Dyno'd my Capo - it's running VERY rich.

[craig david]

My Capo has always given poor fuel economy (30-35mpg - UK gallons).
I suspected it was running very rich.

I got it dyno'd today at a main Aprilia dealer. It is indeed running very, very rich (the fuel/air mix drops off the chart which only reads above 10 by about 4000rpm - run was done in fourth gear).

The power curve is good (they even got me an extra 6bhp - now 85 bhp at the rear wheel - thanks to a new map). The bike is completely fine in every way except the poor fuel consumption. The Aprilia dealer were unable to solve the problem and the bike is still running really rich.

Any ideas what I can do to sort it or what might be wrong?
I'm thinking a Power Commander might be the way to go.

Any thoughts gratefuly recieved!

Cheers

[Ergo]

Cool info...thanks!

Year?
Mileage?
Mods?
Service performed/not performed?
Which Map?
History? (Always high consumption?)
Plugs? (Type and current condition.)
Air Filter? (Age and condition?)

[craig david]

Cool info...thanks!

Year? 2002
Mileage? 9500
Mods? end cans may have been internally modified as they're quite loud
Service performed/not performed? serviced by non-aprilia agent, valve clearances done at 8500 miles
Which Map? previously and old one, now 'the latest' according to the Aprilia place I was at today.
History? (Always high consumption?) In the three months I've had it, yes fuel consumption has always been high
Plugs? (Type and current condition.) the recommended NGK ones - I changed them (plus airfilter) recently - made no difference. obviously the old ones were very black.
Air Filter? (Age and condition?) see above - 500 miles old! Genuine Aprilia item.

I'ver seen lots of bikes dyno'd and I've never seen anything like this before - literally off the scale.

[ian-parkes]

Tim iam wondering if your bike has something causing it to stay in a cold start state ie still on choke . Iam not sure how the fuel enrichment system works for cold starting but it is a likely cause other than an air leak somewhere .

The mods on the exhaust etc should if anything make it run leaner .

The dealer didn't sound very helpful who was it ?

if they gave you the latest map then I was right your bike missed the map recall in early 03. that was the latest and only map for our non cat bikes . At least its making the right power now .

[craig david]

Good thoughts Ian.

I just rang the shop (Max Moto in Bury St Edmunds - seemed really good to be honest).

He said he thought about the cold start thing - but checked the temperature senders and they were fine plus there's no sign of this abnormal richnes on a closed throttle so this seems unlikely.

The map is 1105 - correct for a non-catalyst bike apparently.


He said the next thing he'd check is over-high fuel pressure. Anyone any idea how to do that?

[monoi]

If my past experience is anything, solving this rich condition should also increase the BHP...

I can see a trip to the dyno in my near future to check things out on my 05 as I also think its using too much petrol...for £20, its worth it !

[craig david]

Monoi - dynoing a bike is well worth it - it tells you loads about it.

How bad is your fuel consumption?

My light comes on at about 150 miles - I think this should be more like 200 if the bike is running correctly.

[Stu_O]

The map is 1105 - correct for a non-catalyst bike apparently.


He said the next thing he'd check is over-high fuel pressure. Anyone any idea how to do that?

Fuel pressure check is what I was going to suggest - it should be right at 50psi. There may be a factory gauge w/fittings for the Capo that your dealer will use. Another way would be to make a T-fitting to go between the tank and fuel supply line. Use quick connect fittings to hook to the bike and a threaded port in the center to screw in a standard fuel pressure gauge.

Look at the fuel return line where it exits the regulator on the left side of the throttle body. It takes a sharp bend back towards the right side of the bike at that point, and it could well be kinked. If it causes significant flow restriction, it'll raise the fuel pressure more than enough to cause what you're describing. Also don't discount the possibility of a restriction somewhere else in the return line, like at the QD fitting where the large hose joins the skinny one.

Stu

[craig david]

Many thanks Stu - excellent advice!

[CapoExplorer]

I am quite lucky in that Both I and my girlfriends dad both ride capos, so its great for comparison. mines 2004 and his is 2005. He does seem to get a little more to the tank out of his mile for mile, I have put this down to my tendency to try and wheely all of the time cant help it.. I get between 175 and 185miles to the tank where as he gets 180 - 200. I have have a max of 200miles.

I do seem to recall him taking this lead since he put on his staintune exhausts.

Does anyone know when the lastest map was released?

[juan lauda]

Keep us posted on how you get on.

[ian-parkes]

Tim like stu says the fuel lines could be the problem . I know you recently replaced the conector to the tank but did you do the other end that the reducer I sent you was for .
If you still have the original plastic conector on the pipe from the tank < the steel bound one > you could have a problem there , that one kinks really easy as the inner is thin plastic tube .

As I said to you before and air leak seems to cause the engine to go really rich , which surprised me untill I saw the effect on Joe's . He had ridden 300 miles on the motorway with the bungs removed from the balance tubes and the plugs were black and sooty .

As for fuel consumption I get about 160 - 170 before the light comes on . 16t sprocket and staintunes . The staintunes make no difference to the fuel used . I don't ride in town at all so 150 if you are in traffic may not be too bad . Its more a case of how much you get in after the light comes on , they probably all vary , mine takes about 17-18 litres. in general .

[craig david]

Good points Ian, thanks.

I haven't replaced the fuel return line connector with that one you sent me - the part you sent was excellent but I was nervous about making a good connection where the fuel lines leaves the injectors - If I get that wrong, it could pump loads of fuel onto the hot engine. I'm not sure I could do a good enough job.

It sounds like the fuel lines are the next thing to check so I might let a professional do it - apparently Taz who are local to me are Aprilia agents now so I might let them have a go.


As for tank range / mpg - I think I generally put in about 20 litres after the light comes on and I'm pretty sure I get 30-34mpg. I'd be happy with anything abive 40. The air / fuel graph on the dyno run shows something is very wrong!

Thanks for all the great advice so far - I'll keep you all posted!

[Northy]

Not sure how some of you guys manage over 175-180 miles to tank ,still not in that league, up to about 38 mpg and yes I think mines is running too rich as well .....so Dyno for it too.

Did notice some thing really werid the other night, smoke from the exhaust but I'd just turned the engine off ! OK could be exhuast gases from the engine but it going for about 3 minutes ...gentle whisp of smoke from one exhaust, so something was burning in the exhaust ?? ( unburn't petrol? ) .
So I started the bike up, the smoke goes , good ! .....I reckon she was just seeking attention !

Northy

[ian-parkes]

Northy that smoke is probably just steam . Unless you had the engine warmed up and rode fairly hard for a good few miles there would be some moisture in the exhaust this time of the year.