400ex dyno'd today!!!

[meanyellow03ex]

Hey everyone!!! I wanted to share the reults of my dyno tuning I had done today. I installed a HMF slip-on, proflow air intake kit, powroll vented airbox lid, and a dynojet kit. First off, they had to remove the $50.00 crap jet kit because the air/fuel ratio wasn't consistant. They put the carb back to stock and tuned from there. They put in a 155 keihin main and ran it. Too lean. It finally took a 170 keihin main jet to put the air/fuel ratio between 13:1 to 14:1 . Well the end result was 27.3 horsepower at the rear wheels. The dyno tech said that my 400 put out over 1 horsepower more than any 400ex he's tested with similar mods. Thanks HMF:D Later ya'll

[Antnee77]

Cool! :cool: How's it ride?

[cals400ex]

i want to see a dyno sheet with the 155 in and also with the 170 in. i wouldn't even run a 170 in a built engine unless it was totally decked out. going with a 170 totally hurt the power output of my bike, even when i was running a 406. i only run a 158-160 with the air box lid on on my 426. i am curious in seeing dyno sheets of both runs though. i have seen 416's that had their bike on one dyno produce best results with a 155 mainjet and others say that a 190 gave the best power and it was increasing still but they didn't have larger mainjets with them. i see A LOT of variance with these dyno's. i am not sure why either.

[QuadJunkies]

Very cool!!
I have to run a 178(was a 170-175 until summer) in mine, I find my quad runs alot better a bit on the fatter side..... ;)

[ZSK]

Mine runs great at a DJ165 main.

[plkmonster2]

Yeah, it does seem funny that a lot of you are running such a high main jet, when stock is 148... The stock is also a tad rich, so a 170 seems really high with just a slip on. Unless your lid is off, I don't see how it could run very well.... I would like to see the air fuel ratio difference in the 148 with a totally stock machine at ~1500 ft above sea level. It would be best to maintain this air fuel ratio, as you mod your machine, for maximum performance.

[ZSK]

Mine is a 440 with an open lid and slip on that's why it might seem high. And I know QJ has a built motor too.

[Steve-o 400EX]

Originally posted by cals400ex
i want to see a dyno sheet with the 155 in and also with the 170 in. i wouldn't even run a 170 in a built engine unless it was totally decked out. going with a 170 totally hurt the power output of my bike, even when i was running a 406. i only run a 158-160 with the air box lid on on my 426. i am curious in seeing dyno sheets of both runs though. i have seen 416's that had their bike on one dyno produce best results with a 155 mainjet and others say that a 190 gave the best power and it was increasing still but they didn't have larger mainjets with them. i see A LOT of variance with these dyno's. i am not sure why either.

I agree, i have a 416 kit and run a 155 Main jet with a 42 pilot and no choke. The plug checks show i'm runnin right on with my mods, which you can see in my sig. I do know that jetting will change due to altitude, but i dont think that they will change that much:confused:

[Toadz400]

I run a DJ155 with my airbox lid off and a Big Gun slip-on. Anything above that runs horrible, anything below that is too lean.

[cals400ex]

i can honestly tell you that my 426 and cam only changed my jetting by 1 mainjet size. the pipe or air box mods changed jetting more than my engine work.

[meanyellow03ex]

I don't get it either. After the techs put my carb back to the stock needle etc., They put in a 155 keihin right away because he said that is what most 400's take with similar mods. It put out 27.1 horsepower with the 155 but the air/fuel ratio went between 16:1 and 18:1 between 4,000 and 9,000 rpm. Not good. They jumped it right up to the 170 and ran it again. 27.3 horsepower and the ratio is between 13:1 and 14:1 in the same rpm band. It runs great too. Has a good deal more power across the board. It pulls so fast I keep looking for 6th gear :D I do have the dyno graphs but have no means to post them. Any questions, pm me... Later

[cals400ex]

i am not saying your wrong, it is just crazy. i know for a fact my bike is quicker when it has a smaller mainjet in than that. i don't see how going from a 155 to a 170 will only change 2 tenths of a horsepower. i can feel a very noticeable difference between a 155 and a 170. what rpm did it produce max (27.1) horse with the 155 in and what rpm did it produce max (27.3) horsepower with the 170 in?

what needle clip position is it set at? what elevation you at? what was the temp in the room?

[plkmonster2]

the reason why the jets don't change much when changing bore is that it pulls in more air volume. The more air volume, the more gas it pulls in too. Its not like the carb only squirts out a limited amount of gas. The more air the motor pulls in, the more gas it will pull in. If you make it easier for the motor to get more air, it wil need a lot more gas, since the carb can't keep up with the demand. A larger bore motor won't pull more air faster, so no drastic changes are needed. It is hard to explain, but thats why you need an exhuast an intake to get full potential. Just a 416 426, etc won't be much better than stock.;)

[meanyellow03ex]

Cals, the two charts between both jets were almost identical, except the air/fuel ratio. Both seemed to peak out at 6,800 to 7,400 rpm area. Horsepower was almost identical. Both tests were done in a climate controled dyno room at 76 degrees F. Both lines are mostly overlapping except the 170 jet put out better power between 2,000 to 4,000 rpm than the 155. I'm sure a 155 jet would feel fine seat of the pants. And with the gas we have now days, probably couldn't see a different plug reading too. The clip is in the stock position and my altitude is 650 ft above sea level. Hmf stands by the 170 jet everytime I email them and call. I didn't believe them either thats why I posted on here. I'm glad I had it tested this way. The bike ran fine with the 148 jet too... I just wanted to let you guys know what I ran into just for a FYI...

[Fortman_400]

the reason for the jet is because of air density within elevation.
thats why when carburated cars and bikes go to a completely different elevation of the state or country, they ride completely different.
denser air has more oxygen molicules, so they would run better when its denser. thats why engines are blown for performance, because they increase the density of the atmosphere in the intake.

so the results of the dyno could be the same but the jets could be incredible different, depending on the elevation.
the only way to control it would be to dyno the 2 quads at the same elevation.

[pnut420]

Originally posted by cals400ex
i am not saying your wrong, it is just crazy. i know for a fact my bike is quicker when it has a smaller mainjet in than that. i don't see how going from a 155 to a 170 will only change 2 tenths of a horsepower. i can feel a very noticeable difference between a 155 and a 170. what rpm did it produce max (27.1) horse with the 155 in and what rpm did it produce max (27.3) horsepower with the 170 in?

what needle clip position is it set at? what elevation you at? what was the temp in the room?

You take it a little to far, on paper or logically what your saying makes sense, but a larger bore motor does not necessarily need larger jets, maybe to some degree but its not a night and day difference alot of times. Also on a motor that is ported along with a larger bore and higher compression, everything pretty much matches on that setup and is going to pull more fuel and air because there is now somewhere for it to go. Also a bike that is running lean in most cases is going to be a little faster, but doesnt mean its the thing to do, if his air fuel ratio is raight then its all good, also elevation changes things, as well as temperature etc...

[Steve-o 400EX]

But, a larger bore will pull more out than a stock one, i dont understang how it can pull more thorught the same jet, thats why there are different sizes, only so much can go through it. I ride at many different altitudes and my jetting doesnt change more than 1 size, i'm not lean or rich, i have it dialed in pretty much perfectly. i dunno, where are u located meanyellow03ex?

[meanyellow03ex]

I'm located in Milwaukee, Wisconsin. The 400 was dyno'd in menasha, near Green Bay, Wisconsin. The elevation is in the 600-800 feet area.

[cals400ex]

Originally posted by pnut420
You take it a little to far, on paper or logically what your saying makes sense, but a larger bore motor does not necessarily need larger jets, maybe to some degree but its not a night and day difference alot of times. Also on a motor that is ported along with a larger bore and higher compression, everything pretty much matches on that setup and is going to pull more fuel and air because there is now somewhere for it to go. Also a bike that is running lean in most cases is going to be a little faster, but doesnt mean its the thing to do, if his air fuel ratio is raight then its all good, also elevation changes things, as well as temperature etc...


yes, i mentioned that my larger, higher compression piston along with my cam only changed my jetting 1 mainjet size. so, i agree that the jetting won't change much with a larger bore.

you mentioned a lean running bike will produce a bit more power. i agree. however, if this is the case why didn't the dyno show this??

i will agree with the dyno on one thing. he mentioned that at lower rpms, the little richer jet produced a little more power. my bike seems to run a little quicker when drag racing in the lower gears when i put in a jet 1-2 sizes larger. however, once you hit the upper gears, the smaller jet pulls harder.

it still doesn't make sense how the jump from a 155 to a 170 only produced 2 tenths of a horsepower difference?? i, just by feel, and tell a substantial difference between a 155 and 170. this difference is mainly in the upper gears though. did you try a 160 and a 165 for comparison??

on my bike i can tell you when the mainjet was changed 1 size by plug readings, every time. the color change on the bend of the plug will slightly change positions. if you go 1 size larger, the color change will be closer to the tip of the plug. if you go one size smaller, it will be closer to the base of the plug.

one thing i cant tell you is my stoichiometric air/fuel ratio. however, i can tell you which jets make my bike the quickest when drag racing (which i realize could be on the lean side). i do not run the jet that gives me best top end. it is just smaller than i prefer to go.
i am not saying anything/anyone is wrong, but it seems to appear your bike is acting a lot different than mine.

[meanyellow03ex]

Yeah, it seems everyone is running something different. They didn't try a 160 or 165. But with the 170, the air fuel ratio is bordering on 14:1 or a tad higher between 6,000 and 9,000 rpm. That is about as lean as I would want it anyway. Usually 13:1 is the safest. The 155 main was a hair better in the upper band after peak power, but was so minimal. I could see how a smaller jet may pull better way up in the rpm band, but was too lean for comfort . Alot of interesting comments in this thread though.

[cals400ex]

Originally posted by meanyellow03ex
Yeah, it seems everyone is running something different. They didn't try a 160 or 165. But with the 170, the air fuel ratio is bordering on 14:1 or a tad higher between 6,000 and 9,000 rpm. That is about as lean as I would want it anyway. Usually 13:1 is the safest. The 155 main was a hair better in the upper band after peak power, but was so minimal. I could see how a smaller jet may pull better way up in the rpm band, but was too lean for comfort . Alot of interesting comments in this thread though.


yeah, i find it quite interesting too. i would actually go and get mine dyno tuned but i don't know where to go around here. is this a regular car dyno or do they have different ones for quads?

[03EX]

most places that dyno atv's use one for bikes the car dynos dont go low enough for that small of hp's, try your local bike shop!

[tommydogtv]

I run a 155 in mine and i have a e series slip on and a white bros air filter

[meanyellow03ex]

This was a motorcycle & Atv dyno only. Alot of shops can dyno a motorcycle, but are not equipped for atv's. The place I had mine done was the only place in southern Wisconsin that I could find. They charged $70.00 which included taking out the jet kit and the new Keihin jet. I would have been better off saving the $50.00 on the jet kit and just got it tuned to begin with. I'll know better next time.

[TC426EX]

As far as jetting goes, all I know is that when i was running a stock carb with the choke out before I got the FCR, I was running a 185 or a 192 in there and it was just right in my built motor. Anything below the 185 was extremely lean here in OH.

[cals400ex]

Originally posted by TC426EX
As far as jetting goes, all I know is that when i was running a stock carb with the choke out before I got the FCR, I was running a 185 or a 192 in there and it was just right in my built motor. Anything below the 185 was extremely lean here in OH.


i am not saying your wrong, but how did you know it was lean? i think it is hard to tell if it is lean. i know i am too lean (from what i consider lean) when my bike is running really hot, or the midrange power feels to just be fading away, or by doing plug chops. what size jet you running in the fcr? sparks says told me to only run a keihin 165 in a fcr 39 and that is with my 426.

[tinner]

Wow, a 170 sounds pretty fat. Mine would be drowning with that jet. I have a stock bore that's built up internally and externally. I run a 160 which is probably a shade fat. So, what's the name of the shop that you had it dyno'd at ??

[cals400ex]

i just read a dyno from a buddy. he ended up with a keihin 155 in a fcr 39mm carb. he had a pipe, gt thunder "play" porting, modded air box lid, 10.8:1 416, stage 2 hotcam, etc. in the stock carb they used a keihin 150 mainjet. with these in the air/fuel ratio was at 14:1.

these jets do seem small to me. the bike put out 38 horsepower. as you can see, the dyno's must vary drastically.

[nakomis0]

My nearly stock bike also had a large main jet, it was like a 172 or something around there.

My current setup runs a 190. Heres a scan of my ratio...

We try to keep the ratio inbetween 12-13.

The 190 (blue) starts to lean out at the end, tried to fix it with a larger main, 200 (red) but got less hp. We where gonna try and fix it with a different needle but never got around to it.

as far has hp put out it was something like 43.2 blue, 42.9 red, 42.5 green.

sorry theres no rpm, but it didnt get hooked up good for some reason.

http://memimage.cardomain.net/member_images/7/web/343000-343999/343319_56_full.jpg

[meanyellow03ex]

Mine was dyno'd at Mike's cycles in Menasha, Wisconsin. Near Appleton. It's the oldest Honda dealership in Wisconsin.

[tinner]

Gotcha. I looked for a dyno in the milwaukee area. Everything was setup for a bike.

[meanyellow03ex]

Yeah, I checked all around Milwaukee too. I looked on the internet to find Mike's Cycles. It's weird how everyones 400ex run different jets. I guess I just have to believe the dyno graph that the air/fuel ratio is correct. I rode after the dyno tune this past saturday up in Langlade County about 60 miles and it ran good. No bogging, popping, nothing funny. It is very responsive in any gear whether tached out or lugging around. Still needs more power to keep up with my brothers Predator. That Predator rips higher in the rpms, kinda where the 400 tapers off. The 400ex has a better low and mid range though...

[TRXRacer1]

Hey guys, interesting subject here. I'm in the milwaukee area too and have been thinking of having this done. What does it cost?

[meanyellow03ex]

Dyno time was $70.00 an hour. They said it usually takes about an hour. Mine took 1.5 hours because they had to pull out my jet kit but they still charged me the $70.00. It was worth it. It'll help prevent engine damage from being too lean. Get it tuned and it'll only cost ya $15-20 dollars more than buying a crappy jet kit...


www.mikescycle.hondamcdealers.com

[TRXRacer1]

Thanks for the info! I want to get it done before and after I do my next mods. I'm not sure about the tuning part though, sounds like they got you a hair rich but the numbers show different so I don't know. I just wouldn't want them changing anything on mine. Thanks again.