Dyno test

[JetDriver]

Allright.  Thanks for the info, Tim.  Looks like I'm in for an adventure.

[rdunbar123]

one more question on magna charger, how is the amount of boost controlled? by pulley change?  Dag mentioned that he was now running 8lbs boost. Magnacharger claims 4 to 5. I know a roots blower is rated by inlet cubic feet so as the rpm increases so does the drop through the air filter and therefor less LBS of air are taken in. I Know turbos have wastegate. just wondering. Install starts tomorrow.

[Tearless-Tom]

Thanks for the info.  I've bought a used DAJ from a Valk guy, but haven't installed it.  I didn't realize it involved changing jets in the installation.  I'm not much of a carburetor guy- I may end up looking for help....  Dag mentioned using a 92 or 93.  I know nothing- should I just blindly buy a set of those jets and install them when I install the DAJ?

I am still saving my pennies for the DAJ for the Valk however I did have one I installed on a 750 American Classic.  It really did make a HUGH difference in the performance.

The reason most change the jets is to force the bike to run a bit leaner. If the bike is running normal to rich the DAJ has little or no effect. You need to lean it out so it can work its magic and increase the fuel flow back to its optimal level.  The DAJ "atomizes" the fuel better so it gives a more fuel injected response.

By advancing my spark about 4 degrees and playing with the DAJ I could have a bike that ran smooth and pulled hard all the way through the rpm range or I could back off and it would run nice easy through low rpm but if you romped down on it it felt like a 4 barrel kicking in.

 My mileage dropped slightly from 55 to 52 but my fun factor went through the roof.
 Tom

[JetDriver]

If the bike is running normal to rich the DAJ has little or no effect. You need to lean it out so it can work its magic and increase the fuel flow back to its optimal level.  The DAJ "atomizes" the fuel better so it gives a more fuel injected response.

I know people are doing this and are pleased with the results, but it sounds like you are saying, "Put jets in it to lean it out so the DAJ can enrichen (sp?) it again."  Maybe the DAJ is more precise?  Most of my hesitation now is fear of the unknown.  I know this guy took this DAJ off his bike before he sold it.  Makes me wonder why.  Is there a way to check the DAJ jets to see if they're working properly before I install them?

[timk519]

I know people are doing this and are pleased with the results, but it sounds like you are saying, "Put jets in it to lean it out so the DAJ can enrichen (sp?) it again."  Maybe the DAJ is more precise?  Most of my hesitation now is fear of the unknown.  I know this guy took this DAJ off his bike before he sold it.  Makes me wonder why.  Is there a way to check the DAJ jets to see if they're working properly before I install them?

The DAJ jet's atomizes the gas more finely than gas that passes through the carbs so it burns better. Consequently, you want more of the bike's gas to pass through DAJ jet instead of the carb jets, hence the need to run the bike carbs with leaner jets.

If the carbs are running too rich I don't think the DAJ's jets would have much effect since there's already too much fuel in the airstream.

If the jets you have now don't work, it won't be hard to replace them with new units - for each jet it would just be a matter of disconnecting the fuel line, cutting the zip-tie, pulling the jet, then reversing the process to put the new jet in.

[Tearless-Tom]

I know people are doing this and are pleased with the results, but it sounds like you are saying, "Put jets in it to lean it out so the DAJ can enrichen (sp?) it again."  Maybe the DAJ is more precise?  Most of my hesitation now is fear of the unknown.  I know this guy took this DAJ off his bike before he sold it.  Makes me wonder why.  Is there a way to check the DAJ jets to see if they're working properly before I install them?

The DAJ jet's atomizes the gas more finely than gas that passes through the carbs so it burns better. Consequently, you want more of the bike's gas to pass through DAJ jet instead of the carb jets, hence the need to run the bike carbs with leaner jets.

If the carbs are running too rich I don't think the DAJ's jets would have much effect since there's already too much fuel in the airstream.

If the jets you have now don't work, it won't be hard to replace them with new units - for each jet it would just be a matter of disconnecting the fuel line, cutting the zip-tie, pulling the jet, then reversing the process to put the new jet in.

Exactly correct!

[JetDriver]

If the carbs are running too rich I don't think the DAJ's jets would have much effect since there's already too much fuel in the airstream.

I think it's Tearless-Tom who has the avitar of a man beating a dead horse, but....   I'm just going for understanding at this point.  If my fuel mixture is too rich with the stock Honda set-up, but I'm ok with the fuel mileage I'm getting with that set-up, is there a reason to install DAJ?  I'm thinking there is, but you both have said now that if indeed my stock set-up is running too rich, then I won't notice much difference.  Is this a situation of, "I won't know until I try it?"

[Tearless-Tom]

If the carbs are running too rich I don't think the DAJ's jets would have much effect since there's already too much fuel in the airstream.

I think it's Tearless-Tom who has the avitar of a man beating a dead horse, but....   I'm just going for understanding at this point.  If my fuel mixture is too rich with the stock Honda set-up, but I'm ok with the fuel mileage I'm getting with that set-up, is there a reason to install DAJ?  I'm thinking there is, but you both have said now that if indeed my stock set-up is running too rich, then I won't notice much difference.  Is this a situation of, "I won't know until I try it?"

From my personal experience and from what I have read from the Thunder Products site that is correct.  The bike needs to be in a lean mixture for the DAJ to work at its best. You may see some effects but by no means see its potential.

I plan on leaning mine out when I get mine. Another advantage is it equalizes the fuel mixture across the full range so if  one jet is rich and one is lean it will increase the lean and leave the rich alone.

Giving an even smoother linear pull.

If you don't want to re-jet you can also modify your pipes to reduce the restriction. It doest take much to lean the bike a bit.

Tom

[timk519]

I think it's Tearless-Tom who has the avitar of a man beating a dead horse, but....   I'm just going for understanding at this point.  If my fuel mixture is too rich with the stock Honda set-up, but I'm ok with the fuel mileage I'm getting with that set-up, is there a reason to install DAJ?  I'm thinking there is, but you both have said now that if indeed my stock set-up is running too rich, then I won't notice much difference.  Is this a situation of, "I won't know until I try it?"

If you can get the exhaust gases metered to see if you're running rich or lean, that would give you an idea of whether or not you need to replace the stock jets in order to get more benefit from the new jets. Having an exhaust gas meter will also come in helpful after the DAJ installation so you can adjust the individual cylinders to their optimal setting.

[Tearless-Tom]

I think it's Tearless-Tom who has the avitar of a man beating a dead horse, but....   I'm just going for understanding at this point.  If my fuel mixture is too rich with the stock Honda set-up, but I'm ok with the fuel mileage I'm getting with that set-up, is there a reason to install DAJ?  I'm thinking there is, but you both have said now that if indeed my stock set-up is running too rich, then I won't notice much difference.  Is this a situation of, "I won't know until I try it?"

If you can get the exhaust gases metered to see if you're running rich or lean, that would give you an idea of whether or not you need to replace the stock jets in order to get more benefit from the new jets. Having an exhaust gas meter will also come in helpful after the DAJ installation so you can adjust the individual cylinders to their optimal setting.

Well sounds right but I don't think you are in this case.

 My understanding and experience is that the DAJ only functions with the engine under load You can not set it on a stand and rev the engine and see gas flowing though the tubes. It just doesn't work this way.

 So in reality having a gas meter will tell you if you are lean or rich but will not help you adjust you DAJ... That is a seat of the pants or dyno evaluation.

Tom

[timk519]

True - the fuel only flows when the engine is under load - so what Dag did was put the meter electronics on the back, and the probe in the exhaust, and then drive down the highway to take his measurements.

[Tearless-Tom]

True - the fuel only flows when the engine is under load - so what Dag did was put the meter electronics on the back, and the probe in the exhaust, and then drive down the highway to take his measurements.

Leave it to Dag to figure out a way to make this happem!

[Dag]

You have to change the main jets.
Std is #100 and I changed to #98. I regret I didn`t go for one size smaller. (Next time...)
With a smaller jet I could take more fuel from the DAJ.

The DAJ will start working when you twist the throttle. Than vacuum from the air filter tube sucking fuel from the carburetor bowl through a fine nozzle before it reach the carburetor.

To adjust the air / fuel Mixture the bike must run at different speeds under load. At a Dyno bench or with a CO meter that can store data for printing a graph.

I have 6 into two Viking exhaust, so it`s impossible to measure the CO individually for each cylinder.
I use a digital temperature sensor for measuring the temperature of the pipes on the exhaust header. The pipes with the highest temperature has the leanest mixture. I adjust the pilot screws on the carburetors until all have the same temperature at (at idle)
before I start with the fine tuning of the DAJ.