A little while ago someone asked about a dyno run for a stock bike.

Being curious I had my completely stock 93 put on the Dyno.

Condition of the bike; 7000 miles, bone stock.  I've had it about 3 months, the only thing I've done is to change the oil and the plugs.

I think the A/F ratio graph bears out a lot of comments made on the board.

The interuption at ~7600 RPM is caused by a balky ignition pickup on the dyno.

(alt+p)

wow

40.28hp got to give the 487 props for that


HEHE 29.71 ft/lbs just enough to tighten up bolts :lol: that's funny a GS500 powered tourque wrench.

Man, the max torque point comes from a little blip. That's a tiny blip, too. 40.28 RWHP, not bad at all! That air/fuel mix is CRAZY!!! Look at thing, bouncin around like nothing else.

I'ma get my '04 dynoed next week, hopefully.

any chance the carbs were synced? tryin to reason that "thing" of a mixture line

Thanks a lot dbarile!!!

That is exactly what I was looking for... and what I expected somehow:
the "optimum slow" riding spot is around 4500 rpm.  There the air mix is closest to the theoretical optimal ( 1 : 18 ).
Hence -this was my point in changing the sprocket to 17 teeth- by lowering the rpms on the cruising speed of 60 mph (yes, that's the kind of slow-po riding I do... ), the engine falls into the hoop of the curve between 4000 and 5000 rpm... for better mileage and engine efficiency...

How does this sound?

Cool thanks, I've been wanting to see one. Now if I'm not mistaken, for 1/4 action, shift at redline should suffice. At least is sure looks like that.

oh wait. the graph stops at 9500. NVM.

Well I wanted a stock run to compare to any later mods I do so I didn't touch a thing.

My thoughts are to adjust the valves, change the jets and rod and do it again.


I belive the crazy A/F ratio is tied to the jets and metering rod.

The next dyno run should tell.

Should have asked for another run that had contiguous data and ran all the way up to 11K.

This is actually one of three runs that were done. I'm not sure if there is just a printing problem or a software problem but I know it was taken up to redline for each run because I watched.  The spike showed up in each run. Maybe a glistch in the pickup because I didn't notice the bike cough at all.  

I was more interested in the trip to peak power and the A/F ratio than the area from 9500 to 11K.  The power has already peaked and I don't plan on spending a lot of time at 11K.  This gives me what I was really after which is a baseline for any mods. Your are right however that it would have been nice to see the full range.

I know that the cheapest method woud be to complete intake, carb and exhaust mods and then retest to get the jetting perfect. But I'm just curious enough to change the intake and jetting and retest.

not bad for a stocker ive seen as low as 33 hp and as high as 42hp on stock gs's .last time mine was dyno'ed made 66 ponies and wasnt even broke in yet

66hp...what all is done to it?

Quote from: AlphaFire X5Man, the max torque point comes from a little blip. That's a tiny blip, too. 40.28 RWHP, not bad at all! That air/fuel mix is CRAZY!!! Look at thing, bouncin around like nothing else.

I'ma get my '04 dynoed next week, hopefully.

Is that really rwhp or just the max hp?

porsche- the list is long 9mm over custum pistons,EXTENSIVE headwork,giant megacycle cams,dual plug head 4cyl.coils,39 CR specials carbs more &more  bike will run with sv 650's all day long ,also reworked tzr 250 front end fox shock 4.5in gsxr wheel .i used to race clubman class in wera am thinking about putting it back on street ,just need to add lights and charging system

Alright, here's a question.

That bike is CRAZY rich from 5500 up and very lean from 3500 to 5500. The consensus on the board is to bump your main jets up a few sizes.

Why on earth would you increase the main jet size when it is already SO rich up top? This is driving me crazy, because if something is already THAT rich, why would you want it to be even richer? Opening up the idle screws should clear up the low end leanness, but the top end doesn't look like it needs to be increased.

Someone please explain this to me.

Quote from: onefastgs500porsche- the list is long 9mm over custum pistons,EXTENSIVE headwork,giant megacycle cams,dual plug head 4cyl.coils,39 CR specials carbs more &more  bike will run with sv 650's all day long ,also reworked tzr 250 front end fox shock 4.5in gsxr wheel .i used to race clubman class in wera am thinking about putting it back on street ,just need to add lights and charging system

I would just like to get around 50-52 HP.

I wonder what kind of would that would involve?

Well this is a bone stock bike. I imagine that putting a freer flowing exhaust on it and/or a freer flowing air filter will move the whole range up or leaner. Then you probably would want bigger mains.

Looking at the jet chart/matrix that I've seen on the web, the reccomendations are for setting the stock main jets to 125 from about 122.5. Not much of a jump. But it would push the high end richer, how much who knows.

The guy who dyno'd the bike seemed to think that the high end mixture was too bouncy. He reccomended replacing the metering rods with a tapered set. He was really perplexed that I wanted to dyno a stock bike, but went about it with glee once I explained that it was a simple matter of curiousity.

I am seriously considering simpy rejetting the bike and putting it on the dyno again. I'm curious what it would look like.

There is another dyno place closer to home than this place. I will call them sometime this week and see what their prices are. I might even do another stock run just for fun and see how they compare

blazin,we did one gs with just the piston kit and rejet and got 51 ponies,but the pistons are expensive and require new sleeves and boring of cyl and cases.

What else are you gonna spend money on?

Dyno Runs?

Seriously, I would like to try some engine mods, but it will likely be next year.  

I'm keeping my eye out for a cheap engine to change out pistons on.

Optimal jetting would air/fuel around 12.5 It's at that point for a split second of a rev, but it's rich aside from that one point. Putting in an air filter that is freer flowing should lean out the top end, thus making it operate in the optimal jetting range. I don't see why you'd bump the mains up on a STOCK bike when it's like that. A freer flowing exhaust (caused by the diameter of the headers, not the open can) would likewise need a jetting change if it pushed the ratio too far to the lean side of things. However, the drastic changes proposed in the jetting matrix perplex me.

Think about it. If a stock bike is THAT rich with 122.5, why would you go to a 147.5 or even a 145 main? I highly doubt that a simple exhaust and filter change could create such a drastic need for jetting.

On my '04 I changed the jetting to 137.5 mains while using a K&N filter. That's a bump of 3 sizes. I highly doubt that a K&N filter would cause such a dramatic change and need. I'm going to pull my carbs and put the jetting back to stock.