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RCF RCF
5/19/2020 5:14 PM

What does step 3 in this torque sequence mean ?

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Keith72 Keith72
5/19/2020 5:17 PM

You need a torque angle wrench for the last step.

No brains, No headaches.

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RCF RCF
5/19/2020 5:34 PM

I never even heard of that I just looked it up, this is for KTM 350 they are always 35 foot pounds I was doing a rebuild on a 2018 decided to check the torque spec just in case something change. I hope I didn't screw up $150 worth of gaskets since they're only one time use.

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Motoxtombo Motoxtombo
5/19/2020 5:43 PM

Back when I used to work at a Harley shop the head torque used to be like that , I think the Harley torque was something like 7 ft lbs, then 14 ft lbs the tighten them 90 degrees, so if its the same sequence stage 3 for you would be tighten them 50 degrees which is a little over 1/8 of a turn, but that's a weird sequence for sure.

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UGOTBIT UGOTBIT
5/19/2020 5:45 PM

It means to tighten the bolt an additional 50* rotation, after tightening to 22.1 Ftlbs

If a bolt is calling for a rotational torque value it usually is a TTY (torque to yield) bolt and can not be reused.

Does the service manual call for replacement bolts?

A digital torque wrench with angle is nice, there are also mechanical type angle gauges, but you could just mark the socket and keep track of your rotation.

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Keith72 Keith72
5/19/2020 5:46 PM

You could probably get it close enough with a regular wrench.

No brains, No headaches.

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RCF RCF
5/19/2020 5:59 PM
UGOTBIT wrote:

It means to tighten the ...more

No they don't require the studs to be replaced.. I'm going to call KTM Tech hopefully somebody's there to see if the 35 lb is okay, not sure why they changed it.

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RCF RCF
5/19/2020 6:13 PM
Keith72 wrote:

You could probably get it ...more

Do you think it'd be okay to back off to the second torque or do you feel the gaskets would be ruined bike hasn't been started or fluid put back in it.

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Moto520 Moto520
5/19/2020 6:20 PM

Trust yourself. Go by feel. You will be close enough. Don’t overthink it or you will wind up starting over

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RCF RCF
5/19/2020 6:47 PM

They've been running the same torque spec Sense 2001 the engine changes weren't that drastic , I don't understand them changing it . maybe somebody will come along and let me know what the 50° degrees equates to in foot pounds

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GoggleFiend904 GoggleFiend904
5/19/2020 6:53 PM

Speaking of torque wrenches, what are you guys using these days? I bought two cheap ones recently and I’m pretty sure they aren’t even close to calibrated property. Are there any good priced ones that you can recalibrate yourself

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Keith72 Keith72
5/19/2020 7:08 PM
GoggleFiend904 wrote:

Speaking of torque ...more

I like craftsman. Gearwrench makes some quality tools at a good price too.

No brains, No headaches.

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Keith72 Keith72
5/19/2020 7:10 PM
RCF wrote:

They've been running the ...more

You can double check me but I believe you turn the fastener another 50 degrees after you do the second torque. Meaning 50 of 360 degrees of a circle.

No brains, No headaches.

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Keith72 Keith72
5/19/2020 7:13 PM
UGOTBIT wrote:

It means to tighten the ...more

What he said.

No brains, No headaches.

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JM485 JM485
5/19/2020 8:11 PM
Moto520 wrote:

Trust yourself. Go by ...more

That’s not true at all on a critical fastener like a head bolt, you better follow the correct tightening procedure or you’ll risk a fatigue failure over time due to cyclical loading.

OP, the reason they specify in degrees is because they want a specific tension, or pre-stress, in that head bolt at all times. I’m assuming there is probably a necked down portion of the bolt that begins to taper up toward the threads and bolt head, this section is a specific diameter that is held to a tight tolerance. Because the thread pitch is known, and any slack in the bolt has been taken up by the first two torque sequences, it’s easy to induce a specific amount of stretch (or elongation if we want to be fancy) in the bolt, which translates to a specific tension. This tension is likely close to the yield strength of the bolt, but as long as it’s not over it can likely be safely used again which is why they don’t call for a replacement.

As a simple example, let’s say that the thread pitch of that fastener is 1mm per revolution. If we take all the slack out of the joint and assume the assembly is now rigid, by turning it 50 degrees ( or approx. .14 revolutions) we induced an elongation of roughly .14mm into the fastener. I won’t get into the rest of the math because it would put everyone to sleep, but from that elongation, the known cross section if the bolt body, and the known elastic modulus of the material, we can determine the installed stress on the fastener much more accurately than with only a torque spec. In reality, torque specs are not all that reliable due to variances in friction during install, but elongation doesn’t lie.

The reason this is important is because of metal fatigue. These four strokes are pushing pretty high compression ratios, and that bolt is undergoing a lot of force every time your piston hits TDC on the compression stroke. After a while, that repeated loading would fatigue the bolt material and a failed fastener will be the result. But, by inducing an installed stress that is higher than the load the bolt will see in operation, we can essentially fake it out into not feeling each cyclical load, and prevent fatigue failure. Hopefully that makes sense, I got going and couldn’t stop myself laughing

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PFitzG38 PFitzG38
5/19/2020 8:30 PM
JM485 wrote:

That’s not true at all on ...more

Thanks for that. Interesting shit I did not know - but should. Your explanation makes perfect sense. I was just wondering the other day about how and why does a nut keep turning once it's bottomed out. Inclined planes, screws, wheels, fire, fossil fuel. Things that make you go hmmnnn

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RCF RCF
5/20/2020 2:25 AM
Moto520 wrote:

Trust yourself. Go by ...more

JM485 wrote:

That’s not true at all on ...more

Now you got me wondering if they do want the studs replaced, I noticed on the previous torque page they had a torque listed for them I've never seen that in the manual before. I was looking at the manual online kind of a pain to scroll through the pages.
Kind of sucks to have to take it back apart because the gaskets were so expensive. I'm going to try and call KTM Tech today hopefully there somebody there..
If the studs are reusable I guess I could back it off 50% and then check to see where I'm at in the torque. I did notice to head bolts weren't as tight as they were on older style engine when I was taking it apart.

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kb228 kb228
5/20/2020 3:20 AM

Its 30Nm + 50 degree rotation. You need a torque wrench that calculates angles to do it perfectly.

What you can do to get close is mark a 90 degree angle, then a mark between your 90 marks to get a 45, then just turn your bolt a little past your 45 mark. Id be comfortable with that torque.

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charlie68 charlie68
5/20/2020 3:47 AM

A quality torque wrench and a degree wheel, dont mark the socket and give it another little turn.

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crowe176 crowe176
5/20/2020 4:14 AM
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RCF RCF
5/20/2020 4:19 AM
charlie68 wrote:

A quality torque wrench ...more

I think it would be over torqued then, I need to back off to the 23 foot pounds and then do the third step. I'm worried that I have it over torqued at 35 lb. if I have to take it apart to replace the studs then the gaskets are ruined , pretty sure they're not reusable once they've been crimped.

If this was my bike I would just run it with it torque at 35 lb but it's not.

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RCF RCF
5/20/2020 4:28 AM
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Rick Amatuzio Rick Amatuzio
5/20/2020 4:47 AM
Moto520 wrote:

Trust yourself. Go by ...more

JM485 wrote:

That’s not true at all on ...more

Do you REALLY want to know why they use rotational degrees, like Rolls Royce and other manufacturers? Did you notice they say use motor oil on the threads?
If you use a torque wrench, different lubricants will yield different results. WAY different.
Using moly paste vs motor oil vs ATF, torquing a bolt to say 50 ft/lbs, and you will be shocked how much more rotation (stretch) you will get with moly. The absolute pinnacle is measuring stretch .006-.008” on the bolt to maintain tension as you said.
Built lots of test engines, I’ve watch so many stock small block Chevy rod bolts destroyed using moly, you just can’t get 50ft lbs of toque without over stretching the rod bolt. ARP has their own moly formula with high end bolts and also say to measure stretch or go to 35ft lbs, then quarter turn approximation. If you use motor oil and a torque wrench, 50ft lbs won’t stretch the bolt enough. Moly is always close
Drives me nuts when machine shops bake your block with the main caps on too.. the bolts are all heat treated.

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kb228 kb228
5/20/2020 4:47 AM
charlie68 wrote:

A quality torque wrench ...more

RCF wrote:

I think it would be over ...more

I know its a different bike; but my kx250f calls for 36ft-lbs with m10 bolts. My kx450 calls for 44ft-lbs with m10 bolts.

I would think somewhere in that range is good for any bike. With the bigger motor it requires more clamping force compared to a 250.

Wouldnt overthink it too much. Get it close.

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RCF RCF
5/20/2020 4:55 AM
kb228 wrote:

I know its a different ...more

I'm trying to convince myself the same thing basically nothing looks different from the pre 2016 engine and 35 lb was fine for them. I'm hoping to get a hold of somebody I KTM and they tell me just send it, until then my OCD has me overthinking it lol.

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UGOTBIT UGOTBIT
5/20/2020 6:14 AM
RCF wrote:

I'm trying to convince ...more

If you loosen the nuts back up, IMO the gaskets should be replaced.

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Ken202 Ken202
5/20/2020 7:51 AM

My experience with adding oil to the bolts/studs prior for torqueing has been to be careful. Most times I'll over torque and blow the threads off, even with a high quality torque wrench. just for myself it's too easy to over torque.. Loctite works as a nice protective film for the bolt.

Simply I don't like lubing bolts. BIG bolts are a different story. I'm talking about engine bolts above.

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JM485 JM485
5/20/2020 8:05 AM
Ken202 wrote:

My experience with adding ...more

It would depend on whether the torque specified was intended to be used with dry or lubricated threads. On head bolts like we’re talking about here I can almost guarantee that the first two torque specs are meant to be used with lubricated bolts. If you don’t lubricate the threads (which would be almost impossible since there’s pretty much always oil on them already unless you did a full year down and vapor blasted the cases), the increased friction when tightening will lead to a much lower tension/torque ratio, and the bolt will be under stressed when installed. This is the same reason they often specifically say to lubricate under the bolt head as well, we’re trying to get as consistent of a torque reading as possible.

Make Hillclimb Great Again

Ratbeach Racing

Instagram / YouTube: @485Josh

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RCF RCF
5/20/2020 8:17 AM

you guys are all full of good news LOL, I'm still waiting to hear back from KTM I'll post here what they say in case somebody stumbles across this tread with a similar question. I tried looking the price up on those studs there dealer only. all my service manuals only go up to 2015 because the dealership I work for closed after the owner died in 2014.

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mxryan25 mxryan25
5/20/2020 8:40 AM

When I did a top end on my 2019 350 sxf there wasn’t anything like that for the sequences just nm/ft lbs. also, after I did the rebuild and had it basically back together I wanted to put in a new spark plug (should’ve done this while the head was off). Well there was a bit of dirt down in the spark plug hole and when I removed the plug some dirt fell on top of the piston pinch took the head off again and cleaned it off, and did not get new gaskets even though I probably should have. Haven’t had any issues

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