[xotoby]

sup "peepz"

having a bit of an annoying issue of my 91 cbr250RR running on 3 cylinders.

originally was an issue of it not starting, and mechanic found that ignition switch/wiring was burnt out. +replaced it.

bike now starts.. but it looks as if he's forgotten to plug something back in, because my dash doesn't light up, and my neutral and sidestand lights don't light back up either.

HOWEVER, the guy also did a service on the bike, pulled carbs apart, cleaned them etc.
after this the bike was running on 3 cylinders.
he did a 'compression test' thing on the cylinders and found that one had less than normal compression (i believe).
he simply suggested to buy a new cdi and left it at that.

can tell by spraying water on the headerpipes, 1 has no heat.
checked the plug for that cylinder, looked fine, tested the lead with a screwdriver to make sure power is getting to it. it is.
swapped the coils. no change.

my question now is, what should I check NEXT.
(it would be good if I could fix this easily and not have this mechanics worthless hands on my bike again).

ps. I just read this from an old post of someone else having a cylinder not firing.

"do you have the speedo/dash hooked up?

If you haven't, you'll be chasing that miss for ever." -- Studricho.

my dash doesnt light up? is that related? anyway.

any help would be appreciated.

 

[xotoby]

RE: running on 3 Cylinders

yeh. from 4k up to 20k it would seem, rumbly grumbly and weak.

none of the fuses are blown.

would nulon carby cleaner work the same as this 'start ya bastard' stuff.
else i'll have to buy that and give that a go,




is there some kind of link between the dash and cylinders, as per that post I quoted of you stud from a few years ago.
as something in my dash is unplugged at the moment.

 

[xotoby]

RE: running on 3 Cylinders

ah jets hey. thanks. hmm il check em tomorrow.
yeh up to 4k it seems to be smooth then suddenly shit afterwards.

mechanic pulled carbs apart and "cleaned" them though so I don't understand why it would be clogged.
however perhaps didnt put something together properly..
either way he has fucked something somewhere.


anyone have any input on this "something from the dash being unplugged can cause a cylinder not to fire" theory which i've seen suggested in a few threads around the place.

 

[xotoby]

RE: running on 3 Cylinders

wtf ????

if one cylinder has fuck all compression then there is nothing NEXT to check bikes dont work without compression

fuses, start ya bastard and all that other shit is going to do FUCK ALL

5 hours, $900 and the suggestion of trying a new CDI ???

you need to work out why you have no compression in 1 cylinder

leaking valve, blown head gasket

that's not very comforting..

can I check these things myself easily or is it for a workshop.
i dont think it was 'no' compression, i think it was 'less than normal' compression..
and um.. what could the mech have done to cause it..
coz bike was 100% power before he did his service on it

 

[xotoby]

RE: running on 3 Cylinders

where can i get a cheap pressure metere thing to check each cylinders compression?
if thats a problem it should be the first thing to be fixed right?

 

[xotoby]

RE: running on 3 Cylinders

fixed.

Running on 3 cylinders.
Cable behind dash (also responsible for the dash lighting) was unplugged.

Plugged it back in, and all 4 cylinders up and running again.

Who can explain this please, as I'm interested in knowing why a dash plug for the lighting can stop a cylinder from firing.

 

[xotoby]

haha yeah but it didnt make sense to me so i never checked it.
any idea how that causes it?