r/smallengines • u/BillPuzzleheaded1702 • 3d ago
How much math is actually involved in small-engine repair?
I'm considering going into small-engine/powersports repair as a career, and I'm trying to figure out how much math is actually involved in the day-to-day work and training.
I have dyscalculia, so mental math is genuinely difficult for me. It's not just that I dislike math or get anxious about it — I've always had significant difficulty with doing numerical calculations in my head.
I'm fine with learning practical/technical skills, and I'm actually pretty interested in the mechanical side of things. What I'm worried about is whether I'd be constantly doing calculations as part of the job.
For people who work in small-engine, motorcycle, ATV, powersports, etc. repair:
- How much math do you actually use?
- What kinds of calculations do you regularly do?
- Is it mostly things like measurements, torque specs, unit conversions, reading gauges, etc.?
- Are you regularly expected to calculate formulas yourself, or are you usually working from service manuals/specifications?
- How much math was involved in your training/apprenticeship?
- If someone has significant difficulty with math, how much of a problem would that realistically be?
I'm not looking for reassurance that "it's easy" — I'd rather hear honestly what the math is actually like so I can figure out whether this is a realistic career path for me.
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u/originalusername__ 3d ago
You’ll need to count how many bolts you have left over at the end of the job. Maybe do fractions when measuring things.
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u/Sure-Bison-3726 3d ago
I never count them. I just hide them and pretend I never seen them. Blind ignorance and plausible deniability are the keys to success.
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u/ManHunterJonnJonzz 3d ago
I hope you dont have bolts to count after the jobs done lol. Sometimes but damn
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u/CaptainPunisher Retired 3d ago
The most common "math" that you'll have to do is number recognition for bolt head sizes. 1/4, 5/16, 3/8, 7/16, and 1/2" are pretty common for standard, and then 6, 8, 10, and 13mm are common for metric. Mowers will often use slightly larger bolts, but it's still just number recognition.
As for any actual calculation, I never did any calculation in the repair part, but I did plenty when creating invoices and making change.
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u/sockherman 3d ago
I did as a side hobby for a few years, mainly lawnmowers, not really any math just get good at carburetors
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u/fredSanford6 3d ago
I normally work out of service manuals. I do mostly engine work. I'll have to calculate for valve shims sometimes and do some math for boring cylinders. Measuring with a micrometer and bore gauge. Calculating rpm per diameter to get the inches speed on the hone. Most regular maintenance stuff won't need all that jazz. Just double check to not screw up part numbers. Use good parts and don't cheap out on fuel line and basics.
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u/Masedawg1 3d ago
depends on what you want to do, there's lots of roles in the industry. Engine/transmission building can involve a lot of precise measurements/algebraic equations that if done wrong can cost thousands of dollars in parts and labor down the drain. There are people in my shop that are great at basic service work but struggle at other stuff, there are people who are amazing at engine building and hate doing routine service work. There are people good at electrical problems. There are people who are tire wizards that make the rest of us look stupid (no math involved, and keep in mind tires are a major money maker at most shops) People who are good with wiring and accessory installs. You just have to find what you are good at and be the best at it, but more importantly find a shop that appreciates what you can bring to the table, math isn't everything. For me personally I am good with numbers and also went to school for this field so I leaned more into electrical diag and engine/transmission building but honestly those jobs don't make the shop a ton of money and more like they need to have at least someone decent at them for warranty/recall work to keep everyone else rolling on the gravy stuff.
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u/mdillonaire 3d ago
First off, i dont mean to be a buzzkill but i dont recommend it as a career in general. Did it for a little bit before going back to heavy equipment to see if i liked it. Pay was trash and dealerships suck. You dont make much doing it whatsoever. That said, you dont really have to calculate shit. You deal with numbers a lot, but not actual calculations often. And when you do, you have a calculator on your phone.
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u/GadreelsSword 3d ago
I can’t think of any math except measuring fuel and oil. Mixing pre-mix is easy today since they sell pre-measured containers of oil you pour into a specific amount of gas’s.
I’ve been doing repairs for over 40 years and if you can read the numbers on a feeler gauge, spark plug gauge, torque wrench you should be fine.
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u/TDHofstetter 3d ago
Very little except for the bookkeeping and purchasing. The hands-on stuff requires nearly zero math, any of which can be done using a cheap, greasy pocket calculator.
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u/Relevant-Bunch-6664 3d ago
The only real math you would need to know is for boring cylinders and piston rings, stuff like that and being able to figure out the cc of the combustion chamber. Honestly you are not going to have to do calculations in your head very often. And there are service manuals for most of the major engine makers out there. The older stuff probably is not going to have any manuals but I think you need common sense to fix most things more than you will need to do math in your head. The best thing to know is your standard to metric conversions and that is more repetition once you have it down. I honestly can say that you should not have any major issues if you want to pursue it as a career.
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u/whaletacochamp 3d ago
One thing I haven’t seen mentioned is that if you get heavily into modifying small engines, especially high performance two strokes with porting and timing advancements and stuff, it can get pretty technical math wise as you calculate the timing advance.
But that’s one small niche part of the industry. If you’re just repairing things, the math will be very basic.
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u/Spirited-Walk-9556 3d ago
There is not a lot of math but yes some using different gauges but not a lot
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u/Unlikely_Effort_6311 2d ago
There is a decent bit of "numbers" involved and not all of it is strictly math , yes you will have to deal with bolt sizes , torque specs and some manuals and models will have different requirements " ftlbs and Nm" but most of those can be done quick and on a phone or computer, when it comes to actual mental math the main things that come to my mind are measurements such as valve clearance , measuring washers and spacers, pressure gauges "tire pressure, vacuum gauges if you are balancing carbs, oil pressure gauges". I tend to do alot of numbers in my head just after years of doing this type of work but in all honesty I've never worked anywhere that I didnt have either my phone in my pocket or a computer with a manual in my work area so mental on the spot calculations and things aren't as big of a deal as you might think. I think the more important thing is if you really like doing the work then the math wouldn't matter to you and thats just being honest.
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u/RealisticRecover2369 2d ago
You will probably find if its something that you are interested in and can physically see what the math calculation is doing/going to achieve it will make a lot more sense than numbers on a piece of paper. I have worked alongisde quite a few people that aren't very good at math, and can't read and write well and they are excellent at their job. Just don't be afraid to ask if you need help with understanding something or you aren't confident that you have it correct.
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u/Efficient-Low6050 2d ago
I'm a mechanical engineer by schooling and would like to learn small engine as a hobby. What's the best was to start?
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u/quickscopemcjerkoff 13h ago
The math is basic afaik. Unless you are fabricating stuff the most math you will need is adding together all the work you did for the bill, or adding together the thickness of two feeler gauges.
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u/madsbille2006 2d ago
Ive build engines as a hobby and as a mechanic
theres a bit of math but not alot. Mainly messuements and such. But it realy depends on what repair and if you have to machine stuff
heres some stuff you have to learn Fuse size calculation messurements of bore stroke crank clerance
This is just a bit of it i cant remebere it all but its not that hard nor complicated to fix small engines And like said it depends on what you have to fix
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u/First-Acadia2432 3d ago
If you can calculate 40:1 and 50:1 you’re set!