Do It Yourself cheap 'Dyno' tune

[vonkas]

I have done my own TC88 upgrade to 95c", G-cams, etc. To finish the job I invested in a NGK AFX which I first tried on my Honda XR with great success. It worked a treat on my twincam too and made a huge difference in both power & fuel economy. Can highly recommend it to the intrepid home bike tuner. For some details re my work on the motor look here: http://www.space100.com/tc/tc.html - this does not show the deployment of the AFX. For that refer to my Honda site: http://www.space100.com/xrr/xrr.html for technical details.

Excellent,,keep us posted.

[milindh]

I really like this NGK AFX thang. Much better than reading spark plugs. Very tempting to weld a bung on my pipes and try it out. Actually this sounds a lot like what I thought our compadre Wrightturn has been working on. A handlebar mounted meter getting its input from O-2 sensors mounted on the muffs.

One great thing about this setup is that if we ever have to get our bikes smogged we could set them up to pass before we even go to get them inspected. Then after we pass we could go back to the fast and cool setup.

Another thing came up when I read the part about leaner mixes giving more power goes along with my own beliefs and experience. I've always felt this was true in general since lean mixtures tend to fire quicker and hotter than richer mixtures. The effect is to artificially advance the timing. Of course too lean and you get harmful pre-ignition and a hot running engine.

My other hobby is radio control planes and I read a tech article by an engineer named Dave Gierke and he explained how and why you get max power out of glow powered engines with an extra lean mixture and it goes pretty much like I said above. When you set the jetting on your engine, either two or four stroke, you lean them out till you get max rpms and then richen the mixture until the rpm drops about 300-400 rpm. If you let the engines run at their leaned out max power setting you get too much heat and poor transition from idle to high speed. This seems to match your experience with your Honda XR Vonkas.

Good work Vonkas!


P.S. Wrightturn, is this setup similar to what you've been working on?

[vonkas]

funny you should say this. I also learned my ropes with carbies on model airplane engines. They only have one jet so there is little confusion as to what happens. My hair stands on end when I watch the 'experts' do their thing with computerised engine tuners - tuning manual in hand...! I know, that well adjusted carburettors can be as good as fuel injection in most respects. I don't know if we go the right direction with hi tech in our bikes. But then again, I LIKE to be in control - it's a bit like packing my own parachute..

Originally Posted by milindh

My other hobby is radio control planes and I read a tech article by an engineer named Dave Gierke and he explained how and why you get max power out of glow powered engines with an extra lean mixture and it goes pretty much like I said above. When you set the jetting on your engine, either two or four stroke, you lean them out till you get max rpms and then richen the mixture until the rpm drops about 300-400 rpm. If you let the engines run at their leaned out max power setting you get too much heat and poor transition from idle to high speed. This seems to match your experience with your Honda XR Vonkas.[/U][/B]

[frisco-rigid]

It doesn't actually artificially advance the timing,, it only finishes the burn sooner.. And if you're already advanced a wee tooo much there's gonna be trouble..

Bosch says in their EFI closed loop manual that 14.7 (stoichiometric value 1) is supposed to be the Optimum for virtually all conditions except of course when you need more power then the system fattens up, hmmm, that should be a clue..

I have 2 of those sensors and gauges set up in the pk-up and the EFI Porsche and 14.7 is waaay lean..

If you lean it out looking for that extreme edge of performance,, good luck.. Good for the track and deep pockets, bad for the street..

[evoKENevo]

Hey,frisco/others
If I've been reading this right I believe milindh was just using the term "artifically advancing timing" as a bit of an anology...in that,generally speaking, a richer AFR needs more ign. advance than a leaner AFR to burn/combust at the same rate, under the same conditions. Which,of course,could also be applied to needing more advance to compensate for higher octane rated fuels...vise-versa.

That and correct me if I'm wrong in either case...I'm assuming that what's meant by saying (frisco) "it only finishes the burn sooner" includes by starting the burn/combustion sooner,too.

One thing for sure though is that running on the extreme edge of lean and/or advance ain't good for the street. Nope..not when even a little thing like just a cooler more humid day than when tuned could put just enough more oxyen in the mix to queer the works...as well as an engine.

[Wrightturn]

Hey guys,

This is exactly what I have been working on. Vonkas you have done great work and excellent photography. I like your meter better than mine except for one thing. I read from an LED array instead of the digital read. I paid $5.00 at a swap meet and sent it back to the factory for repair. Less than $50.00 to get started.

I agree with everything you are doing but I am not hung up on 14.7. Testing on the road is different from loading on a dyno. I have a cyl head temp gague, I take oil temp readings, I record weather info during the road test and try to learn as much as possible. I read spark plugs and try to correlate with the readings. Testing has been limited to my two carb bikes and one EFI.
So far:
Decel pops are caused by lean conditions. Yeah we knew this but didn`t think jet size would have so little effect. Had changed the jet to a 48 with the 27094-88 needle and it was rich. Went back to a 45 and the needle alone is still giving me 13.8:1 with no pops. Goes to 16:1 on decel but no pops. Around 13.6 get max temp reduction. This bike has SE breather, 26g cam, AR100 pipes, stock heads

I have a tech guy working on a variable efi control for a pclll. When I learn performance,mixture,temp, settings will be easy. Cheap dyno is what it is all about.

[vonkas]

Originally Posted by Wrightturn

This is exactly what I have been working on.

Thanks for your input and appreciation Wrightturn. The NGK kit was about $250, which I think is great value. It has a very low latency - fast enough to see what the accelerator pump is doing even at short blips, which was revealing and made me to use the smallest pump jet Mikuni makes. I managed to correct to a decent amount of injection with a little reaming of the jet and pump stroke adjustment. This would not have been possible without a fast reacting measuring device. I was also surprised how well the digital display worked (although an ACCURATE analog needle would be superior) and even with just glancing at the display when overtaking etc, after a while I'd 'sample' enough data to know what's going on. I had sceptical comments from the Mikuni guys regarding the jet sizes I ordered, but the results speak for themselves. My Fatboy feels so much more responsive and especially in city stop and go traffic at low speeds the throttle is so smooth ... wonderful!

[vonkas]

Originally Posted by Wrightturn

Decel pops are caused by lean conditions.

Decel pops are caused by air (oxygen) mixing with unburned fuel and combusting in the exhaust system ignited by the occaisonal flame front from a partial combustion. The 'hotter' your cam (higher tuned engines) the more the likelyhood of air getting sucked passed the cross timed valves. The 'traditional' approach is to enrichen with special overrun systems in carbs to make this after-combustion less explosive (burn slower) which also requires well sealed exhaust pipes. But you can't avoid it completely with carbs. Injection systems can shut off fuel completely, but catalytic convertors don't like that much because they can cool down too much. All of this fiddling at the factories is to comply with emission legislation (both gas and noise), not much else. Popping has no detremental effect to the engine and actually, I quite like it!

[vonkas]

Originally Posted by evoKENevo

One thing for sure though is that running on the extreme edge of lean and/or advance ain't good for the street.

thinking in absolute figures (14.7 etc) is a bit theoretical. My aim was efficient combustion and rideability: to be smooth, yet powerful, with no acceleration 'holes' and capable of covering altitudes (sealevel to 800m) and all this without being unnecessarily rich. The AFR meter allowed me to find the optimum calibration with high consistency - without it, most short term conditions would go unnoticed. On top of this I achieved noticable fuel savings, which is good for the wallet AND for the environment!