Knock when getting off the throttle

[jasonglad]

Hey all

 

I’m new to the venture scene, if I’m hoping someone might be able to give me some advice. Just bought a 2009 royal star 1300 (XVZ13CT), I just did the valves and a carb sync this week. The bike runs perfectly aside from a noticeable knock sound when letting off of the throttle just slightly. The sound only rears it’s ugly head when the bike is warm and goes away upon acceleration or full off on the throttle. Only happens while driving/under load. Any idea what it might be? Rod knock?

 

thanks in advance

 

after thought....if the carb sync isn’t good, could that cause a knock from one of the Pistons??

Edited May 22, 2018 by jasonglad

[bongobobny]

What it could be is the notorious "popping during deceleration" which is usually caused by the Air Injection System. The AIS is known for causing this and you have one of two options, either fix it properly or eliminate it completely!

 

Do a little search here on the site and you should find adequate information on this. There is also a downloadable factory service manual here in the Read Only Technical forum. There is also a remote possibility that your Throttle Position Sensor can be dirty, but I kind of doubt it because you are only noticing it on deceleration.

 

I kind of doubt it is a rod knock as these engines are pretty much bulletproof. Improper carb sync will just make them run a little rough, run a little hotter, and lower your MPG.

 

Have you changed the oil yet?? Make sure you use the proper oil in your engine as you have a "wet" clutch and you do NOT want to use any oil with friction modifiers in them as that will cause your clutch to slip...

[jasonglad]

Thanks for your advice! Much appreciated, what oil is recommended? I did just put new 10w-30 motorcycle oil in, maybe that oil has something to do with the noise?

[bongobobny]

I believe the book calls for 15W45, so 10W30 is way too light. A lot of us use Diesel engine oil, with Shell Rotella T being the most popular.

 

Here's another remote possibility. Is there, by any chance, an aftermarket metal radiator cover on the bike? If there is one and it was not properly installed with the rubber bumpers on it the grill can and will vibrate and hit the radiator on the edge making a terrible racket at certain RPM's.

 

Speaking of RPM's, you are not trying to drive your bike like a Harley, are you? These V4's like higher RPM's as your power band doesn't even start until above 3500 RPM! Maybe you are lugging your engine! To give you an example, 1st gear should be good for 20 to 25 MPH, 2nd up to 35 to 40, 3rd gear around 50, 4th up to 65 to 70, and don't even THINK of using 5th under 60! To give you another example, the top speed in 3rd gear is around 90 MPH! The bike has a rev limiter so you won't hurt the engine by over-revving it! Your fuel economy actually is less at lower RPM's than at higher RPM's!

 

Perhaps if you could make a sound clip of what it sounds like we can analyze it better...

[BlueSky]

Only use oil that meets the JASO MA specification. It is for motorcycles with wet clutches. Rotella meets that spec. Choose the correct viscosity and the proper spec as stated.

[tz89]

Speaking of RPM's, you are not trying to drive your bike like a Harley, are you? These V4's like higher RPM's as your power band doesn't even start until above 3500 RPM! Maybe you are lugging your engine! To give you an example, 1st gear should be good for 20 to 25 MPH, 2nd up to 35 to 40, 3rd gear around 50, 4th up to 65 to 70, and don't even THINK of using 5th under 60! To give you another example, the top speed in 3rd gear is around 90 MPH! The bike has a rev limiter so you won't hurt the engine by over-revving it! Your fuel economy actually is less at lower RPM's than at higher RPM's!

 

 

[jasonglad]

I believe the book calls for 15W45, so 10W30 is way too light. A lot of us use Diesel engine oil, with Shell Rotella T being the most popular.

 

Here's another remote possibility. Is there, by any chance, an aftermarket metal radiator cover on the bike? If there is one and it was not properly installed with the rubber bumpers on it the grill can and will vibrate and hit the radiator on the edge making a terrible racket at certain RPM's.

 

Speaking of RPM's, you are not trying to drive your bike like a Harley, are you? These V4's like higher RPM's as your power band doesn't even start until above 3500 RPM! Maybe you are lugging your engine! To give you an example, 1st gear should be good for 20 to 25 MPH, 2nd up to 35 to 40, 3rd gear around 50, 4th up to 65 to 70, and don't even THINK of using 5th under 60! To give you another example, the top speed in 3rd gear is around 90 MPH! The bike has a rev limiter so you won't hurt the engine by over-revving it! Your fuel economy actually is less at lower RPM's than at higher RPM's!

 

Perhaps if you could make a sound clip of what it sounds like we can analyze it better...

 

 

thanks bongo, sounds like I have some bad riding habits I’ll have to get past. I’ve definitely been driving like a Harley, didn’t realize these bikes were designed that way

 

today I’m going to check for the radiator cover issue, plug the AIS and sync the carbs. Just got my carb sync mamomiter today so we’ll give it a go. Oh, I’ll also drop the oil and put in some fresh 15w-40 and see where we end up. If the noise still hangs around, I’ll try to get a recording of it and post it on here. thanks for your help! It’s very much appreciated!

[bongobobny]

Glad to be of assistance! You will find out we are one big happy family around here!

[jasonglad]

Quick update.....I haven't had time to block the AIS yet, but I did sync up the carbs and drop the old oil. I can't believe the difference, I thought it was running great before but after carb sync the difference is incredible!

 

As for the noise, I tried getting a good recording of it, but road noise and wind made it pretty difficult. However, when I was tinkering around with it in my driveway, I was able to get the noise (albeit much quieter without the driving load) by throttling up a bit and letting off, I can also get the rattle if let the clutch out really quickly. It sounded to me like it was coming from the clutch cover. So, next project will be doing the clutch.

 

Any advice on process / parts when doing this job?

[bongobobny]

That depends on how much money you want to spend!

 

The most expensive conversion is to go with the Barnett kit. A cheaper upgrade is to replace your clutch spring with a thicker PCW Racing spring. Member Skydoc_17 (Earl Harrell) sells these. There is also an upgraded Heavy Duty Yamaha clutch disc which has about twice the area of the stock one. Do a search and there is a nice step by step instruction article complete with pictures here on the site...

[jasonglad]

Blocked the AIS tonight, thought I’d share these cool little plugs I found at my local auto parts store. They’re 3/4” expansion plugs, cost $3 ea. Worked great and was still able to Recconect time the hoses over the top of them.

[Freebird]

Looks like a good solution. I had just used rubber stoppers and they worked ok but those look like a better choice.

[ChiefGunner]

That depends on how much money you want to spend!

 

The most expensive conversion is to go with the Barnett kit. A cheaper upgrade is to replace your clutch spring with a thicker PCW Racing spring. Member Skydoc_17 (Earl Harrell) sells these. There is also an upgraded Heavy Duty Yamaha clutch disc which has about twice the area of the stock one. Do a search and there is a nice step by step instruction article complete with pictures here on the site...

 

I rode my 91 VR pretty hard. During the 120k miles I had to rebuild the clutch 3 times UNTIL I found a tech tip in the OLD Venture Touring Society. Remember VTS before it became MTS (Motorcycle Touring Society)?

Anyways, the problem with the wear and sometimes “chatter” is because of the weak clutch spring. Just a single concave ring that sits in a retainer basket. The Barnett Clutch springs wouldn’t work on this application, so I used the Barnett rings & friction plates but HERE’s the key. The spring retainer basket is just deep enough where you can STACK TWO of the stock clutch springs. The retainer basket is deep enough to still hold 3/4 of the spring thickness so it does fine.

Now you WILL feel a difference in the clutch pull, but when you romp HARD in the engine that power has no where to go so the front end IS , I repeat IS coming UP!!

 

I kept her SHOWROOM clean and had her repainted a 96 Dodge Viper RT Blue![ATTACH=CONFIG]112697[/ATTACH]

[RDawson]

Great looking scoot Chief. Still got her? Love the looks of the 1st n 3rd gens.