ActionStarCBRxx Posted February 13, 2007 Share Posted February 13, 2007 Greetings All, I have a 1997 carbed bird. She has 27K miles on her. She has a stage one jet kit, and a full Two Brother exhaust. I finally got most the bird back together. I just finished putting in the new fuel sock, rebuilt petcock, and ensuring all my hoses are attached correctly and tightened. ( I was missing a hose from carb to air cleaner, and the boots were loose) I have it down currently I am waiting on a slave cylinder clutch gasket. (not relevant other than stating the bike is un-ridable at the moment) Anyway, I fired up the bike, let her run a while. She sputtered and spit a bit when applying throttle, but then when she warmed up, she evened out and sounded pretty decent. However, when giving a hefty bit of throttle, say 6000 + RPM to 9000 RPM, and then letting off the throttle, she back fires (not an abrupt pop more like a Tommy gun - short bursts) through the exhaust, and there are pretty blue flames emitting from the pipe as well. The inside of the pipe is extremely coal black, much worse than it was before I started all this. As much as I like the effect and the look of the flames, I don't think it should be doing this. (insert REALLY?? comment here) My original problem was a lean condition at higher RPM, but with the new fuel sock, petcock rebuild and hose fix, there are no stumbles when applying throttle after it warms up. Now it seems I have a reverse condition, where she is too rich. Mechanically, I am fairly decent... what I lack in experience I make up in patience and a factory book. I have yet to tackle the carb's, the stage 1 kit was done prior to me buying the bike. So I have no idea what was done for jets or needles etc. I don't think there is anyway to alleviate the rich condition, with out getting into the crabs correct? She has a history of poor gas mileage and dark rich pipes, but the flames and Tommy gun backfire are new. Any recommendations and links would be helpful. Thanks! Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted February 13, 2007 Share Posted February 13, 2007 You need to yank the carbs. Since someone else did the jet kit you don't know what was REALLY done. Backfiring on deceleration through the pipes (pipe) is a lean condition, not rich, although I've never seen it before just sitting there revving it. You might want to check your exhaust gasket sealing because an air leak can cause it also. When you have the carbs out be sure to turn the pilot screws out to 3 turns. This is the circuit which causes the lean backfire on deceleration. Quote Link to comment Share on other sites More sharing options...
ActionStarCBRxx Posted February 13, 2007 Author Share Posted February 13, 2007 You need to yank the carbs. Since someone else did the jet kit you don't know what was REALLY done. Backfiring on deceleration through the pipes (pipe) is a lean condition, not rich, although I've never seen it before just sitting there revving it. You might want to check your exhaust gasket sealing because an air leak can cause it also. When you have the carbs out be sure to turn the pilot screws out to 3 turns. This is the circuit which causes the lean backfire on deceleration. Read some other posts on carb issues... your a bit of an expert eh? What source did you get your knowledge from? Any suggested reading? Carbs have always been like a black box to me. I came across this link where you posted about pilot jets... http://www.factorypro.com/tech_tuning_proc...pm_engines.html What main jets are you using or would you recommend? Am I going to need a gasket kit when I start disassembling and reassembling, or is it going to come off and go back on clean? thanks again for your input! Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted February 13, 2007 Share Posted February 13, 2007 You won't need a gasket kit, everything is reusable. I'm running the stock pipes and filter so it won't be the same for you. But for the record 142 mains all 4, slide drilled out, needle shimed to 25 thou., and pilot screws out 3 turns. I read everything I can get my hands (or browser) on, but the best thing is the Honda Service Manual it's VERY thorough. Quote Link to comment Share on other sites More sharing options...
airborneXX Posted February 13, 2007 Share Posted February 13, 2007 You won't need a gasket kit, everything is reusable. I'm running the stock pipes and filter so it won't be the same for you. But for the record 142 mains all 4, slide drilled out, needle shimed to 25 thou., and pilot screws out 3 turns. I read everything I can get my hands (or browser) on, but the best thing is the Honda Service Manual it's VERY thorough. Are you using the factory needles? For the shims I take it you used washers stacked to measure 25 thou. Did you buy or make a tool to adjust the pilot screws or just notch the screws and use a small screwdriver. I'm back to stock exhaust and I'm trying to get my mileage up. So far I'm running the 142 mains, but with dynojet needles. I also have a set of stock needles to put in if need be. Quote Link to comment Share on other sites More sharing options...
Pete in PA Posted February 13, 2007 Share Posted February 13, 2007 mhttp://www.cbr1100xx.org/forums/index.php?showtopic=8763&hl=rimfire Do what you have to to get the pilot screws out then cut a slot in them with a dremel for a screwdriver. I'm using the stock needles with a different washer that is at 25 thou. Stock washer is 20 thou. I'd go back to the stock needles, the Dynojet needles have a big taper on them. (more fuel) I keep bouncing good running off of good mileage and wind up in the middle somewhere. Quote Link to comment Share on other sites More sharing options...
airborneXX Posted February 13, 2007 Share Posted February 13, 2007 Thanks Pete! I've got to pull my airbox to replace my choke cable soon. While I'm that far I want to get this sorted out. Quote Link to comment Share on other sites More sharing options...
rockmeupto125 Posted February 13, 2007 Share Posted February 13, 2007 Be DAMN sure you have the hoses on the right way. I wish I had a buck for every time somebody said they were on right, only to find they were on WRONG. Quote Link to comment Share on other sites More sharing options...
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