My EXUP Adventures

[YZFBuck]

I have a 97 YZF1000 with around 14,000 miles on it and I thought I would pass on some recent events related to the EXUP system. I know this is a "well discussed" topic.

I started noticing this rattle and a few reads on this site had me pretty sure it was the EXUP. I was a little baffled since the bike only had about 10,000 miles on it at the time. I recently had the bike in the shop to have some oil seals replaced (front sprocket, shifter, etc - the dreaded kickstand oil footprint) and new chain and sprockets, so I asked the guy if he would look at the EXUP. He told me a few days later the collar and the valve itself needed to be replaced. I was looking at a few hundred dollars in parts that I just wasn't ready to spend.

We decided (on his advice) to remove the valve and see if I noticed a difference. I retained the parts. He fixed it up with a nut and bolt in the hole in the housing and simply removed the valve and related parts.

The first thing I noticed is how much LOUDER the bike was at idle and low rpm. I have a V&H SS2R can on the bike. I didn't notice much of a difference sound wise and higher rpms. Figures since the valve was no longer there closing up the exhaust at lower rpms.

I also noticed a HUGE difference in power at around 3000 rpm, there simply wasn't any. I would be riding around town and roll on the throttle and it would sort of stumble and finally get into some power. It really resulted in a downshift where one wasn't needed before. It was really a BIG difference. The bike also now had a very rough idle.

I decided to replace the EXUP and started looking around to order parts. I was messing with the old parts to see how it all went together and I'll be darned if I could detect any "play" between the collar and the valve, just and snug as could be. I decided to put the old parts back in and adjust everything according to the service book and see what happened. I did that and adjusted the cables and I'll be darned if that thing doesn't work like a champ. I have put a few hundred miles on since then with no rattle and the bike is running better than before.

So, why did I have the rattle? I have two theories. First, the cables were way out of adjustment, althought the mechanic said they were fine. Second, I think perhaps the valve was shaking side to side. There is a little spring in there between the washer and the pulley that is meant to keep it from doing that, but it is not much of a spring. I tool real care to make sure it was installed properly. Either way, the rattle is gone and I did do anything else to it than put it back together the way the book says. Go figure.

By the way, replacing those seal fixed the "oily kickstand footprint".

[djalbin]

I didn't do anything else to it than put it back together ... Go figure.

Similar to the experience I had with my '94 FZR1000. Horn stopped working. I took the horn off and dismantled it. Nothing apparently wrong. I put it back together and it has worked fine ever since. Some mechanical assemblies just seem to get stuck, loose, or out of alignment, etc ... and the simple act of disassembly/reassembly puts them back into working order again.

Don

[ftang]

Mechanical Repairs Rule #2: Take it apart, clean it, put it back together again.

[jjs777]

Mechanical Repairs Rule #2: Take it apart, clean it, put it back together again.

my experience has been....

Take it apart, look at it...keep looking at it....still looking at it, throwing it back together without having touched a thing because I didnt see anything wrong, and then the thing works


so forme dj's rule applies...take apart put back together and wah-la....it workie

[WickedFZR1K]

Funny how things work like that huh? Yes, the exup cables could have been out of wack, if one was loose, it COULD possibly cause the valve to rattle as it bounced off the bottom of the housing (engine pulses could cause this), but thats a pretty big COULD, if they were that loose, you would have surging all over the place. My cables got out of wack and it felt like I had a MAJOR hop in the front rim, the bike lunged and felt like complete poop!!!

Second theory, yeah you had some slop in the bushings, being that the exhaust exits the engine at well over 1000 degrees F, the cast iron housing that hols the valve is gonna get hot, break down the lube on the bushings and accelerate wear...

I had a similar noise that I just couldnt seem to track down, sounded like a knock around 4500 rpm on the highway in top gear. After going nearly mental I figured it out. It was one of the face sheild side covers on my helmet, the bolt was loose and it was flapping a bit, tightened it with some blue thread lock, bye bye knock! LOL