Faster in reverse?

mudtrux · 10-19-2007, 03:44 AM

Since I've gotten this rig it's ran ok forward but like a raped ape in reverse.
It has no governor. I understand that I probably should take the two comp readings but keep forgetting my gauge at work.

I'm not very familiar with two strokes, Why is the comp. different from forward to reverse anyway?
Thanks, muddy

spriddle · 10-19-2007, 06:24 AM

Wow, never even heard of this. My guess would possibly be a valve problem.

NO NO NO E-Z-GO! · 10-19-2007, 06:34 AM

I have always heard that it's because the cylinder wears into an "egg" shape because of the 99% forward run time and 1% reverse run time. When the engine is turning one way it creates forces different from those when it's turning the other way. Thus, the piston pushes harder on one side of the cylinder walls than it does the other in forwards and reverse.

tew45 · 10-19-2007, 07:47 PM

The reason it runs in reverse better than forward is the charging circuit is not active in reverse. Therefore less load in reverse than when running forward.

roady89 · 10-19-2007, 08:30 PM

Quote:

Originally Posted by tew45

The reason it runs in reverse better than forward is the charging circuit is not active in reverse. Therefore less load in reverse than when running forward.

So Then that would explain the compression difference in reverse?

....

....the piston is always pushing on one side of the cylinder wall on the upward stroke. When put in reverse the piston is pushing on the other side of the cylinder wall. (less wear) This can go both ways....you can gain some compression or loose some compression. Watch the gif below and see what I mean.... Most car/truck engines offset the piston pin to help with piston to cylinder wall loading.

tew45 · 10-20-2007, 12:03 AM

Yes you are right but the compression difference from forward to reverse is normally considered to be of no important difference except that it is something you should know and you covered that very good. The compression will also be different on the Harley engine because it is a loop scavaged engine. I'm not sure exactly why. The charging has no effect on compression difference because the starting circuit is working both ways. It also could be that the starter turns the motor at a slower speed in forward mode due to ? I don't know if the pin hole is off center on the 2 cycle engine or not. It is marked for forward placement for the intake holes in the piston (maybe). So what I am trying to say is I really don't know why the compression is different forward to reverse but you are probably right. But the running motor has a heaver load in forward than reverse because of the charging circuit and it may run faster for both reasons. I don't know for sure!

mudtrux · 10-20-2007, 05:37 AM

So if I disable my charging system by using a switch, it would be like a shot of no2

I may have to experiment. By the way is anyone doing the penny thing, do I need to send some out?

mb523 · 10-20-2007, 09:47 PM

Charging works in both directions, thus the micro on the F/R switch. It reverses the polarity. The reason is as a few stated, the motor running more in forward than reverse. Basically, you have more compression in reverse, which equals more power. This is due to the "egging" effect NO NO mentioned. I has this SAME exact thing happen to my 2-stroke EZGO and when I tested compression, it was 95 forward and 110 reverse. Upon dismantling it for a top end rebuild, I could see the wear in the cylinder on only one side. The rings also wear on one side more than the other and cause the piston to tip, potentially causing the skirt to come in contact with the cylinder wall. I had some scoring marks where my skirt hit. If this happens too much, the skirt can break off and be thrown into the crankcase, potentially causing a very bad situation.

tew45 · 10-21-2007, 07:37 AM

You may be right but I am still not convinced for mine ran faster in reverse when it had a brand new top end and still does and it has no more than two tanks of gas ran through it. Wear must be rapid! And I still think the charging circuit is out when in reverse. I will try to confirm this week and report.

roady89 · 10-21-2007, 08:14 AM

I think there may be some confusion. The original posted didn't specify what kind of cart he is asking about. Which we will assume is harley powered... Just because a harley cart may not charge in reverse doesn't mean an ezgo doesn't. Theres no doubt in my mind if the charging circuit is deactivated there will be more power there.

10-19-2007, 03:44 AM	#1
mudtrux Gone Wild Join Date: Sep 2007 Location: Central Mn Posts: 270	Faster in reverse? Since I've gotten this rig it's ran ok forward but like a raped ape in reverse. It has no governor. I understand that I probably should take the two comp readings but keep forgetting my gauge at work. I'm not very familiar with two strokes, Why is the comp. different from forward to reverse anyway? Thanks, muddy

10-19-2007, 06:24 AM	#2
spriddle Admin Join Date: Dec 2006 Location: TN Posts: 101,858	Re: Faster in reverse? Wow, never even heard of this. My guess would possibly be a valve problem.

10-19-2007, 06:34 AM	#3
NO NO NO E-Z-GO! Gone Wild Join Date: Dec 2006 Location: ComplainAboutNoNo'sProfile-Ville Posts: 4,995	Re: Faster in reverse? I have always heard that it's because the cylinder wears into an "egg" shape because of the 99% forward run time and 1% reverse run time. When the engine is turning one way it creates forces different from those when it's turning the other way. Thus, the piston pushes harder on one side of the cylinder walls than it does the other in forwards and reverse.

10-19-2007, 07:47 PM	#4
tew45 Gone Wild Join Date: Aug 2007 Location: North Texas Posts: 2,312	Re: Faster in reverse? The reason it runs in reverse better than forward is the charging circuit is not active in reverse. Therefore less load in reverse than when running forward.

10-20-2007, 12:03 AM	#6
tew45 Gone Wild Join Date: Aug 2007 Location: North Texas Posts: 2,312	Re: Faster in reverse? Yes you are right but the compression difference from forward to reverse is normally considered to be of no important difference except that it is something you should know and you covered that very good. The compression will also be different on the Harley engine because it is a loop scavaged engine. I'm not sure exactly why. The charging has no effect on compression difference because the starting circuit is working both ways. It also could be that the starter turns the motor at a slower speed in forward mode due to ? I don't know if the pin hole is off center on the 2 cycle engine or not. It is marked for forward placement for the intake holes in the piston (maybe). So what I am trying to say is I really don't know why the compression is different forward to reverse but you are probably right. But the running motor has a heaver load in forward than reverse because of the charging circuit and it may run faster for both reasons. I don't know for sure!

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10-20-2007, 05:37 AM	#7
mudtrux Gone Wild Join Date: Sep 2007 Location: Central Mn Posts: 270	Re: Faster in reverse? So if I disable my charging system by using a switch, it would be like a shot of no2 I may have to experiment. By the way is anyone doing the penny thing, do I need to send some out?

10-20-2007, 09:47 PM	#8
mb523 Peanut Join Date: Feb 2007 Location: Western Massachusetts Posts: 656	Re: Faster in reverse? Charging works in both directions, thus the micro on the F/R switch. It reverses the polarity. The reason is as a few stated, the motor running more in forward than reverse. Basically, you have more compression in reverse, which equals more power. This is due to the "egging" effect NO NO mentioned. I has this SAME exact thing happen to my 2-stroke EZGO and when I tested compression, it was 95 forward and 110 reverse. Upon dismantling it for a top end rebuild, I could see the wear in the cylinder on only one side. The rings also wear on one side more than the other and cause the piston to tip, potentially causing the skirt to come in contact with the cylinder wall. I had some scoring marks where my skirt hit. If this happens too much, the skirt can break off and be thrown into the crankcase, potentially causing a very bad situation.

10-21-2007, 07:37 AM	#9
tew45 Gone Wild Join Date: Aug 2007 Location: North Texas Posts: 2,312	Re: Faster in reverse? You may be right but I am still not convinced for mine ran faster in reverse when it had a brand new top end and still does and it has no more than two tanks of gas ran through it. Wear must be rapid! And I still think the charging circuit is out when in reverse. I will try to confirm this week and report.

10-21-2007, 08:14 AM	#10
roady89 nimda Join Date: Jun 2007 Posts: 13,022	Re: Faster in reverse? I think there may be some confusion. The original posted didn't specify what kind of cart he is asking about. Which we will assume is harley powered... Just because a harley cart may not charge in reverse doesn't mean an ezgo doesn't. Theres no doubt in my mind if the charging circuit is deactivated there will be more power there.
roady89 nimda Join Date: Jun 2007 Posts: 13,022

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