ulmer stage 2

[rxrider]

I have one more question that no other have asked, have your checked fuel tank vent line, if it gets pinched it will cause problems and the sled will act inconsistenly, every time vacuum in the tank gets high enough the fuel pump will cavitate and AFRs will fly all over the place. Just a thought.

 

[thefin]

The vent line did seem to be fine I don't like where it is on the trail tank tho if you fill up to much-or are on a small
Down hill angle It drains out the vent line. Should have motor back together Tuesday I'll see how she runs this time

 

[mtdream]

just get a check valve, from like a YZ or something, and place it inline...it solves the leaking problem without a doubt...and if you trailer the sled, no more gas leaking in the trailer...most dealers have them in stock...it is just a one way check valve for a gas tank...got the trick from Alpine Motorsports...

 

[big_red1a]

Can we see a picture of the leaking valves? was there any obvious signs or they just would not hold solvent???

 

[thefin]

the head is at the machine shop so im sorry i cant show you but all valves were leaking badly when i put water on them it leaked out the valves very quickly nothing appears to be warped just the gasket was leaking on center cylinder

 

[thefin]

Well I got it all back together long process but after all that it runs the same still same bad miss in the same place terrible disappointment

 

[mbarryracing]

thefin,

So to summarize what this bad miss is, and when it occurs...
It does a pop, pop, pop when accelerating the throttle quickly but doesn't do this when squeezing the throttle slower?

It misses at around 7000 RPM... does that mean when punching the throttle when around 7000 RPM but doesn't miss when you accelerate at any other RPM?
or does it miss as the RPM's are passing 7000 RPM point regardless of where you started accelerating from?

What PC controller are you using? Does it have an acceleration feature (fuel acceleration pump) enabled?

I still believe, as i posted earlier, because it is very repeatible that it is a program transition point, either adding too much fuel or not enough. You are experiencing this misfire right when certain conditions are happening in the program, you need to identify what that is.
Even though you tried 9 different maps, they all likely share the same parameters that are contributing to this misfire as they are all built from a base program with certain things tweaked, that is why it still happens no matter what map you run...

 

[rxrider]

If the controller has transition points and it's causing trouble I would suggest to remove it and add a Power Commander or Rapid Bike controllers. Very easy to configure and no transition points to worry about.

 

[mbarryracing]

rxrider,

I think the Ulmer kits use Power Commanders (PC), depends on what version.
Regardless, you still have transition points on the PC and RB3 when programs are changing from one column to the next (boost, RPM, throttle, etc).
Also, the one PC model and some Dobek boxes (maybe even RB3) have an accelerator pump feature that you can program to add a specified amount of additional fuel blast for a specified amount of time (or crank revolutions) based on a specified % throttle position change (like an accelerator pump on a carb).
These are all the parts of the programs that are overlooked or are unknown.

An example for discussion sake, thefin claims this stumble happens at 20-30% throttle opening... pop, pop, pop and then takes off. What if the program was setup from a pre-existing NA engine program as a base and is subsequently adding a whole bunch of fuel for 1/2 second when that throttle % occurs and at that RPM?
That might be a great program to alieviate a lean spot on the NA, but then floods the cylinders out on a boosted application where the intercooler / airbox is a restriction. Could be a reason why it clears up after 3 pops and that transition has passed...
Or maybe it is actually a lean misfire and under boost is getting more air rushing into the cylinders for a brief second when the throttle is wicked open fast, therefore actually needs more fuel for a split second (or several crank rotations) in that certain parameter condition then a NA sled needs.

Just thinking outloud... food for thought because I am currently trying to tune out an annoying transition myself, different symptoms though.

 

[thefin]

The miss does seem to be around 7000 and seems to happen when boost comes on if I nail the throttle fast it does not cough but will always do so if I ease into it could be that i don't feel it when I nail it cause I get past that spot faster im not sure but afr goes to 10 everytime it's very hard to pin point and I do have the power commaner 3

 

[mbarryracing]

Do you have the software to view the PCIII program?

 

[rxrider]

I know the RB3 and MCX controllers to the T, I have not encountered problems with transition points on those units. You can add resolution by adding more rpm columns in the offending areas. In general the more expensive units have way better resolution in their maps. And the most important feature with any system is the support for logging equipment as the LM-1 or MCX Display Unit. I always use datalogging when tuning, else it would be virtually impossible to tune it to perfection

With the RB3 I use DimSport native software RapidBike Pro, with MCX Display unit I use MegaTune.

 

[thefin]

Yes I do have the software but I do not have any data logging device

 

[rxrider]

What is the AFR meter showing when this happens?
You may run too rich in the offending area, have you tried to remove fuel, if so what did it do?

 

[yooper1]

Any updates?? I am hoping you get her dialed in.