Can anyone identify these rotors?

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Jasonk

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Hi everyone. Just bought a new to me 1985. Had a bunch of yamahas (fz1, Fjr) even rebuilt an old venture royale several years back.

I noticed some rattling when I first rode this new bike thought it was the headlight bezel then noticed these rotors seem to have a crazy amount of play built into them. I’ve heard of floating rotors but this is something new to me. Everything looks in order as far as the rivets that hold the outer part of the rotor in place. The braking is sufficient and it’s smooth without any pulsing. I have video w/ sound but dont think I can post it here.
In any event thanks for the well organized forum already been doing lots of lurking and searching.
B567147A-4F69-4C4D-A2D1-5B74C9DB3AA9.jpeg
 

Jasonk

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Thank you! Is it common for these to have a lot of play in your experience? It’s hard to estimate but they can move maybe up to 1/16” inside the riveted housing. I can grab the rotor with two fingers and make it go clicking clack in a way that just doesn’t seem right. I’ve never had a set of rotors constructed like this
 

Fire-medic

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What you have encountered are referred to as floating rotors. If they stop making that clacking noise, it means that they need cleaning at the rivets to remove the build-up of brake pad dust. Ducati's that use floating rotors and dry clutches are notorious for making a racket.
 

Jasonk

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What you have encountered are referred to as floating rotors
Yes is suppose what I had on other bikes was semi floating. They are noisy at idle but seem to work just fine. I dont think they are my thing.
 

totalcomfort

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Remember on these bikes start slow. Take 1 v boost a day and slowly increase the dose till you hit o s#$t.
Then back down dose a little and enjoy!!
 

Jasonk

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Remember on these bikes start slow. Take 1 v boost a day and slowly increase the dose till you hit o s#$t.
Then back down dose a little and enjoy!!
Thanks! Apparently PO removed the v boost. My dad had 3 gen1s over the years as I was growing up.
 

Fire-medic

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Removing the vboost is the Dynojet stage 7 Kit along with other changes in intake. The four individual pod air filters, the air filter Breather assembly with what looks like a black canister that goes to the oil filler cap, needle and jetting changes.
 

Jasonk

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Removing the vboost is the Dynojet stage 7 Kit along with other changes in intake. The four individual pod air filters, the air filter Breather assembly with what looks like a black canister that goes to the oil filler cap, needle and jetting changes.
affirmative. Thanks. It’s got a stumble/bog at top end. Bike has been sitting for a year. PO said he started it occasionally but I’m wondering if those main jets have some buildup I can blow out with some avgas. It idles and puts around smoothly.
 

Fire-medic

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affirmative. Thanks. It’s got a stumble/bog at top end. Bike has been sitting for a year. PO said he started it occasionally but I’m wondering if those main jets have some buildup I can blow out with some avgas. It idles and puts around smoothly.
Hah! I beat desert_max, again! I suspect your pilot jets are plugged, though the top-end isn't where they are metering things. When these bikes sit for several months, with gas, the tiny pilot jet passages frequently clog-up.

You can try some-sort of additive, or your choice of av-gas, but in the end, it's usually the thing to-do, to remove the carbs, and to clean them thoroughly. I use an ultrasonic cleaner. Try draining the individual carbs into a receptacle, via the float bowl drain screws, and those small rubber tubes sticking-out the carburetor brackets. Closely-examine the drained gas for contaminants: water (it appears as a 'lens' floating on the gasoline, due to different viscosities) and particulate material. If you see particulate material, next check is the bottom of the inside of the gas tank. Assuming it's not been coated, you should see a shiny-metal interior. If not, you need to clean the gas tank. Do a search on-here for Kyle's choice of tank liner, if you go that route. Also search for various tank cleaning methods, I use a pressure washer and then vinegar. Remove the fuel level reserve sending unit before using a caustic liquid cleaner, like vinegar because if you don't, you risk destroying the potmetal die-casting for the fuel level reserve sending unit. Fabricate and install a block-off plate from a piece of strap steel or aluminum plate. You can also search for pics of one of those, and cleaning methods.

A dirty air filter can also cause top-end issues. A common mistake for new users of the K&N-type pleated gauze air filter is to use too-much spray-can oil.
 
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Jasonk

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Hah! I beat desert_max, again! I suspect your pilot jets are plugged, though the top-end isn't where they are metering things. When these bikes sit for several months, with gas, the tiny pilot jet passages frequently clog-up.

You can try some-sort of additive, or your choice of av-gas, but in the end, it's usually the thing to-do, to remove the carbs, and to clean them thoroughly. I use an ultrasonic cleaner. Try draining the individual carbs into a receptacle, via the float bowl drain screws, and those small rubber tubes sticking-out the carburetor brackets. Closely-examine the drained gas for contaminants: water (it appears as a 'lens' floating on the gasoline, due to different viscosities) and particulate material. If you see particulate material, next check is the bottom of the inside of the gas tank. Assuming it's not been coated, you should see a shiny-metal interior. If not, you need to clean the gas tank. Do a search on-here for Kyle's choice of tank liner, if you go that route. Also search for various tank cleaning methods, I use a pressure washer and then vinegar. Remove the fuel level reserve sending unit before using a caustic liquid cleaner, like vinegar because if you don't, you risk destroying the potmetal die-casting for the fuel level reserve sending unit. Fabricate and install a block-off plate from a piece of strap steel or aluminum plate. You can also search for pics of one of those, and cleaning methods.

A dirty air filter can also cause top-end issues. A common mistake for new users of the K&N-type pleated gauze air filter is to use too-much spray-can oil.
awesome info thanks!
 

Jasonk

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while I have you, is there a way to quiet down the kerker 4-2-1 without messing Up the balance of the carb setup (presuming this thing is just dirty).? It so damn loud. I got this bike so my son can ride with but I think he’ll be scared shitless. Was thinking a different slip on might be an option but wondering if the extra noise is more or less due to the headers.
 

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