Carbs - Condensation in D9 carbs?

[jeepster1]

Had to go to essex from bristol and back on saturday, trouble is I had a small missfire a couple of times. I was about 50miles down the M4 when after rolling off the throttle I started to roll back on and got a miss on one cylinder for a few seconds. Then again about 10miles further on when starting up at the services after a break.

I'm not too concerned as the bike did the rest of the trip without a hitch but i'm wondering if the cause would be a buildup of water in the carbs? she does spend alot of time sitting in the garden shed, which tends to get alot of condensation in it and on the bike, however I've never had this before in the 2 years i've owned it.

[werner1]

Could also be carb-icing . But the 900 normally has carbheating .

You an easaly drain the carbs in a glass bottle/jug, leave it for a few hours (the glass)
and then see of there's water at the bottom .

[General Gman]

well.... I would imagine that fuel contamination would have caused more probs.
I'd be more inclined to check the electrics - always worth looking at the HT side of the ignition system - could be a dodgy plug cap, lead, plug... anything.

[jeepster1]

Thanks guys, it doesn't look like it's a common problem with D9s then.

So i'm gonna drain then pull the carbs and have em apart for a clean. and as i'm in there i'll go through the ignition side, The girl is nearly 10 years old now and it can't hurt.

Both have an exhalt for replying.

Cheers, i'll let you know what I find.

[Fiasco]

Sounds like classic carb icing to me.

Not sure about the carb heater but my first 900 used to do it, especially on motorways, just as you describe.

Was it a cool damp day ?

I would try it on warmer days before throwing time or money at it. Also try some Redex in your fuel. There is also an additive by Silkolene that can apparently help - oh and treat it to some Optimax.

HTH

Dave ;D

[General Gman]

I sort of discounted carb icing because he said it happened when starting up from a break - I've never had carb icing probs that caused problems at start up.
Of course, 50 miles down the M4 from Bristol is into the heart of 'wrong turn' country, so it might have been a trap set by the yokels to capture and devour you.....and use your head for playing Aunt Sally. ;D

[jeepster1]

I don't think it was carb icing, however i havn't checked the heaters are working. But what I did find was the some of the HT leads had some corrosion at either end, so i've cliped them back about 1/2 inch and refitted them, The fappin little clips that hold the leads into the coils are a waste of time. I managed to save some of them but I've cable tied the leads tightly to the coils, just hope that works!

The carbs were alot cleaner than I expected. only the tinyest little but of crud at the bottom, but I did find a hair in no2.

Anyway, all back together now, she seems to be running great but the only way to tell is to take it for a run i guess ;D any excuse.

I got a load of photos so i'm thinking of doing a article in a day or two, what do you guys think?

50 miles down the M4 from Bristol is into the heart of 'wrong turn' country, so it might have been a trap set by the yokels

;D ;D ;D nice one Gurninman!

Was it a cool damp day ?

I would try it on warmer days before throwing time or money at it. Also try some Redex in your fuel. There is also an additive by Silkolene that can apparently help - oh and treat it to some Optimax.

It was a cool damp day funnily enough, Redex a good idea but now i've seen inside the carbs i'm sure there's no need. Whats the deal with the optimax stuff then?

Generally I don't bother putting 100ron fuel in because the Divvy has a fixed ignition map so cannot alter the timing to take advantage of the extra octane.

[teejayexc]

but I did find a hair in no2


Cue Derefood! ;D

Trev

[cam7777]

My 900 used to exibit the same symptoms as you describe when the temp was 5 degrees C or colder - mine was down to carb icing.
[1998 XJ900S]

HTH

[chunk166]

my d9 suffers carb icing, worst times it happens is after riding at a constant 70 mph then stopping for a roundabout it tries to die then, but i have found that if i pull the clutch in about 100-150 yrds and let it roll to the roundabout its not too bad.

ray

[CD]

jeepster1 said:

Generally I don't bother putting 100ron fuel in because the Divvy has a fixed ignition map so cannot alter the timing to take advantage of the extra octane.

I think Optimax etc is 97RON instead of 95RON so not that much different.
But a thought...
Can the ignition map be changed and is the D600 or D900 set retarded as standard to cope with poor fuels. It would be nice to know if its possible to move the spark timing. And is it worth the effort.

[Fiasco]

jeepster1 said:

It was a cool damp day funnily enough, Redex a good idea but now i've seen inside the carbs i'm sure there's no need. Whats the deal with the optimax stuff then?

Don't ask me to get technical, it just worked for me ;D

Regards

Dave ;D

Ps If you are going to use Redex, make sure you clean up any spill so us city slickers don't become country slippers - ta

[teejayexc]

.........country slippers.......


Are these different to Fazer slippers?

Trev

[jeepster1]

Can the ignition map be changed and is the D600 or D900 set retarded as standard to cope with poor fuels. It would be nice to know if its possible to move the spark timing. And is it worth the effort.

It would be possible but i'd imagine the only way to do it on a divvi would be to move the crank position sensor, trouble is if you do that then go somewere that higher octane fuels are unavailable you'll end up putting holes in pistons ect, or have to return the sensor to it's original position.

Modern systems that can cope with different ocatane fuels have a knock sensor. it allows a self learning ignitor unit/ecu to alway try and advance the ignition as far as possible until detonation is detected by the knock sensor.

A friend of mine is going to fuel inject his FZR1000exup with megasquirt, it's basicly a very advanced homebuilt kit ecu which will handle ignition and fuelling, with a full set of sensors it will set it own maps and adapt them as the engine wares and fuels change ect, it's a brilliant bit of kit. I would prefer to simplify things and do a single carb conversion on my D9, but not while it runs fine

[General Gman]

you can make your ignition slightly adjustable by elongating the mounting holes on the ignition pick up plate - that way you can advance / reatard the ignition according to the type of fuels you're likely to be using.
Wouldn't advise more than 5 degrees, though or summat's gonna go pop.

[CD]

Surprised there's room for a rabbit in there never mind a flippin great hare

jeepster1 said:

The carbs were alot cleaner than I expected. only the tinyest little but of crud at the bottom, but I did find a hair in no2.

[CD]

Back in the 70's, a guy called Dave Vizard wrote a tuning book on the BL A Series when tuned BL minis were all the rage. His "fast road" engines made as much power with a single SU carb as they did with twin carbs. Only full race benefitted from twin SUs or split webers. For those not familiar with BL A, B & C Series engines, 4 carbs/chokes were no benefit as the inlet ports siamesed in the cyl head. He was getting 120bhp from a 1275 mini engine with fast roads cams. Fully tricked up racers made 140, but not for long. Much the same state of tune as a Diversion.

I believe electronic injection systems on bikes need the throttle/fuel stepper motors to move in really fine steps at low openings or the power take-up will snatch (a la BMW boxer 1150).

I'd love to make a fully tricked up 2 stroke diesel bike with modern electronic engine management just to prove one of those could be seriously quick. Shame I don't have about 2 years worth of time & a small mortgage for tools & equipment.