Run a bike on half cylinders.

[The Pastor]

Will it be bad for a bike to be run on half its cylinder?

i.e., if i ran a cbr250rr (4 cyl 4 stroke) on 2 cylinders by removing the spark plugs would it break it?

and if it would break it, what would the damage be.

[NordieBoy]

You'd be spitting fuel out the plugholes in a fine mist...

Otherwise no problem.

If you just pulled the leads it'd be more successfull but it'd still be a CBR125RR with an extra pair of pistons to move around.

Make sure it's on video whatever you decide to do :D

[Ixion]

No fuel mist unless its injected. Spark plugs out means no suction to draw fuel in.

I've ridden twin cylinder bikes for a hundred kilometres and more on one cylinder. No problems, just VERY gutless.

Not a practical thing to do of course unless half your cylinders have crapped out. Though, some late model cars do exactly that - the new Honda Accord V6 runs on 6 cylinders, or 2 or 3 depending on demand etc.

Why do you ask?

[The Pastor]

I was thinking about the less than 200cc ride to the cape challenge, would it qualifiy? Sure the bike costs more than 1000$ but the point is to do it on somthing unsuitable...

[Ixion]

Ah, Youd have to ask the organisers.

Overheating could be a problem, since it's water cooled.

[pete376403]

If you pull the plugs out the dead cylinders will act as an engine brake - the drag of moving air into and out of the cylinder will slow the engine right down. It used to be common (before decent brakes on dirt bikes) to have a decompressor screwed into the spare plug hole of two strokes, and this was used as an engine brake. Leaving the plugs in would be less drag as the energy expended compressing the air (on the upstroke) is returned by the spring effect of the compression on the downstroke. The engine will still run like shit, however.

[The Pastor]

Ah, Youd have to ask the organisers.

Overheating could be a problem, since it's water cooled.
sorry for being a noob, but how would it overheat?

[Steam]

Full marks for cleverness, that's an excellent and hilarous way to qualify for the challenge!

[Ixion]

Cos you're asking it to work very very hard, at low speed (only the two working sylinders would get hot of course).

Working hard, firstly as the numerically imposing gentleman said, pumping air, and working hard with only 125 cc to lug around a bike meant for twice that.

Low speed, cos it's going to be gutless! And thus not much air flow. (I think those motors don't have a fan ? ).

It's unlikely that the designers took such circumstances into account when doing their sums about cooling areas and flow rates , etc

[Steam]

sorry for being a noob, but how would it overheat?

From what the knowledgeable types say, it sounds like it won't hurt it too much, have a go and just keep an eye on the temperatures. Tell us how you get on!

[EJK]

I believe thats how skidMark blew his bike...

[Slingshot]

You'd want to be selective about which two cylinders to choose to disable too. Ideally, the two that you'd want to have firing would be fairly opposite in their cycle...one at (or near to) top dead center and the other at bottom dead center.

[breakaway]

Low speed, cos it's going to be gutless! And thus not much air flow. (I think those motors don't have a fan ? ).

But it is a water cooled engine with a radiator (which has a fan). Will it still overheat?


I believe thats how skidMark blew his bike...

No, that was due to lack of oil and missing a gear change. Apparently.

Apparently.

[EJK]

well for a while he was running on 3 cylinders.... then it "suddenly" siezed lol meh

[Padmei]

ive often thought about running my bike on old oil from the deep fryer mixed with vinegar for a bit of omph what do you think? You know biofuel kind of... would it work?

[offrd]

ive often thought about running my bike on old oil from the deep fryer mixed with vinegar for a bit of omph what do you think? You know biofuel kind of... would it work?

Yeah sure if your bike is a diesel......

[Motu]

I've just tried this idea on my bike - I've removed the sparkplug,and now it won't start! Do you think I've done any damage? I'm really puzzled be cause it always went before...now it's just dead - HELP!

[McDuck]

1

If you leave the spark plug lead off it can root the coils. Not worth the risk IMHO. (Besides wouldnt you only have to remove one to do the CCC?)

[NordieBoy]

ive often thought about running my bike on old oil from the deep fryer mixed with vinegar for a bit of omph what do you think? You know biofuel kind of... would it work?

Depends which tyre you put it in.

[NordieBoy]

I've just tried this idea on my bike - I've removed the sparkplug,and now it won't start! Do you think I've done any damage? I'm really puzzled be cause it always went before...now it's just dead - HELP!

Think of all the fuel you'll be saving :D

FuelUsed%=FiringCylinders/TotalCylinders*100


Wonder what would happen on a dual spark head like the DR :devil2:

[swbarnett]

Will it be bad for a bike to be run on half its cylinder?

i.e., if i ran a cbr250rr (4 cyl 4 stroke) on 2 cylinders by removing the spark plugs would it break it?

and if it would break it, what would the damage be.
I lost a solenoid in the CB750 (one of two) when I was visiting my grandparents in Turua (10km south of Thames). Rode it all the way back to Auckland on 2 of 4 cylinders. It took a couple of minutes to accelerate to 80kph and wouldn't push any more. Caused no damage to the bike, just replaced the solenoid and all was right as reign. Also, I had no comments from the rider covering my rear about clouds of unburned fuel.

[xwhatsit]

I've just tried this idea on my bike - I've removed the sparkplug,and now it won't start! Do you think I've done any damage? I'm really puzzled be cause it always went before...now it's just dead - HELP!

Buy a bike with more than one cylinder, you cheap moustachioed bastard :D

[inlinefour]

Will it be bad for a bike to be run on half its cylinder?

i.e., if i ran a cbr250rr (4 cyl 4 stroke) on 2 cylinders by removing the spark plugs would it break it?

and if it would break it, what would the damage be.

Is your middle name skidmark? Why the hell would you want to do that???

[pyrocam]

I was riding my cbr250rr and one of the plugs popped out. I kept riding it to my destination, it was loud as fuck and very VERY gutless.

didn't do any damage though, I had the engine pulled apart and rebuilt by Kerry after. probably did 50k with it like that.

[scumdog]

If you pull the plugs out the dead cylinders will act as an engine brake - the drag of moving air into and out of the cylinder will slow the engine right down. It used to be common (before decent brakes on dirt bikes) to have a decompressor screwed into the spare plug hole of two strokes, and this was used as an engine brake. Leaving the plugs in would be less drag as the energy expended compressing the air (on the upstroke) is returned by the spring effect of the compression on the downstroke. The engine will still run like shit, however.

There is a major flaw in your theory, without going into it try this:

Next time you have the plugs out of you engine spin it over using the starter motor.

Then try it with the plugs back in.

And notice the cranking speed.

[Motu]

But at 17,000 rpm your bike is really going to be pumping a lot of air in and out of the plug hole.

[NordieBoy]

But at 17,000 rpm your bike is really going to be pumping a lot of air in and out of the plug hole.

Yeah, should really stick a bit of rag in the hole.

[scumdog]

I lost a solenoid in the CB750 (one of two) when I was visiting my grandparents in Turua (10km south of Thames). Rode it all the way back to Auckland on 2 of 4 cylinders. It took a couple of minutes to accelerate to 80kph and wouldn't push any more. Caused no damage to the bike, just replaced the solenoid and all was right as reign. Also, I had no comments from the rider covering my rear about clouds of unburned fuel.

Hmm, the petrol washing the bore clean would have caused extra wear on the cylinders that were'nt running But whether you would ever notice is another matter.

[FilthyLuka]

Hmm, the petrol washing the bore clean would have caused extra wear on the cylinders that were'nt running But whether you would ever notice is another matter.

Carbs rely on the vacuum caused by the piston moving downwards, with no plug, there would be no vacuum, therefore no fuel.

[scumdog]

Carbs rely on the vacuum caused by the piston moving downwards, with no plug, there would be no vacuum, therefore no fuel.


I was refering to about three or so posts back when somebodys bike was ridden with only two cylinders running, (as per the quote on my post) no mention was made of plugs being taken out.

[swbarnett]

I was refering to about three or so posts back when somebodys bike was ridden with only two cylinders running, (as per the quote on my post) no mention was made of plugs being taken out.
The plugs were still in place. Just had a blown solenoid so they weren't firing.

I certainly never noticed anything wrong. Not that I pushed it to it's limit anyway.

[pete376403]

There is a major flaw in your theory, without going into it try this:

Next time you have the plugs out of you engine spin it over using the starter motor.

Then try it with the plugs back in.

And notice the cranking speed.

It's not just my theory...

I did install a compression release on my kawasaki F9 (350 single two stroke) for the very purpose of assisting the braking - it was much more controllable than the drum brakes, especially when they were full of water or mud.
Most twostroke singles of that era did have two spark plug holes in the head, the second ususally had a blanking plug installed.

http://www.dansmc.com/comp_release2.htm

Some 1960s and 70s two stroke engine heads have two spark plug holes. You can put a compression release in the extra hole.

The compression release can be used for something else on two stroke engines... an engine brake. This was all the rage in the late 1960s and early to mid 1970s. By putting in the right kind of compression release the engine would act as an engine brake if activated when the engine was running. There were problems with this. If you did not have the right design, the engine could draw in dirt and the hot engine gases could weaken the decompresser spring.

also check out the operation of the jacobs exhaust brake (Jake brake)

http://en.wikipedia.org/wiki/Jake_brake

When the accelerator is released on a truck, its forward momentum continues to turn the crankshaft and compress air inside the engine's cylinders. When the crankshaft passes the top-dead-center position, the compressed air in the cylinder acts as a spring and pushes the piston back down the cylinder, returning the energy to the crankshaft and pushing the truck forward. Little of the energy absorbed by compressing the air is lost, so the engine does not effectively aid in slowing the truck....A compression release engine brake uses an extra lobe on the camshaft to open a second exhaust valve at the top of the compression stroke. The stem of this valve telescopes during normal operation so the valve remains closed, but is locked at full length by a solenoid when the engine brake is engaged so that the valve opens as directed by the cam. This releases the compressed air in the cylinder preventing it from returning its energy back to the piston and accordingly, the vehicle speed is reduced.

While that refers specifically to four strokes, the principle is the same - by releasing some of the air inside the cylinder, the "spring" effect of compression is removed - just the same as running some cylinders without a spark plug.

[TygerTung]

You still have to draw air in and out of the cylinder with the spark plug in, PLUS you have to compress it.

I would suggest that running a CBR250 with two cylinders, IF you can get it to start, will be MUCH slower than a 125.

[breakaway]

A compression release engine brake uses an extra lobe on the camshaft to open a second exhaust valve at the top of the compression stroke. The stem of this valve telescopes during normal operation so the valve remains closed, but is locked at full length by a solenoid when the engine brake is engaged so that the valve opens as directed by the cam. This releases the compressed air in the cylinder preventing it from returning its energy back to the piston and accordingly, the vehicle speed is reduced.

/breakaways' head explodes

[.produKt]

LOL!!!! @ above.
Can smell it from 'ere :P

I have carefully read thru the forum (Tui moment), and noted that no-one pointed this out.

You could just remove a lead, BUT, all that mass of the unburnt fuel compared to the mass of burnt fuel will damage something.

And also, the unburnt fuel\air mixture would bypass the piston and contaminate the oil, (assuming that not all engines have perfect compression!)

Just my 2c :D

[scumdog]

LOL!!!! @ above.
Can smell it from 'ere :P

I have carefully read thru the forum (Tui moment), and noted that no-one pointed this out.

You could just remove a lead, BUT, all that mass of the unburnt fuel compared to the mass of burnt fuel will damage something.

And also, the unburnt fuel\air mixture would bypass the piston and contaminate the oil, (assuming that not all engines have perfect compression!)

Just my 2c :D


Well worth $2!!

SO, so true!!

(And I tried to say that earlier to the non-believers bit oh no, they knew better)

[mark247]

Doesn't the fact that the crank is pulling the conrod instead of the conrod pushing the crank mean it can cause wear or crack the crank or something? I was told this by someone and i dont know if its true or not...

[AllanB]

If your plug is out you will also be open to any shit flying through the air going down there.......

[.produKt]

Think he's given up on the idea yet? :D lol