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Has anyone any information about how to make the bike run smoother at low speeds, i.e. the bike gets to 3,000 revs and I change gear from 1st to 2nd and then again at 3,000 it wants to go from 2nd to 3rd and if I don't change gear at 3,000 revs the bike runs lumpy and I end up going faster in low gears than I actually want to.

Somebody has suggested to me that I might change front and rear sprocket but not being technically minded I haven't got a clue if this is correct. The bike currently has a rear sprocket with 48 teeth.

Has anybody out there experienced this and if so, found a solution?

I'm not after top speed just a better running at lower revs.

Thank you
Les
 

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Is it running lumpy over 3000 rpm, or is it running badly/surging/hunting between 3000 rpm and 3500 rpm? Both have diffrent answers to them. Whats it like in higher gears?
 

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Better running below 3000 rpm will be a problem.It has to be kept above 3500 rpm really. Unfortunately this is part of the design. One of the things that I dislike about the bike but can live with it.

Ton
 

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Have you had bike long ? was it running ok before ?
Plenty of info on FAQ's here,
few things to check if not done so already,
ie ; battery terminals not loose?
Metal plug caps can cause problems,
Plugs past their best ?
If yours has EMU? (bit hazy on models/spec) , try resetting?
If carb model, are inlet rubbers split? water in float bowls ?
Engine mountings loose or missing ? (speak from experience here)

Mine is fine once over about 2,250 rpm, then pulls smoothly and yes its a single spark too!
Agree that once over 3,500 it smooths out, up to almost the red line (don't take it further than 5,000 normally, but occasionally have some fun :big grin: )
 

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No one has mentioned the condition & tension of the Chain & Sprockets yet.

Badly worn, badly adjusted, or simply not lubricated Drive Chain can give the impression of poor running, but it's not the engine.

I would agree with Ton regards running these engines below 3500rpm, it is not what they are designed for, unlike many old British Singles which were supposed to fire once every other lamp post :cool:

Give the Chain a checkover & some lubrication & open the Throttle a bit more before changing up a gear.

:riding:



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One thing I have found helps, and is easy, is changing your fuel. Go as cheep as you can. I found on Esso and BP my bike was surging, so I tried super unleaded which seemed to make it worse, so I went for supermarket bog standard fuel and its much better. I think its to do with it being set up to run on Ron 91.
 

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Hi Paul
Ron91 is just about octanenumber. Some can run on Ron91 and others need Ron95 as a minimum requirement. If anything supermarket petrol is of a slightly lesser quality which you probably don't notice
So a better running engine has nothing to do with cheaper petrol. But you might have had some water in the petrol which might has cleared up after a few tanks of petrol.

Ton
 

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Ah, ok. Makes sense. Ignore me. I was rubbish at chemistry. Better advice would be run your bike every day then :)
 

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Water doesn't get in with using it less. But leaving the bike stood for longer periods will make the petrol go worse.

Ton
 

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Better running below 3000 rpm will be a problem.It has to be kept above 3500 rpm really. Unfortunately this is part of the design. One of the things that I dislike about the bike but can live with it.

Ton
is that right? Above 3500?
 

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If it is below it in third gear you will feel that the bike doesn't feel happy doing less . Below 3500 rpm it doesn't seem to run very well. I think it might be because there is no big flywheel attached to this crankshaft. You can't really have both advantages I suppose.
It seems to move quickly enough but when you close the accelerator it falls back quickly too.


Ton
 

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If it is below it in third gear you will feel that the bike doesn't feel happy doing less . Below 3500 rpm it doesn't seem to run very well. I think it might be because there is no big flywheel attached to this crankshaft. You can't really have both advantages I suppose.
It seems to move quickly enough but when you close the accelerator it falls back quickly too.


Ton
yes i noticed it but i thought at least i could accelerate from 3,000 or cruising in these revs is that bad for the engine you mean?
This quick falling back gives you the impresion of a heavy duty Rotax with a lots of compresion right
 

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If it feels okay do so. I usually get it above 3500 but not looking at the revs all the time just go of the feel of the bike.

Ton
 

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good trick to clean water out of the fuel. methylated spirits Alcohol mixes with water, also mixes with petrol, it will te the water and just mix it in with the petrol in the tank
 

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I always use the easy method. Water is heavier as petrol and because of this water will go to the lowest point which is the float chamber. Drain them and the water is gone. Some bikes though have pockets in the petrol tanks where water collects. Like on the old Yamaha 600 and 900. In that case the water there will corrode the petrol tank and make a nice hole in there.

Ton
 
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Hiya all, I think changing any gears below 4000 rpm is labouring the Rotax engine, Having no flywheel there's no counter weight to help the crank and also been over square design! Not good to use as a low revving cruiser, The Rotax engine was designed for high revving off road use,
To help with the speed and rev control check to see who many teeth the drive chain gearbox sprocket has? If 17 then I would change it to a 16 or even 15 tooth sprocket,
I had the same problem with my Dakar with gear and speed control and found I had a 17 tooth gearbox drive chain sprocket, changed it to 16 and made a good difference in gear change and nicer to use around town,
Good Luck
 

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Hiya all, I think changing any gears below 4000 rpm is labouring the Rotax engine, Having no flywheel there's no counter weight to help the crank and also been over square design! Not good to use as a low revving cruiser, The Rotax engine was designed for high revving off road use
I'm not sure I agree with this. The Dealer gave me two instructions for running in:

1. Try not to exceed 4000 rpm
2. Dont labour the engine.

If what you said is true then these things are mutually exclusive.
 
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