So not to big a carb to keep throttle response but no accelerator pump to reduce throttle response. I'm a little confused. The pump is there so you can tune in low speed throttle reponse and still run a large enough cfm carb to keep top end performance seems like a win win to me.
Yes no AP may have worked OK on a slow-revving XR-based motor but I'd bet hard cash it isn't the hot setup for a modern 4t, definately would be a step back from a FCR.
I spoke to Dwight about this. He said the accelerator pump carb was so responsive and jumpy that it was sometimes to responsive and made it harder to ride in the trees. The non accelerator pump carb he said works about perfect, nice smooth snappy throttle response but not to hyper sensitive. He has hundreds of hours with the quick silver in ISDE metal contention races. He might just know something. He had both carbs and lots of times used the non acceleration pump one. Real world experiences not internet guessing.
You have to realize how jumpy the bike was with the accelerator pump to understand. All these carbs flow more than a Keihin or Mikuni so you need to go 2mm smaller to keep close to same flow. Also the smaller carb allows more signal at the needle for cleaner response. But not jumpy.
Are you sure ? I'm not. Even the models that I used with the pump. I turned the squirt way down. AP hurt fuel economy also.
No, I'm not sure! And it certainly matters on the intended application. The more though I gave it, the more I see how your setup could be superior in offroad finesse-type situations. On the other hand I don't see any way it could be superior in producing outright peak horsepower and RPM (whichmay be next to useless for some!). Especially in a modern short-stroke 4t. I have no doubt that the raw unatomized fuel squirt of the AP hurts fuel economy.
Remember, an Accelerator pump has no influence on peak horsepower. Only throttle response off idle / low rpm. Once past the squirt of the pump the RPM will continue to build normally and horsepower is at a steady rpm so once again the pump has little to do with HP. Only the jump just off idle and low RPM. Some bike with huge carbs need the pump to overide that lean spot just as you jerk the throttle open before the signal at the needle and main jet kick in with normal velocity of air through the carb. That is why you don't want to go too big on the carb. With the Lectron you don't need to.
Technicaly what the ap does is provide fuel when the vacuum signal drops upon fast application of throttle in larger-venturi carbs. Large venturis most certainly allow for more peak power and RPM. So, the AP does indirectly influence peak HP, by allowing a larger carb to provide acceptable performance at low RPM while not hindering peak flow. A pumpless carb simply cannot cover all the bases, just physics not my opinion. And again, the type of riding and conditions and skill level mean everything! I mean, I'm sure the (prototype) PE125 you rode to a silver in the '81 ISDE differed QUITE a bit from Mark Barnett's 1981 RM125
With the RB Designs divider plate I was able to dial the pump down quite a bit without suffering flameouts. Better mileage and no more afterburner like exhaust color when the throttle is yanked.
Got my second ride on the Lectron. Super smooth is the word here. No glitches of feeling of crossing over circuits. Just super smooth controlled power. I'm going to adjust (my first adjustment at all of the Lectron) the metering rod slightly leaner and I think it will be absolutely perfect. Rode with 3 other 125/165 setups yesterday most of which have had extensive time and parts lavished on the carbs and I felt my Lectron, no adjustment and right out of the box worked better and metered fuel much more consistently. Smooth glitch free from bottom to top where all the others you could feel the different circuits and glitches between them. Is it the end all carb, no, the others all worked very good too. Does it bring simplicity and really nice smooth performance to the table? I think so. Everyone who sampled my bike yesterday commented on the smooth perfect throttle control. the smooth power, no jets to deal with or swap out and bolt it on and go performance really has me liking these carbs. I really look forward to leaning the rod and seeing what that offers. Bet it will run the same only more snap and MPG.
Have the adjustments put it into the APT's "ballpark"? By the way, I just wanted to thank you for doing all this carb testing, it is really nice to already have baseline knowledge of the performance. Oh, and Happy New Year!
Great reporting as expected here from U guys ... And you might have already addressed this to some degree in this thread and I missed it ... But how much better will the gas mileage be with one of these CARBS over my stock 08 WR250 with stock gearing and ~normal trail riding.. This mileage is one place my 4t machines beat the 2t banger up pretty bad .. Performance is not really an issue with me as I'm not using all the bike has to offer now but riding as much as I do, I really really need gas mileage improvement over the stock CARB on this WR ...
Will report ion MPG when I have more solid info. Seems better is all I can say right now. What the Lectron does do Is make seamless power. I really like the throttle response and liquid power. Also love the simplicity and feeling that it wants to run correctly all the time. Zero issues with how it meters fuel (other than it seems slightly rich) and I have don't nothing but set the idle. Time will tell but seems like seamless bolt on power with near zero messing around. More testing on more bikes is in order. First few impressions are very favorable. Blakes bike runs real good but he is also talking about getting a Lectron after riding mine. Likes the super smooth liquid power.
Funny thing is AA rider Scott said to Jake "Lectron? Old school man" and I think that is the perception. Rest assured Mark and crew at Lectron have done a lot on these carbs in the last 5 years plus and have countless dyno runs. They are highly developed at this time with metering rod grinds far surpassing the old school ones. Proof is in the pudding. My Lectron, which I through on my bike and adjusted nothing but the idle ran as good or better than all the reworked Keihns and PWKs that were there Sunday or any carb I have used in the past. Works great, smooth seamless power and seems very flexible to temps, altitude and fuel. Working on getting these in stock now and working on a demo program. should have a lot more info and drop in solutions for our huskys by the end of the week. Thanks K
The funny thing to me is that I remember these carbs being pretty popular for racing applications on the British twins like the BSA and Triumph. Now I'm hearing that they aren't the best choice for 4 strokes because of the lack of a AC pump. I'm not sure that they wouldn't be a good choice for a thumper, I sure would like someone to give it try.
I wish I had a 310 with farked up EFI. I would love to yank all the EFI of a 310 and give it a go. simplicity at it's finest.
