7ESKY9 Posted December 14, 2011 Share Posted December 14, 2011 hi just wondering if any 1 here could give me some info on tuning bike carbs on 2l sierra motor in my escort. ive just fitted 40mm bike carbs off a gsxr1100 ive had the jetts drilled to 1.5 and a fuel pressure regulator that turns presure down to 1-5 psi ive tried a few things checked the float levels had a play with pilot jetts set it at all fuel presures i can and adjusted timing checked spark thats algood. but it sounds like 2 wants to go but will never fully fire up just a quick fire then die cant work it out hope someone can help? cheers Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted December 14, 2011 Share Posted December 14, 2011 maybe tip a little fuel/engine start down the plug holes and crank it, might help to suck everything through and get it ticking over, failing that, vacuum leaks? Quote Link to comment Share on other sites More sharing options...
Unclejake Posted December 14, 2011 Share Posted December 14, 2011 Go back to basics first and check you have the firing order correct, good spark to all four plugs and the advance close to correct. Quote Link to comment Share on other sites More sharing options...
peteretep Posted December 14, 2011 Share Posted December 14, 2011 1.5 jets sounds way too small, my motor is 1800 and im running 1.8 jets setting fuel pressure basically put it up till it comes out the overflows then let it back a bit I set the pilot jets to standard which was all the way in then 1.5 turns back, although I have different carbs but first thing is to check firing order correct and dizzy isnt 180 degrees out or even 1 notch over on the dizzy teeth Quote Link to comment Share on other sites More sharing options...
BlownCorona Posted December 15, 2011 Share Posted December 15, 2011 surely he wouldnt have touched the ignition system when installing new carbs? crank it over and take the plugs out for a look, might be flooding? got chokes? Quote Link to comment Share on other sites More sharing options...
Jase Posted December 15, 2011 Share Posted December 15, 2011 read your plugs Homie, wet = pilot jet too rich, dry+grey = too lean are they flatslides ? if they're running needles as most do you can lift the needle for a richer mix or drop it a notch for leaner by moving the circlip up or down. But none of this will matter if your jets are too small, get it running and then access your plugs as too whether you need a bigger jet size. Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 15, 2011 Author Share Posted December 15, 2011 i have rebuilt the motor might rip bike carbs off and run it in on standard carb get it running mint then chuck bike carbs back on so i know everythings algood. i think im just been 2 excited to hear the bike carbs run. ive checked all my dizzy and timing marks but il check them again. my plugs got wet when i started playing with polit jets so il turn them back 2 standard. intresting on jet size retep130 i read article on running and installing them and they said 2 run 1.5 what size and type of carb are you running? and yes they are flat sides thanks for the help so far guys Quote Link to comment Share on other sites More sharing options...
peteretep Posted December 15, 2011 Share Posted December 15, 2011 Flat slide carbs? I haven't seen a car runnin on flat slide carbs and tuning them may be completely different to cv type carbs which most people have fitted including myself Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 15, 2011 Author Share Posted December 15, 2011 whats the difference? Quote Link to comment Share on other sites More sharing options...
kicker Posted December 15, 2011 Share Posted December 15, 2011 Aren't the GSXR carbs just CV ones with a 'flat' slide? Quote Link to comment Share on other sites More sharing options...
phatt20 Posted December 15, 2011 Share Posted December 15, 2011 flatslides are usually a pumper carb, ie; have an accelerator pump and the slide works via the throttle linkage instead of the engine vacuum dictating the rate of slide-opening. flatslides are awesome but are a little more complicated to tune. what do the carbs say on them are they mikuni or keihin? Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 15, 2011 Author Share Posted December 15, 2011 there mikuni's Quote Link to comment Share on other sites More sharing options...
Jase Posted December 15, 2011 Share Posted December 15, 2011 flatslides are usually a pumper carb, ie; have an accelerator pump and the slide works via the throttle linkage instead of the engine vacuum dictating the rate of slide-opening.flatslides are awesome but are a little more complicated to tune. what do the carbs say on them are they mikuni or keihin? not too sure on that but all the flatslides i have mikuni's and tm's are venturi activated, ie there is no pump as such the slide opening and needle lifting away from the jet allows the fuel to be sucked into the intake charge. If one of your plugs were wet but not all check that the fuel stop plunger that clips too the floats hasn't slipped off the float bracket as that will make it flood that cyclinder Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 16, 2011 Author Share Posted December 16, 2011 flatslides are usually a pumper carb, ie; have an accelerator pump and the slide works via the throttle linkage instead of the engine vacuum dictating the rate of slide-opening.flatslides are awesome but are a little more complicated to tune. what do the carbs say on them are they mikuni or keihin? not too sure on that but all the flatslides i have mikuni's and tm's are venturi activated, ie there is no pump as such the slide opening and needle lifting away from the jet allows the fuel to be sucked into the intake charge. If one of your plugs were wet but not all check that the fuel stop plunger that clips too the floats hasn't slipped off the float bracket as that will make it flood that cyclinder what do mean by having no pump? Quote Link to comment Share on other sites More sharing options...
phatt20 Posted December 16, 2011 Share Posted December 16, 2011 flatslides are usually a pumper carb, ie; have an accelerator pump and the slide works via the throttle linkage instead of the engine vacuum dictating the rate of slide-opening.flatslides are awesome but are a little more complicated to tune. what do the carbs say on them are they mikuni or keihin? not too sure on that but all the flatslides i have mikuni's and tm's are venturi activated, ie there is no pump as such the slide opening and needle lifting away from the jet allows the fuel to be sucked into the intake charge. If one of your plugs were wet but not all check that the fuel stop plunger that clips too the floats hasn't slipped off the float bracket as that will make it flood that cyclinder what do mean by having no pump? basicly, if ithe carbs have a butterfly AND a 'flatslide' then they are a cv type carb, if they have a flatslide that is mechanically operated and an accellerator pump , and no butterfly, they are whats refferred to as a 'flatslide carb' . im guessing your carbs are the factory cvtype mikunis. i apologise in advance for the drunken spelling. etc. Quote Link to comment Share on other sites More sharing options...
phatt20 Posted December 16, 2011 Share Posted December 16, 2011 also, what type of fuel pump are you using? some/ alot of bike carbs are pretty sensitive on fuel pressure. every bike carb conversion i do i try to fit the matching bike fuel pump, or at least one from a bike with the same type of carbs/displacement/cylinders. Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 17, 2011 Author Share Posted December 17, 2011 it fired up yesterday had 2 block 2 small holes at front of each carb and it run mint expect 4 that a pick up or the oil pump is hitting on sump and making a hell of a noise. Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted December 18, 2011 Share Posted December 18, 2011 those are your air idle jets and can be tuned by redrilling etc it is also wise to get the carbs balanced this will effect your low and midrange drivabillity hugely (this means having your butterlys tuned so they opperate in symmetry) to simplyfy flatslide vs cv cv- you stomp foot and a butterfly opens and the slide is vacuum controlled for smoother acceleration flat slide- you stop foot and the slide opens in relation to your foot (tricky to tune and drive but make me weep with joy) 1.5 on gsx11 carbs is a good starting point but id say you will be looking for somthing around 1.65-1.75 on a stock pinto retep your carbs 26% more dope and create a lower vacuum over the main jet orifice requiring a larger jet for same engine Quote Link to comment Share on other sites More sharing options...
7ESKY9 Posted December 18, 2011 Author Share Posted December 18, 2011 those are your air idle jets and can be tuned by redrilling etcit is also wise to get the carbs balanced this will effect your low and midrange drivabillity hugely (this means having your butterlys tuned so they opperate in symmetry) to simplyfy flatslide vs cv cv- you stomp foot and a butterfly opens and the slide is vacuum controlled for smoother acceleration flat slide- you stop foot and the slide opens in relation to your foot (tricky to tune and drive but make me weep with joy) 1.5 on gsx11 carbs is a good starting point but id say you will be looking for somthing around 1.65-1.75 on a stock pinto retep your carbs 26% more dope and create a lower vacuum over the main jet orifice requiring a larger jet for same engine thanks man that explains alot but why would the motor run better when those holes are blocked off? Quote Link to comment Share on other sites More sharing options...
bubblegoose Posted December 19, 2011 Share Posted December 19, 2011 those jets tune the idle air/fuel mixture/emulsification/etc just roll blocked off its pretty common also your carbs would like to be fed 2-3psi fuel pressure, if it sits and idles then starts smogging up and cutting out its too high Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.