Jetting advice: CPR air filter on 950

[mountain eagle]

Originally Posted by Sporting Wood

Also, the stock needle has to go!

In just the H2W set up?

Or in the CPR set up?

or in any setup to get the most out of the carbs?

and then where would one source a different needle?

Heading out now to run in the 165's and see the plugs look........

[mousitsas]

Originally Posted by Sporting Wood

From lots of dyno time, the snorkle restricts airflow into the box. Simply taking it off makes a huge difference in top end, this after upsizing mains. In stock condition, the first thing to run out are the mains. Factory mains are still lean even with the snorkle on. I assume the 990R makes its higher top hp numbers from either/ or both more fuel flow through the injectors or higher rev limit, greater displacement...dunno. I have a 950. Simply put, an airbox equipped 950 benefits from a bigger main, its smaller fueling ability being the top end restriction in stock form, a 950 without an airbox benefits far more, as the next restriction caused by the snorkle is eliminated.

In regards to using h2w's kit intended for the prefilter, this would be a total donkey show. That system relies on greater vacuum and less atomization. The airjets will be way off, really way off, and the mains beyond dangerously small and lean. I'd not be at all surprised to see a seized motor as a result! I'm certain Ken has warned against this, repeatedly. Shifting to a tune with greater airflow, less vacuum and better atomization is totally, completely different, and require totally different settings.

Also, the stock needle has to go!

Well, I will report first hand tomorrow when I get to ride my previously H2W jetted SE, with 160/165 mains and obviously the snorkel in place of the prefilter. But various people have reported that the bottom H2W jetting works fine both with CPR as well as pod filters, as long as the mains are correct. Which sounds logical to me since at small throttle openings , the restriction of the filters combined should not make a difference compared to the stock setup.

I still cannot understand why a snorkel that has larger inlet area than the carb inlet can restrict the flow (as far as top power is concerned) it makes no sense to me. I don't dispute anybody's experience, but it is a mystery to me nevertheless.

[Sporting Wood]

Originally Posted by mountain eagle

In just the H2W set up?

Or in the CPR set up?

or in any setup to get the most out of the carbs?

and then where would one source a different needle?

Heading out now to run in the 165's and see the plugs look........

IIRC, we developed what became the H2w kit with the stock needle and the FP needle. I ran the FP version, lots of guys also used the stock. I don't think its as important. I noticed though, that in an open breathing setup that the FP needle really shines...and imho, is a necessity to get the transition from slow jet to main to work well. I found that suddenly dumping the throttle wide open with the stock needle would produce a seizure, the motor coughing and wheezing until it spooled up.

Originally Posted by mousitsas

Well, I will report first hand tomorrow when I get to ride my previously H2W jetted SE, with 160/165 mains and obviously the snorkel in place of the prefilter. But various people have reported that the bottom H2W jetting works fine both with CPR as well as pod filters, as long as the mains are correct. Which sounds logical to me since at small throttle openings , the restriction of the filters combined should not make a difference compared to the stock setup.

I still cannot understand why a snorkel that has larger inlet area than the carb inlet can restrict the flow (as far as top power is concerned) it makes no sense to me. I don't dispute anybody's experience, but it is a mystery to me nevertheless.

Good luck with that. I tested airjet combinations on k&n pods...back in '07. I know what I came up with on the dyno, real world, and through the use of an onboard o2 meter...after many hours and many different settings. YRMV

[mousitsas]

Originally Posted by Sporting Wood

IIRC, we developed what became the H2w kit with the stock needle and the FP needle. I ran the FP version, lots of guys also used the stock. I don't think its as important. I noticed though, that in an open breathing setup that the FP needle really shines...and imho, is a necessity to get the transition from slow jet to main to work well. I found that suddenly dumping the throttle wide open with the stock needle would produce a seizure, the motor coughing and wheezing until it spooled up.



Good luck with that. I tested airjet combinations on k&n pods...back in '07. I know what I came up with on the dyno, real world, and through the use of an onboard o2 meter...after many hours and many different settings. YRMV

Well well well, luck was excellent indeed. Bike works flawlessly, bottom and midrange is identical to the prefilter setup. Top end is stronger as expected, I suspect slightly rich with the exhaust inserts (and summer temperatures), will have to try without them at some point as well as a DNA filter.

For the record, 950SE
Jetting is H2W sans prefilter with snorkel, stock airfilter/airbox and 160/165 mains
Akras with large inserts
30C @ sea level
Nothing lost compared to prefilter setup gained a bit power on top of the rev range.

[mountain eagle]

Originally Posted by Sporting Wood

I ran the FP version, lots of guys also used the stock.

FP version? What's FP?

[buzybraza]

Originally Posted by mountain eagle

FP version? What's FP?

factory pro

http://www.factorypro.com/

[Sporting Wood]

Originally Posted by mousitsas

Well well well, luck was excellent indeed. Bike works flawlessly, bottom and midrange is identical to the prefilter setup. Top end is stronger as expected, I suspect slightly rich with the exhaust inserts (and summer temperatures), will have to try without them at some point as well as a DNA filter.

For the record, 950SE
Jetting is H2W sans prefilter with snorkel, stock airfilter/airbox and 160/165 mains
Akras with large inserts
30C @ sea level
Nothing lost compared to prefilter setup gained a bit power on top of the rev range.

Do you have a dyno chart with afr too or is this a predetermined outcome?

[Navin]

Originally Posted by mousitsas

Well well well, luck was excellent indeed. Bike works flawlessly, bottom and midrange is identical to the prefilter setup. Top end is stronger as expected, I suspect slightly rich with the exhaust inserts (and summer temperatures), will have to try without them at some point as well as a DNA filter.

For the record, 950SE
Jetting is H2W sans prefilter with snorkel, stock airfilter/airbox and 160/165 mains
Akras with large inserts
30C @ sea level
Nothing lost compared to prefilter setup gained a bit power on top of the rev range.

Moose, sounds like my experience with the K&Ns. Good for you. Ken's advice to me was that the bottom stuff should be close and the mains very lean. Exactly my findings and the bike carburated far better with a snorting pull to the limiter with the 170s or thereabouts. I expected to need to rejet everything over and over but the mains really did the job.

[mousitsas]

Originally Posted by Sporting Wood

Do you have a dyno chart with afr too or is this a predetermined outcome?

When it comes to AFR, I only trust measurements taken on the road with a good tool and when it comes to power, I only trust my butt. Dynos are very good for tuning a bike to run on them.
By the way, had a longer ride yesterday, actually low end and midrange might as well be stronger than the prefiltered setup and also smoother, definitely more crisp. No vibes anywhere. The trick with H2W is not the prefilter....it is the bottom jetting.

I sense you want to prove that something which is not rocket science actually is.
Similar to the 'you need vacuum' for crisp throttle response fixation going on for years in advrider, an opinion widely popular within 'the experts'

[mousitsas]

Originally Posted by Navin

Moose, sounds like my experience with the K&Ns. Good for you. Ken's advice to me was that the bottom stuff should be close and the mains very lean. Exactly my findings and the bike carburated far better with a snorting pull to the limiter with the 170s or thereabouts. I expected to need to rejet everything over and over but the mains really did the job.

Finally I chickened out with the K&Ns Navin and went to the original airbox and snorkel. The rear intake positioning does not allow a clean solution on the SE due to the proximity of the seat pan and filtering surface area becomes problematic. But I had a couple of ideas for an alternative airbox which I will revisit later in the year.

[Sporting Wood]

Originally Posted by mousitsas

When it comes to AFR, I only trust measurements taken on the road with a good tool and when it comes to power, I only trust my butt. Dynos are very good for tuning a bike to run on them.
By the way, had a longer ride yesterday, actually low end and midrange might as well be stronger than the prefiltered setup and also smoother, definitely more crisp. No vibes anywhere. The trick with H2W is not the prefilter....it is the bottom jetting.

I sense you want to prove that something which is not rocket science actually is.
Similar to the 'you need vacuum' for crisp throttle response fixation going on for years in advrider, an opinion widely popular within 'the experts'

Guy, I was trying to help you... Thats ok. Ride your own ride.

FWIW, as I indicated in an earlier post, I did a tremendous amount of r&d with this, and with an onboard wideband too. I have ran what you are running, I have logged the results from sea level to 6000'. I know exactly whats going on with your mix, and what the airjets are doing to the midrange, which ones give the better results and which ones don't. Cold hard numbers, not a butt impression...

Here's the problem as I see it. There is no shortage keyboard genius know it all's that will post as an 'expert' to every thread regardless if they happen to have a clue or not. Some do it so long around here that they actually pick up a shred of knowledge which reinforces their self image as bike guru extraordinaire. Thing is though, without a background of real experience or professional education in this stuff, these guys are often wrong, misleading and post information that's unhelpful to the reader faced with picking out a hidden nugget of gold in a mountain of obfuscated cow shit. I'm only posting information I know to be factual, writhed from 6 years experience with these carbs and 30+ years of tuning and development.

From your posts, you're saying that you bumped your mains, put the snorkle back on and viola, its just peachy now. That's great! Consider this, you may have had a fat girl with a sloppy gash...traded her in on one a little better looking, but still a little heavy and her tits not so big, and think you're on the top of the world now. Paulina Rubio came knocking at your door and you aren't answering, because you're elbow deep in bed with this chunky A cup girl who you've convinced yourself is the best you can ever do. You hear the knocking, she's right there and you're yelling through the door, 'Fuck off, this isn't rocket science. You experts were all wrong'. She turns around and leaves you to your chubby lover, muttering, 'WTF is this guy talking about...why do I even bother'.

[bruceca2002]

What would be the optimum jetting for my mostly stock SE950. 2 into 1 pipe with an Acra silencer with spark arrestor. All pollution equipment removed and needles moved up one clip position. I get no popping on deceleration but it only gets about 30 mpg. How many turns out should the fuels screws be set at? The bikes runs very well as is but goes through a lot of gas. Thanks, Bruce

[mousitsas]

Originally Posted by Sporting Wood

Guy, I was trying to help you... Thats ok. Ride your own ride.

FWIW, as I indicated in an earlier post, I did a tremendous amount of r&d with this, and with an onboard wideband too. I have ran what you are running, I have logged the results from sea level to 6000'. I know exactly whats going on with your mix, and what the airjets are doing to the midrange, which ones give the better results and which ones don't. Cold hard numbers, not a butt impression...

Here's the problem as I see it. There is no shortage keyboard genius know it all's that will post as an 'expert' to every thread regardless if they happen to have a clue or not. Some do it so long around here that they actually pick up a shred of knowledge which reinforces their self image as bike guru extraordinaire. Thing is though, without a background of real experience or professional education in this stuff, these guys are often wrong, misleading and post information that's unhelpful to the reader faced with picking out a hidden nugget of gold in a mountain of obfuscated cow shit. I'm only posting information I know to be factual, writhed from 6 years experience with these carbs and 30+ years of tuning and development.

From your posts, you're saying that you bumped your mains, put the snorkle back on and viola, its just peachy now. That's great! Consider this, you may have had a fat girl with a sloppy gash...traded her in on one a little better looking, but still a little heavy and her tits not so big, and think you're on the top of the world now. Paulina Rubio came knocking at your door and you aren't answering, because you're elbow deep in bed with this chunky A cup girl who you've convinced yourself is the best you can ever do. You hear the knocking, she's right there and you're yelling through the door, 'Fuck off, this isn't rocket science. You experts were all wrong'. She turns around and leaves you to your chubby lover, muttering, 'WTF is this guy talking about...why do I even bother'.

Peace SW, it all is ok!
Point is that cool hard numbers have nothing to do with what we are talking about. For me in jetting, all I want numbers for is when it comes to mains to not run lean (or very rich) on the top end. But KTM did the work for us here, by setting the ballpark. Also you and H2W and K2M did a lot of wideband work, I acknowledge that and gave us a nice running low-midrange. From there on I really don't think I need any numbers, I only rely on my feeling of what a nice running engine should be like. And if the two are in dispute, I would always tune to what feeling is telling me.

[mountain eagle]

Fat girls need love too..............

[randel]

Thank you all, a lot of valuable information!
As a conclusion, I thought about following setup going from H2W prefilter setup to CPR filter when it arrives:

Main Jets 175/175 front/rear
Idle Air Jet 50
Mixture Screws 2 turns
Float Level 4mm
install Factory Pro needles (I have FP kit), 3rd clip?

Did I miss anything?