Bimota Forum

[SethG]

Well, my new jetting arrived recently and I figured this was the right time to get it on the dyno and jetted properly. As a reminder, I have one of the later variants with jolly moto exhaust and Dell'Orto carbs. When I checked the existing jetting it seemed to be initially wrong.

Remember recommendation from Piero:
220 main top and bottom (used to be 230 main top)
K76 needle for bottom, K83 for top (3rd notch on both)
DQ 258 sprayer/atomiser.

My carbs arrived at:
215 bottom carb, 210 top carb
K76 needle both
DQ 258 atomizer/sprayer

Obviously pretty far off. I used the Dell'Orto carb tuning software to get a look at what was going on, the first thing I noticed is that the DQ 258 sprayer creates an effective max jetting of 206, so the 220 vs. 230 debate on the top carb is really just a question of low end fuel. It's not obvious to me why you would't just run the 220 at a higher notch setting, rather than switching to 230. I need to take a close look at it but I'm not sure what the value proposition is to running too small a sprayer.

I also checked the fuel inlet valve, recommended would be 300, and it was set for 350.

Anyway, here was the output from the software:






So, I ran it on the dyno before and after, the before run was 84 hp, the after run was... 84 hp. No idea what's wrong. It struggles with the load and seems to hit a wall before 9000 rpm.

We changed out plugs and wires in between changes, obviously went way richer on jetting, fuel flow looks good (impossible to be sure). I checked PV's with the kill switch on/off method and I see them moving around 3/4 of the way down and then returning in short order. I'm running out of ideas.

[JRH]

What an excellent post!
Just done a trackday on mine, and I had a job getting another gear before mine was shooting past 9500.......is yours hitting a hard limiter, or just getting strangled?
Might pay you to check the power valve cables are set correct.
Is your bike running the Pegaso dash/ecu combo, or separate ecu?

[vort28]

Hi Seth.
Just had a quick look through your ' just got it post' and question as to whether your bike a trofeo or EF.
I know the fitting of Jolly's to a standard bike, although physically possible means that the bike has completely the wrong map in the pegaso dash , so maybe that might be an issue. Also have you checked all the throttle cable routing etc as it is very poor and I have found 2 seperate issues with mine .
Alternatively , one of us Brits needs to get an EF on the dyno I suppose !!!!

[SethG]

The US importer was pretty sure it was an EF, it arrived in 2010, but it was one of the first ones. From what I can tell it was sent separately from the exhaust and the wheels, then everything unified in the US before being sent to the purchaser. I still have the stock exhaust in a box, and I verified the dash has the wrong map in it. No separate ECU, just the Pegaso dash.

If it was a trofeo, then it was something underhanded, because the owner didn't expect a former race bike.

But, we're missing like 20-30 hp here.

The power valves move, but I think to JRH's point, maybe not enough? I'm not sure how far they are supposed to move. It moves around 2/3.

I've never actually seen a dyno chart for a modern v due, anywhere, ever. I've seen one from the original Cycle World review.




It's definitely not hitting a hard limiter, it feels strangled. I guess what I didn't check is if they're opening when the bike's running on the dyno, although it wouldn't be hard to check with a flashlight.

[vort28]

I know of a few people that have EF10's and not one of us have the stock exhausts . Piero always tells me that there is a completely different map for the Jolly pipes and that standard and jolly's are not interchangeable without a different map. I also know that written on the underneath of my pegaso dash is the word JOLLY.
I would say you have the wrong map.
I have to speak to Piero soon so if you give me your frame number I will ask him what he knows about the bike.
Looking at your dyno, not being a master on these, but my vdue really takes off between 6-7k . I would expect to see a big step change on the graph around this point but yours seems linear.

[SethG]

378 delivered to the U.S. in mid 2010, thanks!

Wrong dash for sure, but 20-30hp?

[vort28]

I know Piero can re-flash dash, but think he is the only one that can this.
I also know 372/383/400/408 are all EF10 bikes, so sort of in the right numbers.
Will ask.

[mm500]

This is really interesting, please keep us updated on the progress

[SethG]

Well, I found one major problem. The petcock under the fuel tank has a major design flaw, well several.

The metal corrodes quickly and it becomes hard to work the knob, what you think is full open was for me half-open. Once I put a wrench to it, it opened 50% more.

There's nothing to stop the adjuster from coming completely off the petcock, if you open it too far it'll just fall off. If you open it almost too far, but it's still attached, it'll probably fall off while you're riding and light you on fire.

But, the big problem is that the plunger/piston that controls the fuel supply is way, way, way too long. At full open, with the thing about to fall off, it's more than 50% blocked. At any logical level of opening, it's more than 80%. This chokes the fuel supply dramatically.

I would recommend anyone with this type of Petcock, pull it and take a look to see if the design is identical to mine.


Tank Petcock with plunger and knob removed


Tank Petcock disassembled



Also, the tank vent is way too small

Tank vent

[JRH]

That is nothing like my (or lots of other) VDues.
Most Carb'd VDues do not have a petrol tap. There are two pipes that come from the tank, with QR connectors. That tap looks like it's off a tractor!!!!
Some bikes have a tap in the LH side panel, so I'm sure someone will come along and explain that arrangement.
Does that pipe split into two in order to supply the two carbs? That's small bore for two supply's ....

[Bud977]

KTM 50 MX bikes have a similar screw out fuel tap. But they have a stop so you can't wind it out the knob. I wonder why yours doesn't?

[2bims]

I'm with JRH on this one.........my tank has a quick release connector one piece built into the bottom of the tank.....that when released seals the tank...then splits into two large hoses for the carbs........

It should alsways be remembered that whilst all Vdues may be classified as "brand new" or low mileage.........the parts that make them up are all up to 17 years old...and hence some corrossion or old pieces may still be in there.....hence the reason to check them all out.

It could be that your tank and outlet are a throwback to it being an injected model at one time...later converted to carbs but the tank outlet wasnt modified.......Dont forget that the whole purpose of Bimota originally going the "Direct injection" route was to satisfy new regs on emissions and fuel consumption...making a two stroke more efficient and hence use less fuel per mile and hence less emissions to satisfy rules..particulalry in America.....so yours could be just that...a throwback to originality from its Direct injection route.........Sure you seem to have a problem as regards bhp on a dyno...and fuel starvation could be providing that....Only real test that is standard for most carbed models is that they have a From full tank range to Fuel warning light coming on is roughly 70 miles...never any more or less no matter how you ride it...as in effect its always having its neck wrung to keep it on the boil.......If yours is down on power and say your range was 90miles by comparison...then indeed you may have found the culprit.

As to models with a side mounted fuel tap on the left hand side of the seat unit...this is a pseudo Honda type unit Piero fitted to really the last of the last models...as we all like to switch off the fuel or disconnect the twin lines...and evidently disconnect, turn off the oil supply between runs...the later side mounted "switch" making this easier

[SethG]

Does anyone have a photo of the underside of their tank? And the other connector?

Yes, mine is just the one, and it goes to the side mounted petrol tap Piero installed which splits it into one line for each carb.

It's not in the original parts diagram for the bike, but it looks very similar to the one under the oil tank, which is in the original parts microfiche. I think it's an Acerbis part.


I can't believe I ended up with an odd connector, clearly poorly thought out.

[vort28]

Mine has the 2 pipes also, only ever seen 1 with this arrangement on and that went to Norbo, but his never gets ridden so no issue's there with fuel.
Not sure the injection ones have it either as they have a pump in the tank, so no real need for a petrol tap.

[JRH]

On injector bikes the second pipe is a return feed to the tank.