Slowly lost a cylinder... but only at revs

[Lucky13]

Hey all

Serviced the bike over the weekend (fresh oil & filter, cleaned the K&N air filter also). The bike was also nearly running on fumes to drain the tank Friday night in prepr for a service, but she's got a fresh tank of BP now. I drained the carbs in case of crap from the tank getting in as it ran low (some bikes tanks do that).

Anyhoo. I rode into work this morning (15 miles), bikes running perfectly. Best she's been since I bought her actually. gentle ride all the way in, 30's & 40's mainly.

Riding home, I cracked the throttle on a long straight and she didn't rev up all the way - revs strangled around 7k. From there, she then developed a very slight misfire then started sputtering into the airbox and developing an occasional knocking sound under the tank. Popping massively on the overrun as one cylinder wasn't combusting well.

(In my head there's pictures of CCT's failing, valves meeting pistons, etc)

Anyway, the bike ran ok-ish around 3k revs, idling fine at the lights, but misfired dreadfully above or below 3k (so enough to limp home and coast on the clutch).

Now the bike idles, but any revs/load means she drops a cylinder. The engine was too hot to tell which one tonight, and when idling they both fire so can't tell easily.

I noticed the oil's a little over the level (although I used less than the manual states she'd need). I wonder if that's a cause. Could oil have just blown past the rings and fouled plugs if she's just over the limit? Alternatively it's all a coincidence and a plug is just shot perhaps.

I'll order up replacement plugs, and the right plug wrench as the tool in the kit's not the original/doesn't reach the plug (off to david silver spares).

Other than a faulty plug, has anyone got any ideas? I'm pretty good with inline 4's (rebuilt 2 engines), but this is my first storm so I've not done work on her before, and can't instantly pin down why she's sick.

[cupasoop]

Check if you've put the vacuum hose on the correct bit of the fuel tap under the tank (if you had the tank off). It should go on the horizontal connection, not the vertical one.

[Lucky13]

Didn't remove the tank completely. Have pulled the tank to check for pinched hoses though and could find any

Seems David Silver don't sell the spark plug tool either. Not my night really is it!

[RedStormV]

Eyup mate,

Make your own!

Check out this thread :

Plug Wrench Clicky

Alternatively look on e-blag, there are lots of bikes with similar 'identical' spark plug wrenchs in their tool kits.

Hornet 600 & 900
GSXR 600 SRAD (prolly 750 & K too)

I know cos we got both and plug spanners are same.

HTH

Graeme.

[sirch345]

I would have also thought that it could possibly be a spark plug breaking down now we know it's not the vacuum hose wrongly connected Definitely worth checking that out first.

Chris.

[Lucky13]

Ok, new Plug tool ordered from the dealers. Look's like I'll start tearing things down on the weekend.

order of checks planned

1. pull plugs and see what's goin on (could be failed, or oil fouled)
2. If not that, fit carbtune and check sync and pressure
3. If not that, dig deeper and pull the CCT's (could be timing's slipped)
4. If those don't do it, kick it and swear at it


Always funny working on a new type of engine for the first time. You know how they work, but the layout and workings seem alien. Gimme a 4 cylinder and they automatically feel like home

[sirch345]

Lucky13,

As in your list No3, don't remove the CCT's without setting the valve timing in the correct position first

Anyway just to check the valve timing you won't need to remove the CCT's to do that. IMHO I wouldn't have thought the valve timing had slipped if you haven't removed the CCT's for any reason, other than a spring breaking in one of them, in which case you will be experiencing new noises from the engine that you'll definitely be aware off

Chris.

[Lucky13]

Cheers for the heads up there mate.

I think if I get to valve timing and CCT's I'm going to be clutching at straws.

Dealer's just got the plug spanner I ordered up to add to the kit, so hopefully today i'll pull the plugs and find a duff one.

[Lucky13]

Checked the plugs and found one was heavily carbonised (strange as the other one's perfect, suggesting the front cylinder suddenly went extremely ric).

So I popped the airbox lid off to check things out in there, and noticed something was a-miss. One of the two rubberised covers that live inside the airbox, covering the foam filters, had shaken off and landed in the intake trumpet for the front carb. Effectively almost blocking it - which explains why it would tick over, but lose the cylinder when revving up.

To prevent it I've taped both rubber covers down now! Pesky things.

[Pete.L]

I stuck mine down will some silicone sealant.
The petrol fumes will probably brake down the gum on the tape and you could get the same problem again or even have the tape come off and jam up the carbs.
Once you are happy (and it sounds like you have) you've sorted the problem, I'd recommend making a more permanent fixing of the rubbers.

Pete.l

[Lucky13]

Cheers buddy.

Gotta go back in there to replace the rotten filters the covers were hiding so I'll do that. Was thinking of trying the airbox mod where you effectively remove the top too.

[Collywog19]

Did you get this sorted?

Ive got this problem now.

Thanks

Colin

[Pete.L]

Yes he's sorted Colin (See the post just above my last one )

So what have you been upto with yours?
Was it just running fine and then just started out of the blue or have you been having a play recently?

Pete.l

[Pete.L]

opps

Just saw you other post about this.

Pete.l