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Jankyl29

Beta2Stroke '17 300rr rattle sound, can't figure out

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Posted (edited)

 

Hey all, hopefully this video shows up. I forgot to turn the gas on during the video, so it's kind of short. 

2017 300rr has a rattle after revving. I know everyone is going to say "it's the pipe". This has started last year, the bike was torn down completely and motor sent out. They had the motor for 130 days before I finally just got it back with all this Covid issues. To my disappointment I still have no idea what this sound is.

New frame, every new bearing

New plastics

Motor rebuilt, brand new cylinder, new piston, crank rebuilt. Now I have 2.5 hours on rebuild, runs great.

It's not the pipe, all new o rings, undamaged pipe, sound does not change if I'm standing on the pipe.

Sound still there with tank off, radiator guards off and radiators loose.

 

To me, it sounds like it's behind the clutch or stator cover.....or it's something with the powervalve? Any ideas?

I'm original owner, unknown original hours...probably close to 300hrs I'd guess. Motor was rebuilt at 55hrs when I drowned it in a mud puddle, and again just now by the same shop. Original clutch which I know needs replacing soon. Not much else on bike is original.

All dealers are still over 4 weeks out to book for service, so taking it to a dealer isn't an option.

Edited by Jankyl29
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I know you don't want to hear this but it's the pipe. My brand new orings did this and I had to put high temp rtv around the orings to get it to stop. After 15-20 hrs the RTV gets blown out and I gotta do it again. I think the tolerances where the pipe meets the cylinder aren't very precise on the Betas. 

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Posted (edited)

I know you are saying its not the pipe, but just to make sure you tried everything.

Have you tried removing the silencer, and unbolting the pipe from the frame on the bottom and on the side of the bike?

Its possible that the pipe is mounted just barely off engine, and doing the above makes sure that the springs are pulling the pipe all the way to the motor. Then press hard backwards on the pipe towards the motor while revving.

Also have you replaced the stock springs with aftermarket springs?

Does it only happen in neutral?

 

Here are MUCH better springs, note you will likely need a spring puller to install these

https://www.amazon.com/gp/product/B0022ZH9I2/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Edited by Matthew Larson
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 Thanks for the advice. I will try the RTV sealant, and leaving the pipe unbolted as you guys recommend when I get home.

I was to the point i was going to just replace the pipe anyway but it's not physically damaged that I can see, so I did replace the springs with new oem springs, and I've tried the green ktm o rings, and some aftermarket ones the dealer had and it has not changed.

The old cylinder was worn out and grooved pretty badly in the pipe area, which was why I was hoping this new cylinder would have fixed it of that was the issue.

 

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Posted (edited)

Remove shock and do same rev test. Sometimes it's a harmonic range that vibrates the shock spring.

I use KTM O rings (tusk branded), RTV (as needed), and cheap Tusk (raven?) pipe springs. The Tusk springs really require a spring puller to install - lots of tension there.

Edited by shrubitup
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It is hard to tell from the video, but are you running a pipe guard? My 2014 used to rattle similar to that if the pipe guard was misaligned slightly. 

Other than that, I can only suggest the power valve flapper. My GasGas used to rattle like a bastard due to poor adjustment from the factory. It sounded differently but rattled when the engine was coasting down from a throttle blip. 

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Are you running an aluminum skid plate? The aluminum skid plate on my KTM 300 magnified the 2T engine noise. You could also try loosening the mounting bracket for the pipe to see if it makes the rattle louder or quieter then your can try loosening the muffler bolts to see if that makes the rattle louder or quieter.  

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My 18 XT makes a similar sound. Im about to change the exhaust O rings and use RTV as well. Hopefully its the fix. 

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Posted (edited)

Plastic skid plate on the bike.

I removed the carbon pipe guard, pulled the pipe and put rtv all around the oring area and let it sit over night.

With all the pipe bolts out and the springs tight, with rtv, it did not change anything. Again pushing, pulling, I even wrapped a ratchet strap around the pipe and motor to pull it tight, and still no change. Then I took the springs off and pulled the pipe all the way out so only the 1st o-ring was sealing, and while it had a slight exhaust leak then, the rattle is still here. 

I'm still pretty confident the sound is not from the pipe

Edited by Jankyl29
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I had same noise last year,ended up being loose front engine mount bolt.

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One last thing to check, see if the exhaust header springs are touching/rubbing against the pipe. The vibrating springs can cause a rattling sound when the bike is being revved but not at idle.    

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32 minutes ago, Jankyl29 said:

Plastic skid plate on the bike.

I removed the carbon pipe guard, pulled the pipe and put rtv all around the oring area and let it sit over night.

With all the pipe bolts out and the springs tight, with rtv, it did not change anything. Again pushing, pulling, I even wrapped a ratchet strap around the pipe and motor to pull it tight, and still no change. Then I took the springs off and pulled the pipe all the way out so only the 1st o-ring was sealing, and while it had a slight exhaust leak then, the rattle is still here. 

I'm still pretty confident the sound is not from the pipe

I got an aluminum combo skid plate pipe guard and I don’t have that sound. Not sure from the vid what that is..

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Posted (edited)

Here's another video, can't really see but all pipe bolts are off, tight springs and I'm pushing / pulling with a tire iron and it makes no change in pitch at all...I STILL don't think it's the pipe...you can clearly hear the rattle. It sounds like a bolt just laying inside the clutch cover (which it is not) . This phone is a piece of crap, sorry for the shit videos.

 

I believe it's the powervalve to some degree still...with the pipe off, how much should those powervalve flaps inside the cylinder rattle around? Mine are quite loose feeling and I can jiggle them pretty easily to make a chatter sound.

EDIT: YES, it sounds like this in neutral, In gear, while riding, under load, just all the time...But it seems to quiet the ever slightest once the bike is hot, or maybe I'm just going loopy from all the rattling 

Edited by Jankyl29
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25 minutes ago, Jankyl29 said:

Here's another video, can't really see but all pipe bolts are off, tight springs and I'm pushing / pulling with a tire iron and it makes no change in pitch at all...I STILL don't think it's the pipe...you can clearly hear the rattle. It sounds like a bolt just laying inside the clutch cover (which it is not) . This phone is a piece of crap, sorry for the shit videos.

 

I believe it's the powervalve to some degree still...with the pipe off, how much should those powervalve flaps inside the cylinder rattle around? Mine are quite loose feeling and I can jiggle them pretty easily to make a chatter sound.

EDIT: YES, it sounds like this in neutral, In gear, while riding, under load, just all the time...But it seems to quiet the ever slightest once the bike is hot, or maybe I'm just going loopy from all the rattling 

I’m wondering if I had taken a video of my bike and went close to the motor like you have?? if my bike would sound similar??? Im wondering about comparing how 2 phones make videos different too??? Idk. Not conclusive. Have you gone through the whole bike tightening everything??

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Posted (edited)
7 minutes ago, hawaiidirtrider said:

I’m wondering if I had taken a video of my bike and went close to the motor like you have?? if my bike would sound similar??? Im wondering about comparing how 2 phones make videos different too??? Idk. Not conclusive. Have you gone through the whole bike tightening everything??

Yes. There is nothing loose on the exterior. There is now literally 2.5 hours on a brand new Beta frame, complete motor rebuild, all new plastics, bearings everywhere. The reason the bike was pulled apart last November was for this sound, then found a crack in the frame. It took so long for the new frame and motor to get back that I just recently got to assemble the bike. Every bolt was torqued to Beta specs on the chassis and installing the motor.

And at the track, this is the shittiest sounding 2 stroke I came across.  Literally every other beta or old ktm at the last race does not sound like my bike. I was on the line next to 2 xtrainers, neither rattle like mine. 

Edited by Jankyl29
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24 minutes ago, Jankyl29 said:

Yes. There is nothing loose on the exterior. There is now literally 2.5 hours on a brand new Beta frame, complete motor rebuild, all new plastics, bearings everywhere. The reason the bike was pulled apart last November was for this sound, then found a crack in the frame. It took so long for the new frame and motor to get back that I just recently got to assemble the bike. Every bolt was torqued to Beta specs on the chassis and installing the motor.

And at the track, this is the shittiest sounding 2 stroke I came across.  Literally every other beta or old ktm at the last race does not sound like my bike. I was on the line next to 2 xtrainers, neither rattle like mine. 

Rings? Maybe it needs to seat? Idk. Ride it. It’s all new. I don’t think it sounds shitty. It’s hard to tell compared to being there I think. Im wondering how much different it is compared is  to other Betas. It’s hard to tell unless side by side. 

Edited by hawaiidirtrider

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5 hours ago, Jankyl29 said:

Yes. There is nothing loose on the exterior. There is now literally 2.5 hours on a brand new Beta frame, complete motor rebuild, all new plastics, bearings everywhere. The reason the bike was pulled apart last November was for this sound, then found a crack in the frame. It took so long for the new frame and motor to get back that I just recently got to assemble the bike. Every bolt was torqued to Beta specs on the chassis and installing the motor.

And at the track, this is the shittiest sounding 2 stroke I came across.  Literally every other beta or old ktm at the last race does not sound like my bike. I was on the line next to 2 xtrainers, neither rattle like mine. 

have you tried removing the shock and then idling/revving?

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5 hours ago, shrubitup said:

have you tried removing the shock and then idling/revving?

I will drop the shock and forks from the bike after I get back from Battle Of the Goats today.

I understand some people may think this is normal from hearing it in a video, it is not. Ive owned this bike from new, ive had it for 2 motor rebuilds, this is not how it always was. It may not be anything serious at all (which I don't think it is) but I'm not stopping until it stops. 

My 350rr in the background of those videos is waiting for a fuel pressure regulator from the dealer. He told me to stop by with the 300 for him to hear the sound. So hopefully the regulator comes in next week and I can let the dealer hear this.

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