View Full Version : how to build a shifter kart with a mx cr125 engine???
hello everyone i am a complete novice to go karts but i am planning 2 building a shifterkart for summer 2010 just for personal use. so please can anyone tell me where i can sorce parts from and some sort of build guilde and would i be able to use a kx125 engine 92 or a cr125 engine 96 because i already have these engines lying around.:thumbsup:
motor_head
10-11-2009, 08:05 PM
that building guide you speak of is your head always more satisfying when you design it your self
modelengineer
10-12-2009, 04:05 AM
You need to be more specific with your question. Just start making some drawings and post them here if you're not sure.
You need to be more specific with your question. Just start making some drawings and post them here if you're not sure.
ok i have done some research since my post i konw i want to make a shifter kart using a honda cr125 engine. i have seen it done on here, i have now found a engine mount kit which just bolts on the frame. now where can i source parts like an axle, brakes, wheels, pedals, and steering gear, hubs, fuel tank fuel pump if i need 1, any1 no where i can i get these parts from to fit an rotax chassis???
i jus want some advice i dnt fancy welding a frame together so i will much rather buy the parts to bolt on a good well made chassis which will be able to handle the abuse.
is the any threads on here about the gear shift mod cuz i wud like to see 1 fitted?
Smurph
10-12-2009, 02:45 PM
There are plenty of videos on here about the shifter.
Get you an old margay frame or something, you can find them all over the internet. Check ebay and craigslist.
Mounting the engine won't be too difficult. You might need a good drill if your holes don't match up. The worst case scenario is that your mounting plate would need moving, then you might fire up a welder.
Typical bike engines have a lever that you're supposed to operate with your left foot to shift. Take the lever portion off the shaft, and add a much longer pole/shaft that goes up to where you can grab it from the driver seat.
One idea for the clutch is to keep it a lever (just like on the dirtbike), but attach it to the longer pole or shaft.
That's a good idea on how to do it pretty cheap. Don't be afraid to make it a way that looks better or works better for YOU.
modelengineer
10-12-2009, 04:43 PM
Take the lever portion off the shaft, and add a much longer pole/shaft that goes up to where you can grab it from the driver seat
Bad idea. The weight of the lever can cause the bike to shift by itself when you go over a slight bump, not to mention it can wear out the mechanism from the constant pressure on the lever.
Better to make a new lever where you can use it, and connect it to the original shifter with a push-pull cable, or a linkage.
anderkart
10-12-2009, 06:12 PM
where can i source parts like an axle, brakes, wheels, pedals, and steering gear, hubs, fuel tank fuel pump if i need 1, any1 no where i can i get these parts from to fit an rotax chassis???
Rotax makes a very popular kart racing motor, but as far as I know they don't make a chassis. Looking around the net, you'll see the term "Rotax kart" used a lot, they're talking about the engine and the class it races in. (these karts/engines don't have a transmission)
Many of the shifter kart parts you mentioned will interchange between several different brands of European race chassis.
I noticed your from the UK. and I just discovered something kinda important, In the UK racing shifter karts are called Gearbox Karts. So use that term when searching the net for used karts and/or new part suppliers in the UK.
Check out this search: http://www.google.com/search?sourceid=navclient&ie=UTF-8&rlz=1T4DMUS_enUS221US222&q=Gearbox+kart++UK.
Here's Rickracers shifter kart thread, he's got a bunch of good build info posted that might help you out: http://www.diygokarts.com/vb/showthread.php?t=4742&highlight=shifter+kart+video
This video shows the shifter/clutch paddles under the steering wheel:
http://www.youtube.com/watch?v=1u53K8AufxY
lol thanks for correcting me mate see i told ya i am a novice, i am new to the karting world, i look stupid now lol. what sort of chassis/frame shall i be looking for? shall i buy 1 of the engine mount kits or make some sort of mount myself? thanks for the help:thumbsup:.
02mx-5
10-13-2009, 10:25 AM
If you want a build guide, you came to the right place. Just read through all of the realated threads. Its been discussed MANY times on this site.
anderkart
10-13-2009, 04:10 PM
lol thanks for correcting me mate see i told ya i am a novice, i am new to the karting world, i look stupid now lol. what sort of chassis/frame shall i be looking for? shall i buy 1 of the engine mount kits or make some sort of mount myself? thanks for the help:thumbsup:.
You didn't come off looking stupid at all man, we always refer to these karts as shifters on this forum, I'd never even heard of UK's Gearbox Kart term until yesterday. (I saw the "Rotax kart" term used in a bunch of UK kart sites/forums too, it did kinda seemed like they also made the chassis)
If your going to use your kart "just for personal use" and not race against other Gearbox karts on a track, you can use most any kart frame you want.
If you think you might possibly end up racing, I'd suggest finding a used 125 shifter/Gearbox race kart without an engine. It would come equiped with the clutch/shifter paddles and linkage, 4-wheel brake system, over sized 50mm. axle & bearings, a radiator & necessary plumbing, plus Its frame would be specially designed and built to handle the added stress of a shifter motor. (might even come with a motor mount) You might end up saving some money this way cause these shifter race kart parts can be very expensive to buy new.
Before you buy or make a motor mount, I'd suggest waiting until you buy your chassis. I've heard of a couple race kart brands that have odd-ball frame rail spacing/diamitor. On these, other brands of motor mounts might not fit the frame...
mike75925
10-13-2009, 04:19 PM
bolting engine mounts on is not a great idea, unless you bolt it in place to weld it. imho, even locktite would come loose, especially if using a two stroke engine.
Rickracer
10-13-2009, 04:28 PM
The motor mounts they are talking about are production mount for racing chassis, they need to be able to slide back and forth to adjust the chain tension. Even my "home" (shop) built mount adjusts. ;) :cool:
mike75925
10-13-2009, 04:34 PM
why not use a sprung tensioner like on dirt bikes multispeed bicycles, or cam chain tensioners? seems a lot less hassle to me
Rickracer
10-13-2009, 04:39 PM
It can be done like that, but actually, the sliding mount is easier, loosen two bolts, slide it till the chain is tight, tighten the bolts up and you're good to go, :cool:
mike75925
10-13-2009, 04:46 PM
on what size motor? and what size bolts? i'm hard on the throttle, and the brakes. tires don't hold up for me either. jackrabbit stops and starts, mainly on gsxr750. i'm thinking an alternator type tensioner, (one end slides, the other is a pivot) would be better, but not really feasible.
anderkart
10-13-2009, 05:47 PM
Most all (side engine) race karts have been using these bolt on style motor mounts since the 70's. Theres a bunch of diferent brands and styles but some can hold up fine with 60+ hp race motors.
(the mounting bolts do need to be checked and re-tightened every once in a while)
Here's a pic of one mounted up: http://www.zanardiusa.com/pg/mount.jpg
And then it very tightly locks down using 2 or 3 these butterfly clamps and 3/8" bolts, threading into the top plate from the frames bottom side: http://www.cometkartsales.com/store/chassis/intrepidkart/intrepidparts/intrepid-butterflymt.jpg
mike75925
10-13-2009, 05:57 PM
ok, but those still look like they are for go kart engines, not bike engines.
anderkart
10-13-2009, 06:35 PM
Here's one for a Honda CR shifter kart motor: http://sharkshifter.com/zc/index.php?main_page=product_info&cPath=31&products_id=357
As far as I know, you'd have to build your own for larger sized motorcycle engines.
Rickracer
10-14-2009, 05:09 AM
For a big 4 stroke engine (like one that weighs more than the kart), a tensioner would be a better solution, but for up to a 250~350 cc 2 stroke, the sliding mount works better, IMHO. :cool:
Smurph
10-19-2009, 02:03 PM
I've found a few links for ya:
http://www.kartbuilding.net/
Offers some pretty detailed plans. I recommend you use these as a basis for your designs, and modify them to suit your needs, desires, and the parts you can get your hands on.
To find go kart parts, either check the classifieds here, or click this link (http://www.google.com/search?q=go+kart+parts&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:official) and you'll see a good list of online retailers for kart parts.
Also check local atv shops (especially the non-corporate ones) as they might have parts, frames, or anything else you might need.
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