Hello all,
So my princess of a grundle rumbler has struck again.
I just got my heads back from Speeddog and they are completely rebuilt.
I installed them with all the proper procedures in mind and torqued everything back down and took her for a spin.
The beast runs terrible still. Just as bad as when it had worn rocker arms and a cracked exhaust valve and a broken exhaust stud.
I'm thinking it is an issue with the ECU or fuel system.
I'm hoping to get down to Southern Cal Motorcycles for a trim adjustment next week.
There seems to be a loss of power, rough running, popping and backfiring under engine braking, especially at lower RPMs. And upon cold start up theres a "chug" noise that happens twice as the bike tries to start. Almost noises like a hiccup.
If anyone can think of anything that might be the culprit i'm all eyes.
-injectors
-throttle body sync
-ecu
-spark timing
?
What do the plugs look like?
what is the cranking compression?
how much leakdown?
how much fuel pressure?
battery charging voltage?
voltage at coils and injectors?
Brand new NGK plugs.
How do I test fuel pressure?
with a fuel pressure gauge.
Okay heres what I got:
Cranking compression: ~100psi both cylinders
Leak down: No audible leak. Used the Harbor Freight leak down tester setup and it read less than 5% leak.
Battery charging voltage: I ran the bike at ~4000 rpm and the battery read 13.6VDC.
Coil voltages: Running the bike at idle both read ~3VDC each.
Fuel pressure: Didn't check the recommended operating pressure before buying gauge. Gauge only went to 15psi and It was pinned while bike was running.
Injector voltage: Not totally sure how to measure this.
What else are we thinking?
Maybe the injector/spark timing it off.
A trim adjustment is needed but I dont think it would run this bad if that was the only issue.
How'd you check cranking compression?
Warm motor, throttle Wide open?
Quote from: koko64 on April 20, 2014, 10:04:42 PM
How'd you check cranking compression?
Warm motor, throttle Wide open?
Exactly
I think that's pretty low compression
Compression numbers and cylinder leakage don't seem to agree with each other. 5% is good, 100PSI is not. I suspect either one gauge is off or valve timing off a bit if you have adjustable pullys.
I have the stock pulleys which do have slots for adjustment.
Does anyone have a source for the timing procedure?? I can't seem to find it in the Haynes Manual.
Otherwise that might be pricey at the shop.
Compression should be around 160psi correct?
Round about that, say even 150 according to Haynes. For reference I've seen 150 in a 750, 160 in a 900, 190 with hi comp and 200 with hi comp big bore.
Cranking compression should be somewhere close to 150 or so.
Fuel pressure should be 45psi.
I wouldn't put much meaning on HF Leakdown numbers.
So I found this article:
http://www.ducati-upnorth.com/tech/camtiming.php (http://www.ducati-upnorth.com/tech/camtiming.php)
I'm not sure If this is what I should be looking into but its a start.
Id be willing to get this looked at at a garage but its my only vehicle and thus tough to let go for extended periods of time.
This is also an interesting article:
http://www.ducatitech.com/2v/maint/rebuild/headwork.html (http://www.ducatitech.com/2v/maint/rebuild/headwork.html)
I'd say there's a fundamental problem.
Small adjustments to cam timing or port work to improve airflow aren't going to solve the problem.
Did you get a fuel pressure reading?
Just ordered a gauge 0-100psi.
update to follow receival.
OK UPDATE:
Fuel pressure from pump is 45psi.
Running condition:
hard to start
when starting; occasional popping sound from intake. Almost like intake valves are being slammed shut or spark timing is off.
idles low when cold and "cold start" lever is off. Stalls.
high pitch ring at ~4000rpm
sounds like knocking when under load
regardless of Termi slipons, the bike is really load (louder than usual).
That fuel pressure is OK.
Perhaps the TPS is fuxxored, or is way off.
Or the trim is at some crazy setting.
Both are easy (read cheap) to check at a shop, or if you've got the VDST or similar diagnostic equipment.
I really wish this wasnt my only ride. Every shop wants to put it in the que and "get to it" in 4 days. Nick you are awfully far away for me to get rides back and forth from. What would be the best way to test the ignition timing without a diagnostics computer?
Quote from: DesmoTillDeath on May 25, 2014, 09:04:11 PM
I really wish this wasnt my only ride. Every shop wants to put it in the que and "get to it" in 4 days. Nick you are awfully far away for me to get rides back and forth from. What would be the best way to test the ignition timing without a diagnostics computer?
Well, you could call and we could set up a time where you can ride it in and I can hook it up and see what the ECU is doing/saying.
You could try checking the ignition timing with an inductive pickup timing light, you know anyone with one of those?
Quote from: DesmoTillDeath on May 25, 2014, 09:04:11 PM
I really wish this wasnt my only ride. Every shop wants to put it in the que and "get to it" in 4 days. Nick you are awfully far away for me to get rides back and forth from. What would be the best way to test the ignition timing without a diagnostics computer?
lucky you're not near me, my next day is july 29. do people make bookings in the usa and wait for that day to come then drop the bike off? seems to be a lot of people dropping their bikes off, then waiting for the shop to work on it. just seems to upset everyone.
if it is injected, then the timing is not adjustable and no one ever checks it anyway.