I could use some help here...I'm using a Troy Bilt 4 stroke TB-6042 xp

jitterbug3000

jitterbug3000

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okay i could use some help here my first build and im using a troy bilt 4 stroke tb6042 xp and im pretty much stuck with 9 on the clutch its going on a 20 in bmx bike what should i put on the wheel how many tooth im not lookin to go crazy fast just to cruse and get up hills cause im 43 years old and need a heart transplant and biking it is my only form of transportation and pedaling in my condition... yeah not to smart

so... im using a 25cc troy bilt tb6042 xp and pretty much stuck with 9 on the clutch and its going on a 20 in bmx bike what tooth sprocket should i put on the wheel im not lookin to go crazy fast just to cruse and good for up hills. im 43 and in need of a heart transplant and biking it is my only form of transportation and pedaling in my condition... yeah not to smart i have a 32 tooth on there now and it dont go nowere.
 
Some of our 4 stroke expert guys should be along soon enough to help ya out Jitterbug...lol.

Ps...I combined both of your posts together in a thread of their own for better exposure for your questions on this Troy Bilt 4 stroker.
 
What's your skill set? Can you fabricate anything? A little BMX is good for a rack mount friction drive, especially with the 25cc engine.

What kind of brakes do you have?
 
Ok let's start with the information you have given. Here's what specs I was able to gather about your engine, along with personal knowledge of what 4 stroke 25cc engines are capable of. It was used on a discontinued weed eater model. Here's the specs on the engine. I can even get you valve setting adjustments.

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The no load rpm is 9300. The max hp rpm is 6800 (1hp). The max torque is 5000 rpm (¾ ft/lbs). The idle rpm is should be around 3000.. You're wanting to put it on a BMX bike with 20" wheels. You live in Philadelphia the steepest grade there is Manayunk Wall a 17% grade. Kelly Drive has around a 9 mile continuous grade.



So now we need the information you haven't given yet.

1) How much do you weigh?
2) How frequently are you encountering hills/long grades?
3) Are you going to transport cargo?

I live in a mountainous region (up to 30% grades/up to 5+ mile grades), I'm a large person (245 lbs/bike 100 lbs, full load trailer 200 lbs), over a life time have had 5 heart operations along with various other surgeries.

I use a Robin Subaru 4 stroke 33cc 1.6 hp 1.2 ft/lbs torque engine. I've also been riding motorized bikes for almost 16 years. My bike is a shifter bike; so I'm very good at doing gear ratio calculations. Reduction range 66.79\1~16.25\1.

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Answer the 3 questions I asked then I'll let you know what your options are. You're going to need a bare minimum of an 18\1 reduction. A 32t/9t is a 3.56\1 reduction now where near enough. Meaning you're going to need a reduction transmission system.

In all honesty, somebody in need of a heart transplant shouldn't be operating any kind of vehicle. It won't just be you at risk; you're also endangering others as well.
 
Sidewinder Jerry said:
In all honesty, somebody in need of a heart transplant shouldn't be operating any kind of vehicle. It won't just be you at risk; you're also endangering others as well.
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I agree, maybe have a friend give you a ride or get an Uber if you need to go somewhere. If you really want transportation get something where you don't have to pedal. With an engine that small you are going to be pedaling alot. With a heart condition it could be disastrous if you over exert yourself. I tend to lean towards the 50cc range although I did have a subaru motor like jerry and the bike went about 28mph and I had to pedal to help the motor going up these steep western Pa hills. 25cc 4 stroke will be pretty gutless roughly 1 hp. I've seen those little Troy bilt motors had a few of them and I think I have one in the garage. They aren't that good.
 
Will'smotobikes19 said:
I agree, maybe have a friend give you a ride or get an Uber if you need to go somewhere. If you really want transportation get something where you don't have to pedal. With an engine that small you are going to be pedaling alot. With a heart condition it could be disastrous if you over exert yourself. I tend to lean towards the 50cc range although I did have a subaru motor like jerry and the bike went about 28mph and I had to pedal to help the motor going up these steep western Pa hills. 25cc 4 stroke will be pretty gutless roughly 1 hp. I've seen those little Troy bilt motors had a few of them and I think I have one in the garage. They aren't that good.
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The only reason I can use the engine I have is because of the wide reduction range it has 66.79\1~16.25\1. In the past I've rode by 50cc mopeds riders using throttle assist to help push the moped up some of these Tennessee hills.

Speaking as someone who has had heart operations a transplant is the biggest surgery one can have. Since @jitterbug3000 is on a transplant list, he would have a medical suspension on his driver's license. You'll have to get medical clearance before your license can be reinstated.

After my open heart surgery in January 2010 I wasn't cleared to drive for 6 months. I already had my bike built before the surgery and started riding after my sternum had healed 6 weeks latter. Technology has greatly improved fortunately for me. The last heart surgery in November of 2020, I was released from the hospital the next day. I was cleared to drive after 30 days.

Another factor here is what's being used for the build. An old weed eater engine, a BMX bicycle, a 9t centrifugal clutch, and a 32t rear sprocket. This suggest to me the budget to do a build is very limited. I'm almost certain a self-propelled moped (no pedaling) requires a driver's license in Philadelphia. An assist system doesn't require a license.
 
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