Popping from Exhaust on Overrun

gippo · Post by **gippo** » Mon Aug 14, 2006 9:23 pm

Hi all

My little beauty (Orange Y2K model) has recently started to pop and backfire slightly from the exhausts on slow speed overrun. I have also noticed that she seems to be vibrating slightly more than usual. General running and fuel consumption don't appear to have changed. Does this sound like a carb balancing job is required or is it more serious?

The 16k service is due soon ....does anyone know of a half decent dealer in the Bucks (Aylesbury) area????

Thanks

G

Fireman on a Storm · Post by **Fireman on a Storm** » Mon Aug 14, 2006 10:35 pm

Have you got a set of race cons on it?

Sometinms they have a bit of a poping session if one of the joints is leaking a bit.

I think it sounds great though

rst steve · Post by **rst steve** » Tue Aug 15, 2006 8:48 am

I've got microns on mine and it pops like mad on overun sounds ace

BazF · Post by **BazF** » Tue Aug 15, 2006 10:26 am

Mine pops and bangs!

curly · Post by **curly** » Tue Aug 15, 2006 4:12 pm

Let it pop and bang!!!

You don't want it to sound like a sewing machine like an inline four!
It's a twin, vibrating and real!!

Keep it real. The louder the better.

baldzone · Post by **baldzone** » Tue Aug 15, 2006 5:06 pm

Mine sounds like s shotgun on overrun at times! Love it!

gippo · Post by **gippo** » Tue Aug 15, 2006 10:05 pm

No worries then...!!!!!

Anyone any ideas as to what the going rate is for the 16K service......

LLoyd Cooper (Watford) have quoted me Â£350 plus extas as required (valve shims etc)

....should I sell the family silver now or has anyone out there any better suggestions???

Cheers for the response

Gip

richard · Post by **richard** » Wed Aug 16, 2006 9:18 pm

perhaps its just me !

given all responses im the one with the different story,

my storm has a poor quality rubber pipe fitted to the carbalancer port on the front cylinder.. which from time to time splits due to heat etc...

when the pipe is ok the bike is smooth...as in less vibbey...and there is no popping on overrun ( engine braking )

if pipe splits then i know because the bike is alot more vibbey and it pops through the exhaust...

i prefer it to be smooth without the pops !...so i cut tube down a bit and shove it back on and the bike is smooth again..

when it pops = air is getting sucked into the system and allowing unburnt fuel to ignite in the exhaust system and create the sound...providing your headers are in good nick then you will probably be ok...but you need to be satisfied that the air leak is not leaning the mixture out ( ie between carb and engine - so if leak in exhaust then you should be ok )

cheers
rs

gippo · Post by **gippo** » Thu Aug 17, 2006 8:16 am

Hi Richard

What you are saying seems to make sense...!!!

It only seems to have started since I fitted new CCTs over the winter.
So perhaps I may have disturbed something when moving the tank and the airbox etc.

It is getting worse though...which ties in with your suggestion of the split or poorly fitting pipe.

The pipe you mention...could you describe where it comes from and goes to...and what dia it is... so that I can identify it more easily.(Excuse my ignorance!!!!) The lack of familarity with the mechanical bits proves how good this bike has been!!!

Just for the record I still have the standard cans fitted...

Cheers

G

lavula · Post by **lavula** » Thu Aug 17, 2006 11:27 am

Wotcha, I live in Aylesbury and use Dave Wood Racing off the A41 near the big tescos. They sold me my VTR and have been nothing but helpful and reasonably priced.
http://www.davewoodracing.com/

lavula · Post by **lavula** » Thu Aug 17, 2006 1:16 pm

Hi Kaz, been reading the forum here for ages and have only just got round to becoming a member. Just got back from Durham this weekend (Mum lives in there), fantastic blast there and back.
As an addition to the above, I've been advised that Mick Surman motorbikes in Aylesbury will charge you for stuff you don't need if they think they can get away with it. I've no experience of this but just a friendly warning.

lavula · Post by **lavula** » Thu Aug 17, 2006 1:47 pm

Mum lives in Gilesgate, about a mile from centre on the Sherbourne crossroads (near the DLI pub). Found some great roads up there (and the odd great pub too!). Everyone's really friendly and people actually talk to you in pubs!!!

lavula · Post by **lavula** » Thu Aug 17, 2006 2:12 pm

I have cousins that go there, small world eh?
I'll be going back up within the month and will give you a shout.

richard · Post by **richard** » Thu Aug 17, 2006 10:13 pm

gippo,

the pipe i described is my own fitment ( to aid carb balancing ) with a golf tee stuck in the end !!...

roughly speaking leaks above engine are usually rubbers between bot of carbs and engine intake or take-offs for carb balancer on front cylinder - some bikes have a bolt screwed in to cap it off, some ( mine ) have an adaptor if they've been balanced before and this is where the cheap pipe is on mine - look down idle speed adjustment side of engine - and below where adjuster is - you should see a bolt head etc screwed below where 'big' rubber connector between carb bot. and engine instake.

on rear cylinder this take off is used to create vacuum for fuel tap on underside of tank - follow it from tank to carb base and you'll see what i mean...if any of this makes sense

other leaks are from exhaust pipework or - if it where a car - the valves not closing / burnt out !..

it really is a matter of just looking where air could get into the engine or exhaust system without going through a carb...

cheers
rs