Carb issues

yellowstorm · Post by **yellowstorm** » Wed Jul 16, 2008 10:16 pm

I've trawled through many of the threads, but haven't found the answer yet.

I'm new to VTR's and the P reg (1997) one i've just bought has carb issues (carburettor - not the things you find in pasta!!!)

At a constant speed (30-40 mph, between 2500 and 4500 revs) the bike is very 'jerky' and occasionaly backfires. It accelerates perfectly and pulls fine at higher revs. It also idles perfectly.

The bike had been standing for 2 years prior to my purchase, so I stripped the carbs expecting to find a jellied mess of fuel in the float bowls, but they were clean as a whistle. All jets clear, diaphragms and floats all ok and needles on standard settings.

The previous owner removed the race cans and put the originals back on. The bike is running a K&N filter and only has around 13000 miles on the clock.

A suggestion is that the K&N may be sucking in too much air for the standard pipes and thus the bike is running lean.

I am yet to try balancing the carbs as the blanking plugs seem to be a bugger to get to without alot of tank/airbox removals and re-assembling. Any suggestions for easy balancing?

Could it be something that simple??

I have a CD copy of the workshop manual and the good ol' Haynes manual and it seems that Honda changed the carbs after 1997, so is this just a problem I have to put up with? If so I will have an exceptionally clean 1997 Firestorm for sale.

One shop did recommend a stage 1 Dynojet kit, which they also claim will improve fuel consumption. Is it really worth it for a stock bike? I would welcome better fuel consumption though if this claim is true!

Many thanks in advance

yorkylancs · Post by **yorkylancs** » Wed Jul 16, 2008 10:31 pm

Best bet for balancing the carbs is to cut the vacuum pipe,and fit a T piece,then you do not have to bother trying to get at the rear take off point.Just connect your gauge pipe to the T.Dont forget to blank it off when not in use.Failing that just disconnect the vacuum tube from the fuel tap end,and connect the gauge pipe to that,you will have to be quick with adjustment though,as it soon runs out of fuel,make sure you have a screwdriver that fits the throttle adjuster,as it is quite awkward.The front take off is just a matter of perseverance,difficult if you have sausage fingers!But do-able.

lee67 · Post by **lee67** » Wed Jul 16, 2008 10:38 pm

junk the k&n and problem sorted i garuntee...there shite

RedStormV · Post by **RedStormV** » Thu Jul 17, 2008 1:35 am

Tut

Bet their sales figures disagree with you there Lee - I guarantee it

Stage 1 Dynojet kit

K&N Filter

Microns Race cans

No issues - Recommend it

Post by **kevg** » Thu Jul 17, 2008 8:26 am

i had a dyno kit, K&N and blue flame cans, and had the exact same problem you are describing, makes it interesting to try and tour around town and manouver round mini roundabouts when the bike is trying to stall all the time, i had it set up on a dyno, the fueling was spot on but the problem still wouldn't go away.

i took Lee's advice and changed back to the origional filter and the bike runs fine now, i'll get it down to roger one of these days and let him set it up the way it should be with a K&N, must be some black magic he uses to make it go properly that others don't know.

Pete.L · Post by **Pete.L** » Thu Jul 17, 2008 8:48 am

A o.6mm thick washer placed under the main needle normally sorts out the effects of a K&N filter on a std Storm but yours sounds a little different from the std complaint.
If its surging and on steady throttle and popping on the overrun I would suggest you check all your exhaust joints for leaks first. Pay special attention to the one by the rear header pipe. It can blow out and ruin your fueling. Once you are sure all the joints are fine then I'd start messing with the carb settings and don't forget to rebalance them after every adjustment.

Pete.l

Beamish · Post by **Beamish** » Thu Jul 17, 2008 11:29 am

With BMC race filter and scorpion race cans mine had a big flat spot at around 3K and it could misfire occasionally but bought some custom race cans and it ran superbly. Swap the filter back to standard or get it set up proffesionally (also explain to them current problem), your issue does not sound like carb balance problem more of a fuelling prob IMO

lee67 · Post by **lee67** » Thu Jul 17, 2008 1:01 pm

my storm, ex john's off here..was set up right according to the dyno place...stage 1 dyno jet..k&n set up to pipes...never felt right, as soon as i junked the k&n..smooth running and i aint the only one...sales figures mean jack sh1t graeme...people buy em cos they think its makes there bikes go faster, load of ballcocks!!..

yellowstorm · Post by **yellowstorm** » Thu Jul 17, 2008 2:40 pm

Some useful tips here Thank you all.
I braved the carb balancing. Spent 10 mins swearin and battling with the forward cylinder blanking screw trying to get it out. Even took the tank and airbox off to gain marginally better access. Realised I was turning it the wrong way and tightening it!!! Doh!!
Past that bit it was pretty straight forward. Scalded my hands on the thermostat housing trying to adjust the screw.
Carbs were out of balance, so now fully balanced. I took her out on 20 mile test run whith high hopes. NO CHANGE!!!
Cheapest option is standard air filter i think. At only Â£17 (if you know of any cheper, please lent me know, ta) on ebay, can't go far wrong.
Local dealer does dyno runs for Â£35 so that may be the next option.
Thanks again for everyone's help, I'm new to this forum and I've been made to feel very welcome.
Cheers

RedStormV · Post by **RedStormV** » Thu Jul 17, 2008 4:47 pm

Yeah Yeah Whatever Lee

Like I said - No issues here.

However, as some of you know, the Storm was my bruv's before me, bought it new in '98.
Now I don't know if it was an official re-call or not (tried finding info on Google and drawn blank so far), but very early on, it cut out on him at low speed, low revs while manoeuvring. He ended up dropping it and scratching fairing and zorst if I remember correctly.

After taking it back to shop, he ended up getting all the repair / replacement work done under warranty. I'm 100% sure he said it was a recall and it's highly unlikely that a shop would do work for nought if it weren't. Trouble is I can't remember what was changed or modified at the time to rectify the problem and he's no longer here to ask!

(5 years today bro! I ain't forgot ya).

Anyone know of this recall? as this may have something to do with the above prob.

Anyways, in process of looking, found another recall - going to post separately.

Graeme.

*

yellowstorm · Post by **yellowstorm** » Thu Jul 17, 2008 5:48 pm

Looking at the replies, it seems to me that K&N filters should only be used with free-flowing race exhausts.

The people who don't have issues with the filters all seem to have race cans.

As I said, when I bought mine the seller replaced the race cans with the original ones. So the bike is running with standard exhausts.

I don't know if these problems point to the bike running lean as if I ride it on the choke, the problems aren't so obvious.

RedStormV · Post by **RedStormV** » Thu Jul 17, 2008 6:02 pm

Cheers Tim,

Should really have taken day off - cos me mind's been elsewhere most of it!

Bloody 2 leap years between, so twas same damn day 5 years ago too

Went to local charity bike show (Howarth) last night with fellow bike and bigs mate of me bruv's from schooldays - lots of lovely bikes there right up to LC350! A few FS1E's too - were reminicing about mate, Neil's purple one (that don't quite sound right!) - and me bro's maroon / red one - good laugh.

Will have a dram or two for him later - got to go watch junior in Orchestra first for an hour or 2 - but that will be nice.

*

Anyhoo, just got off phone with service manager a local Honda dealership who's been there since '78. Very nice and well knowledgeable bloke!
He sort of confirmed what I suspected....

Although there wasn't an 'official recall', some of the early Storms did suffer from coughs, splutters and occaisional cut outs at low speed /revs.

These were down to carburation and / or ECU issues, which were dealt with under warranty in most cases as a 'Product Update' rather than a recall [edit].
'tech briefings' were issued from Honda stating "if X is complained about on Y model or year, solution is Z"

So it's entirely possible, infact very likely, that there's lots os Storms out there that have never been taken in nd not had these issues addressed.

Also likely that there are some that have, but for various reasons, have had carbs or ECU's replaced with 'disimilar' items over the last 11 years.

Whether it would be possible to get these addressed now I wouldn't like to say. Perhaps your local Honda dealer would check back and compare old tech docs with your serial numbers or part markings for you, who knows?

Worth a try I suppose.

Mr_Rusty · Post by **Mr_Rusty** » Thu Jul 17, 2008 7:12 pm

On a similar note my one is doing much the same but I have a Pipercross filter with ART Pro cans with baffle removed and supposedly a Stage1 kit in however...

The previous owner gave the the Dynojet box with bits in, but no fitting instructions and i have a feeling it may not have been done correctly as the new needles are still in the box unopened. Should they have been fitted?

Does anyone have the fitting instructins for the UK kit as the instructions off the US site are for their models (obviously

)

Also is the tool DT009 referred to in the US instructions suppled or needed for the UK kit if so what on earth dies it look like?

Cheers

Chris

yellowstorm · Post by **yellowstorm** » Thu Jul 17, 2008 8:47 pm

Just to throw another quetion into the mix.

Mine is an import. The original clocks were kmh but were changed to mph ones in about 2000. The logbook (V5) indicates that it was imported. Although it was sold as new in the UK in 1997

Don't know which country it was from. I know that there were alot of Belgian imports kicking around at that time, so maybe that could be it.

Whether that could effect the carburation (possibly set up for a diffent climate or emission laws etc) i'm not sure. However, I doub't that anyone would have put up with this problem for 11 years.

Could explain why it may have missed any Honda recalls though.

Pete.L · Post by **Pete.L** » Fri Jul 18, 2008 9:18 am

Mr Rusty Said

The previous owner gave the the Dynojet box with bits in, but no fitting instructions and i have a feeling it may not have been done correctly as the new needles are still in the box unopened. Should they have been fitted?

Personally I don't like the Dyno jet needles. They can cause excessive wear in the emusion tube and then completely muck up the fueling. If you can get the right mix using the original Honda needles your bike will run much better and last longer in my opinion. A small shim/washer under the needle will richen the mixture and and counter act the effects of a high flow filter on std pipes. ( See earlier post for size)

Pete.l