YFZ Motor Problems

[DuneJunkie]

Well, Bay Area Yamaha Shop called........camshaft went and the gears on the countershaft are about gone. So, after all parts are ordered and we are going to add the extra oil mod, should be back on the sand in a couple of weeks, pending any parts backordered.

The scarry thing is that they can't figure out why.

[duraraptor]

Uh Oh DJ that stinks, sounds like you had a rough weekend.

[Dune Dude]

I wonder if there was a harmonics vibration in the cam?

[DuneJunkie]

Uh Oh DJ that stinks, sounds like you had a rough weekend.

well, a good friend of mine just lives about .5 miles from the dunes..........he let me ride his yfz for the weekend!

got to love great friends like that!

[2fun]

Well, Bay Area Yamaha Shop called........camshaft went and the gears on the countershaft are about gone. So, after all parts are ordered and we are going to add the extra oil mod, should be back on the sand in a couple of weeks, pending any parts backordered.

The scarry thing is that they can't figure out why.

What year is the YFZ??

What kind of cam did you have in it??

How many hours on the machine??

So many questions.........

[DuneJunkie]

05 yfz
stock cam
many hours!

[2fun]

05 yfz
stock cam
many hours!

Did you do the cam mod, or leave it in stock position???

[DuneJunkie]

cam mod completed!

[2fun]

Sounds like we may be set up similarly...

I am mostly stock with a DR D slip-on, K&N intake and cam mod. 

[DuneJunkie]

i don't think its a yfz problem, its just my POS bike!

[2fun]

i don't think its a yfz problem, its just my POS bike!

you mean you ride it too often and it has high hours?  OR...?

[DuneJunkie]

I figure that I have had that bike for 24 months, and have been at the dunes at least 16-18 trips.  almost one weekend a month.  and those are usually 3 or 4 day weekends, plus a day trip in there occasionnally........

however, my bike doesen't get beat as much as other bikes.........I am just not sure why this happened.  The bottom end just went and thats all we can figure.  Bad metal..........

[2fun]

I figure that I have had that bike for 24 months, and have been at the dunes at least 16-18 trips.  almost one weekend a month.  and those are usually 3 or 4 day weekends, plus a day trip in there occasionnally........

however, my bike doesen't get beat as much as other bikes.........I am just not sure why this happened.  The bottom end just went and thats all we can figure.  Bad metal..........

Interesting......
I know I have read where a few people did the "oil" mod because they felt the stock 04/05's didn't get enough oil to the rod???  Luckily I have yet to have one of those problems (knock on wood), BUT I also have a LOT less hours on my bike than you do.  Especially since I have been in college and was only ably to ride during the summer, and once every three months while in school. 

I HAVE however made 3 trips to St. Anthony with it for a week at a time each trip.

I would guess that I've got well over 100 hours on the machine???

[DuneJunkie]

mu friend just called from diamond lake...........they were up riding in the snow............

guess what? his yfz has the same problem.  and our VIN's are within 10 of each other!

[2fun]

mu friend just called from diamond lake...........they were up riding in the snow............

guess what? his yfz has the same problem.  and our VIN's are within 10 of each other!

Now THATS pretty freaky!!

By the way, I just changed the oil and filter in the ole YFZ tonight in prep for the dune trip coming up next weekend!
I have been only using Mobil 1 fully synthetic in it for the last couple years.....

Hopefully this will help to curb any lubrication problems!

[DuneJunkie]

never gonna believe this one, it wasn't just 1 yfz, it was 2 yfz's dropped the bottom ends, plus, one yfz blew an inner coolant seal, so, that's a total of 3 yfz bottom ends, plus another with a coolant leak! ( and one broke a front sprocket) so, really 4 overall..............

[2fun]

never gonna believe this one, it wasn't just 1 yfz, it was 2 yfz's dropped the bottom ends, plus, one yfz blew an inner coolant seal, so, that's a total of 3 yfz bottom ends, plus another with a coolant leak! ( and one broke a front sprocket) so, really 4 overall..............

Holy CRAP Batman!!
Thats GOTTA look bad for Yamaha!!
Now you're making me even MORE nervous!!! LOL;D

[Dune Dude]

DJ,

Did you get your quad back?

[2fun]

DJ,

Did you get your quad back?

Yeah! Whats the scoop??

[DuneJunkie]

should be done this week.  gonna have to drive up and pick it up.  I sure will be happy to get it back, though, it does have good company there in the shop with all the other bikes!

[Towman 1]

My YFZ was the one that eat a front sproket.  You guys know what. I have the oldest YFZ 450 in our group. I ordered it 3 months before they come out on the market. I can honestly say that I ride it probably 3 times as much as any one in the state. The front sproket is the only thing that I have ever done to it. It just simply wore out. No teeth left.  I have had a couple of other things happen like the full exhaust system came apart and I had to re weld it again. But you can't blame that on the motor or Yamaha. 

I asked the Yamaha shop where DJ's bike is at about why all of these bikes are going bad all at once. Tony the mechanic told me that it was probably because the owners will wind the engines up to the full throttle and wait for long periods of time before shutting them down. Which means over reving the motors. We all know that they have an oil problem in the piston area, so that is probably what is going wrong with them.  Those 2 guys up at the lake done exactly that. Over reving there motors.  My bike is just as fast as there's and they would out run me around the lake by quite a bit. They also told me that once they get it into 5th gear, then hold it wide open.

What can I say.

[2fun]

My YFZ was the one that eat a front sproket.  You guys know what. I have the oldest YFZ 450 in our group. I ordered it 3 months before they come out on the market. I can honestly say that I ride it probably 3 times as much as any one in the state. The front sproket is the only thing that I have ever done to it. It just simply wore out. No teeth left.  I have had a couple of other things happen like the full exhaust system came apart and I had to re weld it again. But you can't blame that on the motor or Yamaha. 

I asked the Yamaha shop where DJ's bike is at about why all of these bikes are going bad all at once. Tony the mechanic told me that it was probably because the owners will wind the engines up to the full throttle and wait for long periods of time before shutting them down. Which means over reving the motors. We all know that they have an oil problem in the piston area, so that is probably what is going wrong with them.  Those 2 guys up at the lake done exactly that. Over reving there motors.  My bike is just as fast as there's and they would out run me around the lake by quite a bit. They also told me that once they get it into 5th gear, then hold it wide open.

What can I say.

I have held mine wide open for a minute or two out on the flats at Florence.  I am using fully synthetic Mobil 1 though.  Hopefully that will give some extra protection for down the road??

[Towman 1]

I run Yamaha  oil in mine.  When I open mine up all the way it is for maybe 5 seconds at the best.

[2fun]

I run Yamaha  oil in mine.  When I open mine up all the way it is for maybe 5 seconds at the best.

Many of the times I am coming out of treeshots I have it pinned for longer than that.  Sometimes however, I can get away with "blipping" the throttle all the way out.   

[Dune Dude]

So, Yamaha makes a race quad that you can't use at full throttle? 
Seems like they better address that oiling problem...

[Sandflicker]

I have the Predator TLD.  So far it's great what do the rest of you think.
Probably just opened a big can of worms   

[DuneJunkie]

motor should be back to the shop next week.  its getting some drilling work done..........

[2fun]

So, Yamaha makes a race quad that you can't use at full throttle? 
Seems like they better address that oiling problem...

I've never had a problem using it at full throttle??

Maybe I just don't have enough hours on it yet...
Posted on: February 16, 2007, 11:43:31 PM

I have the Predator TLD.  So far it's great what do the rest of you think.
Probably just opened a big can of worms   

You know, thats about the only ATV I haven't had a chance to throw a leg over??

I have nothing against them??  I think they are a bit heavier than the YFZ/TRX??

I would like to try one out sometime though!

[Towman 1]

Well I guess it is like the decussion we had a Diamond lake. Do you all drive your truck or the wifes car wide open to the grocery store ?  Why not, aren't  they ment to do that. No, I don't think so. You run any motor out of the box full throttle all the time and I guarentee you will not get to many hours on it before you have motor trouble. JMO

[DuneJunkie]

very true Towman, very true!

[2fun]

Unless there is a specific problem causing the motors to let go??

And the YFZ was made to be a racer right out of the box!

Comparing the YFZ to your wifes car is kinda like comparing a Ford focus to an F1 racer

I know the older Hondas go for decades sometimes (on the same piston and rings), and I can assure you they are also ran at full throttle a lot of the time.

[DuneJunkie]

you all are somewhat correct, but, here is what Yamaha did with the YFZ.

Yamaha took the motor size, just like taking a big block of metal, and drilled the hole for the piston, Yamaha made that hole as large as they safely and efficeintly could, without risking blowing a hole out the side, or destroying anything.  Then, they built motor around that.  That is why the YFZ was the FASTEST showroom produced quad at the time when it came out. (argue that point all day, its true!)
So, when you take that motor that was made that large and build it, then sell it to someone that wants more.  So, the customer takes it  and modifies the hell out of it.  Aftermarket CDI Rev Box, for and extra 1000 rpm, aftermarket exhaust, advance the cam timing, and all the other stuff we do to these bikes, we have taken a bike that was built to max performance and pushed it even farther!

THEY ARE NOT MADE TO BE PUSHED LIKE THAT! and last for long periods of time.  I may not ride as often as others (Towman) but, when I do, I push that YFZ to the limit!  No questions!  I ask a lot of it! 

Do I think it should have failed?  NO
Do I think Yamaha owes me something? maybe.......(only cuz it sucks rebuilding a motor)!
Is it Yamaha's fault that it's in the shop?  NO!

It's mine................end of story!  I have no hard feelings about any of it, and once I get my bike back, I will continue to push it just as hard as before, (maybe with a change of throttle usage though).............

[Dune Dude]

It would be interesting to see if pushing the machine to its limits for extended periods of time causing it to fail is an inherent problem with any engine or just specific to Yamaha?

Does anyone have any of these same stories with Honda? Suzuki?

[DuneJunkie]

I don't think you will find the problems with the other makes, because they didn't design the engine the way that yamaha did..........just my .02....................

[Towman 1]

Well there is no doubt that some of the YFZ's has problems. But there is other YFZ's that don't. There all built the same way in the same mold. So that means one thing. The 3 YFZ's that froze up was simply rode different than all the others in our group. These three guys all have admitted that they ride a lot of the time full throttle for great periods of time. While I will open mine up full throttle for just a short time. Maybe 5 seconds. We also know that the YFZ's are still the fastest 450's out so far. Thats acording to the magazines.

[2fun]

I know the YFZ is a highly modified motor right out of the box, but you can't help but change the exhaust and intake to let her breathe a little better!

As for the rev box, I left mine stock. 
I DID however retard the exhaust cam one tooth to set it to the dirtbike timing...

[Towman 1]

You are right there about the exhaust and intake. I done the valve adj. on mine to and also I put the rev box on. I really didn't plan on using it that much, but my friend in Portland got me a good deal on it. I am glad I did because in the trails down here in the sand, it lets you rev up a little higher and really eliminates a whole lot of shifting.

[2fun]

You are right there about the exhaust and intake. I done the valve adj. on mine to and also I put the rev box on. I really didn't plan on using it that much, but my friend in Portland got me a good deal on it. I am glad I did because in the trails down here in the sand, it lets you rev up a little higher and really eliminates a whole lot of shifting.

You said you did the valve adj??  Do you mean you did the cam mod or no??
I checked the valve clearance when I did my cam mod and they were still in spec!

[DuneJunkie]

Just got off the phone with Tony at Bay Area Yamaha


The YFZ is ready to rock!

[Dune Dude]

Did ya get sand on the tires yet?

[DuneJunkie]

nope, no sand yet...........I am picking it up on friday!