Hi all, i'm pretty new to the biking world, got myself a Honda CB400SF Superfour, bought it as crashed damaged easy fix, to cut a long story short it flew through its MOT, taxed it and it rides well, like shit of a shovel, took it out the other day and its lost power its as though its running on two cylinders but all four are firing as all down pipes are red hot, ticks over fine no spluttering or anything sounds very whiney, stripped the carbs down and cleaned them no change took the air filter out and it got worse, its had new plugs and ive put putoline in the tank, all the breather pipes are ok, the only thing i haven't done is compression test it and check the timing (only because i haven't got the kit to do it).
Does anybody have any ideas to what the problem may be, any sugestions would be greatly recieved.
Cheers Lee...

just an idea but have you stripped the fuel tap if your bike has 1 i had a bike in the past was sluggish and it turned out it was rust in the fuel tap often overlooked.

Hi yes checked that fuel runs freely, have been told its electrical, coil packs, CDI, ect, stumped big style...

I downloaded a sheet with universal checks that can be done with a multimeter 1 of the guys in here keeps referring ppl to it when theres an electrical fault if i find it ill get bk to you.

Theres a website called electrosport .com if you go to that you can download a fault finder for electrical problems was a great help to me

Cheers guys, will give this a try, my mate is coming round tomoz with the same bike so i'm gonna rip elec stuff off his and try that.....

berno2020 wrote:I downloaded a sheet with universal checks that can be done with a multimeter 1 of the guys in here keeps referring ppl to it when theres an electrical fault if i find it ill get bk to you.

That might have been me, the electrosport chart is the one, really useful if you follow the chart, its worked brilliantly for me on electrical problems with both mine and my g/f's bike, just not enough people know about it!!

it sounds to me like its a ht coil packing up(two coils Fitted under the fuel tank i think) because one coil works two cylinder so if one was faulty it would be running on two cylinders they can cut in and out when breaking down so may heat the exhaust etc to llook like its firing but not when being ridden under load. hard to tell tho if running on four cylinders normally i would then be looking at blocked jets in the carb obviously you have checked airbox etc or cdi i think it coil or cdi does the bike rev up without spluttering when you say whinny is that exhaust sound or engine sound.try some wd40 as honda are prone to water affecting the electrics, spray on the ht leads and plug caps etc