pace Posted August 27, 2003 Share Posted August 27, 2003 Reassembled the bike this evening and went for a spin around the block (about 8,000ft above sea level at this locale). Still got my bog at 2-3,000rpms but that's no surprise since I didn't adjust the slow speed mixture screws. The #138 jets seem to have given it more snap on top, however I now have a flat spot the size of Texas at 5,750-6k rpms. Versus the previous slight hesitation there, the bike now feels like the throttle has been closed for a brief second. Then it takes off with manic fury toward the redline. Would I be correct in assuming that I'm running lean here, and need to lift the needles considerably or else fit a different profile needle? Given that I removed the existing washer to drop the needles slightly AND then took the main jets down to #138, it's hard for me to imagine that it's bogging due to a rich condition. Comments? Opinions? Have you guys had any success finding an appropriately sized washer to facilitate lifting the needles? TIA. -Pace Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted August 27, 2003 Share Posted August 27, 2003 The best way to tell if lean or rich problem is to start out with the bike cold and immediately ride it at the rpm where the problem is. If the problem gets better when cold you're too rich, if worse your'e too lean. Lowes has perfect washers in those tiny parts bins. Quote Link to comment Share on other sites More sharing options...
jimyz250 Posted August 27, 2003 Share Posted August 27, 2003 sounds like its lean, put the washer back in. how rich was it up at that altitude? my 97 runs fine with my jetting which is jetted for sealevel when I am up in the mountains7-8000 feet, still good and I am richer than stock, stock jetting is so lean, :headscratch: I cant see the need to go leaner if you lived at 7000 ft.. why did you change? Quote Link to comment Share on other sites More sharing options...
mbdean Posted August 27, 2003 Share Posted August 27, 2003 What pipes are you running? With stock pipes at 8600 ft I am running 134 mains with the clips at fourth from the top. During my iterations to get it right I ran into many flat spots, etc, usually accompanied by some amount of sputtering - too lean. Here's the basic pattern I followed: Install some mains with needles on the third clip. If you have soot lower the needles. If you still have soot lower them again. If you reach the bottom of the clip go down a jet size. But if the bike sputters or has a flat spot, raise the needles. If it still sputters go up again. If it still sputters go up a jet size. Please note, though, that I found the bottom needle position to be virtually worthless since it ended up fouling the plugs regardless of the jet size used. Quote Link to comment Share on other sites More sharing options...
mbdean Posted August 27, 2003 Share Posted August 27, 2003 Holy shit, you live in Conifer? So do I, although I am planning to move to Bailey soon. I thought I had seen another bird "up the mountain". Quote Link to comment Share on other sites More sharing options...
pace Posted August 28, 2003 Author Share Posted August 28, 2003 I wonder if that was you I saw on the 'bird in Idledale last Wednesday...? Ok.. my setup is currently 138 main jets all the way across. In an attempt to address the resultant stutter at 6k I re-fitted the factory washers, and added 3 x #4 brass washers to each needle. Each washer is approx 1mm thick I would guess. This appeared to cure both the 6k rpm stutter and a little hickup I was having at 3k rpms. I then decided to see what effect an additional washer would have, and added one to each needle to lift them another 1mm or so. This has resulted in a massive bog when opening the throttle between 3k and 4krpms. The engine actually cuts for a second, before lurching forward. So, not sure now whether I will remove one or two of the brass washers from each needle. I'll probably try two, and see how she feels. My motivation for the main jet swap? I have some experience tuning turbocharged fuel injected cars for altitude, so I know the kind of fueling compensations that are necessary. I note that factorypro and others recommend running #142 jets for all four carbs for a stock 'bird at sea-level. If #142 jets are optimal for a stock sea-level 'XX, then they cannot possibly be ideal for a machine that is operating between one and two miles above sea-level. IMHO. mbdean: What needles are you running? My OEMs don't have clips. Btw, I am currently running the stock pipes with a K&N panel filter. -Pace Quote Link to comment Share on other sites More sharing options...
mbdean Posted August 28, 2003 Share Posted August 28, 2003 Hey Pace, Yeah, OK, you were the guy on the bird with the red and black full suit who I saw at about 5:00 on Wednesday, August 20. Small world, huh? Where do you live in Conifer? I'm not far from the Green Valley Grill, but will be moving out to Burland Meadows in October. Anyway, I am running 134 Mains which I purchased from K&N but are made by Dynojet. They were having a massive sale last spring and I picked up the kit for something like $35 if I recall correctly. I didn't see Blackbird jets listed on the K&N site anymore, but dynojet.com has them as well as mawonline and I'm sure many others. One thing to be aware of, though, is that according to dynojet and factory and cobra and others a jet is not a jet is not a jet. In other words, what dynojet calls a 134 has absolutely no bearing on what factory or Honda call a 134. I am running the needles with the clip on the fourth groove from the top (one groove lower than recommended). While the stock jets certainly do not have additional grooves it is worth noting that when compared to the dynojet needle there is a distinct difference in the needle profile. Also, I would be a bit concerned about placing many shims under the stock needles since you are adding additional weight to the slides which I believe could aggravate the poor throttle response you describe. Also, if you are running stock needles then you are probably also using the stock springs which are significantly stiffer than the dynojet springs - further compounding the throttle lag. The dynojet instructions recomended the 134's for stock exhaust and airfilter at sealevel. However, after many iterations it became apparent that the K&N filter was beginning to flow much better and that the 134's were running considerable leaner than they would with the stock airfilter - lean enough to work well at Colorado altitudes. I found that for given jet sizes raising the needles had the most immediate effect on eliminating flat spots and throttle lags - up to the point where the midrange got way too rich and fouled the plugs. It was also worth noting that moving the clip only one groove did not have a large effect. It is as though moving a single jet size is a medium adjustment while needle position is fine tuning. It sounds like I am running an identical setup to your bird with the exception of the dynojet kit. Should you have the bucks to spare I suggest you go get a dynojet kit, copy my settings, adjust the pilot screw per the instructions (taken into account the high altitude adjustment recommended in the factory manual, of course), and enjoy the whopping midrange boost. You will be very pleased! Of course, should you go this route and find a better setting I would love to hear about it. Quote Link to comment Share on other sites More sharing options...
pace Posted August 28, 2003 Author Share Posted August 28, 2003 If you're on the K&N/Dynojet #134 then you're almost certainly quite a lot richer than me, since I'm on the genuine Keihin #138s. I may consider bumping up the mains a bit then, but I would really like to get my hands on the re-profiled needles. $100+ just seems really expensive for the complete kit, when I know that jets are only about $4 a piece, and needles not much more. Hopefully I can find someplace that has the kit for cheap... sounds like you got a great deal! I noticed that the dynojet PDF lists the 'XX kit contents as including a 136 and 140 set of jets. Did yours come with the 134s or did you order them seperately? Btw, I'm a few miles north of Conifer. In the Shadow Mountain / Brook Forest area. I was on my way down to Bandimere when we saw each other last week.. -Pace Quote Link to comment Share on other sites More sharing options...
pace Posted August 29, 2003 Author Share Posted August 29, 2003 Took all your guys' input and made the following changes: All the mains at #140. OEM needles packed with two #4 washers each, in addition to the OEM washers. Bikes runs much cleaner now. No stumbles anywhere. Flat spot at 6k is minimized, and the bike pulls cleanly past that point and takes off like a scolded cat at 6,500rpms. Cheers. -Pace Quote Link to comment Share on other sites More sharing options...
mbdean Posted August 29, 2003 Share Posted August 29, 2003 Pace Yes, I got the 134's from Performance Cycle. After all the confusion I thought the 134's came with the kit. But I ended up getting every size down to 128 in my pursuit of goodness. Glad you found a sweet spot. Do you run at Bandimere? I tend to be more of a twistyholic myself. In fact, yesterday I played hookie from work and spent 4 hours at Second Creek with my Superhawk. Always good to burn off some adreneline and calories while grinding pucks down to the leather. Quote Link to comment Share on other sites More sharing options...
pace Posted August 29, 2003 Author Share Posted August 29, 2003 I mostly like to do canyon rides, but occasionally go down to meet my car buddies at Bandimere. I used to race the car there, so the bike is a new (fun) challenge. However, drag racing seemingly eats motorcycle tires at a rate I never would have imagined. 2,000 street miles and about 15 passes down the strip, and the rear now looks like a racing slick. Just a little tread left in the chicken strips.. :???: I've run a 1:20 in the car at Second Creek this year. I thought about taking the 'Bird down there, but would be very nervous about laying it down. -Pace Quote Link to comment Share on other sites More sharing options...
spEEdfrEEk Posted August 30, 2003 Share Posted August 30, 2003 Still got my bog at 2-3,000rpms but that's no surprise since I didn't adjust the slow speed mixture screws. Turn in your pilot screws (mabey 1/2 to 3/4). You're running rich.. (specially if it bogs and then takes off if you give it enough throttle) The #138 jets seem to have given it more snap on top, however I now have a flat spot the size of Texas at 5,750-6k rpms. Versus the previous slight hesitation there, the bike now feels like the throttle has been closed for a brief second. Then it takes off with manic fury toward the redline. I had this problem around 4K when I went to 140 mains and raised the needles one position. Seems like the dynojet kit likes to put this hesitation into your powerband if you jack with the clip position. I had to basically use custom washers to raise the needles less than one full clip position to get rid of the flat spot at 5K but still avoid the stutter and bolt at 4.5K. The flat spot is a lean condition and the stutter is a rich condition. That's why you need to keep the clip as close to recommended setting as possible. (My guess is that the profile of the needle is such that it's touchy if you adjust it off the baseline) Your best bet (or so I have found) is to set the clip in recommended position and then adjust main jets until you get your best runs. Then tweak by adjusting the bottom washer thickness. (you can get some great washers at electronic parts stores, I did..) :cool: TJ :cool: Quote Link to comment Share on other sites More sharing options...
spEEdfrEEk Posted August 30, 2003 Share Posted August 30, 2003 I note that factorypro and others recommend running #142 jets for all four carbs for a stock 'bird at sea-level. That is what I found to be the case.. I ended up using #142's with the stock needles and recommended clip setting (with pilots 1.5 turns out) here during the winter. Houston is 60 ft. above sealevel. During the summer I dropped to the #140's and put in washers that were 1.5 times as thick as the ones that came with the kit. (we routinely hit 100+ degree ambient temperatures in summer) :cool: TJ :cool: Quote Link to comment Share on other sites More sharing options...
bar10dah Posted August 31, 2003 Share Posted August 31, 2003 Dynojet. They were having a massive sale last spring and I picked up the kit for something like $35 if I recall correctly. Yeah, I tried to order one back then, too. They had just sold out of the Blackbird kit a day or two before I called in. Quote Link to comment Share on other sites More sharing options...
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