On Cheap vs "Expensive" Engines

Colonel__Klink

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Jul 22, 2020
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Hey folks! I'm so glad that I found this website! I have recently really begun to study my options in building a motorized bike as a replacement for my little electric bike. It's a nice little thing but gas doesn't have range issues, and I hear will get me going much faster than 15mph which both are important as I want to build a bike to commute around town.

So preface out of the way I am looking at 49cc 2 stroke engines (planning on adding a booster bottle at the minimum, possibly an upgraded exhaust kit later) to fit on a beach cruiser style bike for this build. I went for this because it seems to me that without the capacity to cut and weld I may not be able to fit everything in a 4 inch fat tire style bike (my ideal bike for dealing with the occasional snow.) I really am trying to cut this budget down as much as possible ultimately and I have noticed that there are two types of 49cc engines. Those that go for $200 on places like BikeBerry.com and a few (rarely found too) $100 engines on Amazon.

Does anyone know the significant difference between engines like those made by BRR Tuning ($200 engine) and something like the MOTOOS branded $109 kit on Amazon? I can quite assume that I should go down to the hardware store and replace most of the cheap bolt hardware for the cheaper engine but is there really a significant difference performance wise? I don't know anything about this new world of fun little bike engines so I don't know if the price difference is actual quality meaning sometimes you do get what you pay for or if the real difference is brand recognition as the two engines appear to share an identical design.

Thanks in advance for any help folks!

(For reference here's the link to the BRR Tuning engine)
https://www.bikeberry.com/gas-engine-kits/48cc-2-stroke-bike-engines/48cc-flying-horse-silver-bicycle-engine-kit-2-stroke.html

(and a link to the MOTOOS engine)
https://www.amazon.com/dp/B072N4HTLX/?coliid=I1LE6TNJKRTXA8&colid=1C073EXA4MU74&psc=1&ref_=lv_ov_lig_dp_it
 


CrazyDan

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Jul 9, 2016
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2,856
A bolt on boost bottle is worthless, bikeberry is just a step up above gasbike/kingsmotorbikes and that amazon engine is lying with the hp numbers, maths are incorrect. 1 hp is 752 watts, 2 hp is 1504 watts. That ghetto amazon post claims 1600 watts is 3 hp, f***ing liars. Good luck getting that stock kit to hit 2 hp without mods.
I run a 4 stroke with tens of thousands of miles on it, just oil changes and occasional valve adjustments. Get a decent 4 stroke such as an hs142/144 with a grubee kit, much less stress down the road.
 

Colonel__Klink

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Jul 22, 2020
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A bolt on boost bottle is worthless, bikeberry is just a step up above gasbike/kingsmotorbikes and that amazon engine is lying with the hp numbers, maths are incorrect. 1 hp is 752 watts, 2 hp is 1504 watts. That ghetto amazon post claims 1600 watts is 3 hp, f***ing liars.
I run a 4 stroke with tens of thousands of miles on it, just oil changes and occasional valve adjustments. Get a decent 4 stroke such as an hs142/144 with a grubee kit, much less stress down the road.
That's the sad part of the stuff for bikes on Amazon. They basically claim what they want and so instead of trusting that a cheapo $100 2 stroke with the most basic carb ever gets a whopping 3 hp I just assumed it would be trailing just under 2 as more typical. The biggest question I had in my mind was if the price difference between the two actually reflected a genuine difference in quality of say bearings. I'm so new to this that I don't know whether all the engines are pretty much cheap pos or what. TBH I'm quite mechanically minded but engines of any sort are pretty new to me (I'm my schooling was in gunsmithing, not being an auto mechanic lol) so I'm not even sure about the whole boost bottle claims.

A perfect example is that you don't like Bike Berry. What would you recommend for a place to look at for building a bike? And also I had considered a 4 stroke but weight is a factor here. I have to carry the bike, sometimes with groceries loaded into a mounted on box up three flights of stairs. The basic frame of the bike will be 30-35 lbs. A 2 stroke adds another 7lbs. I hear that 4 strokes are about twice that correct? But on the other end, at least on bike berry the 4 stroke HP ratings are slightly higher than the 2 stroke which will be useful.
 

CrazyDan

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Avoid bikeberry and gasbike. They have alternate names like bbr tuning and kmb for their other sites. I use grubee, bicycle-engines, staton-inc, and sickbikeparts. If I follow my newest yearning, I'll be using affordablegokarts and maybe arcracing.
 

CrazyDan

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Once you get a fully built, reliable bike with front brakes and suspension. the extra weight of a 49/53cc 4 stroke is almost unnoticed. My current 4 stroke build is about 97 lbs with roughly 2.5 hp (being conservative). A stock 2 stroke would put me at 85 lbs instead at best. Add my weight and the weight difference is negligible. I'll race for pinks on a similar sized engine :D. Sorry, 66/69cc engines are way bigger than me and I still might win xD.
 

Colonel__Klink

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Jul 22, 2020
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Once you get a fully built, reliable bike with front brakes and suspension. the extra weight of a 49/53cc 4 stroke is almost unnoticed. My current 4 stroke build is about 97 lbs with roughly 2.5 hp (being conservative). A stock 2 stroke would put me at 85 lbs instead at best. Add my weight and the weight difference is negligible. I'll race for pinks on a similar sized engine :D. Sorry, 66/69cc engines are way bigger than me and I still might win xD.
Oh I'm not worried about the weight on the road! It's carrying the bike up and down 3 flights of stairs with groceries in it that's the problem! So one of the factors in engineering a bike for my situation that I need is weight. Ideally around 40lbs or less. 90lbs I just won't be able to do it honestly.

Another factor we need to bring in here is that my tool set is limited. I know how to shape, cut, file solder and weld but I simply don't have the means to weld or honestly heat enough of the metal here to soldier. So modifying the existing bike in any substantive way is a flat no go. I am also a novice so I'm looking at an entry level kit with everything I should need. Sick bike parts looks interesting but I just cannot seem to find a kit there.

Due to local law my engine must be 49cc or less which means that station inc is the only site that was offering a bike kit for me of any sort that's legal in my area. I confess I enjoy seeing the options like the option to mount near the wheel hub.

Due to me needing a cargo box on the bike I specifically need a mid engine mounting system. It's conceivable to make the friction drive as an example work but a serious pain in the neck as I'd have to build a custom box AROUND the engine.... and hope I don't cause an overheat due to lack of air flow.... Anyway station inc is an interesting site but they just don't offer a standard mid engine bike kit and I haven't a clue why....

I have price limitations. If I had $1500 to build a bike I'd get a 1kw e bike with a spare battery. So spending $800 just for the mount alone at station inc isn't an option either. I don't need the best, I'm just trying to find something that's not the worst thing ever that will literally blow up in my face. I was looking at kits within $300. I know that's low in but unfortunately that's my price bracket, building the entire bike for $450-500. Most of what you are suggesting are WAY outside of that.

Seriously I wouldn't have seen those sites without your help and I'm keeping em bookmarked for later maybe sunnier days when I have more cash in my pocket but they are all either offering things that I cannot legally use or are well beyond my price bracket and usually both.
 

CrazyDan

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Oh I'm not worried about the weight on the road! It's carrying the bike up and down 3 flights of stairs with groceries in it that's the problem! So one of the factors in engineering a bike for my situation that I need is weight. Ideally around 40lbs or less. 90lbs I just won't be able to do it honestly.

Another factor we need to bring in here is that my tool set is limited. I know how to shape, cut, file solder and weld but I simply don't have the means to weld or honestly heat enough of the metal here to soldier. So modifying the existing bike in any substantive way is a flat no go. I am also a novice so I'm looking at an entry level kit with everything I should need. Sick bike parts looks interesting but I just cannot seem to find a kit there.

Due to local law my engine must be 49cc or less which means that station inc is the only site that was offering a bike kit for me of any sort that's legal in my area. I confess I enjoy seeing the options like the option to mount near the wheel hub.

Due to me needing a cargo box on the bike I specifically need a mid engine mounting system. It's conceivable to make the friction drive as an example work but a serious pain in the neck as I'd have to build a custom box AROUND the engine.... and hope I don't cause an overheat due to lack of air flow.... Anyway station inc is an interesting site but they just don't offer a standard mid engine bike kit and I haven't a clue why....

I have price limitations. If I had $1500 to build a bike I'd get a 1kw e bike with a spare battery. So spending $800 just for the mount alone at station inc isn't an option either. I don't need the best, I'm just trying to find something that's not the worst thing ever that will literally blow up in my face. I was looking at kits within $300. I know that's low in but unfortunately that's my price bracket, building the entire bike for $450-500. Most of what you are suggesting are WAY outside of that.

Seriously I wouldn't have seen those sites without your help and I'm keeping em bookmarked for later maybe sunnier days when I have more cash in my pocket but they are all either offering things that I cannot legally use or are well beyond my price bracket and usually both.
If you try to go cheap, the repairs tends to cost more over time. Just sayin...
 

Colonel__Klink

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Jul 22, 2020
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If you try to go cheap, the repairs tends to cost more over time. Just sayin...
That's why I was sitting there looking at that $100 engine and wondering "how long till the chain breaks or the crank bearings need replacement?" lol. TBH the parts aren't generally all that expensive for 2 strokes but I am more considering the next step up, the $200-300 kits.

If I'm looking at just $800 for an engine mount I might as well get a mid priced moped. $800 for the mount, $400 for the engine, $300 min for the bike (if I'm doing that I'm not putting it on a huffy...) That's more like a "I got cash lining my pockets and looking for a hobby build" not a "this is a better option" thing lol. One day I hope to be there for the hobby of it all tho :).
 

CrazyDan

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If you buy a cheap sub-$200 4 stroke kit and toss a grubee 4g Tc on it with a better chain and hub adapter, it will be an under $600 build with plenty of power to hit 30 mph+ and take hills without failures every ride.
 

Colonel__Klink

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Jul 22, 2020
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If you buy a cheap sub-$200 4 stroke kit and toss a grubee 4g Tc on it with a better chain and hub adapter, it will be an under $600 build with plenty of power to hit 30 mph+ and take hills without failures every ride.
Now that's starting to be much more in my price range. What's the TC you're talking about?

And yeah, I had figured that eventually I would have to at the very least upgrade the wheel sprocket. The chain of course would stretch over time and need links removed before total replacement ect.
 
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