft set up , I can get to 15:1 if needed.
but the drag strip is 300' long and at 8:1 I am trying to maximize low end torque and take off, with a top speed for their application

chain is 428

02-20-2016, 01:45 PM
That's one bad ass little buggy... What does it weigh I can't wait for the video

herman pahls
02-21-2016, 12:53 PM
Thanks for the detailed explanation of how the belt and 2 chains adjust.
Taking a closer look at your photos and noticing the slotted holes it all makes sense.
To help with these builds I just ordered a bigger metal lathe and unfortunately for my Visa card it is becoming clear that a milling machine is also needed, especially to make all those slots.
Is there a poor mans way to make slotted holes other than drilling multiple holes and filing out the slot?
Your website says you do not sell sprockets.
Are you selling the #428 sprockets you used on the 22HP MXT or are those one off for this project?

02-21-2016, 02:03 PM
I design everything 3D cad then order laser cut plates with the slots in them.
or we have a CNC mill and 2 Bridgeport mills

if you want to make slots old school,,,, drill 2 holes and use a jig saw with metal blade to cut between them and make the slot.
or have your local machine shop machine them in.
Both options are of course way cheaper than buying a mill unless you plan on using the mill a lot

We have a ton of parts that we have not found the time to put on the website yet.
these are #40 sprockets and are available, just shoot me an email to order until they make it on the site

snow melted, but our test track,,,, is super deep mud with the frost coming out of the ground right now :(
still got a test drive outside yesterday though.
very limited video, but I will try to put some together this week.

this MXT has serious low end power and we did not even get close to checking out top speed,,,,,but wow is it fast in this chassis :D
I have no doubt it will top out 55-60 with this gear ratio

weight,,,, have not scaled it yet with the new motor set up and bigger wheels / tires
I am guessing 450lbs

02-22-2016, 08:28 AM
Having had a chance to visit Jody & his wonderful shop (several years ago), I can vouch for the wide variety of parts & the quality of the workmanship.

Love the new MXT frame with this new 670 though... Looking forward to the video, but the weather description brings forth images of what could be a great mud buggy...:)

02-26-2016, 11:15 PM
Thanks Antioch!

got the second one done today
Had no time to mess with the video this week, maybe I'll get to it tomorrow morning

couple of pics of the two MXT670 little rocket ships,,,, they haul azz

https://scontent-ord1-1.xx.fbcdn.net/hphotos-xaf1/v/t1.0-9/12512480_1114890028529212_3914610670359073642_n.jp g?oh=5a961abe94f7a018afa2729301b1f3cd&oe=576CCB16

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02-29-2016, 10:11 PM
Ok , got a short video put together

don't get too excited though.
Only place we could run it was around the shop drive,,and yard.

dog lovers,,,, don't freak out when Jesse (15 year old son) almost hits my dogs,,,,,,twice
Damn dogs always intentionally feel they need to lead every vehicle
UPS, Fedex,,, mail lady,,,every vehicle that shows up,,,,have to walk right in front of it.

Customer may pick them up and test more here if the track dries out.
Then I will try to get more videos,,,
our track is .2 miles long so should be able to get some speed [smilie=big_explode:

anyhow, heres a short clip