Dyno run

[Starquest]

Hi, all. I posted my previous dyno run on the maintenance section before. I think it belongs here.
New progressive springs with 10-30w oil.
Rebuilt gold calipers with oem Yamaha gold pads.
Avon tires on 16 inch wheels and 298mm v-max rotors.
282 rear rotor, rebuilt rear caliper, ebc organic pads.
Stock motor, rebuilt carbs, adjust valves to specs.
117.5 main jets, 40 pilots, clip on middle groove, 3 turns out.
4 degree advance ignition via slotted plate.
Open aibox with uni filter.
New modified clutch and spring.
Stainless steel braided lines for brakes and clutch.
14 mm brake master cylinder.
New ek chain rated at 11.000 tensile strength.
New front and rear sprocket. 17 and 40.
Fixed some minor oil leaks.
I gained 4 hp from previous dyno but the afrs are similar.
On the rich side. The mechanic told me to drop 2 sizes on the main jet. I need to be closer to 13 to 1.
May be I go with 115 or 112.5.
The previous run was on 112.5 and 40.
May be I'm going to make another run after  changing jets.

[Starquest]

Sorry for the sheets.

[Starquest]

I forgot the spin on filter, led taillight and new steering bearings. Most of the parts I got was from RPM. Bike runs good. Happy.

[fj1289]

I think the AFR curve is pretty close.   I wouldn't target 13.2:1 on an air cooled bike at WOT.  I'd rather see a bit richer like 12.5:1.  The additional fuel helps keep combustion chamber temps down a bit and keeps you further away from detonation.   I'll bet it's not possible to reliably measure any difference in power between those two AFRs.  I'd try the 115 jets.   

Nice job!

[Millietant]

113 bhp at at the back wheel from a stock engine, bar air filters/jets, is a very healthy result on a +30 year old bike.

Nice one !!

[Starquest]

Thank you. I installed yesterday the dual foam air filters. I'm going to leave the jets. May be with this filters it's going to lean a little bit. You are right. I prefer a little rich, specially running more ignition advance. May be I'll take to the dyno again and see the difference.

[fj1289]

That will be really cool to see a controlled re-test like this.  The torque/hp may not be quite comparable on different days, but changes in the AFR should correlate pretty well.   Really interested to see how the flow changes with the swap to pods. 

I know there has also been a lot discussed on how going to pods changes how CV carbs respond - but hopefully comparing WOT to WOT will be valid

[Starquest]

Definitely. I'll try to make a dyno run with the uni pods to see what are the changes.

[FJ_Hooligan]

I have a guess.  :-)

Going from a UNI stock replacement to the dual UNI pods "should" remove some intake flow restriction.

Thus, the mixture in the midrange may be slightly leaner due to reduced airflow VELOCITY.  Will it be enough to be noticeable?  Maybe, but probably not.

At WOT, the jet needle restriction is minimal and the main jet controls fuel.  As far as the air filter influence at WOT?  Probably not noticeable either.  Both filter setups should flow plenty of air where and when required.  The carb size is the typical flow restrictor under WOT conditions.

As stated, atmospheric conditions and dyno repeatability may swamp any difference in HP and torque.  AF data will be interesting.

[Canada.Mach]

Just for reference, here's someone else who put the bike on the dyno with airbox vs pods. I don't think I've seen any others posted that I remember. And it doesn't look like he ever came back with the AFR

http://www.fjowners.com/index.php?topic=17799.0

[Starquest]

Here are the AFRs. May be I drop the needle halfway and turn the fuel pilots half turn out. What do you think guys?     
Red line is the dual unipods.

[Starquest]

The blue line is the stock air box with the uni. The red line is the dual unipods.

[fj1289]

My two cents: Based on AFR I wouldn't do a thing.  The differences in the two torque curves is so slight it can simply be different air from a different day. 

How does it feel on the road?  Responsive, no hesitations?  If so leave it and enjoy it! 

As understressed as these engines are from the factory, the tuning window is very wide.  As it is, to me it looks like you are in the middle of that tuning window.  Small changes either way aren't really going to make much difference if any. 

And remember that "razor sharp" AFR in the summer is going to swing toward the lean side with denser cooler air in the fall and winter months.   Leave it a little fat and be happy - leave the AFRs in the 13's to the water cooled guys.

[Starquest]

Well, it's hard to tell. I don feel any flat spots when I drove it today for 150 miles. The bike pulls hard after 6000 rpm and the intake noise is louder than before. For a carburetor bike May be it's difficult to keep a steady line on the AFR. You're right, I'm going to leave it and ride it. Thanks.

[X-Ray]

Just for reference, here's someone else who put the bike on the dyno with airbox vs pods. I don't think I've seen any others posted that I remember. And it doesn't look like he ever came back with the AFR

http://www.fjowners.com/index.php?topic=17799.0

That was me, and I completely forgot about trying to retrieve the A/F ratio results from the Dyno guys    I remember them at the time telling me it was pretty well spot on at 14.7:1 once they had rejetted etc. Still running extremely well that bike, and I still have to get the '93 dynoed as well to see what needs doing.   

Regards
Ray