JE hi-comp pistons, tuning and ignition questions

[hillbillypolack]

Gday again

Just another thought, the beauty of the ignitech module is it will let you advance or retard in small increments compared to the crude 2 stage map on the OEM modules (see Brad's article). Retarding the timing on the pick ups like I did is a big tight arse compromise and if my OEM modules popped I'd get the Ignitech. You can be fully justified in purchasing it as a modernizing upgrade . You wont have to put up with the timing retarded all the way through the map like I do.

Brad's article points out that there is potential to map your module for a more graduated and progressive response from the choke on warm up. This will be a huge bonus to you starting and warming up. The way my bike is set up, the idle speed on warm up changes in a very abrupt manner. It's hard to modulate it with the choke (enrichner). It starts great, but after 20-30 seconds on full choke it explodes from about 1000rpm into a 3-3500rpm fast idle and is fully advanced. I have to stand there and just catch it in time to back off the choke so it stays at 1000-1300rpm or so. Is this your experience?
In cold climates, tuning the timing in this area would be a real asset, letting you bring it up gradually and not waking the kids or neighbours so suddenly. This might let you get a coffee while the bike warms up to reduce the carburetor icing up on the way to work! Or,.. you could complete the package and get FCR's !

Cheers
Tony

YES.

My setup had identical symptoms.  I was under the impression that it was the fault of the Pederzini ingition modules.  As I understood it (for better or worse), the Duc needs a high-ish idle when warming up, say 1100-1200.  The Pederzini OE modules begin boosting advance at 1500, and (again as I understood it) once roms hit 1500, the modules begin taking the revs for a ride, up and up.

So, when I'd be in the driveway, the rpms were sedate.  2-3 miles out at the first stop light, I pull the clutch in and the bike feels like it'd grenade!  This is one of the things I need to sort out during the teardown and winter fixup.  I have Ignitech and FCRs, so I don't know if I'm just widening my confusion, or eliminating the weak links.  I don't think I will go wrong with the FCRs though.

[junior varsity]

i had the same odd high/low idle with choke on the carb'd bikes i've played with.

We had an immaculate 2000 or 2001 M750 in the shop recently. Same thing with it.


Doesn't happen with the FCRs and the performance feel is drastically better!

[koko64]

The FCRs are a superior instrument period. They transform your bike and I have found them easier to tune than the CV carbs. You will miss the choke if you live in a cold climate. Thank God for accelerator pumps.

If my ignition dies then I will buy the Ignitech unit and avoid the ignition compromise I currently have. The ignition is retarded about 3 deg at the pick ups and this stops pinging with the hi comp pistons but I think I would like more idle advance for easier start up, especially in the cold months.

With an Ignitech unit I would dyno tune the ignition right through the rev range for easy starting, maximum power and no pinging. I'd lock my bike, a dyno and Brad Black in the same room until the ignition was tuned in 500rpm increments .