Bogging Down

[Stuajohnson79]

Not sure if anyone has posted this, there's far too many to look through.

Just for back from a ride out, haven't managed it for a couple of weeks now. I noticed when trying to pick up a handfull of throttle leaving junctions it started to bog down quite severely at about 3-4k rpm. If I backed off the throttle it would climb slowly, but if I held the throttle open it would pick up quickly after a few seconds and take off. It's not the best of days here, a bit damp and cold. All 4 pots were warm to the touch, so all pistons are firing.


Any ideas?

[His Dudeness]

did you park it outside while you weren't using it? total guess but there could be a bit of water in your tank or around the plugs

[Major Rant]

"reluctance to rev" can be a symptom of unbalanced carbs...
 
Mine, for example, bogs down at about 8Krpm when its carbs go out of balance but can be coaxed through the dead spot.
 
After balancing it revs freely all the way to 12K...

[Stuajohnson79]

did you park it outside while you weren't using it? total guess but there could be a bit of water in your tank or around the plugs

It's kept garages, but I suppose it could have got cold enough in there to condensate.

"reluctance to rev" can be a symptom of unbalanced carbs...
 
Mine, for example, bogs down at about 8Krpm when its carbs go out of balance but can be coaxed through the dead spot.
 
After balancing it revs freely all the way to 12K...
[/quote

Do carbs unbalance through lack of use? It was fine when the weather was warmer, but I've not managed to get out much since its got wetter and cold

[Fazerider]

Two weeks in a garage won't be long enough for the petrol to have absorbed any troublesome amounts of water.
It might be carb balance, but I'd be more suspicious of the carburettor heating circuit... cold damp weather is the ideal condition for icing to occur.

[darrsi]

I was thinking either carb icing or unbalanced carbs funnily enough, because i've had both before on my bike.
If it was carb icing though it would just run like a tractor, until the ice melts by leaving the bike ticking over, it wouldn't be specific to certain revs, whereas unbalanced carbs would be.
Carb icing normally only occurs between 0 and 5 degrees temperature as well.

[His Dudeness]

yeah i'd agree with the other lads that its most likely carb icing. but carb icing is not necessarily that the carb itself is freezing its where water vapour in the air freezes as it goes through the carbs and it can effect bikes at certain revs depending on the atmospheric conditions. like you could be riding along at 50 and all of a sudden your speed drops to 40 or whatever. foggy conditions are the worst for it. here's a good video of it happening

Carb Icing on my VMax

you can get an additive that helps to stop it happening http://www.opieoils.co.uk/p-809-silkolene-pro-fst-fuel-system-treatment-for-petrol-engines.aspx i'd say its more likely to be carb icing than carbs being out of balance because how can carbs go out of balance by the bike not being used for a few weeks?

[darrsi]

If you're gonna go down the road of trying an additive, buy 5 litres of 99.9% pure alcohol off Ebay and add 200ml per full tank of fuel.
It's much cheaper than using Silkolene Pro-St, and it's tried and tested, by me and many others, and works perfectly.
It will also bind with any moisture that's in your tank and will simply be burnt away as fuel.

http://www.ebay.co.uk/itm/IPA-ISOPROPYL-ALCOHOL-ISOPROPANOL-5-LITRE-min-99-pure-/220546637586?pt=UK_BOI_Medical_Lab_Equipment_Lab_Supplies_ET&hash=item33599a9f12

[His Dudeness]

If you're gonna go down the road of trying an additive, buy 5 litres of 99.9% pure alcohol off Ebay and add 200ml per full tank of fuel.
It's much cheaper than using Silkolene Pro-St, and it's tried and tested, by me and many others, and works perfectly.
It will also bind with any moisture that's in your tank and will simply be burnt away as fuel.

http://www.ebay.co.uk/itm/IPA-ISOPROPYL-ALCOHOL-ISOPROPANOL-5-LITRE-min-99-pure-/220546637586?pt=UK_BOI_Medical_Lab_Equipment_Lab_Supplies_ET&hash=item33599a9f12

cool that looks interesting. have you ever tried it? oh sorry i just saw you said you have.

[darrsi]

Yeah, my bike is just prone to carb icing, i keep the heater circuit pipes clear but in the past as soon as the temperature dropped below 5 degrees i ended up by the roadside trying to keep the bike ticking over enough to warm up the carbs with engine heat.
Ever since i started using Isopropyl alcohol there's been absolutely no issues whatsoever.
I literally have a bike with a drink problem 
You must make sure you only use the 99.9% version though, as they also do one that's about 70% alcohol and 30% water, which is used for general cleaning usage. Because of the high alcohol content it burns just like fuel, but lowers the freezing point of any moisture.
I've never found a place to buy 5 litres off the shelf, which is a shame as the postage is almost as much as the product because of the weight, otherwise it would be even cheaper?
 
What's even more worrying is that propellored planes are prone to carb icing 

[His Dudeness]

yeah i suppose it could happen to anything that uses a carb. i wonder what they actually do on planes to stop it happening?  i'd say carb icing probably effects everyone's bike but the effect is just more noticeable on some bikes than others. a drop of the isopropyl alcohol might be a good idea for everyone?

[darrsi]

It's the only bike that i've ever had the problem with before, and i've had a few over the years!
This should answer your question:  http://en.wikipedia.org/wiki/Carburetor_icing

[Stuajohnson79]

I've just remembered, while I was riding I tried opening the choke and it bogged down even more. Is that more evidence towards carb icing?

[Stuajohnson79]

Also if anyone is interested, I just found this:
 
http://www.shinyhardware.co.uk/prods/showprod.asp?pid=16623

[darrsi]

Honestly, if you have carb icing the bike will barely run, which is why i said earlier it runs/sounds like a tractor, i'm thinking more carb balancing!
Unless the temperature is right for it, 0-5 degrees, below freezing simply doesn't do it 'cos there's no moisture in the air, and above 5 degrees is too warm!

[His Dudeness]

nah you're wrong about it barely running. it can run fine and then have a sudden drop off in power. sure look at the video. that bike is not running like a tractor. check out that link you put up yourself. there's a chart in it that shows the conditions that it can occur. it can happen out a wide range of temps depending on the conditions

[darrsi]

Interesting chart, only problem with it is that i can't remember the last time i made a descent on my bike???
Next time i'm cruising down the M1 at 5000ft i'll try and remember the perils ahead. 


When my bike first suffered from it, it was in exactly the same spot, 1 mile up the road from where i live, on the way to work, 3 days in a row.
And i remember it was sunny, but just cold, and it was a simple 20/30mph ride in traffic until it happened.
I'd imagine if i was able to go faster it would've happened quicker!
I'm just speaking from personal experience that's all.
Anyway, i know now, give the bike a livener every now and then and it runs sweet, i just hope it never gets breathalyzed in winter! 
 
@Stuajohnson79  Putting the choke on is just starving the bike of air so it will simply add to the problem. The Fazer is probably the first bike i've had where i've never really had to touch the choke at all, it's just never needed it!

[unfazed]

Was the bike ok when it reached full temperature? If so it could be carb icing if not then it is a different problem.
Drain the float bowls as a precaution and check the fuel filter for water, The fuel filter is relatively large as it lies on its side and can hold water.
A common problem with the 600 Fazer was blocked coolant pipes in the carbs from new, apparently from little bits of swarf which was not cleared, mine being one of them and I had the carb icing problem until I cleared the blockage. I would advise you to cleck the coolant pipes in the carbs are flowing freely.
I have cleared 3 and some had to have a piece of stiff wire pushed throught to dislodge the swarf. All have been fine since. It is important to clear the blockages with the rubber pipes off as the swarf can get stuck in the rubber. Make sure you can blow through the pipes in both direction before refitting
Giving the bike about 3 or 4 minutes to warm before setting off will also prevent the problem