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Discussion Starter #1
I have a 2007 Grizzly 700 that my son put a HMF swamp series on. We went ahead with the HMF fuel programmer and then also added the Dynatek CDI. As the temperatures drop, it has a very bad off idle stumble, to the point where it will kill 50% of the time. I can't figure out what I might have done wrong with this combo, but generally read it as a very nice combo. Plug is showing fine at WOT. I think its pig rich at idle. I've backed down the fuel to zero at idle on the fuel programmer with no change.


Thoughts please?
 

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Grizzled
2014 Yamaha Grizzly 700 EPS
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I don't recall seeing anyone post recent info about using a Dynatek CDI. Specifically, what Dynatek item # are you referring too?



I recently added a HMF Swamp to my '07 700 and have been using a Dynatek FI Controller since I already bought that FI controller a couple years ago. That Dynatek FI controller uses potentiometers to adjust L, M, H throttle fueling so it is not exactly like a HMF FI controller or EHS FI controller which has the ability of maps. I knew I was always running rich but was too hesitant to turn down the fueling for fear of running lean. I have been told, and read elsewhere, that using a spark plug to understand FI fueling is not the same as in carb machines, so that may be a wasted effort for FI... I'm going off of other's knowledge here as I don't have expertise in that area.

It is only when I followed information from user @RockTaco to get a 4-stroke AFR Wideband installed to know what was happening with air/fueling ratio from sniffing the exhaust. He had told me to either pay a shop to insert their sniffer to measure the exhaust ratio for a one time $$ and assessment, or to get that Wideband installed so I can always know what the ratio is and make adjustments representative to what I observed on the meter while under load. Under load kind of being key since I ride anywhere from 6000' to 12,000'. I try and adjust based on the meter running while at 7700' which is where I live. Going up in elevation will only cause richness so that is not a big concern versus running lean. I realize the elevation part of this is not something a lot will have to deal with but elevation also played into the factor of trying to get my bike tuned properly and get power back.


With the rich issue going on, I also ran into another issue this last summer which I originally thought was related to my fueling problem. I was experiencing cutting out while mostly at medium throttle but it also could have happened at H or L throttle. It is only when I noticed the R light on the POD lighting up that I remembered reading about that happening. Some research on GC and I was able to find info related to the Neutral Assembly Switch (sensor) going bad that caused my cutting out. I recently replaced that switch and haven't experienced the cutting out since but I haven't put too many miles on her yet, only about 20.

Additional to fueling on the '07 700 Grizzly is the ability to adjust via the "POD MOD". This is probably not your issue though as I believe the POD MOD single adjustment is a global adjustment for all ranges of throttle input: L, M & H.

I'm not convinced any of this will help you other than the part about guessing at air/fuel ratio is not an exercise I was able to get right without the proper tool(s).
 

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Discussion Starter #3
I have the Dynatek FS Digital Ignition. My fuel programmer is the HMF Optimizer. I double checked all connections tonight and all looked fine.


I'll more accurately describe the symptoms as when I stab the throttle from idle, it dies every time.


Does that sound more like a timing issue than fuel? I verified again my fuel setting on 1 was all the way down. For experimentation I raised it a couple levels and it still died when I stab the throttle from idle. The rest of the curve runs great. It's only from idle.
 

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Grizzled
2014 Yamaha Grizzly 700 EPS
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Hmm, hoping someone with a bit more experience can lend some input on this.

Truly hard for me to say what could be the problem but your expanded description of yours dying convinces me it is not the same cutting out I had.

I would probably lean towards removing the Dynatek FS DI and see if the same issue occurs. Or maybe start with that removed and get the fueling correct. Curious though if Dynatek recommends using or not using a FI Controller in parallel with the FS DI? Does the Dynatek FS DI impact fueling as well? Seems like it shouldn't but I'm not familiar with that device. There is always the possibility that one or the other device has gone bad. I would lean more towards the FS DI if when you made FI Controller fueling changes and the bike appropriately responded.
 

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Discussion Starter #5
Hmm, hoping someone with a bit more experience can lend some input on this.

Truly hard for me to say what could be the problem but your expanded description of yours dying convinces me it is not the same cutting out I had.

I would probably lean towards removing the Dynatek FS DI and see if the same issue occurs. Or maybe start with that removed and get the fueling correct. Curious though if Dynatek recommends using or not using a FI Controller in parallel with the FS DI? Does the Dynatek FS DI impact fueling as well? Seems like it shouldn't but I'm not familiar with that device. There is always the possibility that one or the other device has gone bad. I would lean more towards the FS DI if when you made FI Controller fueling changes and the bike appropriately responded.

Good thoughts. I added the fuel controller first, and had it running decent. I don't recall it stalling when I stabbed the throttle. I got the Dynatek FS to eliminate the notorious mid range cut out on these early model grizzlies. It did eliminate the cut out, but then added the off idle stall, which has me thinking this is a spark timing problem. Dynatek does make a combo fuel controller/CDI, but this is only the CDI. It does not affect fueling. I'm going to try both HMF and Dynatek tech service to see if they have any suggestions.


I don't want to lose the advantages of upgrading the CDI to Dynatek (better throttle response, rev limit, etc.). It really did wake up the machine.


I thought this combo was used a lot more so am curious what others have done.
 

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I have the same prob but I’m running the gen 1 doneck efi with the dyna fs. I remember reading somewhere with them new push button programmers like the hmf you can adjust when each circuit comes in and that is what needs adjusted to get rid of that stumble if you base setting for fuel are close try adjusting the setting to make the low or mid throttle come in sooner. Check YouTube I think the video they turned a grizzly into a sport quad and they cut the fenders and add a bunch of goodies try looking it up hope. This helps.
 
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