windaelicker88 Posted March 15, 2009 Report Share Posted March 15, 2009 Got a prob with occasionaly revs rising after closing throttle... Have stripped and oiled throttle twist and cable, still does it and don't know why??? Link to comment Share on other sites More sharing options...
fredie Posted March 15, 2009 Report Share Posted March 15, 2009 what bike Link to comment Share on other sites More sharing options...
Barry Posted March 15, 2009 Report Share Posted March 15, 2009 Air leak on the inlet side. Could be a split carb rubber. Link to comment Share on other sites More sharing options...
sparx55 Posted March 16, 2009 Report Share Posted March 16, 2009 ditto Barry , air leak, deffo Link to comment Share on other sites More sharing options...
addiction269 Posted March 17, 2009 Report Share Posted March 17, 2009 air leak.... Link to comment Share on other sites More sharing options...
2639 Posted March 17, 2009 Report Share Posted March 17, 2009 Air leak...pffft. Poltergeist. Link to comment Share on other sites More sharing options...
ronenige Posted March 17, 2009 Report Share Posted March 17, 2009 Air leak...pffft. Poltergeist. spray the manifolds with holy water , if the air filter lid spins 360 and the breather projectile vomits pea soup , then that'll be the culprit Link to comment Share on other sites More sharing options...
wavydavy Posted March 17, 2009 Report Share Posted March 17, 2009 If it's an RX/SXV4/550 then it could be grit in the inlet causing the butterfly to not shut fully, getting it all confused and then open fully,, adding fuel as well, even on a shut throttle... Ask me how I know... Dave Link to comment Share on other sites More sharing options...
VeeTeeArr Posted March 18, 2009 Report Share Posted March 18, 2009 If it's an RX/SXV4/550 then it could be grit in the inlet causing the butterfly to not shut fully, getting it all confused and then open fully,, adding fuel as well, even on a shut throttle... Ask me how I know... Dave If it's a TVR Tuscan racecar, with 450 bhp, going down the mainstraight at Knockhill, then it could be an air cleaner housing bolt that's fallen out, bouncing around waiting for the throttle to be opened fully before jamming the butterfly. Ask my mate how he knows x2 Link to comment Share on other sites More sharing options...
Annaz Posted March 18, 2009 Report Share Posted March 18, 2009 I'm going to go for a split, or bad seal of perishedness in one of the inlet rubbers or, if it's a carb bike maybe a dodgey diaphragm. Do I get a prize if I'm right? Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 5, 2009 Author Report Share Posted April 5, 2009 Hey guys...its a Yamaha YZF 750 streetfighter,have now had carbs off checked all inlet rubbers,all in good nick..hose clips didnt seem too tight! Cleaned out float bowls and jets everything seems ok...only thing not checked is diagphrams cause girlfriend was on the phone wondering how long i was going to be at that stupid f***ing bike??? Bike runs ok when out and giving it large only when you try to back off its revs are not dropping off???? Link to comment Share on other sites More sharing options...
Evilchicken0 Posted April 5, 2009 Report Share Posted April 5, 2009 Did you have it dyno'd after it got street fightered ... if your air/fuel mixture is weak the revs will rise so it could be something around the airbox ... or some fuel starvation issues. It could be there's a diaphram pinched when putting the carb tops on. Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 5, 2009 Author Report Share Posted April 5, 2009 Will go check diaphrams tommorow night if i'm allowed out to play Link to comment Share on other sites More sharing options...
porter_jamie Posted April 5, 2009 Report Share Posted April 5, 2009 has it got separate opening and closing throttle cables? Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 7, 2009 Author Report Share Posted April 7, 2009 has it got separate opening and closing throttle cables? only got opening cable... the carbs are Kehin flat slides if that makes any difference??? Link to comment Share on other sites More sharing options...
porter_jamie Posted April 7, 2009 Report Share Posted April 7, 2009 throttle cable routing is critical on single cable arrangement. unfortunately i know this from bitter experience.....turn left it revs up etc. Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 7, 2009 Author Report Share Posted April 7, 2009 How worn are the slides? If your slides are hanging up instead of closing when you shut the throttle..... Everything shutting off fine,think cable routing is ok...had the same problem on one of my motocrossers got a bit hairy at times... Am really starting to get pissed off with it.!!! oh and no diaphrams on it Link to comment Share on other sites More sharing options...
porter_jamie Posted April 7, 2009 Report Share Posted April 7, 2009 does it only do it when you are really leaning on the brakes? Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 7, 2009 Author Report Share Posted April 7, 2009 does it only do it when you are really leaning on the brakes? No sitting still and rev it,sometimes ok but majority of the time the revs take a bit longer to fall off...think tommorow night i will disconnect cable and try it see what happens?? Link to comment Share on other sites More sharing options...
Annaz Posted April 8, 2009 Report Share Posted April 8, 2009 Are you running it with an airbox or have you got bellmouths or somat? Must admit I'm clutching at straws here, it does sound like air is getting sucked in somewhere or something is sticking. Flatslides are quite problematic to set up, have you tried asking on the streetfighter forum? Link to comment Share on other sites More sharing options...
TKDMitch Posted April 8, 2009 Report Share Posted April 8, 2009 I had a GPz550 that did this. It had a rod that ran across the outside of the bank of carbs that was spring loaded which served to close the carb slides when you shut the throttle. This rod and springs got gummed up with road crud over the years resulting in similar symptoms to the ones you describe. I got in there with a toothbrush and some WD40 and gave it a good clean and it was fine afterwards. Might not be the poblem but certainly worth a look. Mitch Link to comment Share on other sites More sharing options...
windaelicker88 Posted April 9, 2009 Author Report Share Posted April 9, 2009 Airbox is on it still...but not for long once i set fire to the god damm bucket o s**t.. Will have another nosey the night. Link to comment Share on other sites More sharing options...
rc30rob Posted April 11, 2009 Report Share Posted April 11, 2009 If they are proper mechhanical flatslides they need two cables from the throttle (cv type flatslides dont ) ,Common problem so to find out ,off with the tank run her up and with the throttle and a finger on the linkage shut the carbs down and if it does shut down thats your problem .Then contact allens carburetors and they will have a twin cable throttle body. If its not that she is running week for some reason hence the high revs Link to comment Share on other sites More sharing options...
stretch Posted April 13, 2009 Report Share Posted April 13, 2009 you say the rubbers are okay- the intake manifolds-but check them out to be sure: let the bike warm up and idle, and spray carb cleaner on the manifolds one at a time-you will hear the revs rise when the cleaner gets sucked in if there are air leaks. mechanic showed me that trick once- not sure if you can diagnose any other leaks this way, but seems reasonable that you could-good luck! Link to comment Share on other sites More sharing options...
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