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2015 TC125 cutting out.

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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.
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. (This was the jetting for the video)!!! 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 it just does not pull hard at all like I remember my yz125 having great top over rev.

I am running vp leaded 110 mixed 50/50 with 91 pump gas 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. not sure if that could be the issue. Does anyone have an alternative manufacturer part number besides the KTM/Husky number? So I can save a few bucks, hard to justify spending $65 on a spark plug that gets replaced every 20hours...

From about 0:45 until the end you can really hear the bike bog/cut out!

 

Edited by V@sh

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Here is the best pictures I could get of the spark plug, it was leaner last ride, hence the richer jetting.

This bike HAS gone into over-rev maybe 6-8 times since I have owned it brand new, so I know it can do it...

 

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Edited by V@sh
Wanted to add pics.

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I recall reading an article in dirtbike magazine with jetting issues on newer Husky's, I think it was more geared toward the TC250 but Husky engineers told them to run their fuel at 50:1.  I have always run 50:1....38:1 sounds rich but your plug doesn't look rich.  It actually looks pretty good.  Is carb clean?  Reeds OK?

 

Sounds good in the first 45 seconds.  Screamin.  After:45, sounds like its loaded down but I am not hearing the cutting out or sounds of fuel starvation.  usually they gurgle.  Is this only under load?

What are your compression readings?  Young piston doesn't mean you have good compression.

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15 minutes ago, Rob Reffner said:

I recall reading an article in dirtbike magazine with jetting issues on newer Husky's, I think it was more geared toward the TC250 but Husky engineers told them to run their fuel at 50:1.  I have always run 50:1....38:1 sounds rich but your plug doesn't look rich.  It actually looks pretty good.  Is carb clean?  Reeds OK?

 

Sounds good in the first 45 seconds.  Screamin.  After:45, sounds like its loaded down but I am not hearing the cutting out or sounds of fuel starvation.  usually they gurgle.  Is this only under load?

What are your compression readings?  Young piston doesn't mean you have good compression.

Im going to do some main jet changes at the track this weekend to pinpoint where it is and what's effecting it. As well as use that special spark plug, should be in mid-week! 

 

I cleaned the carb when I changed the needle and main last week. 

I'll double check all the electrical connectors and do some contributory checks and such this week. I might take the reeds out and check them but I don't want to until I do these jetting changes. 

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Rob, his video you can hear it much clearer. After both those videos I went to the richer needle and that cleaned up 80% of the cutting out. But it felt sluggish up too with the richer main. 

So so I think I went the wrong direction on the main (too rich, hence no over rev?) and the right direction on the needle. 

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I hear it in that one; sounds almost like clutching it. 

Hopefully your maintenance adventure this week straightens it out.  Too rich will lessen overrev, but spark plug would show it too.  Plug looks good IMO.  Check compression!  Its free, simple and can eliminate a lot of things, as well as explain them.

I'm leaning toward jetting.  Personally, Id keep it as close to stock as altitude allows, even with an aftermarket CDI.  From what I know, your main focus should be on the main jet as you stated.  Needle shouldn't be affecting the far upper RPM range youre talking about.

 

Rob

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50 minutes ago, Rob Reffner said:

I hear it in that one; sounds almost like clutching it. 

Hopefully your maintenance adventure this week straightens it out.  Too rich will lessen overrev, but spark plug would show it too.  Plug looks good IMO.  Check compression!  Its free, simple and can eliminate a lot of things, as well as explain them.

I'm leaning toward jetting.  Personally, Id keep it as close to stock as altitude allows, even with an aftermarket CDI.  From what I know, your main focus should be on the main jet as you stated.  Needle shouldn't be affecting the far upper RPM range youre talking about.

 

Rob

It's actually a KTM offered CDI. That's supposed to increase/allow over rev. They say to run the special expensive plug that I haven't tried so I'm throwing that in this week as well. 

Bikes gonna get all the electrical checked. I'm going to go leaner on the main and do a compression check this week! Hopefully Tuesday I'll have some time to tinker. I'll report my findings! 

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Ok, compression from about 5 full kicks, throttle wide open, I got about 160 PSI, COLD, in my sneakers. I would guess that with a single-ring forged piston that is a decent reading cold (68 Fahrenheit ambient temp) with squish at 1.22mm. 

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.

 

Edited by V@sh
wrong info

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good compression reading.  probably a few psi higher when warm.

I'm no pro but I'm still having a hard time getting over the 38:1 mixture youre running.  Have you always run that?  I see back in November your bike was running like a raped ape. 

Its been a while since I actually wrenched on a 2stroke but I do remember running 50:1.  too much oil = not enough gas, AKA lean.   

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On 8/9/2017 at 0:39 PM, Rob Reffner said:

good compression reading.  probably a few psi higher when warm.

I'm no pro but I'm still having a hard time getting over the 38:1 mixture youre running.  Have you always run that?  I see back in November your bike was running like a raped ape. 

Its been a while since I actually wrenched on a 2stroke but I do remember running 50:1.  too much oil = not enough gas, AKA lean.   

I am going to get her warmed up and see what it is warm, just for funsies! I am also unaware of how accurate this compression tester is. It feels like a 125 when you kick it over... LOL.

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

Someone on another forum mentioned that with my squish and such I should NOT be running anything over 93 octane due to incomplete fuel burn/not burning fast enough. But I do not think it is that personally...

Stuck a 178 main jet in there, just waiting for the spark plug!

Edited by V@sh
typo

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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!

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Good luck with this 

 

I chased this issue on a 14 ktm150sx forever.

bike felt like I was hitting the kill switch repeatedly.

 

i also had a yz125 and it never did it.

weird thing is nobody else ever had issue with it when they rode it.

 

tried 

new reed valve stock and boyesen

Stock reeds would fray in a couple hours

cdi

stator

harness

coil

every jet you could imaging 

I gave up and traded for an rmz250 and kept my yz125.

I think I just expected it to rev clean like my yz and it never did and it was just at its pumping limit ( based on the reed fraying)

 

 

 

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4 hours ago, qwert321 said:

Good luck with this 

 

I chased this issue on a 14 ktm150sx forever.

bike felt like I was hitting the kill switch repeatedly.

 

i also had a yz125 and it never did it.

weird thing is nobody else ever had issue with it when they rode it.

 

tried 

new reed valve stock and boyesen

Stock reeds would fray in a couple hours

cdi

stator

harness

coil

every jet you could imaging 

I gave up and traded for an rmz250 and kept my yz125.

I think I just expected it to rev clean like my yz and it never did and it was just at its pumping limit ( based on the reed fraying)

 

 

 

Hmm, well I know my yz144 did not rev out like my yz125... So may be similar to the 150..? I am fairly certain this is my issue, I found a good price on a Vforce3 cage/reeds that should be here mid-net week! I will try it out and post back my findings, compression and how the bike feels. It felt like it ripped with the jetting combo I put in it, minus the very top of the rpm.

I will check my compression too afterwards.

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Does your issue of cutting out feel like the kill switch is being hit really fast repeatedly?

if so not sure you will ever fix?

only thing I did not try was race gas and they ktm recommended ratio of mix. 

It was suggested once that it was reed flutter! At the time I could not get my hands on an old reed valve with the stops. I think the VForve4 has reed stops though.

I did try 2 vforve 3 reed cages I had  sitting around and they did not fix issue either.

 

 

 

 

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7 hours ago, qwert321 said:

Does your issue of cutting out feel like the kill switch is being hit really fast repeatedly?

if so not sure you will ever fix?

only thing I did not try was race gas and they ktm recommended ratio of mix. 

It was suggested once that it was reed flutter! At the time I could not get my hands on an old reed valve with the stops. I think the VForve4 has reed stops though.

I did try 2 vforve 3 reed cages I had  sitting around and they did not fix issue either.

 

 

 

 

After going 3 leaner on the main than stock, then 3 richer than stock, I figured it was not a jetting issue, because it felt the same at the very top/did the same thing.

So I decided to take the reeds out and inspect them and the cage and found the cage to be warped enough for 3 of the reeds to not be sealing, I flipped them around and they still would not seal. So I took some measurements and sure enough the cage is fairly warped.

I know it has to be the issue because there was also a pool of fuel built up behind the reeds, in the boot from the carb to the reed cage.

I ordered some Vforce3 as they do not make a Vforce4 that fits my bike.
I have used the Vforce3 in 2 of my other bikes and had zero issues, I really liked them, they took 100 hours of hard abuse on my yz125 and never skipped a beat.

I also found a Boyesen Rad valve setup for a similar price, on their over stock section of their website. But I read too many poor reviews about them. Plus me and a few freinds have had great success with Vforce, so what not stick to what has been proven to work.

Were your reeds not sealing, or what was your issue? When I push the kill switch rapidly it just kind of bogs the bike down. Or if I hold it, it does not make it "cut" out like my bike is doing.

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I thought same as you the reeds were not sealing that's got to be it but it was not.

 

honestly the only thing I did not try was race fuel and the recommended oil mixture ratio.

there were a few other riders that had this issue and gave up also.

 

 

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On ‎8‎/‎10‎/‎2017 at 8:32 PM, V@sh said:


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!

Whether or not it is the root cause of your issue, you will never know until you get the proper reed setup in there, so you're on the right track.  Reeds are cheap in comparison to magnetos and such.  Cant thoroughly troubleshoot if you don't address problems you come across, no matter how big or small.

 

Curious to see if the reeds help.

Rob

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3 hours ago, Rob Reffner said:

Whether or not it is the root cause of your issue, you will never know until you get the proper reed setup in there, so you're on the right track.  Reeds are cheap in comparison to magnetos and such.  Cant thoroughly troubleshoot if you don't address problems you come across, no matter how big or small.

 

Curious to see if the reeds help.

Rob

I agree on that 100 percent!

I am fairly certain this is at the least attributing! 
I have a Vforce3 assembly on the way.
Always had great success with them on my Yamaha's, so I thought I would give my business to  a brand that I have used and has proven itself to work for me numerous times.

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The new reeds/cage assembly cured it. No more cutting out, no more fuel pooled up in the carb boot!

Much better pull all the way through now.

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