need help with go cart engine mods

[Monkeys1990]

yea well im new to modding go carts engines i know some but not a whole lot well i get a new honda clone case, just the case so far i want it to be able to do 80mphs, and so far im goig to put a gx 160 head and a gx390 carb on it and i was wonding what eles i would have to put onin order to get the speed..i dont know what parts go witheach other or any good info sites to learn so if someone could teach me and help me or give me a list of parts to buy i would be very thankful...thanks Ryan

 

[Doc Sprocket]

Let's start with some fundamentals first- do you have a kart that is capable of being safely propelled at 80MPH without scattering human remains far and wide? For the metric folks out there that's 128 KM/hr. That's a pretty tall order- be sure you know what you're getting into. I haven't broken out my calculator yet but I'm not even sure it's feasible. Need more info.

 

[Monkeys1990]

its feasible theres people out there with some that does 130+ and what other info is needed?

 

[Jcotz]

It's feasible if you are willing to spend a lot. You could get a shifter cart frame for about 2,000, a rotax 125cc for about 1,000, tires, gas tank, kill switch, safety gear, a place to drive it and you would probably be able to get that fast.

Edit: if you want advice affordablegokarts.com is pretty good. I missed that part of your post.

 

[r_chez_08]

yea well im new to modding go carts engines i know some but not a whole lot well i get a new honda clone case, just the case so far i want it to be able to do 80mphs, and so far im goig to put a gx 160 head and a gx390 carb on it and i was wonding what eles i would have to put onin order to get the speed..i dont know what parts go witheach other or any good info sites to learn so if someone could teach me and help me or give me a list of parts to buy i would be very thankful...thanks Ryan

Gx200 or clone as a guess???
Check out NR racing, arc racing and affordable go karts.
What is your budget? You will want an aluminium flywheel and billet rod for anything above 6000 rpm.

You will also want some heavier valve springs, and maybe some nicer rockers and valves. You could also port and/or mill the head.

I would also get a flat top piston. You will probably wan a high lift and duration cam and maybe some better lifters.

Oh and don't forget to remove the governor, install a high floe header, and wear a nappy

 

[Monkeys1990]

i dont have a budget im willing to spend the mnoney i just lack the knowledge to know what to buy, im able to do the work no promble and a gx200 as a honda clone and i know for the price of building it i can get a gsxr 650 or something like that but its just not the same as building one yourself..what i dont understand is like if i buy a cranksharft what parts will it work with? pretty much whats the best priece on a engine to start upgrading from?

 

[r_chez_08]

What kart are you putting this on?
You can start with a Honda clone from many places like nr racing for about $100. the yellow clones are a good place to start, they seem to be the highest spec.
There is loads of great info on karting.4cycle.com in their clone section in the OHV motors.

 

[Monkeys1990]

i have a littleracing frame, it has a honda clone 6.5 on it already, but i wanted to buy just the case for 45 and start from pretty much nothing and build the whole engine

 

[r_chez_08]

Ok,
About crankshafts: there are stock crankshafts which are obviously stock stroke, these can be used with the arc billet clone rods or a stock rod. There are also extra stroke crankshafts, which can be used with the stroker rods and piston combos.

What HP do you want to make from the motor? It may be cheaper getting a built it yourself kit. Another option is the z208, which is a gx200 clone with a 70mm bore not a 68mm.

Why don't you want to use your current clone?

 

[Monkeys1990]

im looking to get arond like 13-15 hp, and i dont want to use my current one becasue its already runing and a new engine case is 45 and im plaining on upgradeing every part in it anyways and i would like to build one from a case..it will feel like i done something in life pretty much im just looking to go around 60-80 mph i dont need much more than that because im driving onthe road..i may get into racing depending if i like the race style.

 

[bighead]

Wrong thread

 

[Jcotz]

You could probably get a...

-uni air filter
-straight header
-new jet whatever number
-emulsion tube
-remove governor
-new rod
-lighter flywheel
-new push rod
-flat top piston
-new cylinder head
-New cam-whatever type you want
-heavier valve springs
-rev roller rockers

This and whatever mods you want. Most of this stuff is available at affordablegokarts.com or nr racing. This will probably get you up to 13-15hp, but I am not totally sure.

 

[Monkeys1990]

yes i know what mods i can get im not sure about with mods go with what,like if i upgrade the cam what eles should i upgrade? and what kind and if i upgrade the crankshaft than would any pistion work on it or do i got to upgrade that to?

 

[Jcotz]

Ok, Here are some upgrades that go hand in hand...

-Removal of governor
Billet rod, aluminum flywheel, possible throttle setup alteration

-Upgraded cam
Heavier valve springs

-New Air filter or header
Rejet and or new carb

Hope this helps

 

[r_chez_08]

Don't bother upgrading the crank IMO.
I would start with a complete clone for $100, because by the time you have bought a new crank and recoil setup you will be over the cost of a new clone.
If you look at here you can get a 14hp clone for approx $500 (stage 3 kit with a few mods)

You could build a stroked motor if you wanted, but IMO it is not worth it unless you bore the motor too, and the added gain is not worth all the expensive goodies.
Edit: I would not buy that kit, just an idea for parts. I would also get a flat top piston, a +.020 length billet rod (the kit is STD length), arc billet, Honda aluminium or raceseng billet flywheel depending on your budget and preference, and a gx160 head (milled or not, maybe get stainless valves)

 

[trebortaergeht]

First thing, even going 40 on an unprotected vehicle like a kart is dangerous, let alone 80. Make sure you know what you are getting into and that your chassis is suitable for those speeds and in perfect condition. And now:

Biggest improvement would be using an un-milled gx140 and an ARC long rod with flat top piston to get zero deck height along with at least a 24mm carb, that puts the engine at approximately 13.7:1 any higher than that and it will be alcohol only and require extensive block modification. With 13.7 you can still run on premium fuel with a fuel air ratio of 12:1 or greater.

At the very least you will also need a billet flywheel for safety and a large cam to take advantage of the much greater compression. I would also recommend a fully upgraded valve train for longevity and additional power increases

Port the head to match the valve seat id and polish the exhaust port, replace the head bolts with studs drill out the little oil hole between the pushrods in the block, and vent the block and valve cover through a PCV valve and into a catch-can

I run a similar configuration and worst case you will get 20 hp and 8000-9000 rpm, mine gets about 28hp. I reach around 60mph at 8500rpm but I'm gear bound, I could go much faster with a different gear ratio.

If you check the classifieds on http://karting.4cycle.com/ you can get stuff like the flywheel and cam lightly used for a lot less than new, check ebay for the carbs, they are cheap, and get the rod, piston and valve train stuff new.

Also, check out the OHV Motors section on 4cycle, they build some monster engines over there

 

[r_chez_08]

I have heard the 140 head has smaller valves, and without modification, the 160 heads are better.
However if you install bigger valves and port it out, the gx140 head will perform similarly to the gx160 skimmed head.

 

[Monkeys1990]

does someone think they can make me a list of what parts i should get and how much if i use a stock honda clone? and as for my go kart it will handle the speed im still goanna put a bumper graud around it.

 

[Jcotz]

Okay, here goes...

-uni air filter-$29 w/ adaptor
-straight header-$37 (more for stage 2, or with muffler)
-new jet whatever number-$6
-emulsion tube-$15
(you could just replace carb with a higher quality one if you wanted to)
-remove governor-$0
-remove low oil sensor-$0
-new rod-for a honda clone is $83
-lighter flywheel-$99-200 depending on quality and make
-new push rod-$24
-flat top piston-$23
-new cylinder head-$60-200
-New cam-whatever type you want-$50-150
-heavier valve springs-$8 (you need two)
-rev roller rockers-$150-200
-any mods or alterations-depends on cost

All this can be found on affordablegokarts.com. Hope this helps.

 

[r_chez_08]

That's a good list to start with. BTW the rod is $59 for the standard to +.020 length.
I personally wouldn't get the roller rockers, instead I would get stamped ratio rockers.
I would go to the Honda and or clone section on karting.4cycle.com and have a good read.
I have learned a lot by just searching and reading the posts there.