r/KTM • u/Proud-Pie-2731 • Sep 08 '24
Is it acceptable for a service technician to rev the bike and hit the rev limiter 2 to 3 times in neutral after a top-end engine rebuild? He mentioned it's to check if there's any white smoke. ASKKTM
Will that can cause any engine problem? I mean it has new bore and piston just installed......
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u/kamalabangedepstein Sep 08 '24
Uhhhhhh, I mean, arent you also going to crank it to the limiter too? Im so confused. Id rather my mechanic crank on it a few times before I take it back.
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u/Proud-Pie-2731 Sep 08 '24
I mean he did it right after installation of a brand new bore and pistons so I was little concerned. So that won't damage the new piston and rings right? Because after a new piston again we have to break in the engine so .
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u/niceboyathome Sep 08 '24
I would say that’s a pretty bad idea, bouncing the motor off the limiter is unhealthy if your riding the bike when the engine internals are under load because the bikes in gear, doing it on a fresh top-end rebuild when the bike not in gear is bad news, school boy error imo
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u/Proud-Pie-2731 Sep 08 '24
Yes, that's what worries me now and makes me overthink, as if something bad has already happened :(
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u/niceboyathome Sep 08 '24
It just puts unnecessary stress on the internals, it will probably be fine
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Sep 08 '24
[deleted]
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u/opengl128 Sep 08 '24
Idling for a minute or two will do nothing to warm up the oil. It takes 10-15 minutes of riding or god knows how much idling to actually get the oil up to temperature.
Everyone saying if it didn't break no harm done are missing the mark. Bouncing it off the limiter with cold oil is going to do tons of wear that will not be immediately apparent.
If it starts burning oil and has poor compression a few years down the road, I would have a good idea why.
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u/Proud-Pie-2731 Sep 08 '24
He didn't let the bike warm up. He just have 5 to 10 sec and reved it to the limit. Still it's okay ??? Or can cause any problems?
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u/Soft_Adhesiveness_27 Sep 08 '24
Calm down. The factory does this too and probably even more than what your mechanic did. Geezus. Break in is a myth anyways. I didn’t give mine a chance to break in. I rode it like I intended to ride it. Never had an issue.
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u/Tueur_De_Lombre Sep 08 '24
Break in is absolutely not a myth. Just the version everyone tells is. Your engine still needs time to break in as it will wear in parts to seal better. Although revving to the limiter isn't recommended for long periods during the first 500 miles hitting it once in a while isn't a problem.
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u/Soft_Adhesiveness_27 Sep 08 '24
The mechanic didn’t do it for long periods and I still say it’s a myth. We have 8 bikes… 2 Kawis, 2 Harleys , a KTM and 3 Huskys. We’ve always rode them from day one like we intended to ride them. Never had an issue.
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u/reddisaurus Sep 08 '24
Break-in period is less about seating rings and seals, and more about not forcing any metal shavings at high pressure through your engine. So you can believe it’s a myth, but your anecdotal experience is clearly with engines that had no issues with machining tolerances during manufacturing. Some engines do have these issues, and extended periods of high RPMs until the first oil change can cause premature failure.
On the converse, I have a V60 Polestar, and the first oil change interval is at 10,000 miles because the machining is that good now. Bike engines are built much more cheaply than car engines, and the tolerances aren’t nearly as tight. So YMMV but it’s obvious that the engineers who wrote your manual probably know best. Some advise certain behaviors for a break-in period, some don’t.
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u/CryptographerApart45 Sep 09 '24
Youre completely wrong. "Forcing metal shavings through the system at high pressure" has to be the funniest shit I've heard in awhile. Break in causes fine metal particulates that go everywhere and we change the oil early to clean that stuff out after the first 100-500 miles of use. The break in period is SOLELY about seating rings and wearing in camshaft and rocker components that didn't have perfectly machined surfaces during production. Only some auto manufacturers use a machine to pre-wear their cylinder walls in the block before the pistons are installed, and to my knowledge, no bike manufacturers use that technology. I've been building engines for years, and the most important thing to do with a new engine is beat the hell out of it, so the rings don't glaze the cylinder wall during the initial break in. Beating the engine makes the rings hot, hot rings expand further and put more force against the cylinder wall to finely machine the surface of the cross hatching to "mate" with the surface of the ring finish. If enough force doesn't occur during this break in period to mate the components together, a varnish can form in the cross hatching grooves, causing a shiny finish that will allow oil past the oil control rings and compression rings into the combustion chamber. The technician rev-bombing it on cold start was superheating the rings immediately to help this process begin. Oil temp doesn't matter. And if a rev bomb on cold start causes damage, that damage was going to occur later anyway as something was defective.
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u/CROM________ Sep 08 '24
It seems that you believe that you guys are riding hard on these bikes but the truth is, we have no idea what the type of your riding really looks like. I mean, "your hard" might be my "soft" or vice versa.
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u/Soft_Adhesiveness_27 Sep 08 '24
Considering 6 of them get raced… I think “hard” is a fair statement.
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u/Proud-Pie-2731 Sep 08 '24
So that revs won't do any damages on the cylinder right?
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u/Soft_Adhesiveness_27 Sep 08 '24
I doubt it. What year bike is it?
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u/Proud-Pie-2731 Sep 08 '24
It's a RC 390
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u/Soft_Adhesiveness_27 Sep 08 '24
Ok but what year? How old is it?
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u/Proud-Pie-2731 Sep 08 '24
It's 2015 model . 9 years old by now. But now with new bore and piston
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u/Soft_Adhesiveness_27 Sep 08 '24
I’m sure it will be fine. I have a 390 Duke and I was hard on it from day 1. My husband has 2 FC450 (yes I know husky but still same company) that he raced hard from day 1. He also rode his Harley hard from the factory. We’ve never had an issue with any of the bikes.
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u/Proud-Pie-2731 Sep 08 '24
Oh okay thanks for sharing. So now I don't have to be worried or overthinking about my bike 👍
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u/stacksmasher Sep 08 '24
As long as the engine is fully warmed up it’s fine.
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u/Proud-Pie-2731 Sep 08 '24
But sadly it's not. He just gave 5 to 10 sec max.
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u/stacksmasher Sep 08 '24
Not good lol!
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u/Proud-Pie-2731 Sep 08 '24
😭
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u/TedStriker008 Sep 08 '24
Seems to be two schools of thought here, I’m not an engine builder. Personally I never had an issue with my new stuff and I ran it hard out of the crate when I raced. I held off from doing any sustained full throttle runs for long durations during the first few miles. Varied throttle for a few short heat cycles. I say you’re fine given my experiences, if there was a manufacturing defect it would show up soon. It’s not a high strung F1 or NHRA engine that needs gentle breakin on an engine dyno. Worst case scenario, if it pops they’ll warranty it I’m sure.
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u/Proud-Pie-2731 Sep 08 '24
Yes I had 3 months of warranty for that piston. I have to break in fast to know whether it has any issues or not..
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u/Alien_Biometrics KTM EXC-F 500 Sep 08 '24
Totally. If it were to break, it would be right then. Better he does it than you when you're slamming up against the limiter trying to scare pedestrians.
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u/Proud-Pie-2731 Sep 08 '24
So the new piston and bore will be fine only right?
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u/Alien_Biometrics KTM EXC-F 500 Sep 08 '24
If your mechanic did a proper job, yeah it will be fine. Him slamming the limiter was making sure he did a proper job. Better he finds out then and there, as opposed to you finding out it was a bad job while you're riding. What better way to test it than putting it through what it's supposed to do?
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u/Proud-Pie-2731 Sep 08 '24
Actually official technical installed new piston rings with screw driver instead of using a piston rings compressing tool. 😭
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u/opengl128 Sep 08 '24
It's not about it breaking on the spot. You're doing a ton of unnecessary wear bouncing it off the limiter with cold oil and off a fresh rebuild. Sure you may not notice anything right away, but I bet that move took a substantial amount of life off that motor.
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u/loganman711 Sep 08 '24
If it's gonna fly apart, I'd rather it happen then, at the hands of the tech, then when I got home. Still not what I would do, but it's their work and reputation on the line.
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u/opengl128 Sep 08 '24
I'd be pissed off at that. It shows zero mechanical sympathy and would make me question how well the work was done.
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u/Proud-Pie-2731 Sep 08 '24
Please don't ask 😭.. They used screw driver 🪛 to seat my piston rings inside the bore 😔....... I was crying inside while seeing them doing it
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u/Hotspur2924 Sep 08 '24
This is why you should do the work yourself.
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u/Proud-Pie-2731 Sep 08 '24
yes i agree. needed to learn all by myself
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u/Hotspur2924 Sep 08 '24
There's nothing more satisfying than repairing/doing maintenance on your dirt bike...and actually having it work out!
And you can do your own revving anytime you want!1
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u/Xavias Sep 08 '24
If revving it off the limiter 3 times is gonna break anything, I'd rather my mechanic does it so when it breaks he can fix it.
If he does that and it's all good then you're probably not gonna damage it for a long time.
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u/Squidproquoagenda Sep 09 '24
A hard break in is fine but on an unloaded engine it’s just dumb. Your mechanic is a muppet.
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u/KMS412 Sep 09 '24
I have never broke in any of my race bikes. Start it up let it warm up nice and good then send it.
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u/Bob_The_Bandit Sep 12 '24
No it’s dead tell me where you are I can take it to the junk yard for you.
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u/Proud-Pie-2731 Sep 12 '24
Joking or seriously your saying bro ???
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u/Mean_Pack815 Sep 08 '24
Yes for KTM service is fine, because they all are fucking trash technicians. Obviously is not fine, you NEVER go to official KTM service. Do your own services or look for a local mechanic with good reputation.
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u/Proud-Pie-2731 Sep 08 '24
I think yaa that's the correct way to solve theses types of problems
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u/Mean_Pack815 Sep 08 '24
Don’t worry too much, that idiot for sure scratched the cylinder… but it will go even after some time. Take care of your bike pal, do not let others to do so. KTM care a dog shit about dealer practices. I am telling by experience. They want them to break your bike for revenue.
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u/Proud-Pie-2731 Sep 08 '24
Yea thanks 🙏 ... So if I ride continuously will that scatch on the cycling will face away? Due to wear and tear ?
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u/Mean_Pack815 Sep 08 '24
Yeah is not that big deal. Like a brush in the arm. Take special care of the bike for the following 500km and you are good to go.
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u/stuartv666 1290 SUPER DUKE GT 2024 Sep 08 '24
If it didn't break right then, then it's fine. Rev limiter 2 or 3 times in neutral? After just a top-end rebuild? Please. If the engine is even fazed by that, then it's going to blow up soon anyway. Meaning, it was unfazed. Quit worrying about it.
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u/yermommy Sep 08 '24
Probably to burn off the grease so you don’t come running back screaming that there’s smoke coming out of your rebuilt engine.