CBR helping my headache

[e-a-m-o-n]

Hi guys, Brought myself a CBR 600 F4 about two weeks ago, and its been running sweet untill tonight when she dropped two cylinders suddenly while riding. Stood by the side of the road looking like a sad sack for about 10mins while i waited for the headers to cool down, started her back up to find that #2 and #3 headers stayed dead cold..

Now normally i would think that one of the coils was playing up, but seeing as this bike has a direct ignition coil for each plug, loosing two at the same time seems kinda unlikely..

Should mention that three days ago I installed a manual APE cam chain lifter, and checked the valve clearances while i was in there (clearances all within spec) but i cant think how i could have stuffed any thing up to cause this problem. The bike has been running fine for the last 3 days after these changes.

Carbs were cleaned out about a week ago.

New plugs last week.

Could be a ECU problem? Anyone know how to diagnose a faulty ECU?



Any ASAP advice would be awesome as im suppose to be doing a tour on friday!

Cheers, E

[spanner spinner]

Check the input voltage to the coil packs, you realy need a peak voltage meter to test this but to prove that the coils are getting voltage put your multi meter on AC range and look for 5 to 6 volts. The coil packs do fail if there is voltage to 2 and 3 swap the coil packs to see if the problem migrates to 1 and 4. See this link for a wiring diagram http://imageshack.us/f/135/cbrf4wiringdiagramfn5.jpg/. All the coils have there own feed so i would not suspect the ingition unit, more likely is a fuel problem. The fuel pump on these bikes is a known problem and can cause strange running issues when they part fail. Pull the feed to the carbs off the fuel pump and fit a temporary feed, the temp tank needs to be set quite high as the carbs are high up under the tank. If it still running on two after checking the coils and fuel feed time to pull the carbs out again. If the APE cam chain lifter was playing up the noise and the fact that all 4 cylinders would not go would point to this, you can count this out.