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putting bike under load in garage

  • Thread starter Thread starter 79-GS550-L
  • Start date Start date
7

79-GS550-L

Guest
Hello,

I need to adjust the carbs on my bike (I'm running too rich) and was reading about doing a plug chop. From what I understand, to adjust the carbs for WOT I need to run the bike with the throttle completely open for about a minute then kill the engine. And I guess that means that I need to run it with some resistance (under load) so that I can hold the throttle completely open without revving the engine too high (past redline). The page I read suggested driving uphill to do that. The problem is, I don't have anywhere nearby where I can drive really fast uphill for a minute (not to mention having a safe place to suddenly pull over and check the plugs). Is there some way to add the load in my garage? I guess using the brake would work, but would wear my brakes out pretty quickly. I'm thinking something like a magnetic brake from a treadmill/elliptical. Do they make things like this (that are affordable)? What does everyone else do?
 
Easiest way is to run about 35 mph in top gear, hold the throttle wide open to about 60 or so, then chop.


.
 
79-GS550-L said:
Hello,

I need to adjust the carbs on my bike (I'm running too rich) and was reading about doing a plug chop. From what I understand, to adjust the carbs for WOT I need to run the bike with the throttle completely open for about a minute then kill the engine. And I guess that means that I need to run it with some resistance (under load) so that I can hold the throttle completely open without revving the engine too high (past redline). The page I read suggested driving uphill to do that. The problem is, I don't have anywhere nearby where I can drive really fast uphill for a minute (not to mention having a safe place to suddenly pull over and check the plugs). Is there some way to add the load in my garage? I guess using the brake would work, but would wear my brakes out pretty quickly. I'm thinking something like a magnetic brake from a treadmill/elliptical. Do they make things like this (that are affordable)? What does everyone else do?
Click to expand...

Just strap it to the chassis dyno you have tucked away in the corner of the garrage. No problem. :shock: :-D
 
txironhead said:
Get a Morgan Colortune and do it that way.
Click to expand...

The colortune is only effective for checking the pilot circuit. They say not to run the engine at high rpm while using the colortune. In order to do an accurate plug chop on the mains, you pretty much have to be on the road.... or on a dyno. No good freeways around your place?
 
Just get one buddy to stand in front and push and another buddy to sit behind you. Do a burnout and there you go!:-D
 
Wonder if there would be a way to rig a temporary-mount O2 sensor to the exhaust....it would be more expensive than checking the plugs, but it could fit several bikes and there'd be less chance of burning your hands or getting pulled over for "excessive demonstration of speed". Yeah, the cops in my area hate bikes. And they would think plug chop was either a Kung Fu move or some kind of drug.
 
I know this may sound stupid but it works. Take the caps off 3 of the four plugs. put extra plugs in the plug sockets and ground them to the cylinder head. to make this a bit clearer you would now have 7 plugs on the bike, one in the head with a wire on it,3 in the head with out wire and 3 with plugs in them that are touching the head to ground them.
If the load from compression of the cylinders is to much, pull a plug from one of the cylinders that are dead . Take a plug out of the dead cylinders one at a time until there is just enough load to run WOT at about 5500-6000 rpm. Just make sure that the plug wires have plugs in them and they are grounded to the motor. You do your plug chop and read the firing plug.
I've done this with my drag bikes when ever I go to a new track to see how far off the jetting is. A quarter mile is not long enough to get a decent color on plugs. I learned this from Dave Schultz. It was how he set up bikes before there were onboard computers. I always figured if it was good enough for him It was good enough for me
 
I forgot to mention you do this in neutral, in the confines of your garage
No muss, no fuss
 
madjack57754 said:
I know this may sound stupid but it works. Take the caps off 3 of the four plugs. put extra plugs in the plug sockets and ground them to the cylinder head. to make this a bit clearer you would now have 7 plugs on the bike, one in the head with a wire on it,3 in the head with out wire and 3 with plugs in them that are touching the head to ground them.
If the load from compression of the cylinders is to much, pull a plug from one of the cylinders that are dead . Take a plug out of the dead cylinders one at a time until there is just enough load to run WOT at about 5500-6000 rpm. Just make sure that the plug wires have plugs in them and they are grounded to the motor. You do your plug chop and read the firing plug.
I've done this with my drag bikes when ever I go to a new track to see how far off the jetting is. A quarter mile is not long enough to get a decent color on plugs. I learned this from Dave Schultz. It was how he set up bikes before there were onboard computers. I always figured if it was good enough for him It was good enough for me
Click to expand...

madjack57754 said:
I forgot to mention you do this in neutral, in the confines of your garage
No muss, no fuss
Click to expand...

Man, I learn something new everyday around here. I love this place!

Nice tip. I will try it. :-D
 
Yeah! This is exactly the kind of thing I was hoping for. We do have some places here where a good rider could get up to speed... but I am still learning how to ride, so I wouldn't want to take my chances trying to get up to 60 mph in residential streets... and I wouldn't feel safe pulling plugs out on the side of the interstate. Oh, and technically I can't even go on the interstate with a learner's permit :)

The colortune seems like a great idea, and I was very close to buying one, but then I realized you couldn't use it under load, so since I have to do plug chops anyways for mid & wot, it seems silly to spend the money on a colortune for just the idle circuit.

One question though... I heard that it is bad to run the engine with a plug missing for longer than a few seconds. Is that true? Is it just because dust/grit could get in? If so I'll just cover the open ones with some foam or cloth or something. I have a feeling I won't be able to start my engine with 1 cyl firing and 3 blocked off.

Thanks for the help,

Alex


madjack57754 said:
I know this may sound stupid but it works. Take the caps off 3 of the four plugs. put extra plugs in the plug sockets and ground them to the cylinder head. to make this a bit clearer you would now have 7 plugs on the bike, one in the head with a wire on it,3 in the head with out wire and 3 with plugs in them that are touching the head to ground them.
If the load from compression of the cylinders is to much, pull a plug from one of the cylinders that are dead . Take a plug out of the dead cylinders one at a time until there is just enough load to run WOT at about 5500-6000 rpm. Just make sure that the plug wires have plugs in them and they are grounded to the motor. You do your plug chop and read the firing plug.
I've done this with my drag bikes when ever I go to a new track to see how far off the jetting is. A quarter mile is not long enough to get a decent color on plugs. I learned this from Dave Schultz. It was how he set up bikes before there were onboard computers. I always figured if it was good enough for him It was good enough for me
Click to expand...
 
You'd be amazed....my brother-in-law's Nighthawk 650 will run on only one plug.....matter of fact, that's about the only way it does run.....piece of crap......

Actually, what I'd like is for someone to post definitive, high-res pics of just what exactly the stages are from lean to rich. I can tell when it's one extreme or the other, but the middle stages get iffy.
 
79-GS550-L said:
I heard that it is bad to run the engine with a plug missing for longer than a few seconds. Is that true? Is it just because dust/grit could get in? If so I'll just cover the open ones with some foam or cloth or something. I have a feeling I won't be able to start my engine with 1 cyl firing and 3 blocked off.
Click to expand...
The way I read it, there are NO open cylinders. There are plugs in all of them, but the wires are disconnected from 3. Take those 3 wires and connect them to 3 more plugs that are well-gounded to the engine. You have to have the right load on the coils for them to work right.


.
 
That's how I read it too Steve.....

If there is too much compression to turn it over using only one plug then take another plug out of the head but leave the other 3 grounded to the engine so the electrics work.

Interesting way to do it.

:)
 
Steve said:
The way I read it, there are NO open cylinders. There are plugs in all of them, but the wires are disconnected from 3. Take those 3 wires and connect them to 3 more plugs that are well-gounded to the engine. You have to have the right load on the coils for them to work right.
.
Click to expand...


Yeah, that's how I read it too - except if compression was too much and I had to pull out one (or two) of the plugs to vent it. I just want to make sure that nothing bad will happen if I have to resort to this.

One last question for everyone, do I need to use a brand new spark plug every time I get a reading? At $2 each that could get expensive - 4 cyls, 3 stages to test, that's 12x$2=$24 just to get a single reading on each stage. And since I've never done this before, I'm sure I'll need to take several readings and do a little trial & error to get the mixture right.
 
On the road you would ride for a while at constant speed to clean the plugs if possible.

In the garage I guess you just whip them out & clean them up with a wire brush, no need to use a new one....

Dan :)
 
Now there's a great idea...played with toys for many years and never thought of that one. Great Idea and it makes sense!! Bonus \\:D/
 
Taking a plug out to reduce load then running it could potentially pull contaminants into the cylinder. Just make sure that there isn't any dirt or gravel at the base of the plugs before removing the plug. normal precaution for a plug swap. When done in the garage, dust in the air would and should be minimal.
 
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