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113
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1/3/2016
Location
San Marcos, CA
US
i3oykin
8/6/2017 7:17pm
8/6/2017 7:17pm
Edited Date/Time
8/11/2017 2:42pm
2015 Husqvarna TC125
I have this odd issue, bike seems to want to cut out up top and not really pull as hard as I would like or as cleanly once around half throttle and up. Have had this issue for about 20 hours or so, bike has 43 on it.
I got the SXS CDI that had been recommended a thread of mine about 6 months ago and it only seemed to help with mid. I still have no over rev, it seems like the bike cuts out up top. It does not feel that different other than in the mid-range (should give me over rev). The cutting out is with the stock CDI as well, I have ridden them back to back.
I had a 180 main jet in there, NOZI needle, 4th pos, 42 pilot 1.5 out. Elevation is around 3500 feet, weather about 80 degrees both days, same track. Although it does this at sea level too...
Then I went to a 185 main, NOZH (richer), 4th pos, 42 pilot 2 1.0 out.
That seemed to do better but but I think that was mainly affected by the needle change...
I am running vp leaded 110 mixed 50/50 with 91 pump gas (comes out to around 100 octane),38:1 pre-mix. My squish is right at 1.2mm, piston (Wiseco single ring) has about 4 hours on it. New (4hours) OEM spark plug. Stock pipe, Pro Circuit shorty silencer. SXS CDI/ignition. Holes in the fender/airbox. I AM using the OEM spark plug, they recommend a different plug that costs like $65 to use with the SXS CDI. I just found one for around $20 that I ordered along with some main jets: 172, 175, 178, 188, 190 and 192.
I have this odd issue, bike seems to want to cut out up top and not really pull as hard as I would like or as cleanly once around half throttle and up. Have had this issue for about 20 hours or so, bike has 43 on it.
I got the SXS CDI that had been recommended a thread of mine about 6 months ago and it only seemed to help with mid. I still have no over rev, it seems like the bike cuts out up top. It does not feel that different other than in the mid-range (should give me over rev). The cutting out is with the stock CDI as well, I have ridden them back to back.
I had a 180 main jet in there, NOZI needle, 4th pos, 42 pilot 1.5 out. Elevation is around 3500 feet, weather about 80 degrees both days, same track. Although it does this at sea level too...
Then I went to a 185 main, NOZH (richer), 4th pos, 42 pilot 2 1.0 out.
That seemed to do better but but I think that was mainly affected by the needle change...
I am running vp leaded 110 mixed 50/50 with 91 pump gas (comes out to around 100 octane),38:1 pre-mix. My squish is right at 1.2mm, piston (Wiseco single ring) has about 4 hours on it. New (4hours) OEM spark plug. Stock pipe, Pro Circuit shorty silencer. SXS CDI/ignition. Holes in the fender/airbox. I AM using the OEM spark plug, they recommend a different plug that costs like $65 to use with the SXS CDI. I just found one for around $20 that I ordered along with some main jets: 172, 175, 178, 188, 190 and 192.
After the 0:50 mark of this video you can hear it again multiple times.
Both videos with the jetting mentioned first, I tested again at the same track, same ambient temps with the two steps richer main and the richer needle.
The plug reading for both videos was much whiter. Hence why I richened it up a little, I think I am on the right track with the needle setting but I am unsure of the main.
I really am hoping it is not my reeds already....
Have you checked how far your power valve screw is in or out? That can also affect your bike falling flat up top. I like my 2016 Ktm at 1.75 turns in from all the way out.
This one is too, just having a minor issue. I have checked the powervalves on my bike though
I feel that it falls flat really early, but takes a minute to get there, almost laggy then nothing. I have the KTM Factory SXS ignition too that is supposed to allow these bikes to over-rev.
I just ordered that spark plug they say to run with it. Hoping that is my issue.
The Shop
This video is with the first jetting, the richer needle almost alleviated that cutting out issue! But still no over-rev, did I go the wrong direction and actually should have leaned out the main?
https://youtu.be/lispvPALNfM
Have you looked into trying a JD jet kit? I just put one in my bike and it's phenomenal!
We will see how it goes with testing this weekend, I should have those jets in a few days, as well as that super super special spark plug
Does it cut out at a single throttle position? This could be a clue to jetting vs something mechanical
It was mainly cutting out at mid-throttle. The richer needle cured this about 80%, if not more.
Right now I feel that with the richer main it pulled worse up top, so I think I went the right direction on the needle but the wrong direction on the main.
I am also going to be putting that special plug in this week as well.
Fuel also a bit too high oct for what you need. All you need is 91-93 oct. Higher octane fuel burns too slow for your bike.
Paw Paw
Please explain your reasoning, it says to use at the least 98 octane with this KTM factory/SXS ignition.
Manual says to run 40:1, should I start there?
The octane stated in your book is a non US rating and that is much different than here. Our 93 pump octane is about what the other countries call 100 octane.
In truth, our US 100 octane fuel ( or the mix you are using) burns way too slow for your application.
Paw Paw
I went through all the electrical and found the ignition map wires connector to be pretty crusty and full of dirt... I took the harness off the bike, cut the connectors and soldered it together (both wires attached are the aggressive ignition map), because the connector was a little wiggly and I never use the soft map anyways.
I showed my father (Mechanic of 40 years) the ignition map connectors and he started laughing, we both think that was possibly attributing to it and decided the solder method would be best, for peace of mind at the least!
I double checked the manual again last night, in TWO different sections of the manual it specifies 98octane at 40:1
You were correct about the octane rating, thank you for the information as I was unaware of that previously.
I think I will get a can of 91 and mix that at 40:1 to start with.
178 main jet is in there now, just waiting for my spark plug now!
Paw Paw
FOUND THE ISSUE!
Reed cage is warped, they do not seal. If you flip the reeds around on the cage they still do not seal...
So I took some measurements and sure enough, the cage is warped.
So I am unsure what to pursue. Neither Vforce or Boysen make a reed cage assembly for my specific year, but cross referencing I found some superseded numbers claiming that 06-15 is the same.
I found a rad valve for a good price but have been told Boyesen is junk. I have only had experience with vforce and really liked them on my yz125!
https://www.ebay.com/itm/281623258031
Pit Row
I leaned the main out 3 more than what it was, from a 180 to a 172 and still the same problem, went to a 190 main, same problem, just took longer for the RPM to build with that rich main.
There was a pool of fuel behind the reed cage, and they do not seal at all, you can completely suck through the back side of the cage (the inlet side, carb side).
I flipped the 3 that clearly weren't sealing around and same issue, then took some measurements and the cage is fairly warped.
Even if it is not the issue, it is an issue nonetheless...
I ordered a vforce cage, had great success with them on my Yz's, so at least it is worth a try.
It always does it, regardless of temp. (Of course I warm my bike up before revving it to the issue..).
I pulled the harness off the bike and sent 12v regulated DC through every single wire, did Voltage drops for every single wire... I swapped CDI/ignition boxes, same issue.
Only thing at this point it can be if indeed it is not the reeds, would be an ignition coil or stator. Both check out resistance wise, but I never trust ohm readings alone, so I need to do some voltage and current ramp testing for stator output.
My past 125 wows on different brands when they start acting up halfway into the moto is the high speed coil breaking up from heat. Shows a wet plug of course and leads to leaning the main....this was catastrophic one time on a CR 250 micro-sprint motor when it sputtered and fouled plug in practice, we leaned main for heat race and it completing shut-off after a few laps,,,,we switched everything cdi,stator coil and went back out for main event and melted piston...we should've went back to original main jet when we swapped everything and we'd been fine...
Oh yeah, that is crazy!!! Thank you for the useful information!
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