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Has anyone here any experience of having a bike's fuelling set up just right on a dyno? Any idea of a rough price?

I have had the carbs off and done the float heights but TBH I could spend the rest of my life trying things, it needs some one who does it day in day out. If I knew what the actual problem was I'd stand half a chance.

All the plugs looked a bit brown but not to the point of looking as manky as the one shown in the Haynes plug diagnostic chart. It smells very petrolly though and has a crackle from the exhaust at about 6000rpm.
 

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A basic dyno run is about 30 quid, it can start to become expensive once they start making alterations and how much, depends on what is involved & how many times the carbs need to come off to get it running right.
Personally I'd have a fiddle myself (ooer missus) & take it to a dyno for final check/peace of mind.

Also gut feeling is a wonderful thing - if it feels 'right' it probably is right.

Is the airfilter clean?
Are the needles\needle jets worn?
Is there any suggestion that somebody has had the carbs apart before you (dynojet kit etc?) - mushed screw heads etc?

Phil
 

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Sorry to suggest the obvious... but check that the petrol smell isn't because of a simple fuel leak! Also check if the vacuum-operated fuel tap is sticking open.

Otherwise the VFR is pretty reliable except for reg/rec problems (before something like 2001). There may be some VFR-specific advice; try the VFR Owners' Club at Bikers Oracle: http://www.bikersoracle.com/vfr/forum/
 

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The Angry Pasty Muncher
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Has anyone here any experience of having a bike's fuelling set up just right on a dyno? Any idea of a rough price?

I have had the carbs off and done the float heights but TBH I could spend the rest of my life trying things, it needs some one who does it day in day out. If I knew what the actual problem was I'd stand half a chance.

All the plugs looked a bit brown but not to the point of looking as manky as the one shown in the Haynes plug diagnostic chart. It smells very petrolly though and has a crackle from the exhaust at about 6000rpm.
I had my xr setup on a dyno when i took it back to 400 from 440, I also had it as a 440. It all depends on what needs doing and what they supply you. If it's just running rich adjust the carb mixture screws and make it run leaner. If you go to a dyno you will get a dyno graph telling you max power and torque figures through the rev range which will indicate what needs doing, however alot of setup is trial and error mine was on the dyno for 3 Friday mornings and that cost around £65 but they didn't need to supply anything. If you go there and they say it needs rejetting, cost then incurred are for the removal of fairing plastics. removal of carb bank and supplying the jets then retesting and then rejjetting again if required. Fortunatly on the xr you don't need anthing other than a 17mm spanner to get the bottom off the carb and a 6mm spanner to get the jet out. All depends on how far you want to go or how fussy you are about getting it bang on. If it's injected then it's easy as you can set the fueling map up at every 250rpm intervals. So you can watch the dyno graph and then adjust it to run richer or leaner at every 250 rpm from tick over to 16,000 rpm or what ever your bike red lines at. Hope that has helped and not bored you too much.
 

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All depends on how far you want to go or how fussy you are about getting it bang on.
I don't think there is such a thing as bang on.

Petrol bikes will generally run happily at anything between 13:1 to 14.5:1 and beyond. Optimum power is generally around the lower 13:1's, optimum economy around the lower 14:1's.

Phil
 

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The Angry Pasty Muncher
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I don't think there is such a thing as bang on.

Petrol bikes will generally run happily at anything between 13:1 to 14.5:1 and beyond. Optimum power is generally around the lower 13:1's, optimum economy around the lower 14:1's.

Phil

13:1 is optimum fueling and is what was recommended on my xr but it changed slightly all the way through the rev range low down it was running slightly rich then leaning off as it got to the high end of rev range
 
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