I've got a problem that I haven't been able to solve with my 1990 Indy 650.
Has anyone heard of the flywheel magnets loosing their magnetic strength on these machines? If so, are there places where they can be re-saturated? Or is a new flywheel required.
Here's the current situation:
- I've been working on the clutching to improve off the line acceleration (there are older posts here about that...). I believed the clutching was pretty much sorted out with the right rpms at WOT and good backshift. Performance was amazing compared to stock.
- After a few hundred miles or so it started to loose the quick responsive backshift, so I made some additional clutching changes (stronger secondary spring, etc.)
- After a number of cycles through this I've started to realise that the problem isn't the clutching, the engine is missing and not producing any power at lower rpms (used to pull moderately at 5500, then 6000, now it requires a cruise rpm of 6500 in order to backshift and pull 8000 at WOT). I'm now running the Polaris blue secondary spring in order to have enough backshift (and it still misses on acceleration - even off the line with the 5000 engagement).
- what the engine was doing was missing and popping when I was trying to lightly accelerate after cruising or decelerating. WOT would miss and pop severly, but most of the time (depending on secondary spring & helix) the clutches would backshift enough to get the rpms up and the machine would take off. This critical rpm where it stopped misfiring and starts to pull and properly backshift has climbed from 5500 to about 6800 now over the past month.
- The missing tend to be very abrupt, often with explosions (loud popping) in the exhaust as if raw fuel/air mix is entering the exhaust.
- Also it is getting harder to start (easy to flood).
- I've pulled apart the carbs many times and even tried different mid-range jetting with no change to the problem (plug color changes as it should though).
- Plug color is good.
- compression is good (120-123 psi across the board).
- I believe the problem is weak spark.
- Checking all of the coils cold and hot to spec, all of the wiring, ignition leads, spark plug boots, kill switches, etc. comes up with no problems. I haven't tried a new CDI though.
- During the same 800 miles this season the headlight has noticably become dimmer and dimmer (It was starting to get quite dim the last season I drove it but it's definitely getting worse). Now it only glows with the handwarmers on and even with them off the headlight is still emitting a yellow light even at 8000 rpm (both high and low beam).
- I've also checked the entire electrical/wiring system and can't find any problems.
The only single thing that I can think of that could cause both of these problems is weak magnets in the flywheel. Otherwise there must be at least two separate problems.
Any ideas? Suggestions?