Are 2 stroke engines reliable?

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Naheed

New Member
Apr 3, 2012
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Calgary, Alberta
Hi,

I am planning on changing my bicycle into a motor engine bicycle and would like to ask if 2 stroke engines are reliable. I have seen a 49cc 4 stroke engine and a 80cc 2 stroke engine and cant decide on which one to go for.. As I have heard 2 strokes are not very reliable and have lots of problems.. Please suggest if you any idea..

Thanks..:)
 

Cavi Mike

New Member
Dec 17, 2011
189
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Rochester, NY
Sounds like you're comparing a quality 49cc to the cheapest of the cheap 80/66cc China Girl engine. That's not comparing 4-stroke to 2-stroke, that's comparing quality to quantity.

Now if you were actually comparing 4-stroke to 2-stroke, 2-stroke is more reliable. There are less moving parts, the fuel can't wash away the oil from the cylinder walls because the oil is in the fuel and there's no sump full of oil to get dirty and clog up things.
 

Tyler6357

Well-Known Member
Mar 15, 2012
1,293
294
83
Santa Barbara, CA
I believe that two stroke engines are less reliable. 4 strokes are slightly heavier, harder to pedal without the engine running, while 2 stroke engines are cheaper to buy, poorly built, and don't last as long.
 

wayne z

Active Member
Dec 5, 2010
1,743
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38
louisiana
As far as our application goes, the 4 strokes are way more reliable than the 2 strokes. The only problem with the 4 strokes, is there isn't many options for a reliable transmisson.
 

Chitty

New Member
Jun 3, 2008
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Souris Manitoba Canada
I built a 49cc china girl 5 years ago, and sold it to an old fellow across the road. He has done almost nothing to the bike and it is still going. I got a what they call an 80 last summer and had to tinker with it quite a bit, new speed carb etc. It runs good when warmed up and runs fast, but the 49 was a lot smoother and better starting.
 

thegnu

New Member
Sep 15, 2011
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freedom pa
I think you should compare a chinese 2 stroke to a quality 2 stroke a good quality 1 is a strong an reliable motor , altho after proper prep a chinese 1 can be just as reliable I have read here of many members getting 1000's of miles on them . compare apples to apples , not apples to oranges ....just sayin, ya know .
Gary
 

Al.Fisherman

New Member
Sep 9, 2009
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Calera, Alabama
I'll weigh in.... First you can't compare a 4 stroke to a 2 stroke. Just like you can't compare a California orange to a Florida orange...see they are both oranges, but different.

A 2/4 stroke made in say China cant hold a candle to one made in Japan, or many other places. Many products made in the world today can and will be made in China, but for the most part start out as inferior. Basically from a very low quality control, and cheap castings.

I built my 2nd (66/80cc) MB in 3/2009, I did some modifications to the fasteners and some other items (running the same OEM internal parts), and I haven't had 1 minutes problem out of the engine itself.

Since 2009 I've built 4 other MB's all using the 66/80cc engine. Not one rider (my sons own 2 of them) has contacted me about any problems. If and when I have to go into the engine, I'll replace the cheap Chinese bearings with a much better quality.

On MB's I prefer the looks, performance and the simplicity of installation of the 49/66/80cc engine. They, as mentioned, have less parts, and one of the simplest and easiest engine I've worked on. Yes I'd rather have a 2 stroke say made some place other then China, but for the price difference, and it's not a every day commuter, it's a no brainer. I'll stay with the HT. If I spent $300-$500.00 on a well made 2 cycle engine, I can replace the HT 4+ times. The HT in my opinion is the best bang for the buck.

Basically these engines are like women, for the most part if they are treated right, they will treat you right. On the other hand if treated like c@@p, that what you will get in return.

Funny, I didn't read past the OP's question before I answered...Apples to apples ...;>)
 
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motor_bike_fanatic

New Member
Jul 26, 2011
377
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Pennsylvania
In terms of long-term reliability, a 4 stroke will be far more dependable and outlast a china motor by years, no matter how long a china motor does last. That being said, when it does come to china motors, you really wont know what you're getting until you get it. I have had 4 china motors, 3 with thee standard manual clutch, and one with an automatic clutch. the one way bearing in the automatic clutch failed after only a few rides, making it useless. on a 66cc engine, one of the rear mounting bolts snapped. my current engine is a 68.5cc engine, what some would refer to as old stock. I have had it for a year, and it is currently still in good running condition. If you do get a china motor, if it lasts more than a year, you got your money's worth. when I have the money, I am going to have a buddy build me a bike with a 99cc predator engine. He is an ezm dealer, so I will be getting the q-matic gearbox. his 99cc bike does almost 50mph and has plenty of torque with a 56t rear sprocket. gonna cost me a lot, but worth it for how long the engine will last.
 

moonerdizzle

New Member
Jun 28, 2009
874
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Cheese head capitol
if you do some work before install on a china 2 stroke you can get alot of miles out of them. But you might go threw magnetos unless you silicon up the cover and the little exit nut thing. My china doll just ticked over 4xxx miles not too long ago.
 

NormO

New Member
Jun 15, 2011
197
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New Brunswick,Canada
Two strokes have always had a bad rep. But if you get a quality made two stroke they'll last a good long time. Maybe not as long as a 4 stroke because they put out 20% more power than a 4 stroke of equal displacement. As an example i had an 1982 Honda Express. 49cc two stroke. Never had to touch the engine and it is still running now. Even though i sold it 5 years ago.
 

happycheapskate

New Member
Nov 26, 2009
1,989
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Rockwall TX
Buy a Dax Friction Drive, and an upgraded pocketbike engine from Dax. You should like it plenty. Light weight, plenty of power to go 30mph, fuel mileage far better than cars, reliability far better than a lot of common yard tools, as long as you mix the oil right. Later, you can get a Japanese high quality engine off Amazon or E-bay if you hunt, or a new one for $400.

Even if you blew up the pocketbike engine in a year somehow, $100-150 for a motor is less than 1 car repair most of the time. But if you oil it, and use quality gas, and do minor maintenance like not letting your pull cord get frayed after years, not letting it sit in the rain, not letting your spark plugs go on to the point they fail, you will do fine.

http://www.facebook.com/pages/Dax-Friction-Drive-fan-club/218445778250153
 

AslansMonkey

Member
Oct 2, 2008
194
1
16
Most four stroke guys will tell you that four strokes are the way to go and that the quality is so much better. In truth, I am sure that is correct.

But most two stroke guys will tell you that despite the reported bad reputation the china girls get, they seem to last a good long time when properly cared for. This too, is correct. I have four china girls and they've all been good runners. The original is 5 years old now and is probably the best of the bunch.

Frankly, if you have the inclination to tinker enough to put one of these on your bike, you probably have enough inclination to maintain it no matter what you buy so the real questions are more one of looks (most people think the two strokes look better in frame than the fours) and how lazy are you about mixing gas (fours don't require oil/gas mixing, twos do). If you have other small two strokes in your garate (weed wacker, chainsaw, etc) then mixing gas is a non-issue, you can probably run the same mix.

Personally, I like the two strokes, they look better (to me) and I've no problem with mixing the gas. All four of mine (one 55cc, three 66cc) run pretty good, though some like more warm up time than others, despite the fact that they probably are not the best quality. Also, their dirt cheap comparatively, so if they go, it's pretty inexpensive to replace one, or buy the parts needed to fix them. Four strokes are about twice the cost.
 

happycheapskate

New Member
Nov 26, 2009
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Rockwall TX
If you are comparing the beer-can motor (happytime) to any commercial 4 stroke pull start engine (Hua Sheng, Subaru, something like that), of course the 4stroke is superior. The serious fans of the ht engines say you will need to take apart a new one, replace the gaskets with superior gaskets, replace the chinese bearings with press in bearings, and replace the studs with high grade hardware, clean out all the factory shavings in the block, mill the head, and replace the spark boot, and the carb manifold, then it will last a really long time. I can take a Tanaka out of the box, bolt it on a Dax with 4 bolts, gas it and start it, and skip all that.

If you are comparing something like a Tanaka or Subaru/Robin 2 stroke with a 4 stroke of similar displacement and quality casting, I'd take the 2 stroke any day. For this application, the 2 stroke is great! You need all the raw power (torque) you can get, when you are so limited in displacement. You need the wide RPM band esp if you are limited to one gear or a roller. The popular Titan and Hua Sheng 4 strokes look pretty good though. I'm sure they are a fine choice. I just like the fun and practicality of the 2stroke. Less components, less weight, less rotating mass and no springs to fight. No valves to adjust, no camshaft or gears to wear. I've got just a roller on a spindle clutched 1:1 to the engine.
 

AslansMonkey

Member
Oct 2, 2008
194
1
16
If you are comparing the beer-can motor (happytime) to any commercial 4 stroke pull start engine (Hua Sheng, Subaru, something like that), of course the 4stroke is superior. The serious fans of the ht engines say you will need to take apart a new one, replace the gaskets with superior gaskets, replace the chinese bearings with press in bearings, and replace the studs with high grade hardware, clean out all the factory shavings in the block, mill the head, and replace the spark boot, and the carb manifold, then it will last a really long time. I can take a Tanaka out of the box, bolt it on a Dax with 4 bolts, gas it and start it, and skip all that.
All probably true. I've done NONE of that, however and have five years on my oldest "HT" motor. Do I think it's the same quality as a four stroke? Of course not. And I've had to tinker with them from time to time, but that's half the fun, right?

But I guess that gets to the real question in away. Do you want a motor you can throw in your bike that you NEVER plan to mess with afterwards? If your answer is yes you're probably a little delusional but should definately go with a four stroke. But if you expect to tinker and even enjoy that part of the equation, "risk it" with a two.
 

happycheapskate

New Member
Nov 26, 2009
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Rockwall TX
I tinkered with one of my Tanaka engines. :) You can see my boost bottle and intake mods on my user page. I think most people want something they can "set it and forget it", though. Sure, with any small engine, eventually it will need minor service (air filter, maybe fuel lines, clean the carb, a diaphragm, fuel filter, or a gasket, maybe the rings after 10 years or so. These are readily serviceable at mower shops, for people who don't want to do any of that, which is a good sales point. I like having something I can trust to go a long way from home. I would trust my job attendance rating more to this bike than the grubee for sure!
 

Ibedayank

New Member
Oct 29, 2011
1,171
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Columbia Tennessee
if grubee had the quality control that honda does none of the motors would make it to the packing area but would be rejected and thrown in the scrap pile to be melted down into hopefully paper weights
 

happycheapskate

New Member
Nov 26, 2009
1,989
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Rockwall TX
hahhaha. I got a kick out of that. I think a lot of Americans are easily fooled by look a likes. If something looks like a "pro" bike (disc brakes, front shock, knobby tires), it must BE a pro bike. Same with small engine equipment. I've got a "Poulan Pro" weedwhacker from Wongmart. I bought it used for $50. It has a lot of power, but isn't even close to the smoothness of Kioritz or Tanaka or Maryauma. And if it grenades someday, I won't mourn for it.
 

haste

New Member
Aug 2, 2009
131
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af
Honestly, take a 80CC HT 2 stroke and do work to it. Replace ALL the hardware, NGK plugs and wires, better fuel tank/petcock/fuel filter/fuel line, swap carb for a decent name brand one such as mikuni, remove all the slag and make sure ports are fine.

you can get many many miles out of them if you put in maybe 20 dollars(other than a carb and pipe), and tuning them.
 

Drewd

New Member
Jul 25, 2008
425
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0
Colorado
I've got at least 3 years (maybe 4, can't remember) use on my HT motor and it still has high compression and runs great. I'm figuring an easy 200+ hours on the engine without a problem.

I run either a blend or pure castor oil in my engines.