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Discussion Starter #1 (Edited)
The Yamaha V-Twin engine used in the Star Venture/Eluders was designed so that the alternators are driven by what Yamaha calls a jack shaft, the Star Venture also has duel alternators putting out a total of 700 amps, 350 amps each.

As the engine warms up you can hear what appears to be a knock from the engine, the hotter the engine gets the louder the knock is. The Stratoliner and Roadliner use this same series of engine and have the same sound.

Yamaha determined years ago and issued a service bulletin on this and explained why and what this knocking sound is.

The steel parts and the aluminum case all expand at different rates plus you have the magnetic pulses from the alternator(s) that create a push back on the gears, this all combined together causes this knocking noise. It does not hurt anything or the longevity of the engine/alternator(s).

You can run a 20w-50 weight oil to help dampen the knocking sound if it bothers you.

Some people mistake this knocking sound as a bearing knock, but as Yamaha correctly points out in the service bulletin a bearing knock will not go away and will progressively get worse until it fails altogether.

Yamaha has instructed their service people to explain to the customer what I posted above and to tell them it is a normal sound and will not harm the engine.

I continue to run Redline 10w-40 synthetic oil in my 2018 Star Venture Transcontinental and my Blackstone lab reports on the used oil samples all come back showing excellent wear numbers with much lower wear numbers than the universal averages for this series of Yamaha V-Twin engine. Just as an example my last used oil sample revealed the following after a full 4,000 mile run on the oil:

Aluminum was 3 parts per million universal average 7 parts per million.

Chromium was 0 parts per million universal average 0 parts per million, this engine series does not have issues with ring wear.

Iron 6 parts per million universal average 12 parts per million

Copper 2 parts per million universal average 6 parts per million.

Lead 0 parts per million universal average 1 part per million.

Tin 0 parts per million universal average 1 part per million.

As you can see the Redline 10w-40 oil is providing excellent documented protection in this engine.

My engine has the knocking sound caused by the jack shaft/alternator(s) and it has not effected the engine wear at all.

You can tell this knocking sound because it will come and go with load on the drivetrain. A bearing knock would stay consistent and only get worse, so if you hear this sound don't be concerned as this is a normal sound per Yamaha.
 

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2018 Yamaha Eluder
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Just wanted some reassurance on this honestly... I'm new to this engine but dang... when hot it's getting a pretty good knocking noise from this engine. It seems to be getting worse... I've only got 4500 miles on it now but it was getting loud enough that now I was starting to think collapsed lifter or the need to check valve adjustment or something along those lines... but this is normal? Does everyone of these do this? Sound like this? Really? I'm running amsoil metric 10w40 currently but next I'll change was thinking of going 20w50.
 

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The only draw back to Yamaha engines is they either sound like a sewing machine or like someone threw a box of marbles in with the rockers.
you just have to get used to it. That is just Yamaha. The 650 is real bad and it has over 150k miles on it, it has sounded like a box of marbles for the last 110k miles.
 

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Not to give you anything to worry about but Go get the engine checked out.
I had this same loud knocking you described and then it stopped, Which required a engine rebuild.
I brought my bike in many times to the shop to have them look at it but they never found anything so when it did die I had history of bringing it in.
I think bucfan11 has a knock which might be the same as what you have and he had no engine issues however he has a different type of issue.
Mine was a knock and then got worst over a 9 month period. I had about 5k on it when it happen.
Anyway as a precaution bring it in.
I did the same and went with the 20/50 oil and that didn’t help. I am now running Redline 10/40 oil.
I have the SVTC 2018.
I have heard of any Eluders that had any of the SVTC engine issues so I hope this is just normal engine noise.
Best of luck. Let us know what you do and find out.
 

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FWIW, I don't hear a knock my 2018 SVTC @ 21k. After it gets good and warmed up (hot) I occasionally hear a ticking type noise I always assumed was the hydraulics in the valve train (it does have hydraulic lifters, yes? I don't really know, shame on me.)

I think @Bucfan's problem is a humming noise coming from the final drive somewhere. Mine will howl a little on deceleration around 30 mph or so, but I blame that on the belt drive. I know it would have been heavier, but I still think shaft drive is the only way to go on these big long haul machines.

BTW, I agree with @GARider to have the shop look at it, if for no other reason than to have it documented for later if something does come apart.
 

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Just wanted some reassurance on this honestly... I'm new to this engine but dang... when hot it's getting a pretty good knocking noise from this engine. It seems to be getting worse... I've only got 4500 miles on it now but it was getting loud enough that now I was starting to think collapsed lifter or the need to check valve adjustment or something along those lines... but this is normal? Does everyone of these do this? Sound like this? Really? I'm running amsoil metric 10w40 currently but next I'll change was thinking of going 20w50.
I’m running Yamalube 10w-40 conventional oil. You should know that if you run any viscosity recommend for this motor from the factory, Yamalube brand only, and keep records performing the oil changes at specified intervals with a variance of no more than 10% mileage you will be under a 20 year / 100k mile warranty from Yamaha, motor only. Does not include transmission or primary.

I don’t really know any specific knocking on my motor but it doesn’t make near the noise my old Vulcan 1600 used to make or any Harley I’ve had. Some have experienced knock, usually at around 7500 miles. They don’t use rollers on the valves/cam shaft setup, just straight tappets. Apparently there have been some serious failures, very few, of the cam shaft on the rear jug causing the bike to completely stop running or run very poorly. But of course it’s covered under the 5 year warranty. The skinny on this is that a few bikes were produced without the proper assembly lube and the damage began upon first start of the bike and slowly worsens from that point. I guess Harito forgot to do it after he got back from his sushi break.

Take it to a good dealer and have it listened too. See what they say.
 

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FWIW, I don't hear a knock my 2018 SVTC @ 21k. After it gets good and warmed up (hot) I occasionally hear a ticking type noise I always assumed was the hydraulics in the valve train (it does have hydraulic lifters, yes? I don't really know, shame on me.)

I think @Bucfan's problem is a humming noise coming from the final drive somewhere. Mine will howl a little on deceleration around 30 mph or so, but I blame that on the belt drive. I know it would have been heavier, but I still think shaft drive is the only way to go on these big long haul machines.

BTW, I agree with @GARider to have the shop look at it, if for no other reason than to have it documented for later if something does come apart.
I get that same howl at between 30 and 34 mph. Since it’s there while in any gear or clutch in, I just attribute it to harmonics of the straight cut gear primary. Nothing to worry about. Hey, who worries with a five year warranty. ✌ I also get that light tapping sound after warm up. Yamaha says it’s temperature variance in the different metals that are used in the system that drives the alternators.

Also my drive belt used to howl like a bitch. The slack from the factory is supposed to be something like 3-5 mm with the wheel on the ground and 5-7 mm lifted. I always ran 10 on my Harleys so I set it at 10mm slack. Quiet as a mouse. I figure a belt is a belt.
 

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I get that same howl at between 30 and 34 mph. Since it’s there while in any gear or clutch in, I just attribute it to harmonics of the straight cut gear primary. Nothing to worry about. Hey, who worries with a five year warranty. I also get that light tapping sound after warm up. Yamaha says it’s temperature variance in the different metals that are used in the system that drives the alternators.

Also my drive belt used to howl like a bitch. The slack from the factory is supposed to be something like 3-5 mm with the wheel on the ground and 5-7 mm lifted. I always ran 10 on my Harleys so I set it at 10mm slack. Quiet as a mouse. I figure a belt is a belt.
Mine was making that humming noise as well then after I got a new rear tire put on at a Harley shop it went away. I don't have the proper gage to check but it seems a bit looser. I'm betting they set it as tight as they would on any of their usual bikes they work on not Yamaha spec.

Sent from my SM-N981U using Tapatalk
 

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Mine was making that humming noise as well then after I got a new rear tire put on at a Harley shop it went away. I don't have the proper gage to check but it seems a bit looser. I'm betting they set it as tight as they would on any of their usual bikes they work on not Yamaha spec.

Sent from my SM-N981U using Tapatalk
The gauge is cheap, you can get one on Amazon. It’s just a pressure spring gauge. There’s a guide on your bike that the belt runs through. It’s just about even with tune front of your rear tire. Specs are in your owners manual or service manual. You can check it on the ground or elevated. 10 mm deflection is a good place. Manufacturers spec is too tight.
 
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