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Dail-A-Jet Review

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Well...  Thanks to the snow storm and weather down here my Dial-A-Jet kit did not arrive yet.

 

But...  I will be doing a complete review of this product.  Although the CRF230 works almost flawlessly with Mike Coe jetting I know it can be better.  For example, for every:

  • 9 degrees F you must increase or decrease your fuel requirements by 1%
  • 1,200 feet you must increase or decrease your fuel requirements by 1%

If a CRF230 runs perfectly with a 120 main at sea level at 68 degrees F it will need:

  • A 105 main at 104 degrees F at 10,000 feet
  • A 122 main at 50 degrees F at sea level

That is quite a spread and we already know a 120 main is slightly rich according to Mike Coe's dyno work.  Frank Nye at Engines Only recommends a much, much smaller main so we know a 120 is too rich but safe.  Keihin offers the following main jet sizes in that range:

  • 105
  • 108
  • 110
  • 113
  • 115
  • 118
  • 120
  • 122

The Dial-Jet system can provide a range of five to ten main jet sizes.  That should easily cover most, if not all, of the jet sizes shown in the list above.

 

I have been considering a do-it-yourself supplemental fuel bleed or air bleed system for my CRF230 for some time.  The air bleed system would simply allow more filtered air (adjustable) once the slide was near the top, leaving the low and mid circuits out of scope.  It would also allow more air into the engine, effectively increasing the carb size and overall air flow.

While searching for a tiny needle valve I came across the Dial-A-Jet system again.  I spent almost an hour on the phone with Lon Peterson and he was extremely helpful and extremely knowledgeable.  I've been in the engineering world and have been tuning carbs for bikes, boats and cars, street, and strip since the mid 80s and I have zero doubt this system works.  Why reinvent something?

 

What I would really like to try is this kit on an XR250-carbed stock CRF230.  I didn't like the XR250 carb because I lost the immediate off-idle response I have with the smaller 230 carb.  My guess is the Dial-A-Jet system would take care of that, giving us the best of both worlds.

 

More information found here:  http://www.thunderproducts.com/dial_a_jet.htm

 

Part Number DJ-109-AH (Rocky Mountain P/Ns 1094280002/1094540001)

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Edited by VortecCPI
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Now THAT is cool. I had no idea something like that existed as a universal solution. I'd love to give it a go on my 230 with the XR250R carb I have on there. I need to slow down and take this one step at a time though. I already promised myself a Nuetech Tubliss, new headlight, and new rear shock. Maybe I'll take it one mod per month to space things out a bit!

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Why not locate or develop a fuel injection system to work on the 230.

The new Honda Grom has a FI system on it from the factory and the aftermarket has been having a field day designing and coming up with larger injectors and throttle body's for it.

The system also uses an O2 sensor.

It seems to me that it's time do put the carburetor on the shelf and finally enter the new millennium once and for all.

I'm just saying.

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Why not locate or develop a fuel injection system to work on the 230.

The new Honda Grom has a FI system on it from the factory and the aftermarket has been having a field day designing and coming up with larger injectors and throttle body's for it.

The system also uses an O2 sensor.

It seems to me that it's time do put the carburetor on the shelf and finally enter the new millennium once and for all.

I'm just saying.

 

Adding FI to to the old-school 230 would require a boat-load of parts, especially if using a closed-loop system.  That adds complexity and weight and might decrease riliability.

That might be a very good idea for an asphalt track but probably not such a good idea for the woods.

 

Just my two cents...

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Huh...have heard of this product but never gave it any thought. Kinda begs the question that if it works well, why the recent appeal of Lectron and APT carbs on 2Ts when the DAJ can be bought for a fraction of a price?

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I didn't discuss any 2T applications with Lon.  We spoke about the CRF230 with stock carb and XR250 carb and quite a lot about HD applications.  We also spent a bunch of time discussing theory, flexibility, limitations, etc.

 

I know nothing about Lectron or APT carbs.  Do they use Keihin or Mikuni jets and associated parts?  How about other parts such as floats, needles, seats, and gaskets?  I think cost is the big differentiator here - A Dial-A-Jet kit is only $77 and can be fitted to just about anything.

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While the OP makes some broad strokes, there is a lot of assumption. Temp, air pressure (not altitude) and humidity are what matters. Combined, it creates a value called 'Air Density'. Air Density is the ability of the air to have O2. Simply put, less O2, you need to lean it out. More O2, you need to richen it.

A hot day in the mountains could be the same as a cold day in a tropical rain forest.

http://en.wikipedia.org/wiki/Density_of_air Air Density

http://www.mergeracing.com/tech/pandora/ Jetting for Altitude and Weather

 

As far as a Dial-A-Jet, it really only affects the main jet and does nothing for idle, and any throttle position up to about 7/8ths throttle. These are popular with sled riders as they spend their time at greatly varying air densities and all time at idle at WOT and very little mid-throttle performance demands as a biker does.

 

FI is the future. Expense and sensors/power requirements are its' current limitations. Expect those to go away over time as emission requirements become stringent enough to warrant the effort.

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FI is the future. Expense and sensors/power requirements are its' current limitations. Expect those to go away over time as emission requirements become stringent enough to warrant the effort.

Correct me if I'm wrong but isn't California gong to require full emission requirements on all off road bikes, including MX by 2017?

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While the OP makes some broad strokes, there is a lot of assumption. Temp, air pressure (not altitude) and humidity are what matters. Combined, it creates a value called 'Air Density'. Air Density is the ability of the air to have O2. Simply put, less O2, you need to lean it out. More O2, you need to richen it.

A hot day in the mountains could be the same as a cold day in a tropical rain forest.

http://en.wikipedia..../Density_of_air Air Density

http://www.mergeraci...m/tech/pandora/ Jetting for Altitude and Weather

 

As far as a Dial-A-Jet, it really only affects the main jet and does nothing for idle, and any throttle position up to about 7/8ths throttle. These are popular with sled riders as they spend their time at greatly varying air densities and all time at idle at WOT and very little mid-throttle performance demands as a biker does.

 

No argument on the effects of altitude, humidity, temperate, barometric pressure, etc. with respect to air density.  Most riders have no idea how a carb works, let alone the factors that dictate air density.  When we're talking about the archaic operation a Keihin PD carb we just don't have much to work with.  http://holtzmaneng.com has several items that attempt to deal with such changes in riding conditions and sled riders are an excellent example as the conditions can change drastically.  I kept the example simple as that is exactly what we're dealing with here - A very simple engine with a very simple carb.  "Archaic" on both accounts might be more accurate given today's mainstream automotive technology.  Not too much sense in complicating the heck out of it in the context of a CRF230.

 

The comment about Dial-A-Jet only working near WOT, however, is not entirely accurate.  It's not my job to describe or defend Dennis Dean's work here so I won't even bother to start as there's nothing in it for me.  Anybody interested should read the technical article at the bottom of the web page for a better description of how Dial-A-Jet works.  According to Lon the part throttle response improvement realized on HD setups is quite significant.  Lon also said Dennis had 100+ speed records and every bike had a Dial-A-Jet installed on it.  Does that make it right or justified?  Not at all but it sure does make it interesting.  Maybe they weren't even connected.  And yes, I realize speed records imply WOT conditions...

 

I don't expect miracles from this thing, especially given such a mild engine and already-great carb response.  This is simply an inexpensive experiment meant to take up some of my free time and to share the results with my fellow riders here on TT.  If it works I'll gladly let them know.  If it doesn't work I'll gladly let them know.  Again - I don't expect much as this engine/carb combination is already darn good.  The Keihin PD series of carbs are simple but very effective (and very forgiving) due to the oval cross-sectional design.  My real issue is jetting the bike while the carb is on the bike.  I already replaced the float bowl screws with socket head cap screws and the job is still awful.  Call me lazy...

 

Besides, most people spend more time and money on handlebars, colored sprockets, and colored chains they don't even need.  No need to mention sticker kits, colored rims, and aftermarket plastic...

 

We really should change the topic from "Dial-A-Jet Review" to "Dial-A-Jet Discussion".  Can that be done?

 

Also - I thought Mike Coe was the moderator here.  What happened to him?

Edited by VortecCPI

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Dial-A-Jet has been around (in various incarnations) since I was a child.

 

FI is the future. Expense and sensors/power requirements are its' current limitations. Expect those to go away over time as emission requirements become stringent enough to warrant the effort.

Correct me if I'm wrong but isn't California gong to require full emission requirements on all off road bikes, including MX by 2017?

 

I doubt you are going to see much in the way of emissions devices on race bikes. I think you may see tougher enforcement against people riding a race bike in a non-closed course race environment. Gone will be the day when you can take a new YZ trail riding even during 'red sticker'. If you are not on a track, you will be out of compliance. So we will be left with woods race bikes (the green stickers) and they will be FI. This is somewhat offset by the fact that most already have a large (relatively speaking) stator for a battery (starter and lights). Once the populace has gotten used to the cost of these items, the additional cost (and weight/complexity) of FI will be merely another increment. All the manufacturers are already slowly doing it. I will be real happy when they have all the sensors and be capable of real, full, self A/F adjustments and only have additional choices to ignition timing to change power delivery. We are close.

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William1 - Thank you - I found this:  http://mergeracing.com/tech/pandora/RADcalc.php

 

Here are some results for BP=30 in Hg:

 

100 degrees F @ 0% RH @ 5000' = 74.7 RAD

160 degrees F @ 100% RH @ 0' = 74.7 RAD

 

23 degrees F @ 0% RH @ 5000' = 86.7 RAD

100 degrees F @ 100% RH @ 0' = 86.7 RAD

 

According to that web page:

  • A hot day in the mountains could be the same as an extremely hot day in a tropical rain forest
  • A cold day in the mountains could be the same as a very hot day in a tropical rain forest

Interesting...  Relative Humidity has very little effect from 30% to 100%.  Below 30%, however, things begin to get very interesting.  Charlotte, NC RH varies from 54% to 82% so it has little effect here:

  • 68 degrees F @ 54% RH @ 30 in Hg @ 0' = 94.8 RAD
  • 68 degrees F @ 82% RH @ 30 in Hg @ 0' = 94.7 RAD

Always very happy to learn something new...

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Edited by VortecCPI

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Okay - The parts are finally here after delays due to Southern snow storm.

 

The parts and packaging are of high quality.  The documentation is excellent.  The kit comes with a lot of parts, allowing for multiple installation options.

 

So now I have to figure out how to mount it so it doesn't interfere with the choke plate.  I may have to mount if in the air boot just behind the carb inlet horn.

 

More information and pictures to come...

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Okay - Severe thunderstorms and a long day at work prevented me from finishing up the Dial-A-Jet installation.

 

The Keihin PD carb has a choke plate so the Dial-A-Jet must be mounted on the boot just behind the carb inlet.

 

I found a position where it will work nicely.  The CRF230 is really cramped on space but this should work great.

 

This position will allow for easy access and quick adjustments and also allow for good fuel and breather routing.

 

I've got a 112 main jet (120 - 3 sizes) ready to go but I feel that may still be a little rich given the 120 is a bit rich.

 

The pictures show position only - Fuel and breather lines will be routed and connected tomorrow.

 

Fuel will come from the float bowl drain cap and the breather will go up to the handlebars.

 

Breather is simply to keep dirt from entering the Dial-A-Jet air bleed orifice.

 

Looking forward to finishing tomorrow and testing...

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Edited by VortecCPI

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Dial-A-Jet installed and ready for a test ride.

 

Everything fit as suspected and all lines are routed nicely.  I used the bowl drain conversion adapter for the test.  I will drill, tap, and thread in the optional connector in the bowl drain when I have more time.

 

The fuel supply line is close to the exhaust heat shield but the kit had a heat-resistant sheath so it should be fine for testing.

 

The breather line is routed along the existing wiring harness up to, and behind, the number plate as suggested.

 

For those of you familiar with Dial-A-Jet you will notice I did not use the included tie-wrap mount.  I spent a lot of time trying to find a way to use the included mount and there is just no way to make it work given the strange shape of the boot.  The injection tube is a very, very tight fit in the air boot.  I will apply a bit of RTV later to provide a more-uniform mating surface for the Dial-A-Jet body.  I don't think it's necessary to prevent leakage, however, but it certainly will not hurt.

 

Test ride coming in just a bit.  We had some very bad storms so the track is a big pile of mud right now.  Useless for any reasonable testing...

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Edited by VortecCPI

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That is quite a spread and we already know a 120 main is slightly rich according to Mike Coe's dyno work.  Frank Nye at Engines Only recommends a much, much smaller main so we know a 120 is too rich but safe. 

 

what size does Nye recommend?

i've  never dynoed a crf230, usually bikes with enlarged air intake need a 5-10% larger main jet, not more.  120 is +18% larger , 132 is +29% larger!

does anyone know the A/F ratio recorded by Mike Coe when he tested a 120 slightly rich?

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what size does Nye recommend?

i've  never dynoed a crf230, usually bikes with enlarged air intake need a 5-10% larger main jet, not more.  120 is +18% larger , 132 is +29% larger!

does anyone know the A/F ratio recorded by Mike Coe when he tested a 120 slightly rich?

 

You are correct that the more open the air box (or none) the fatter the jetting may have to be.  An open air box (or none) reduces pressure drop across the carb circuits, resulting in a leaner A/F mixture.  I can assure you a 132 main in a stock CRF230 is absolutely ridiculous.  I tried a 132 per threads in these forums and my top end was completely flat.  The 120 main made my top end come alive.  I was very surprised.

 

Frank has a completely different recommendation for a stock CRF230 with his Outlaw exhaust system.  I assume the big difference is due to the efficiency of his system.  A good exhaust system scavenges spent exhaust gases, reducing the dilution of the incoming intake charge.  I have experienced the same over my many years of tuning street/strip vehicles.

 

I'll have a look at all the information I saved on Mike's work.  I'm assuming it was only slightly rich if he did not recommend a 118 main.  A slightly rich condition is favorable to a slightly lean condition for the average bike owner.  Not for the average racer, though...

Edited by VortecCPI

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Okay then.  First test:

  • 48 Pilot Jet (same)
  • 112 Main Jet (was 120)
  • Dial-A-Jet dead center

 

Here's what we have:

  • Off-idle  - Same
  • Low end - Same
  • Top end -  Same or better
  • Midrange - FAR better

I suspect the top end is better because I may be leaner than the 120.  I don't care so much about my top end anyhow.

 

The bike has an off-idle soft spot (when going to WOT) until it is completely warm - More data showing the 120 main may be too rich.  Once fully warmed up, however, the soft spot is gone.  The bike will lift the front tire right off the ground now just by opening the throttle.  At first I thought it was a one-time deal but as I went around the track I've been going around for years I was able to lift the front tire time and time again by simply whacking the throttle.  The bike will now carry the front tire quite a distance while standing on the pegs and opening the throttle.  The back end also power slides much easier and much further - The engine moves into a higher RPM range quicker now.  This could be due to the 112 main making more power on top but it's the midrange that is WAY better.

 

For the record - When I talk about lifting the front tire I certainly don't mean like a 2T or new high-tech 4T.  I don't imply the bike is going to loop.  I simply mean it comes up much easier than it did before and I can carry it longer distances.  The back tire is easier to break loose and it stays broken loose longer.  The are no miracles to be had here.

 

I need to do a lot more testing.  There is no place I can maintain high speeds in 3rd gear and above right now.

 

So...  Is it worth the time and $99?  The CRF230F with proper jetting is already a bike that responds incredibly well to throttle input.  It is one of the best carbed bikes I've ever ridden.  It IS better than it was and there is no question about it.  Is it $99 and a few hours better?  That remains to be seen.

 

The Dial-A-Jet definitely improved the transition from mid to top end.  A slightly lean mixture gives best throttle response and feel.  The Dial-A-Jet allows for this by only supplying extra fuel on demand.  You get the best of both worlds - Slighty lean under normal conditions and extra fuel for high demand conditions.  I believe a CRF230F with an XR250 carb and Dial-A-Jet would really be something.  I may try that next.  I have a Mikuni 32mm flat slide from Al Baker's XR's Only but that is probably too big.

 

I will continue this review when I can get to a place where I can stretch the 230's legs a lot more.

Edited by VortecCPI
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I just went out for another test ride.  Carrying that front tire all around sure makes me laugh.  I got going so fast on a straight I locked up the brakes and STILL missed the turn.  The bike came out of the corner (before the straight) much faster than it used to and it threw my timing off.  I'd have to say the big difference with the Dial-A-Jet is how the bike pulls from the mid to the top.  It comes out of turns very, very hard now and occasionally pulls the front tire slightly off the ground as I exit a turn.  I can tell I'm a little lean because the bike pulls just a little harder as I back down from WOT to about 7/8 throttle.  That's a bit odd as the top feels as good or slightly stronger than it was.

 

I'm sure this sounds like BS to many of you but it is what it is.  When my buddy comes back from out of town I'll get his opinion.  We'll ride the two 230s back to back and see what we really have...

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Ride number three.  I richened the Dial-A-Jet one notch and the top end is dead on.  The bike really keeps the rear tire broken loose a lot longer out of power slides now.  I am thinking of going back to a 13-tooth CS from the 12-tooth I'm running now.

 

For those of you who have not seen this I suggest you read the tuning section in this manualhttp://www.bikers-store.fr/data/fichesTechniques/docs/Mikuni%20HSR%2042-45-48.pdf

 

The test is started with the engine running at an rpm high enough to ensure that it is “on the cam.”
Open the throttle fully and let the engine pull for several seconds.
Then, quickly close the throttle to about the 7/8ths position.
If the engine seems to gain power, the main jet is too small (lean). Fit a larger jet.
If the engine hesitates as the throttle is rolled off, the main jet is too large. Fit a smaller one.
When the main jet is correct, the engine will continue to run smoothly and evenly as the throttle is closed.

 

"If the engine seems to gain power, the main jet is too small (lean). Fit a larger jet."  This is what was happening to my bike during the first two test rides.

 

I putted around in some very tight stuff and didn't experience any soft spots or hitches.  It's really nice to be able to lift the front tire more easily and higher when going over trees and such.  It is interesting that the carb responds just as good, if not better, when grabbing a huge handful of throttle from a crawl in third gear. I mention this because going from a 120 main to a 112 main is quite a difference.  The Dial-A-Jet is obviously supplying all necessary fuel to make up the difference.  Under light to part throttle conditions the bike just feels crisper - More sensitive to throttle position.  I need to get it out on a stretch so see if I encounter any lean surge conditions.

 

As the Dial-A-Jet sits now I have one position left to make it richer.  Perfect for cold spring and fall rding.  I have three positions left to make it leaner.  Perfect for hot or high-altitude riding.  Also - The fuel supply line, although close to the exhaust heat shield, is not a problem at all.

 

I think somebody else out there needs to give this a try as well.  I'm pretty sure my buddy will want one after we confirm I can put distance on him...

Edited by VortecCPI

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