MR-1 wasted spark?

[Beachbummer]

I noticed the YDS allow testing of spark only in combination with another cylinder, but it also allows dropping a single cylinder... So as a sanity check I need to ask...

Is the MR1 firing only once per 4 cycles, or does it fire more often? (Like twice)

I'm hunting what I think is an ignition problem keeping an engine from reaching full RPM, and I've tried quite a few things with no results (new plugs, coil swap, ecm swap)

I will be confirming done other things tomorrow, but I wondered if the cylinder pairs that test together in the YDS actually fire together or if each cylinder spark fires totally independent.



Thanks!

 

[212s]

All four stroke engines fire the spark once per 4 strokes. Low RPM or performance is usually one of three things - spark, fuel/air mixture, or compression. I would check your compression levels with a pressure test. Or an injector that is not passing enough fuel into the engine.

 

[84rzv500r]

well harleys have wasted spark and single fire ignitions and they are 4 stroke... I have one of each a 1983 XR1000 fires both plugs at the same time (one spark is wasted on the exhaust stroke of the other cylinder and only one coil) and a 1999 XL1200S that has two coils and fires two plugs in each cylinder at the correct time. I believe there are MSD systems that lengthen the spark event with multiple fires?

 

[dgfreeze]

Yeah, there are some 4 strokes that fire at every TDC, but I don’t know what the MR-1’s are designed to do. If you give me a couple days, I should be able to figure it out. Busy tomorrow eve, would be at least Thursday…. Wonder if the service manual touches on it…?

 

[84rzv500r]

depends on this storm i can look as well i've been over every wire and every connection in the MR-1 harness. IIRC ever coil has two wires that go to 8 different Pins on the ECU and there are 2 ignition pickup coils... Ill pull a spare flywheel and ill bet that there is only 1 magnet so Id guess its a batch fire that it it fires two plugs at the same time and one is always a wasted spark on the exhaust stroke... the other question then becomes are the injectors sequentially or batch fired... I do not know at this point

 

[Beachbummer]

I expect the injectors are sequentially fired since they have individual driver chips that go bad individually... But just a guess.