R & D power bowl


26 replies to this topic
  • William1

Posted April 02, 2009 - 09:33 AM

#21

I am in 100% agreement with Gray on all his statements. I'll add that if you must be able to nail the throttle from idle and not have a bog, then the ALJ or a small LJ will solve it. But you have to have the oring mod or the stiffer sping, you have to have the AP timing right first. The big downside to using a small LJ (or ALJ setting) is excessive fuel use at higher RPMs. In fact, it can result in a high rpm bog due to an excessively rich mix. BTW, I install a O2 bung on all my bikes and use a five wire Bosch Lamda sensor to check/set primary jetting. The AP can cause as much as a 6 point jump in A/F!

  • Brad_Aus

Posted April 02, 2009 - 09:15 PM

#22

Im not going into a discussion on how many degrees per second gray rotates his throttle vs snapping the throttle, but i wil say that, and most of you would have to agree that, most expert riders, especially on the moment just before landing a jump, and usually when dumping the clutch out of a berm, will infact slam the throttle at a very fast rate... If you need to be cautious and thinking about throttle rate, then you are riding around a problem that is easily cureable.. The best thing I can do for a customer, is give them a bike, that has no quirkyness, no bits to watch out for, I just need to be sure, that no matter the throttle input used, the bike will work.

I have also found that, if all other circuits in the carb are metering correctly, then you dont actually need much AP squirt anyway, I wire the linkage solid -as i feel it needs the response, and I set them to just miss the slide.. If you have the ALJ, it allows you to get away with having the pump duration over a large range and its able to be tuned precisely with the ALJ. This saves endless time removing the cover or removing the fuel bowl on and off and having a supply of leak jets on hand.. As its easily adjustable in the future when the weather changes, if its enough to throw the AP fuel metering a bit off.

William and I have the same idea what a Lambda meter is, its a meter using a wideband Lambda sensor to measure a/f ratios, on the other hand, a gas analyzer (typically 5 gas) is a machine which takes samples from your exhaust gas through a filter and gives a readout of HC O CO CO2 NOX. This is the more chemically correct way to determine combustion efficiency, but it is by no means practical..

I love the FCR for its tuning ability, and my opinion is if its setup correctly, there should be no compromise between throttle response at idle, and throttle response at high rpms, regardless of accel rate.. In my opinion, most bikes are lean on the diameter part of the needle, 0-25% throttle, and getting this right, allows you to reduce the size of the pilot jet which is directly related to needle dia, and it allows for less AP squirt quantity.

  • husqy360

Posted April 02, 2009 - 09:53 PM

#23

just use the clutch. ^^

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  • Pilfer8

Posted April 02, 2009 - 09:59 PM

#24

Wow! This has gotten so technical I am way out of my league here. I have read the posts many times and they make sense. I can't argue. But here's my story; I put the thing on and it took me 30 minutes and it worked. It could have just been the 30 cent spring that was supplied with it. (but I doubt it because I had a pretty heavy O-ring on there) Too much money? Probably, but I am just pleased to have the throttle response I have been looking for for over a year. I don't ride MX, I ride trails. Mostly slow and technical. Probably not the right bike for it but that's besides the point. The reason I was looking for this type of response was to pop the front over that stupid log, at low speed, with confidence. Yeah....450, you can pop the front end up anytime you want, but I'm talking about timing. I mentioned in my first post, I have no doubt it can be done with the know how, and experience, but for me, this was the cure. This is why I brought the thread back to life. Not to try and talk the experienced into buying into the powerbowl but a mere suggestion that it might solve someones else's problem. Other (cheaper) products might work, but this is the one I bought and it worked for me and that's why I searched out this thread and put in my opinion on it.

Cheers.

  • William1

Posted April 03, 2009 - 03:01 AM

#25

The bogging 99.9% of the riders experience is from idle to about 1/4 throttle. If you are a good rider (honestly fast, not honestly slow like me) and the rev's are over 5K, you will probably never have a bog.

Devices like the power bowl, power now and so on can appear to fix a problem. Much like a band aid over a deep puncture wound. They cover up the problem. Most of the time, the band aid side effects at not noticed. For those that cannot fully analyze a issue (stitch a wound), they are a work around.

  • grayracer513

Posted April 03, 2009 - 08:09 AM

#26

Im not going into a discussion on how many degrees per second gray rotates his throttle vs snapping the throttle, but i wil say that, and most of you would have to agree that, most expert riders, especially on the moment just before landing a jump, and usually when dumping the clutch out of a berm, will infact slam the throttle at a very fast rate... If you need to be cautious and thinking about throttle rate, then you are riding around a problem that is easily cureable..

And I agree with that. That is a matter of practical performance response. However, this still rarely requires an engine to be capable of dealing with an instantaneous snap from idle to WOT. As far as needing to be cautious of opening the throttle at the appropriate rate, you need to be cautious of that anyway on a 450, just for control and traction reasons, but if you are first cautious about having the bike in the right gear, you shouldn't really need to worry about a bog when you're underway.

I have also found that, if all other circuits in the carb are metering correctly, then you dont actually need much AP squirt

That was one of the points I was trying to make.

anyway, I wire the linkage solid -as i feel it needs the response,

I never recommend wiring the linkage, because as I mentioned in the other post, doing so requires maximizing the AP stroke by removing the diaphragm button (so that the button does not restrict the throttle from opening fully) and eliminates diaphragm selection as a tuning tool. Stiffer linkage springs (or even O-ringing) are clearly a better approach, as they deliver the responsiveness require while retaining the compressibility of the linkage when the stop button bottoms.

William and I have the same idea what a Lambda meter is, its a meter using a wideband Lambda sensor to measure a/f ratios,

OK, I see what you're up to. As a GM tech for so many years, I never used the proprietary Bosch name "Lambda" to refer to an O₂ readout, but a handheld connected to an O₂ sensor is a great approach. Gas analyzers ARE practical, but only on a dyno, or other stationary platform.

.. In my opinion, most bikes are lean on the diameter part of the needle, 0-25% throttle, and getting this right, allows you to reduce the size of the pilot jet which is directly related to needle dia, and it allows for less AP squirt quantity.

You are referring to the upper, or major, diameter of the needle, and here again, we agree.

The bogging 99.9% of the riders experience is from idle to about 1/4 throttle. If you are a good rider (honestly fast, not honestly slow like me) and the rev's are over 5K, you will probably never have a bog.

Devices like the power bowl, power now and so on can appear to fix a problem. Much like a band aid over a deep puncture wound. They cover up the problem. Most of the time, the band aid side effects at not noticed. For those that cannot fully analyze a issue (stitch a wound), they are a work around.

:thumbsup:

  • Brad_Aus

Posted April 03, 2009 - 02:45 PM

#27

I never recommend wiring the linkage, because as I mentioned in the other post, doing so requires maximizing the AP stroke by removing the diaphragm button (so that the button does not restrict the throttle from opening fully) and eliminates diaphragm selection as a tuning tool. Stiffer linkage springs (or even O-ringing) are clearly a better approach, as they deliver the responsiveness require while retaining the compressibility of the linkage when the stop button bottoms.

I had also used the merge racing, stiffer pump spring, and on the 450, while I had a couple of springs still in stock, i opted to wire it..

Its not a major change to the diaphragm, you only need to grind say .010" off the button

so each to their own, ive tried both ways, and they are equal results, just one costs $20 less, and doesnt require you to remove the carb from the bike.





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