Hey DJ

The motor does have 2 counter balancers. I can't remeber the page in the service manual but I've seen them in there. As for Yami not ducking issues do a search for Sticky valves or SVS here and on the RSR forum. Plenty of ducking goin on.

tamaule wrote:
I have an 04 RS with 2000 miles. I'm not sure if I have the same problem or not.
Here is the symptoms and my opinion:
Warm engine, Low rpm high gear (chugging through town). Crack the throttle about 1/8 turn (pilot circuit??) I get a knocking sound. If I throttle up or down it goes away. If I pull in the clutch and free rap the engine there is no knock at all. This alone leads me to believe that it is not piston slap or wrist pin bearings. If you are hearing it when you rap the engine in netural then I would suspect internal problems in a big way. True, sometimes you need to load an engine to have an issue show up -- if it is loud enough to be heard at 70mph by another rider I would think it could be heard in netural as well.

There has been much talk about weak valve springs on some 04/05 R*s. Some people are getting yamaha to pay for new stage II springs to be installed. My understanding is that when this is the issue there is a marked performance hit - you actually lose a cylinder due to the valve hanging open.

If you are getting the cough through the carb as many of us do - look at a jet kit.

Hope this helpsPost edited by: tamaule, at: 2005/05/25 21:00
I'm wondering IF indeed you even have any mechanical issues causing the knocks...
Even though the RS engine is a low compression engine ( 8.3 to 1 ), I am very convinced that when lugging the engine at very low RPM's under load, that it is very possible that this is often a knock caused by the fuel igniting and exploding and smacking the pistons hard causing a knocking sound.
If the engine is under load, and doing an extremely slow RPM, the pistons will not move as fast as the fuel is exploding in the cylinder.
Even if you use premium fuel, you can still get knocks at low RPM lugging in the RS engine. This is why I think a lot of engine "knocks" in the RS engine are caused by lugging and low RPM operation under heavy loads.
Here's something to ponder:
The Ford Model A engine develops it's highest torque output at only 1,000 RPM!
The only reason the engine does not knock itself apart, is because the Model A only has a compression ratio of only 4.1 to 1!

Don't be afraid to drop a gear and rev the Roadie up a little guys. The RS is capable of low RPM operation because of it's long stroke, but it cools better and will last longer when run at moderate RPM's instead of "lugging" under load.
You will not hurt the engine lugging it when just "coasting" through town, but if you need to accelerate, drop down a gear, and THEN give her some throttle. Lugging under heavy load is very hard on your pistons, rings, and rod-bearings no matter how big they are.

Musky wrote:
Hey DJ

The motor does have 2 counter balancers. I can't remeber the page in the service manual but I've seen them in there. As for Yami not ducking issues do a search for Sticky valves or SVS here and on the RSR forum. Plenty of ducking goin on.

Are you referring to the crankshaft throws? It does have two of those, but no gear driven shafts with porkchop counterweights, usually driven in opposite direction at twice engine speed, to nulify vibrations. Harley has this system in some of the Evo engines, as did Yamaha in the old TX750, one of which I bought new in 1974. This bike first came out in 1973, and was the second four stroke marketed by Yamaha behind the XS650. The bike was bedeviled with mechanical problems, oil leaks, and balancer failures. As far as Yamaha's support was concerned, they not only extended warranty on 1973 bikes, but also factory teams intercepted every new 1974 model at the warehouses, removed and destroyed the existing engines, and installed new engines with extensive upgrades. They ceased production of that bike in 1974, but I ran mine for seventeen years.

This noise issue interests me because I became involved in the Road Star after talking to a guy who had 48000 miles in a 2004. Operation was flawless, and to this date the bike has zero oil consumption. He also cautioned me that the engine was not as smooth or quiet as other Yamahas I've had, and was inclined to hammer on low speed pulls when hot. Being thus forewarned, I bought a leftover 2005 last year, and what he'd told me was spot on. Upside is that the bike runs beautifully, at around 3000 miles of operation fuel mileage is up to 45, and in a 400 mile run last week in 96 degree heat, oil level was right there. Hey, man - I'm happy!

One other member brought up a challenging point: how many engine failures have been attributed to this noise? Yamaha had at least five years of R&D in this engine before its release ten years ago. Who knows if perhaps ceramic treatment of the cylinder bores has an amplifying effect on a noise that would be otherwise normal? How many have gone running to their dealers in the last forty years about the starter clutch noise from the engine kicking back when you shut it down? Perfectly normal. I honestly feel that if Yamaha were concerned about this noise resulting in catastrophic failure, they'd do something about it. With all the effort they've made to penetrate the big bore cruiser arena, they'd be nuts if they didn't.

Interesting points made twixt Musky and Diesel Jack. From what I've gathered so far on the forum there has never been a blown R* engine to date. Noisy to many an ear but yet to hear of an "aw-crap-there-goes-the-valves-through-the-heads/pistons" incident. That in itself is a testament to the R*'s durability in my estimation. Mine knocks with a decibel level almost equal to my stage 1 pipes but it just keeps on hauling a$$. Will be doing some carb/pipe/etc. mods this winter so I'll go from there. Till then I'm on the road AMAP!

Mine has always had a slight knock.It`s hot here a good portion of the riding season.I did notice this past trip to Brian Head , UT. that the engine was
quieter at altitude.Between 8,000 to 10,000 feet
(A Road Star runs like a fine Watch,only louder)<br><br>Post edited by: vegasdave, at: 2007/08/15 07:46