Hi after some advice. i am nearing the end of building CRK Cafe racer Kit (lots of posts under builds section) Have rebuilt carbs, new needles all jets etc. carbs balanced New Hall sensor, plugs, leads coils Am running in the garage as not yet ready for the road have small remote fuel reservoir set up with a litre of fuel. Engine ticks over fine all lights and electrics working. Have checked voltages to coils all ok So far so good When the throttle is opened any more than slight twist the engine stutters nearly dies and then revs high, the rev counter will intermittently drop to zero after hitting 8-9 k then bounce back up, have checked all earths Also the temp gauge has been replaced by a temp warning light (existing temp sensor replaced with one supplied kit ) although the temp sender operates the warning light before the fan temp sensor kicks in. Am really struggling now as running out of ideas. Have checked the float levels seem ok although the Haynes manual suggests setting level at rear of the float and read others that say the seam on float should be parallel with the face of float bowl. Any help or suggestions would be appreciated.
Probably totally stupid but are the coils deff ok?? If the rev counter drops and goes up again I know the feed comes from plug 1 so may be a culprit. Sorry if I am a fuckwit,lol, Not a mechanic,just trying to give ideas
many thanks i thought maybe that as bike was 25 years old replaced coils HT leads hall sensor all with brand new checked low tension side with multimetrr all good
Crank position sensor can cause problems, although it usually manifests itself by cutting out the engine when it is hot and going back to normal when it has cooled down for a while. I would also check the carb-inlet rubbers for leakage. Blow some 'Easystart' over each inlet with the engine ticking over - if the revs rise then you have a leak on that inlet. Allegedly, blowing WD40 over the inlet(s) has the same effect. This may be true. Or not! You could also try richening the mixture slightly by using the choke lever to see if that makes things better. Again, it would point to a week mixture. Could be some muck in the carbs, even if they have been cleaned. (Redex or similar could be your friend in this case.) I guess you already have done so, but make sure all electrical connections are clean and sound, and disconnect whatever you don't need to connect up to run the engine. Just use the basic ignition system in case anything else is interfering with it and causing intermittent shorting out/voltage loss etc. Just remembered an old trick from way back when .... if there is no air filter present, start the engine and then wap the throttle open and closed a bit sharpish, with your other hand covering the air intake to each carb one at a time. Allegedly this causes much suction through the carb jets and dislodges any debris that may be lurking therein. Just a few ideas from Chateau Goolie Productions Ltd. (Usually total bollox, but hey, what the hell!!)
many thanks for replies carb inlet eubbwrs brand new so are all jets in carbs including float levels, one rhing ibam going to check tomorrow is cam timing as fitted new tensioner have read in Haynes manual rhT ypu Re sipposed to wedge tensiner blade while doing this as inlet cam may jump a tooth i did not do this so worth a check i had a car once rhat thw cM chain syretched jumped two teeth and still ran but dowm on power i am runnong out of stuff to check !!
Boothy when you changed the jets was it like for like or did you up size cos of the pod filters? ..just a thought
pilot jets brand new as are the needles set at mid position tried at other positions air jets set at 2.5 turns out from full closed
I bought a jet kit from sigma6 for mine it included mains 125 /pilots 45 if I,m right pilots deal with mid range.. On another note you can get carb cleaner aerosol that you can spray into carbs when running,that might clean out anything you've missed
Just had a thought,if your running off a remote fuel tank have you blocked off the vacuum pipe that should go to the back of the tap?
no not even sure where that is on the carbs there are two fuel inlets which i have put a t piece on and fuel is supplied to there from fuel resevoir and there are to air vent pipes at top of carbs which used to feed into air box and are now open i assume these are just breathersfor float bowls
Here pic of vacuum take offs, two are covered with rubber boot one isn`t this goes to your tanktap, if running remote tank then the one without needs to be covered aswell. For experiment just cover hole with your finger, should give enough of a seal to test it
if/when you take the carbs off check those needle clips if one of them has dislodged it will run like a pig mid range,I had that before on a gsxr and it took days to spot it
I was always led to believe hesitation then revs shooting up as you release the throttle are usually an indicator of lean running.... But if the rev counter is playing up too then I'd replace one by one the things you changed before ie. Sensor leads coils etc.
Always a good way if you have changed stuff and got problems is to change everything you have done back to standard and check see if it runs ok. It might be lean with pods on but at least should run pretty clean. Then change main jets see if that causes problem, then pilots etc to see at which point problems start, just a suggestion, I have taken mine off dozens on times doesn`t bother me,rather be outside tinkering with bike than alot of people sitting inside watching crap on TV, that is unless it`s Six Nations Rugby then everything stops for that
thanks for all your advice was cam timing out by a rooth must have been when swapped tension spring didnt follow manual properly !! Still running bit fluffy although just soundsand"feels better still some fueling bits to iron out although think will get on rolling road have it sorted
