125cc pit bike engine

[PatiencePaysOff]

Greetings,
one of my friends is also building a go kart and I might give him a hand. However, he was interested into buying a 125cc-140cc pit bike engine for his "shifter kart" type go kart. Most of the time, we will race on asphalt and sometimes backyard grass. He wants to know if it will go faster than a predator engine with a stage 1 performance kit. What about the acceleration and top speed? We weigh both 140-150 lb.
Thanks you all

 

[Poboy kartman]

Welcome to the forum....please fill out a profile location....so we know where you're from.....

Can't really answer your question directly....but the Predator is a good engine for cheap.....all I can answer right now.....

 

[landuse]

Welcome!!

 

[OzFab]

He wants to know if it will go faster than a predator engine with a stage 1 performance kit.

Can't really answer your question directly...

I can: H E L L YES!

...& here's why:

A predator engine, even when fitted with a torque converter, is limited by the fact that there is only one drive ratio, which need to work within certain parameters; the ratio needs to be high enough to reach a decent top speed but, low enough to achieve decent acceleration; altering the ratio one way or the other means sacrificing either acceleration or top speed...

With a multi gear pitbike engine, you get the best of both worlds, select 1st gear for great tyre spinning acceleration & select the top gear for huge top speed... with three or four gears inbetween...

However, there is a downside: a massive amount of fabrication work to make the engine fit & work...

 

[PatiencePaysOff]

pit bike 125cc/140cc vs predator 212cc


I had already mentioned this question previously but I think I lacked details and information about it.
Purpose: go kart engine for shifter kart frame, such as this one courtesy of cometkartsales: https://www.google.ca/search?q=shif...rtsales.com%2FCoyote-XP-SKU19555.html;640;331
So my total weight is 140-145lb.
Go kart main purpose: road 50% and off-road (grass/dirt) 50%
Price range: 250-350$

Some people say that due to the fact that dirt bike engines possess a transmission, that enables it to accelerate faster than the predator. TRUE

However, a decent dirt bike/pit bike engine costs around 300-350$. Trying to also figure out if paying the extra buck for a 140cc is worth it compared to a 125cc.
At this price, I can afford a predator engine for roughly 150$ and use the 150-200$ remaining to buy a torque converter and do some minimal upgrades such as air filter, re-jet, governor removal and exhaust.

Sidenote: if any of you guys have an idea of where I can purchase whatever engine online, please link me the website. Living in Canada makes the shipping fees extremely expensive.

Based on these two observations, which will give me the best acceleration and reach at least 50 mph the fastest?
What should I pick?

 

[OzFab]

Question asked & answered above...

Why did you start a new thread when the same question has already been asked & answered?

A new engine may cost that much but, have you considered buying a complete, used bike? When you buy the engine, more often than not, that's all you get; no carb, exhaust, electricals, etc, which will run you a few more hundreds of dollars; buying a complete running bike, everything you need is already there...

Yes, it's more expensive than a Predator & TC combo but, it's also more fun...

 

[dwcopple]

What about those 200cc Lifan engines? Those are going for more than $200 nowadays?