Carb iceing

[Drumnagorrach]

Not wanting to buy another injected 900 ,I am thinking of a carb version.
Whats the story with carb iceing ?
I was persuaded to go for the injected model because of the threat of carb iceing ( it can be very cold in the morning here in July ). As it happened the crappy running I experienced out of the injection model was probably more of a problem ,certainly expensive to improve .
What about kits to warm the carbs, is there something available that routs engine oil ,in pipes , around the carbs ?

[Mr Gazza]

My first Monster was a carbie 900.

It did suffer from carb icing every now and then. This happened (as the manual suggests) at times of high relative humidity...It didn't have to be all that cold.

Mine had the oil type warmers which were operated by a diverter valve, or tap, in the oil line to the cooler...People deride these as ineffective, but I found that mine worked well.

I got the first indication of icing when it cut out going down to idle at junctons, ect.

The short stop before a re-start was enough for the engine heat to rise to the carbs and thaw them. That was when I would turn the tap on the warmers and there would be no more trouble.

For what it's worth I think you have had a bad experience with your ie Monster...That's not the norm.

I find my injection M900 to be smoother, more powerful, economical, tractable and simple to operate and maintain than any of my former carburretor aspirated bikes.

Give the injector models another chance...After all you now have more knowledge than most about how to troubleshoot them.

Good luck Monster hunting....Is your's salvagable at all?

[Drumnagorrach]

Don't think so Garry, the frames snapped at the headstock and one of the fork legs is dented in .
I quite fancy a 900ss that one of the Scottish Ducati club chaps is selling, carbs been dynojetted on rollers to suite the Termis. power read out is the same as my monster.
Just have to wait to see how much I can get out of the other parties insurance.
Yes , I know that earlier injected monsters run a lot better than the 2002 year,maybe try a 2001 900SS,although i'm not in love with the styling on the later ones.

[Dirty]

Carbs rock. I think they give engines an extra bit of soul :)

[spacemonkey]

Carb icing is a definite problem. Imagien the fun of riding along a motorway then throttling off to find the engine carrys on.... or dies altogether. Not fun..

I have the carb heating kit too. Later ones had the electric kit, the same as fitted to early SV650s and TDM850s. I found the oil heaters pretty useless, btu often thought about combining the two somehow.

Didn't bother- just ran the bike with Silkolene Pro FST each fill up and problem gone. It's basically surgical spirit whcih is cheaper, which is simply Isopropol alcohol which is cheaper still... Do your research and make yer choice. Interestingly, when I layed my bike up (unknowingly) for 6 years, I had a good dose of Pro FST in the tank and there was no rust when I drained it- the petrol was quite clean and ran through my lawn mower no probs.

[Zimbo]

Pro FST is the cure, add to each tank of fuel, carb icing history.

[Ron1000]

Pro FST is the cure, add to each tank of fuel, carb icing history.

+ 1 I used to use it on my old Yam XS500.

[Darren69]

I found Pro FST helped but didn't cure it completely, In the end I got fed up and switched to injection bike, wouldn't go back.

[utopia]

I have heard that there are no icing problems if you fit Kehin FCR carbs.
Its only anecdotal though, and may not be totally accurate.
I'd be very interested to hear if anyone has any further evidence for or against this.

As a rudimentary analysis, I wonder whether this might simply be because the cable pulls directly on the throttle slide (giving better icebreaking qualities) rather than operating via a diaphragm ....?

Pro.fst is an almost, but not quite, complete cure on my 750.

[don_matese]

Just want to check I am using ProFST correctly. its ratio should be 100:1 - 50:1, for a 17 litre tank like my original one - that means it should be 170ml (roughly 1/5 of the bottle) per tank full?

[Wildfire]

Pro FST is the cure, add to each tank of fuel, carb icing history.

This. 1 litre tends to get me through a season of regular commuting. If you plan it's not an issue, but as I could never do it, I just used to stick the bottle in my Kreiga.

[Wildfire]

Just want to check I am using ProFST correctly. its ratio should be 100:1 - 50:1, for a 17 litre tank like my original one - that means it should be 170ml (roughly 1/5 of the bottle) per tank full?

If you get it wrong, it goes bang a lot and flames come out of the exhaust.:yoparty:

[Ron1000]

I put in a cap or two per tank, never gave me any issues

[jerry]

i have never had carb icing on my M750 but it has the carb heaters ,,,my 750ss has no heaters at all and has also never had carb icing ,, but even yesterday after a long run its carbs were cold and engine very hot ????

[Drumnagorrach]

I have heard that there are no icing problems if you fit Kehin FCR carbs.
Its only anecdotal though, and may not be totally accurate.
I'd be very interested to hear if anyone has any further evidence for or against this.

As a rudimentary analysis, I wonder whether this might simply be because the cable pulls directly on the throttle slide (giving better icebreaking qualities) rather than operating via a diaphragm ....?

Pro.fst is an almost, but not quite, complete cure on my 750.
I think that the problem comes from the energy used to change a liquid to a gas,Vaporizing the petrol. I have experienced carb icing on a Harley sportster ,which had a standard diaphragm carb ( the diaphragm is the key )When I got shut and bought a Buell it had been fitted with a 42 mm Mikuni slide carb with accelerator pump,it didn't ice .
Constant velocity carbs, the ones with diaphragms, have a fairly constant low pressure that vaporises the petrol,but indoing so uses the heat from its surroundings ,which freeze if the temperature is low . When you let gas at pressure out of a cylinder, the liquid gas vaporises as it exits the valve and often freezes the surrounding metal , much the same as the inlet manifold after the venturi, I think it is the self regulating nature of diaphragm carbs giving much more efficient airflow over the venturi that causes the freezing,maybe slide carbs arnt that good at keeping the pressure low and constant.
Diaphragm carbs were once described to me as " for kak handed throttle jockeys who can't ride " and they may have been right. If you were to have whipped the throttle open on the BMW R90S I had ( 36mm del orto slide carbs ) it would have spit back and fired you over the handlebars,the throttle had to be progressively opened as the revs came up .
So I would be interested to know if slide carbs ice ?

[Nickj]

Carbs rock. I think they give engines an extra bit of soul :)

Having had a 750 IE and carbie and done 100K plus on the two I have to say I prefer the carb version, it felt a little rawer on the power delivery. Nicer motor to ride.

[Drumnagorrach]

I think I have a plan , tell me if it makes sense ,buy the 900 SS that I fancy,try silkolene pro fst
If I still have a problem add oil pipes to the carbs ( I think the float chambers all have the provision for oil heating ,just blanked off ? ).
If I'm still having a problem ,fit FCR 41 carbs,they will cost less, £600 from cal cycle works ,than it cost me over last winter trying to get my injected monster to run as I like a bike to run.
Unless a really nice M900 sie ,pre 2002, comes along, and then all my resolve will be gone again.

[Mr Gazza]

..........Or a nice M1000Sie...??

[Drumnagorrach]

..........Or a nice M1000Sie...??

Do you know of one ?

[Mr Gazza]

Sorry not at the moment, but a couple have changed hand on here recently.

I think you and I are pretty much on the same page, as far as bikes we like goes, and if I didn't already have a 2000 M900Sie, I would be in the market for an M1000Sie....Niether models come up particulaly frequently, but if your search is broader it improves your chances.
There is also the S2R1000....Same engine in the single sided swinging arm format....I must say I prefer the traditional swinging arm and low level silencers, but it's another option.

On the SS...I had a 750SS and very nice it was too, but it was a pig to ride sub 30mph because of the low bars and my weak wrists....I swapped to a Monster for the low speed comfort and tractability (and could still crack a ton if I wanted)....Just thinking that a higher geared 900SS will be even less fun at pootling rates?
Not dissing the SS models in any way, but they are a different animal to a Monster.

[DavidT]

Sounds like you have a great plan! My 93 900 suffered from chronic icing from day one and even with the retro-fitted factory heater it still needed FST to run through the winter. Damp conditions below 10c would have it dropping onto one pot or a huge flat spot all the way from the pilot circuit to main jet. By contrast, AnnT's 2000 900S ie is smooth and clean right through in all conditions (except when the temp sensor corroded then it it was a rich running pig).
Since fitting the FCRs I haven't suffered from icing and it doesn't half lift at the top end!

David

[utopia]

Since fitting the FCRs I haven't suffered from icing and it doesn't half lift at the top end!
David

That's exactly what I like to hear ...and this isn't the first time I've heard it.
In fact I think I've heard reports of improved bottom end too.
I'm also told that you can expect a noticeable improvement in fuel economy, despite the accelerator pumps.
If the bike's a keeper, this means that over time, the fcrs somewhat pay for themselves.
And so ....and I meant to post this earlier but it got rambly and I deleted ...I wouldn't waste money on the heaters but put that cash straight into the fcrs.
Furthermore, you'll be spending money on good stuff, rather than messy pipework, so its much more smiley all round, doing it that way.

I'm saving pennies in a tin as we speak.