Raptor 3 questions

[iwanttogofast]

I am thinking of building a drifting go kart(sounds like fun). But the engine is were i ran into a few questions. I want to build the engine but im not sure on how much power i need. A regular 5 horse geared right can do it but i want to do it at higher speeds. I was going to use a dual ball bearing raptor 3 block. So i would start with my cam what size should i use and i can get the block tig welded since it isn't that much and work to the head is fairly minimal for valve clearance. should i get port work done if im going to run gas? Also what about boring it out .050? Does boring make that much of a difference? I was also wondering about valves and valve springs. Im not sure but i thought you had to change them if you did get a bigger cam. Other then that its pretty straight forward after i get the side plate sealed her. Any thoughts would be appreciated.

 

[Kenny_McCormic]

Building a flathead is sort of a lost art, you can build a "clone motor"(a $100 honda GX200) for much cheaper.

 

[iwanttogofast]

ya flathead is a lost art (also a huge polluter) but i grew up working on them and there simple. So what is the difference between a clone and a old flathead? Is parts interchangeable, also could you lead me in the direction of a good site to look at prices?

 

[modelengineer]

Clone is OHV I think.

As always I recommend a motorbike engine for more power, gears, clutch, cheaper in long run, etc. etc.

 

[I like karts]

yeah, 100cc yamaha 2 stroke from 1980 + 5 speed gearbox = fast

(got one for $150 off ebay)

 

[iwanttogofast]

Yes but a 100cc 2 stroke doesn't have a whole lot of torque. Im talking about cruising 20mph slam it down and the tires start screaming.

 

[crazycart]

Depends on what engine, if you used a liquid KX80 engine it would, those things make over 20 hp! Research up before you buy thats all i can say.

 

[oscaryu1]

Anything'll have torque if geared correctly.

Back to your question.

Boring it out .050? For what reason? Stock bore is fine. Start on the cam, throw a 94ss n' some BP'd valves in it. Go for some of COMP's dual springs, some billet lifters, get that lifter bore TIG welded, throw in a WMS or ARC Billet rod, get a Raptor 3 rod in there with new rings, align and hone bore, shave eyebrows, relieve the valve area on head, mill head...

 

[sayre315]

tillotson carb
dyno 00-3 cam some fancy smancy valve springs and a trait header

 

[ed1380]

im w/ the 2stroke engine thing. much cheaper and it was designed for that kind of power, so less chance of money going up in flames.

 

[jr dragster T]

Anything'll have torque if geared correctly.

Back to your question.

Boring it out .050? For what reason? Stock bore is fine. Start on the cam, throw a 94ss n' some BP'd valves in it. Go for some of COMP's dual springs, some billet lifters, get that lifter bore TIG welded, throw in a WMS or ARC Billet rod, get a Raptor 3 rod in there with new rings, align and hone bore, shave eyebrows, relieve the valve area on head, mill head...

Guys...you DONT need those dual valve springs. You guys dont understand that a stock briggs block doesnt like 8 grand. Plus valve springs suck up HP. And what are you trying to do? Mushroom a valve?

 

[oscaryu1]

Guys...you DONT need those dual valve springs. You guys dont understand that a stock briggs block doesnt like 8 grand. Plus valve springs suck up HP. And what are you trying to do? Mushroom a valve?

I'd be worried about your valves, if people are mushrooming them with stock valves, I'd hate to see it with 18lb springs.

On the other hand, dual's start floating at around 8000 anyways. Many people spin Briggs 5HP's 8000+. Just need a few hundred girdles.

 

[Jerryburger]

I think Iwannagofast is definitely going to have to go the motorcycle/sled motor route over the B/S option for his performance target. You have to put lots of $$ and work into getting a B/S engine to keep up with a decent bike/sled motor*, but if you have a proven/developed performance technology available to you, why not use it?
Crazycart says to research ALL of your options... couldn't agree more.

* I know using the "Polishing a Turd" analogy would anger many here, so I didn't use it- B/S motors are NOT turds- they are excellent for spinning a PTO shaft at a constant 3600 rpm under varying loads. High performance cart applications require a lot more than that. Lots of time, effort, and $$$ can put a toilet on the moon, but rockets work better.

 

[iwanttogofast]

Well the reason i came on here was for more options. Just the one i knew was the one i posted. how much harder would it be to mount a 2 cycle to a cart that use to have a 5hp on it? a mount? and also how much are the clutches because i will go through tons of them.

 

[Jerryburger]

Are you thinking LawnBoy type 2 cycles (See Russ' input) or Sled Motor type 2 cycle power (Ask Crazycart)? Both of these options aren't very mainstream but are effective never the less. Take the time, use the search function on this forum/site, and you'll see some pretty good examples. I don't really know if there are any 2 cycle motorcycle engine projects here, or if the KT100 kart engine has made much of a dent here among members.

 

[iwanttogofast]

well i have a 160cc suzuki 4 stroke engine 5 speed semi automatic off of a 4 wheeler. But i want to use that for the other 160 i have for parts so i probably won't use that. I have been looking at 2 cycle engines and they are a lot cheaper. I haven't worked on many 2 cycles except a long time ago when i was putting weed eater and chainsaw engines on everything. I will keep on looking, i do still have till febuary when i get my tax check.

 

[jr dragster T]

I'd be worried about your valves, if people are mushrooming them with stock valves, I'd hate to see it with 18lb springs.

On the other hand, dual's start floating at around 8000 anyways. Many people spin Briggs 5HP's 8000+. Just need a few hundred girdles.

No, Oscar I have the COMP billet retainers and dual valve springs in my rhino and we run 9100 RPM all day long. No valve float here. They are surely more than 18 lbs. The valve springs used in my rhino are 60 LB springs and over 120 LBS compressed.

 

[iwanttogofast]

No, Oscar I have the COMP billet retainers and dual valve springs in my rhino and we run 9100 RPM all day long. No valve float here. They are surely more than 18 lbs. The valve springs used in my rhino are 60 LB springs and over 120 LBS compressed.

Dang that is one heavy spring. what kind of engine is that in? like something with a 15 to 1 compression ratio?lol

 

[Kenny_McCormic]

Dang that is one heavy spring. what kind of engine is that in? like something with a 15 to 1 compression ratio?lol

Its all billet aluminum, purpose built.

 

[iwanttogofast]

i was wanting to know why it needed a spring that big. and is there any good threads on here about valves and how the spring tension affects the engine. I can put a 5hp together 100% correct but i don't know the little fine things about it, mainly cams and valves. Trying to learn a little bit about them. So far i love this site member one day and already learned tons.