GP760 64X Timing Curve Mapped out

[OCD Solutions]

I can't count how many times I've been asked to map out the OEM 64X Timing curve but it's finally done!

It's not what I expected but honestly, I have absolutely no experience with the 760 based skis so I can't say it's good or bad, I just didn't expect the peak timing to occur so late in the RPM range.

If anyone has experience, please feel free to challenge my results. My test bench is improving with each use but it still does have certain flaws.

In this case, I was first able to mock up and test the full range of accuracy using a Zeeltronics GP760 ignition so I am fairly confident in my results. My measured results matched up to within half a degree from 800 RPM, right up to 6000 RPM where the timing light cuts out.

It's now been requested that I compare to the MSD curve but I do not own or have access to one so if you want it mapped, somebody will have to send one in.

 

[obd1kenobi]

very nice work!! truly stoked someone is properly plotting these curves for reference!
having started with a near stock 64x than running a full 62t ignition a few years ago before switching back to the 64x electronics with a pdcis-01t cdi, the 62t cdi favoured the bottom end but the 64x curve pulled way harder in the mid to top end! obviously port timing has its hand but it was a night and day difference between the stock cdis!
never having data for the 64x but plotting the curves (poorly in comparison to yours) on graph paper comparing the 62t, msd, waxheads, and a few others, it made more sense why. I don't have a pyrometer to measure the egts too compare curves back to back, but the wax curve seems to run with a noticeably higher chamber temperature retarding the timing more in the top end.
even with the changes to my curve 3rd season in, its still loosely based off wax's work retarding to 17deg but after holding 30deg until 4800rpm with no issues.
it would be really informative if you could plot curves and log egts for comparison, and if the community would be interested in donating towards a pyrometer for you to do so I would be more than happy to support the cause!
absolutely interested in your work and will keep up with the thread as best as possible!!
just now trying to become active on the x and more involved in the community, thanks to you, waxhead, the dirty river riders, and every one else for their time and dedication to the sport and the x.

andycapped

 

[beerdart]

Here are a few curves i've collected off the net.

 

[bernard]

I have the secondary tune off of the pink wire connected to the available ground circuit on my Blowsion rotary bilge switch so that I can utilize it and go back to the other tune if it is bad. I'm going to test some different tunes. What are the areas of greatest opportunity and what are some of the dangers? My engine is a 760 with a 5mm crank, 155 psi.

 

[beerdart]

I have the secondary tune off of the pink wire connected to the available ground circuit on my Blowsion rotary bilge switch so that I can utilize it and go back to the other tune if it is bad. I'm going to test some different tunes. What are the areas of greatest opportunity and what are some of the dangers? My engine is a 760 with a 5mm crank, 155 psi.

Just an FYI I confirmed with Zee you can switch maps while running on the fly sort of like push to pass.

 

[newbee]

Great job

 

[OCD Solutions]

it would be really informative if you could plot curves and log egts for comparison, and if the community would be interested in donating towards a pyrometer for you to do so I would be more than happy to support the cause!

My test bench is electrically driven so there are no EGT's to be collected.

 

[OCD Solutions]

Here are a few curves i've collected off the net.

I actually printed those off this weekend from the Zeeltronics thread and was using them to confirm my timing points.
I did not observe the dip in the OEM timing like the drawing indicated though and my peak was much higher. It would be nice to see where those curves came from originally.

 

[obd1kenobi]

My test bench is electrically driven so there are no EGT's to be collected.

apologies, can't believe I overlooked that in the op! clearly saw the block off plates in the first picture and test bench in front of the sj in the second, but for some reason assumed it was being tested on a dyno.. my mistake!
very nice setup btw!
the idea has been on my mind for the past couple seasons, so if anyone is up for the challenge I'm very interested in the results. likewise ill take note of my chamber temperatures with an infrared thermometer until I rig up a pyrometer down the road.

 

[OCD Solutions]

I ran a Hottach in my Seadoo 1050 and was using EGT's for tuning assistance on a bastard setup. The info was useful but they didn't have logging ability back then. Without charting ability next to rpm, load, acceleration, etc, I'll argue that the data is almost useless.

SnoPro has always had good stuff, I just think watercraft have too many variables to make the data repeatable enough to be actionable.?.?.?
http://www.precisionautoresearch.com/ECU_DATA/SnoPro/PAR31.htm

 

[obd1kenobi]

undeniable, the egt data alone is useless without a log of the cas for tdc/rpm and primary ignition signal at the very least! a secondary waveform is also nice to have too consider the combustion event reading the spark and firing lines.
tbh the idea of a logger is still just and idea.. but my little brother and I have spent some time with his pico scope recording cranking/running compression tests via a pressure transducer while back probing the cas, coil driver, and a low current probe for the secondary wave form simultaneously.
at one time I showed him a picture of a dual plug cylinder head and may have promised to track one down some day to measure combustion pressures as well.. oops!!
were captivated to bank data relating to static/dynamic compression ratios comparing ports, and cylinder pressures vs egts to test curves and dial fuel mixtures.
ideally it would be an experiment best suited on a dyno (maybe that was the fuel for my excitement of the op), but we have been working on a trailer with the plan of building a box for water testing at home. possibly even equipped with a scale to measure pump thrust and a pitot tube for flow as well if we get ambitious enough with pump tuning!
still learning every day and always down to over think things.

 

[obd1kenobi]

a couple snaps of captures taken with his pico scope

 

[waxhead]

You really need a det counter for this to check it. The curve I wrote was one for zeeltronic to be safe and reliable on all ignitions sold. You may/will get more by playing with it. The big gains are there on the curve I wrote with out having to stress about detonation.

 

[obd1kenobi]

very true, a purpose built knock counter would be ideal only we don't have access to one currently. it's been nics hobby to build sensors for the pico but a knock sensor is on the list, the model he has is limited to 4 channels so the secondary wave form wouldnt be a great sacrifice for a knk.
the curve has clearly been a versatile one with room to work around and I mean no disrespect, we both come from an automotive background and he's a younger inspired mind. my tuning knowledge is limited to experience with my own cars and brawler, what you've done with this ignition is only being tested for personal use and educational purpose really.

sorry everyone, long winded and off topic.

 

[maxboost]

Does 23 degrees advance after 4500 rpm seem like a lot? I think I’m running 17 degrees right now

 

[EFI1200]

This is an interesting post. And I have a stupid question, how do you differentiate high EGT caused by timing VS lean AF ratio?

 

[kevbo]

Does 23 degrees advance after 4500 rpm seem like a lot? I think I’m running 17 degrees right now

Start increasing the spark lead until a piston melts. You can hear the detonation if your exhaust is very quiet. A stock airbox will help a lot with intake noise.

 

[mxracer262]

I can't count how many times I've been asked to map out the OEM 64X Timing curve but it's finally done!

It's not what I expected but honestly, I have absolutely no experience with the 760 based skis so I can't say it's good or bad, I just didn't expect the peak timing to occur so late in the RPM range.

If anyone has experience, please feel free to challenge my results. My test bench is improving with each use but it still does have certain flaws.

In this case, I was first able to mock up and test the full range of accuracy using a Zeeltronics GP760 ignition so I am fairly confident in my results. My measured results matched up to within half a degree from 800 RPM, right up to 6000 RPM where the timing light cuts out.

It's now been requested that I compare to the MSD curve but I do not own or have access to one so if you want it mapped, somebody will have to send one in.

I was reading this thread and wanted to verify. Is (A) blue Wax’s curve and (B) red pen Yamaha 64x curve?

 

[mxracer262]

I was reading this thread and wanted to verify. Is (A) blue Wax’s curve and (B) red pen Yamaha 64x curve?

pen= OEM

Spell check mistake

 

[OCD Solutions]

Yes, you are correct.