still 090 twin cylinder

[asharrow]

Lots of outboards of the 1920s and 30s were set up this way. It was all about balance.

Jim in Maine

 

[oakman]

one currection it actually isn't an opposed twin, its a 180 V-twin. oppossed twin use the same journal & V-twin uses two journals.

hmm......someone explain to me how you get a ''V'' out of 180 degrees.

 

[lesorubcheek]

I've looked at 4 stroke configurations plenty, but this is a new territory with 2 stroke multi-cylinder engines. I've never heard of a 4 stroke engine being designed to fire more than 1 cylinder simultaneously. so, for a 2 stroke, it was hard to understand why a single crank journal (one piston is at TDC while other is at BDC) with alternate firing wouldn't work and be smoother, but after reading eyeolf's post, it suddenly dawned on me that the problem would be with creating internal crankcase pressure to move the air/fuel mixture. If one cylinder is moving up (creating vacuum inside the case) while the other is moving down (creating pressure inside the case), there wouldn't be any pumping going on to create pressure to move the mix! Duh! So then, this arrangement makes perfect sense for a 2 stroke where the piston motion is synced to properly pressurize the internal case. Its hard for me now to imagine any other way it could work unless crankcase area was isolated for separate cylinders. Good stuff for exercising the 'ole brain cells!

Dan

 

[Mange]

If they are to ignite simoltaniusly, I would think that they need to be at the same position, at the same time.
If I am correct about this, there should be better balance. If not I really don't get the point of this.

 

[ScooterDrew1983]

v-twin setup uses 2 crank journals, whereas oppossed twin uses the same crank journal.oppossed twin the rods are connected end to end. "v" setup the rods have end caps on two crank journals. does the clear it up? normally there is a degree that goes with the name v-twin, in this case its 180 degree v-twin.

 

[glens]

The "v" in v-twin denotes anything other than 180° cylinder opposition.  Ask some Harley riders if their single-journal crank engine isn't a vee twin.

My Honda VF750F had two banks of cylinders opposed 90° from each other, with two crank throws.  Was it not a vee four?

 

[ScooterDrew1983]

it might involve the a countinous journal, but each rod has its own end cap, unlike true oppossed setup uses the connecting rods to cap the other off. So in basicly you still have two journals, though they might be countinous. & yes a 90° oppossed setup is a V-twin. & if you look at a motorcycle setup there is an offset on the pistons.

 

[sedanman]

Scooter, The connecting rod idea you propose would not allow the engine to turn over. The rods have to have seperate caps as they do not remain perpidicular to the bore as the piston travels up and down. A one degree angle between cylinder bores make the engine a "V" Volkswagon makes a VR-6 that has such a tight angle between the banks of cylinder that the engine has only one cylinder head! A "V" engine can exist all the way to 179 degrees between banks, hit 180 and the engine is a "boxer" or horizintally opposed. The crank does NOT determine an engines configurtion, the BLOCK does.

 

[sedanman]

One more thing Scooter, Harleys had (still have for all I know) NO offset between front and rear cylinders. They run two con rods on the same crank pin and the rods are two seperate pieces that straddle one another hers a pic that shows how one rod is "split" to acommodate the other. http://www.cas4.com/engine/Flywheels/flywheel4.JPG

 

[ScooterDrew1983]

sedanman. thanks for clearing it up, I guess I miss understood my teacher the other day. he was trying to explain the difference to me.

 

[glens]

Normally I wouldn't argue such a point <tt>:</tt><tt>)</tt> but it would seem you're making a distinction that's unwarranted.&nbsp; I concur that in order for two cylinders to be absolutely opposed they would have to have a common bore centerline, and your example of capping the conrods with each other would fulfill that so long as the interface to the journal were a slot through which the journal could operate.

A quick search of wikipedia indicates that a common-journal layout would in fact be considered by "some experts" as a V-at-180&deg; configuration, while a true "boxer" layout has each piston on a separate journal timed 180&deg; apart.&nbsp; I believe that's the opposite of what you were saying.

Semantically I disagree with you that a common journal would be considered anything more than a single journal, regardless the number of items occupying it.

Send your teacher on over so we can make sure he's got it right, hahaha!

Glen

 

[glens]

BTW, you're young and are trying, so we won't hold it against you.

Harleys speak with forked rods.

 

[ScooterDrew1983]

it was me misunderstanding him, he has been doing it since 73. so he knows what he is talkin about. he has seem most everything in the small engine. have found a few things that he hasn't seen. so it was me not understanding fully as to what he was saying.& he has been teaching it since about 81.

 

[glens]

I don't know if they're still doing it, but I recall back in the mid-80's Honda came out with a v-twin with the cylinders at or near 45&deg; included angle, but to make it run smoother (and possibly to avoid a Harley patent on cadence?) they used offset journals to achieve an <i>effective</i> 90&deg; vee.

I think this was at or about the time they dropped the 750s to 699 cc to avoid paying the "I'm Harley Davidson and I want protection from imports; boo hoo" tariffs.

Glen

 

[ScooterDrew1983]

HD's ns. Honda

My dad has a 97 honda shadow sprit 1100 he out ran a pack of HD's. he also had my mopm on the back of the bike. his bike is stock except for the saddle bags & air horns.

 

[lesorubcheek]

Hey ScooterDrew1983,

I bet a Honda XL125 would outrun most Harleys! Sorry but I'm not a big fan of Harley Davidson. Anything that costs that much for the level of performance offered is ludicrous in my opinion. Lots of cars have better acceleration. I see most Harley's on a trailer being pulled around from town to town. Always ask myself if they even run! For any Harley lovers, please understand this is just my opinion. If you love your bike, that's your business and I'm sure my opinion doesn't amount to a hill of beans.

Dan

 

[glens]

It's not so much about the performance with a Harley, though they can be made to do okay.

 

[bwalker]

Yes, It is true Harleys are over priced POS. Even the new V-rod with a porsche designed motor is painfully slow for a performance bike.
I love the look on the harleys guys face when I blow past them on my little, ring-ding, Rz350 two stroke.

 

[leweee]

Yes, It is true Harleys are over priced POS. Even the new V-rod with a porsche designed motor is painfully slow for a performance bike.
I love the look on the harleys guys face when I blow past them on my little, ring-ding, Rz350 two stroke.

come on now ....no picken on them Hardly Ablesons :blob5:

 

[ScooterDrew1983]

The buel motorcycles are strong motors. they are still HD's if you want up & go try the Boss Hoss. you can't throtle on take off with these.