We’ve got a couple of acres so I’m looking to build two really simple off road karts ie no suspension, no gears with about 10-11hp, (so im not talking blade engined rage buggies here) Im looking to do it severely on the locost, simple as poss, minimal parts count. I’ve got a good source of bits to get going but have hit a stumbling block when it comes to engines as Honda gx industrial engines and copies need a 100 quid centrifugal clutch when they get to 1” output shaft. Small bike engines have gears and a manual clutch, (not really what im looking for as Im trying to keep it really simple). The only other thought I had was a four stroke rev and go scooter engine, make use of the cvt by replacing the rear wheel with a sprocket to drive the rear solid axle but most of these are water cooled.

So im kinda struggling to find a locost 10 ish brake 4 stroke with enough grunt to have a laugh, geared for 30mph on grass without spending £200 plus.

Is there an alternative I haven’t thought of, im pretty good at missing the obvious, thanks in advance.

Lawnmower engine? I have a 3hp Suffolk motor.. its quite old but the newer ones have Kawasaki engines that have grunt...

I reckon with a bit of porting and a decent exhaust they may be OK for a katty???

Other wise a 600cc bike engine

pit bike engines. cheap copies of the c90.

The 50cc in my lads will easy do 30 with a kid on it.

Hmmn, not sure what the equivalent in the UK is but over here in North America there are Chinese clones of the Honda GX series available cheap as chips. Sold at Harbor Freight and Princess Auto over here -- they're cheap tool places so I suppose Halfords, Clarke, or ScrewFix might carry them -- they're all over eBay as well.

The most common (well supported with aftermarket parts as well) size seems to be the 6.5hp which is a knockoff of a GX200.

A governor removal, change to stiffer 18 lb valve-springs and swapping to an open element air filter gets you most of the way to 10hp and they run about $100 brand new. there are clones of the 10 and 13 hp units available as well but they start to cost real money and are comparatively quite heavy.

I wouldn't bother with a cheap centrifugal clutch, they offer crap performance and burn up quite quickly. Look for a Comet Torq-a-verter setup or something similar.

I built a cart with my son this past summer, it's got a pretty heavy frame, no suspension an unmodified 6.5hp clone and a torque converter. With fairly tall gearing (12/45) and 11" tyres it's pretty peppy, it'll do the best part of 60km/h and gets there quite quickly, has enough torque to drift on asphalt.

Cheers, Ted

macro have petrol engined power washers for about £150, but they include a 5.5hp honda type engine (colours are different from the honda ones, but look identical) and the £150 is cheaper than a new 5.5hp honda engine

a new honda 5.5hp engine from machine mart is £260

[Edited on 1/1/10 by blakep82]

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Originally posted by blakep82
macro have petrol engined power washers for about £150, but they include a 5.5hp honda type engine (colours are different from the honda ones, but look identical) and the £150 is cheaper than a new 5.5hp honda engine

a new honda 5.5hp engine from machine mart is £260

[Edited on 1/1/10 by blakep82]

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Yeah, your standard kart has a honda GX with centrifugal clutch.
- GX160 is common for small indoor tracks and junor classes, 320 if you want a bit more go. Buy from anywhere thats cheap (agricultural places, ebay, dead genset, whatever) then just removed and bypass the governer and off you go.

OTherwise we also raced Honda Cub90 engines which are awesome fun. Three speed semi-automatic box.


Daniel

http://www.pistonheads.com/sales/1407354.htm
Ive got a pit bike going for 300 as well

[Edited on 2-1-10 by mangogrooveworkshop]

Honda CG125 lump. You get a strong, super reliable engine, clutch and 5 speed box in a compact unit. Would make a great gokart.

What about a quad or trike engine - you can buy a brand new 110cc trike for about £400 surely engines must be fairly cheap & easy to come by as plenty of people stack quads big time!?

definatley stick with the old honda generator engines they are bullet proof.
just keep an eye on ebay and www.karting.co.uk one will come up at the right price.
GX200 would be ample for off road

What about the 50/125cc moped engines? Seeing as most of these are 1-2 grand new I imagine if you look round the scrappies or the stolen/recovery places you might find one or two.

My 50cc moped's good for about 50mph with my pie-laden body on it.