Will 2-strokes work mounted at 30-45 degree angles?

M

mifletz

Member
Will 2-stroke engines like the Mitusbishi and Tanaka still work if fitted to a bike at 30-45 degrees?

The 4-stroke Robin claims to continue working even if operated upside down. Can other 4-strokes like the Honda do likewise?
 
Most 2 strokes will work fine regardless of angle (including upside down) but sadly, their carburetors may not - the kit supplied side-drafters are particularly sensitive and need to be as upright as possible.

4 strokes are a completely different beastie however, given their internal oil supply it's critical to not exceed the manufacturer's recommendations as the pick-ups wont... well, "pick up" as one example lol
 
The Robin must have a non-critical system to be able to operate at 90 degrees

STMITSUBISHI22ccFrictionKIT2.jpg
 
Last edited:
That would be no doubt the case - I took the question as "will they work upside down (from their stock configuration)" ;)
 
Though I just came across this photo, and it seems that the Tanaka can too!

STTanaka40ccFrictionKit1.jpg


Maybe the latest engines are both lubrication and carburation angle-independent?

The Robin site does say that it can be safely used inverted eg when attached to a power tool.
 
Last edited:
put a walbro on it and ride wheelies all day no bogging nothing they work good on rough terrain too no float bouncin around put it any way it fits and make sure carb is close to level unless you use walbro or tillotsen carbs
 
most 2 strokes from my limited knowelegde will work in any angle its the carb that counts where as a 4 stroke needs gravity to lubricate properly. case in point tip your lawnmower upside down and see what happens!
 
Any 2 cycle engine will run in any position simply for the fact that it does not rely on a sump for the oil to lubricate the engine as long as you have a carburetor that is either:

Float type of Carb that has the bowl mounted near level because it requires gravity to feed the fuel to the engine and shut off the flow of fuel at the needle valve

OR

A diaphragm assisted fuel pump type of Carb. This type of carb can be mounted in any position as it is not reliant on gravity to feed it or to meter the amount of fuel supplied to the engine. These functions are regulated by a pulse of pressure supplied from the engine.
 
Last edited:
biknut said:
Think about a chain saw.
Click to expand...
What about them? I am thinking... Oh you mean that the operate in any position? Not all "Chainsaws" have been 2 cycles and not all 2 cycle chainsaws have always had pressure assisted carbs. Analogy only works part of the time and special rules apply to each motor.
 
Chainsaw? How about a R/C plane doing 4 point rolls or any aerobatics for that matter? 2cycles and even some four strokers will run in any position as long as the lubrication system can work. Carburetion is another matter. Got a float? Needs to be reasonably level. Diaphram or fuel injection? Anyway you want to mount it.
Tom
 
so if i hang my HT upside down from the top tube, and flip the manifold and carb so it's upright, will it run?
 
Yes but I felt gufa'ed when I mentioned it,but if it were rotated 180 up-side down under the seat/top tube the jackshaft for shifting (shift-kit) could be by the head tube and down to the crank,,,Why hasen't some one mentioned an old vertical 2 stroke lawn-boy w/all the ball bearing mains ,etc??
 
bairdco said:
so if i hang my HT upside down from the top tube, and flip the manifold and carb so it's upright, will it run?
Click to expand...

It outa, funny lookin' and as uncomfortable as that would be lol - while to my knowledge it's not been done with one of our HTs, theoretically there's no reason for it to be any different than any other two stroke mounted in an inverted position compaired to it's stock intent.

Personally, I've built and flown an ultralight aircraft powered by a Rotax 440 two stroke - a common snowmobile* engine. While designed for upright use, it was necessary to invert it to conform to the airframe, "flipping" the manifolds and carbs ofc. While some detractors claimed that this would lead to a potential fouling problem w/residual fuel & oil trapped in the heads and that sounds logical, even may be true - I never experenced any problems in spite of the fact I used the choke to shut down after a flight. *shrug* Hardly the same engine as our HTs I'll admit - but it's what experience I've had and the theory is the same anyway lol



*snowmobile engine
This may or may not be true, but it was persistent lol - apparently when two stroke ultralights became popular, a few two stroke manufacturers decided to build up & upgrade their engines to offer specifically to the ultralight community (bearings as one example). Rotax apparently chose another route and upgraded all their 440 and similar engines, regardless of application, resulting in a superior motor even if "just" in a snowmobile.

Jus' thought that a neat bit of trivia lol ;)
 
You must log in or register to reply here.
Back
Top