Questions tagged [two-stroke]
A type of internal combustion engine where all of the cycles of combustion occur in one 360 rotation of the crankshaft.
62
questions
29
votes
2answers
26k views
Why do two-stroke engine exhaust pipes look so strange?
Two stroke gasoline engine exhaust pipes are shaped strange. They expand into a wide diameter and then shrink down to a very small diameter where the exhaust gasses emerge into the environment.
- ...
19
votes
2answers
9k views
What is happening when a two-stroke engine is said to be "four-stroking"?
Many years ago, I was involved in a hobby of building and flying model aircraft. The aircraft used alcohol-fueled 2-stroke engines with glow plug ignitions. When these engines ran rich (and always at ...
16
votes
6answers
17k views
What makes two-stroke engines less fuel-efficient than four-strokes?
It is a commonly-held belief that two-stroke engines are less fuel-efficient than four-stroke engines, and some example BSFC figures appear to confirm this as well.
But what is it that causes two-...
12
votes
1answer
3k views
Does the air screw only affect the pilot jet?
I have a 2 stroke motorcycle, it's Kawasaki KR150. When I try to do some jetting on its carburetor (it's Keihin PWL26), I saw that there's an air screw.
So now I've been wondering about this air ...
11
votes
4answers
2k views
Starting a 2 stroke jet boat after several years
The parents in law gave me a jet boat, it hasn't been started in 5 years. The boat resided in NH on a trailer on their yard for 5 years, so it has seen freezing temperatures frequently. From what I ...
11
votes
1answer
3k views
Brake Specific Fuel Consumption of 2-stroke vs 4-stroke
How much fuel do various types of engines burn per power output? I'm especially interested in naturally aspirated piston engines, and comparing two-stroke to four-stroke.
The wikipedia article gives ...
9
votes
5answers
16k views
What are the problems in building 2 stroke engines with a large displacement?
I understand (from preliminary research) that when engine gets bigger, with a higher displacement that it is practically not possible to have a two stroke engine.
What are the implications in ...
9
votes
5answers
11k views
Is it okay to run aviation fuel (100 low-lead) in a dirt bike?
I'm wondering if it will be okay to run 100 octane low-lead aviation fuel in my 2007 RM250 motocross bike (two-stroke). Half of the people I've asked say yes, while the other half say no. Will it be ...
9
votes
2answers
806 views
Carb. Rebuild or Adjustment?
Just put a rebuilt 2 stroke and brand new Mikuni SBN carburetor in my jet boat. Got her running no problem the first couple times, now it seems I can't get any gas into the carburetor from the primer ...
8
votes
1answer
2k views
Two-stroke dirt bike piston running into spark plug
Recently, I submitted a post on here regarding a broken ground electrode on the spark plug of my 2005 Suzuki RM125:
Bottom piece of spark plug broke off in motorcycle engine
Well, I found out what ...
7
votes
2answers
3k views
Two-Stroke Diesel Engine - Do they use forced induction on them?
As I have indicated before, I'm very diesel ignorant. I just know the basics, very basics.
In a two-stroke diesel engine using forced induction seems necessary but at the same time I see challenges. ...
7
votes
2answers
205 views
Honda R8X-S heat seize
I've got a Honda R8X that heat seizes when I'm riding it when it goes over 40mph.
The lad I got it off said he had it re-bored and that it was run in.
Will I need to re-bore this again or is there ...
7
votes
1answer
3k views
Two-Stroke vs. Four-Stroke Diesel Engines - What is most commonly used in heavy vehicles?
I am not well versed in diesel engines. To prove my point, I've learned in the last month that a two-stroke diesel engine actually exists.
My Question.
What kind of diesel engine (four-stroke or ...
5
votes
2answers
13k views
No compression on my two stroke
I was recently riding racing my Honda 250R (1986) (informally), and, all of a sudden, the engine quit completely. I tried letting out the clutch in second gear (push starting) with my momentum, but ...
4
votes
1answer
2k views
Old gas in 2 cycle engine
I have a 2 stroked engine that sat for over 2 years. I drained the gas and can get it to turn over when I put starter fluid in the carb. it is blowing out a water substance from the muffler and cuts ...
4
votes
2answers
3k views
Single Cylinder 2 stroke bike with twin exhaust, will it need two chambered exhausts?
I am asking specifically about Yezdi (not in production anymore) 250/350cc motorcycles. Yezdi RoadKing was a 250cc single cylinder two stroke with twin exhaust. If upgrading to a calculated chambered ...
4
votes
2answers
405 views
If an engine starts does that mean compression is fine?
I am looking at buying a second hand 2-stroke engine. I have seen a lot online about checking compression before buying used engines. I don't have a compression tester, but will buy one if necessary.
...
4
votes
3answers
8k views
Two-stroke engine won't start - water in gas?
I realize this isn't a car question. There doesn't seem to be an appropriate Exchange for it, so I'm trying it here.
I have a two-stroke engine (for a rototiller), and it worked more-or-less well ...
4
votes
1answer
73 views
Snowblower - 2 cycle oil without stabilizer
I'm not sure if this is the correct forum for this question.
I have some 40:1 mixed gas (for my snowblower) that is about 6 month old with no stabilizer added. I haven't t tried it yet but should ...
4
votes
2answers
2k views
Adjust carburettor without hi-speed adjustment
I've got a Walbro WA226 with no hi-speed adjustment screw. Unfortunately, it seems that the issue is in the high-speed jet. Adjusting the low screw can set me up so long as the throttle is at full, ...
3
votes
4answers
4k views
Derbi Senda 50cc - Low Compression, will not run properly
I have a Derbi Senda SM 50 2005 plate. It has a good spark, however, it's not reading any compression. It's had a new top end and gaskets!
What could be wrong?
Sometimes it starts when you bump ...
3
votes
1answer
4k views
Bottom piece of spark plug broke off in motorcycle engine
I was riding my 2005 RM125 dirt bike the other day when it bogged down all of a sudden. I noticed the spark plug had backed out of the head, thus causing the stall. I pulled the spark plug all the way ...
3
votes
2answers
234 views
Diagnosing a boat that wont start
Having some problems with my '92 Boston Whaler Rage jet-boat again.... See this post for all relevant boat info:
Starting a 2 stroke jet boat after several years
Ok, so I did basic troubleshooting, ...
3
votes
1answer
343 views
JLO Rockwell 2F600
I have an old hovercraft that uses a small aircraft engine in the front to power both the lift and forward propulsion. I was hoping to find any kind of manual or literature on the engine itself. The ...
3
votes
1answer
3k views
Small two-stroke engine runs poor
I have a borrowed cultivator (Echo TC-2100), and having hard time running it. It looks fairly new, and in good condition, but was possibly poorly stored and was not winterized.
At first I could not ...
3
votes
0answers
173 views
Jet Boat, Cavitation or Misfire?
My jet boat is making a 'putting' noise when trying to accelerate.
You can find all details regarding my boat here: My Boat Info
The noise seems to happen in the mid-rpm range; 4,000 - 4,800 RPMS, ...
2
votes
5answers
2k views
Two-stroke vs four-stroke design
Besides the apparent differences in fuel-injection, ignition, and valve timing, are there any other differences in the design/build of two-stroke and four-stroke engines?
2
votes
3answers
2k views
Oil sump for 2 stroke vehicles
I do not know if there is any oil sump for a 2 stroke vehicle and basically it is mixed along with the gasoline. Why is that so in a 2 stroke vehicle. And can we have an oil reservoir or a sump of oil ...
2
votes
1answer
435 views
Is an exhaust mute bad for 2 stroke engines? [closed]
Will an exhaust baffle have any bad effects on a 2 stroke engine if it's used all of the time?
2
votes
2answers
22k views
What is the difference between a 2T oil and a 20-40 oil
I know a 2T oil is used in 2stroke bikes and its sometimes added with the fuel too. And a 20-40 oil also known as the engine oil is used to reduce the wear tear in the engine. I'm looking for a ...
2
votes
1answer
535 views
Two-stroke engine seizing at full throttle
I have an odd problem with a 50 cc air-cooled two-stroke scooter engine that keeps locking up at full throttle, then freeing up again.
I just bought the bike second hand with a new belt needed ...
2
votes
2answers
5k views
Too much smoke in my 2 stroke
I have a 2004 Cagiva Raptor 125 and for the last week it's been letting out smoke a bit too hard:
I have had the bike for a year and a half now. I did an engine rebuild as soon as I got it because ...
2
votes
1answer
60 views
Chainsaw chain spins after start until I hit the throttle
Immediately after I start my chainsaw (Craftsman 358.350280), without holding the throttle, the chain moves fast. As soon as I press and release the throttle, it comes down to idle fine and the chain ...
2
votes
5answers
5k views
2 Stroke engine magneto ignition system
I've got a 2 stroke 1 cylinder engine and its ignition system doesn't seem to work.
I'm having problems with my magneto ignition system and I need help connecting everything up. I think I've ...
2
votes
1answer
1k views
2 Stroke making choking sound on full throttle after carb replacement
I have a Yamaha RX 135 which is a 2 stroke bike, and I have replaced it's carburetor , Previously it was stock 26mm round slide mikuni carb , and its been replaced with 30mm Flat slide mikuni.
After ...
2
votes
1answer
6k views
String trimmer revving too high at WOT?
Someone gave me a 52cc string trimmer for free because they say it wasn't working. We would only get it started by dropping a few drops of fuel into the cylinder, and it would idle quite high for a ...
2
votes
0answers
49 views
Does a 2-stroke engine needs "break-in" after replacing cylinder and piston?
I just replaced cylinder and piston (with new gasket, rings, etc) in a 2-stroke 52cc string trimmer engine. It started at the first pull and sounds great, I let it run for 5 minutes, adjusted the carb ...
2
votes
1answer
146 views
How to clean a muffler from the inside?
I want to clean the muffler (final exhaust pipe) of my motorcycle (2004 Cagiva Raptor 125). It is a 2 stroke engine so a bit of oil has sort of... sedimented on the inside of it. How am i supposed to ...
2
votes
0answers
94 views
Weed Wacker Not Running Properly
I have a Remington weed wacker that is ~2 years old. It worked great for the first 2 or 3 months but then I could not get it to work properly. I have tried new gas, new plug, adjusting the idle on ...
1
vote
1answer
3k views
50cc Two Stroke Scooter/Motorcycle - Idle and start issues
This is my first motor-vehicle ever, a Simson s50 from 1976.
Things seem to be running fine, but there are two problems I need to figure out:
1) The engine dies unless rev'ed constantly - eg at a ...
1
vote
1answer
30 views
Can gasket sealant be used to seal friction fuel connections?
I have a two stroke trimmer with a plastic fuel tank and plastic fuel lines. At some point, these lines have been replaced with new lines that don't quite fit in the holes the old lines did (~0.5mm ...
1
vote
2answers
90 views
Exhaust back-pressure Q on simple 2-stroke yard-equipment engines:
I am having trouble getting a precise answer- is back-pressure necessary on a little single-cylinder 40cc 2-stroke like a chainsaw or a blower? I ask because people frequently modify mufflers to ...
1
vote
1answer
70 views
How fast a 2 stroke engine wears, how much fuel it consumes(compared to a 4-stroke engine) and how to properly mix fuel with oil [closed]
I want to buy a 2 stroke engine to build a minibike. I am 15 years old and i never owned a 2 stroke engine before. I know they wear faster and consume more fuel than a 4 stroke engine. But how fast ...
1
vote
1answer
53 views
This seemed a good spot for engine-stuff, so: What are some ways that *may* lead to greater power in a chainsaw?
This seemed the best area to ask since it's not a tool question so much as an engine question, I use a high-end premade fuel and always have a sharp or sharp-ish chain, am just hoping to learn the ...
1
vote
0answers
14 views
How can find if the CDI of my bike is working fine?
I have a 2001 Yamaha RX 135 2 stroke motor bike and have installed an aftermarket performance CDI which claimed to give me better performance and RPM rev.
But since I have installed it I seem to feel ...
1
vote
0answers
17 views
Is back-pressure (or air-intake suction) of ANY value to a typical little(20-->50cc) 2-stroke engine? Like chainsaws, blowers etc [duplicate]
Have been searching for this answer for a while, typically I look for an answer & give-up when nobody can provide one but this time I'm going to learn the truth!!
For chainsaws, weed-eaters etc, ...
1
vote
0answers
255 views
Johnson 9.9 2 stroke wont idle anymore
I have a 1999 Johnson two-stroke 9 hp outboard motor. I have a 10 foot pelican that I put it on but the other day I almost flipped the boat after making a sharp turn, water got all in the boat about ...
1
vote
0answers
273 views
1997 Mercury 9.9 HP 2-Stroke starting issue
I've been banging my head on a starting issue with the outboard motor mentioned in the subject line (it's a manual pull-start).
Problem is that when I pull it over, it doesn't sound/feel like it even ...
1
vote
0answers
3k views
2 cycle engine has spark and new carb won't start [closed]
I have a 49cc 2cycle engine that I replaced the carb on. It has fresh gas and
appears to have a spark. I can't get it to fire even if I put some starter fluid in the air intake. It seems to have ...
0
votes
1answer
81 views
Which engine type gives more HP- two or four cycle?
Same max. RPM and CC of course. And if possible, an explanation would be nice. Thanks!
