gx200 clones cracking under load

[megacat]

Hello to everyone!

i know that this not the right place to introduce myself, but i need some urgent advice.

My name is Oleg, i work as a mechanic in a rental go-kart track, and i have a serious problem with Honda GX200 clones, specifically Lifan(known Chinese brand?).
most crack after very short time on the track (300-400 WH) , or alternately the crankshaft brakes in two. I install the engines mostly "as is" from the box with the only modification being me welding the crankcase cover to the block (the bolts wont hold it in place, even after torquing and Locktite).

The cracks are usually either under or above the cylinder, or on some r occasions, both and running towards one another, in a few cases, the cylinder actually separated from the rest of the block (the only thing that kept it from going into low-earth orbit was a bolt hole behind the flywheel).

The engines are coupled to 1\2 wet clutch reduction box, and unfortunately i don't remember atm the ratio between the pto output and the axle on the kart. we work on a 10 min per heat, 10 hours a day, 7 days a week schedule, and we get a lot of people(mostly kids) who confuse my karts for bumper cars; so the they do get a fair share of abuse.
my main theory is that because we lack a mechanism to prevent people from pressing both gas and brake together, that additional stress on the clutch somehow causes the engine to fail. the only problem is that it happens ONLY with the clones, on the hondas the clutch wears out way before anything happens to the engine.

my question is basically this, why do clones fail so often?
it's really bugging me, hopefully, you guys can give me some advice.

Thanks ahead, Oleg.

 

[Joe-405]

Honda OEM blocks and supporting parts are a whole lot stronger in general. The whole engine is either stronger, heat treated better, or supported and braced slot better than the clones. Hence why they can sell the knockoffs cheaper. I would on rentals run true Hondas and nothing else cause of the longer run times and heavier abuse.

 

[megacat]

i would too if i had the choice, but in the end its the owner who keeps bringing these engines.

i love the hondas, a few of them lasted for more then 4 years before being scraped, and even then, it was because the cylinder was bored to the max.

i'm stuck with the chinesse, now i need to figure out how NOT to replace an engine once every two weeks.

 

[Bbqjoe]

How far are the pedals apart?
If the problem truly is a brakes an throttle thing, what about making a see-saw like deal between the pedals so you can only stand on one or the other?


What do I know???

 

[B_Bimmer]

Love me some carnage pictures. Thanks for sharing. The reliability and durability of the real thing is tough to beat. If you've explained the situation to the owner as well as pointed out the obvious safety concerns I would say you've done your part, it's all job security if he keeps the knockoffs coming.

 

[chancer]

Well Maybe get him To Try the Predator from Harbor Freight. 99bucks Not an exact Clone. But a great little engine.
My kid abuses the crap out of hers, (so do I) and I mean lap after lap til it is HOT.
never had a problem.

---------- Post added at 09:46 PM ---------- Previous post was at 09:43 PM ----------

Or maybe not. Just saw you are in Israel. Maybe no access to a Predator engine.

 

[Hellion]

How far are the pedals apart?
If the problem truly is a brakes an throttle thing, what about making a see-saw like deal between the pedals so you can only stand on one or the other?

That's really a great idea and something I thought of too.

If not that, have a go kart mock-up somewhere outside the track where the young (and the stupid) can practice the proper application of gas and brake. Make it a game with bells if done right, and buzzers if done wrong.

Well Maybe get him To Try the Predator from Harbor Freight. 99bucks Not an exact Clone. But a great little engine.
My kid abuses the crap out of hers, (so do I) and I mean lap after lap til it is HOT. Never had a problem.

I want to hear of or see video of your kid pressing both the gas and the brake to stop. Over and over again. Let's torture test the Predator.

 

[chancer]

Well not that part, She has more sense.

 

[megacat]

How far are the pedals apart?
If the problem truly is a brakes an throttle thing, what about making a see-saw like deal between the pedals so you can only stand on one or the other?

we actually had that exact set up a long time ago (before i joined the place), from what i heard, they ditched the idea after it became apparent that when someone is PTTM the gas, he won't be able to overcome that with his other foot, leading to some dangerous situations. we are now prototyping a homemade system with a cable running from the brake, to the gas paddle, hooked to the gas with a spring, and from there to throttle, seems to work.

---------- Post added at 08:52 AM ---------- Previous post was at 08:47 AM ----------

If not that, have a go kart mock-up somewhere outside the track where the young (and the stupid) can practice the proper application of gas and brake. Make it a game with bells if done right, and buzzers if done wrong.

on calm days, that might work, but the problems come during the holidays, barely enough time to explain track rules properly, let alone a test drive, i DO explain and demonstrate as much as i can, but some people are too dense, even for me.

 

[Hellion]

...we are now prototyping a homemade system with a cable running from the brake, to the gas paddle, hooked to the gas with a spring, and from there to throttle, seems to work.

Although it might give away your trade secret, I'd love to see how that whole assembly looks and works.

Are there many go kart tracks in Israel and do you have lots of competition (for business)?

 

[Bbqjoe]

Although it might give away your trade secret, I'd love to see how that whole assembly looks and works.

Are there many go kart tracks in Israel and do you have lots of competition (for business)?

Nosy, isn't he?

 

[megacat]

its ok =]

i don't have a picture on hand, but the system is very simple.

the throttle cable goes from the throttle to the gas paddle, hooks with a U shaped support onto a spring that's attached to the paddle, and from there goes to the brake paddle through a sleeve the is anchored to the floor.

when the gas paddle is pressed, and the throttle lever reached its stop, the spring stretches, and if you press the brake and the same time, it will relieve that tension and cause the throttle to return.

simple in concept, a pain in rear to get to work right

---------- Post added at 09:44 AM ---------- Previous post was at 09:40 AM ----------

Well Maybe get him To Try the Predator from Harbor Freight. 99bucks Not an exact Clone. But a great little engine.
My kid abuses the crap out of hers, (so do I) and I mean lap after lap til it is HOT.
never had a problem.

heard about those, doubt that i can get them for that price here

 

[Bbqjoe]

its ok =]

i don't have a picture on hand, but the system is very simple.

the throttle cable goes from the throttle to the gas paddle, hooks with a U shaped support onto a spring that's attached to the paddle, and from there goes to the brake paddle through a sleeve the is anchored to the floor.

when the gas paddle is pressed, and the throttle lever reached its stop, the spring stretches, and if you press the brake and the same time, it will relieve that tension and cause the throttle to return.

simple in concept, a pain in rear to get to work right

Wouldn't a person then be able to keep the throttle floored, and use the brake pedal almost like a clutch?

 

[megacat]

yea, that's exactly the point, the throttle disengages before the brake engages.
i had a few people complain about the kart not going, the look on their faces when i slowly move their foot from the brake and the engine beginning rev is priceless

 

[Hellion]

...and I mean lap after lap til it is HOT.
never had a problem.

A hot engine you say? That's unbelievable. Such abuse!

Did you forget your coolant?

 

[chancer]

There is something that they use here, must be electronic, but when the time is up at the go kart track. the throttle stops working. The karts will only accelerate enough to barely move, But the engine does not stall. As a customer/driver You surely know when the times up.
I have no idea how it works.

 

[megacat]

yea i know that type of a system, saw it in action on a different track. the lead marshal gets a radio remote control, with which he can control the rev limiter on each kart from anywhere, works using an induction tach and by rapidly grounding and un-grounding the the ignition, basically skipping a few power strokes every second to keep engine rev below a certain limit.

very cool system, but best used on large tracks, mine is only about 260m in length, so a two person team is enough to cover the whole thing.

 

[mckutzy]

So why are you welding the covers on? Based on the pics shown... they jug is breaking off at one of those weld points at a bolt boss.

Can you post a few pics of an installed motor... maybe there is some thing that is amiss here...

 

[Whitetrashrocker]

I'd explain the monetary issues to the boss.

One good Honda will outlast the clones how many times over?

Seems simple to me.

 

[mckutzy]

I've never heard of such a thing... Money aside I still think there is drastically something wrong.