Why does the '99 RMX250 power valve break?

Russell McInnes

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Feb 12, 2001, 10:24:14 PM2/12/01

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Hi there,

as the subject says, I am trying to figure out why the power valve has
cracked. I'd much rather have a good idea of why it has broken before I put
the new one I just paid $280 bucks for in. If anyone else has any
experiences to relate I am interested.

It is the bottom layer of the valve, below where the pin that attaches to
the arm that opens and closes the valve is attached. Pictures would be good
hey :)

|--/-|
__|/ |__
| |
| |
| |
|_ ------ _|

It is broken where I have put the /'s. What confuses me is that there is
really no force that twists or flexes the valve in a way that would cause
this type of break. The valve is only pulled in and out (up and down the
page). And yes, I recently cleaned it out - it wasn't all gummed up.

The '99 RMX250 power valve consists of three layers that slide across one
another, opening up more as the revs increase (I guess). It is pulled open
and pushed closed by the action of an arm that connects to the bottom layer
of the valve. The top layer rests in against the cylinder head - two tabs
fit into two depressions in the cylinder head to prevent it from sliding in
too far and hitting the piston.

So, suggestions?

Cheers,
Russ.

dsc

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Feb 13, 2001, 9:03:27 AM2/13/01

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I think it is piss poor design. :) Either that or something happens that
puts it out of adjustment enought to get slapped by the piston. I have a
friend that has a 1989 RMX250 and a 1998 RMX250. He has had this failure on
both bikes... twice on the 1989.

dsc

Russell McInnes <R.Mc...@latrobe.edu.au> wrote in message
news:96a9cd$t1v$1...@news.latrobe.edu.au...

Aaron Swarvar

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Feb 13, 2001, 4:14:23 PM2/13/01

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It's a suzuki...that is explanation enough! I have never been to impressed
with the way Suzukis are put together and their reliability. My bro had a 96
RM125...they had some stupid little plastic clip holding some cheap, crappy
linkage arm on the powervalve that you had to destroy in order to take the
powervalve linkage off! How STUPID! On the plus side the bike was well
suspended and ran decent, except for the constant clutch slip that never went
away, even when the clutch plates were replaced and new springs installed...

Aaron
2001 YZ125
#691

MX Tuner

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Feb 14, 2001, 6:52:55 PM2/14/01

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On 13 Feb 2001 21:14:23 GMT, mxrac...@aol.com (Aaron Swarvar) wrote:

>It's a suzuki...that is explanation enough! I have never been to impressed
>with the way Suzukis are put together and their reliability. My bro had a 96
>RM125...they had some stupid little plastic clip holding some cheap, crappy
>linkage arm on the powervalve that you had to destroy in order to take the
>powervalve linkage off! How STUPID!

Nah. All you had to do was be smarter than the clip.

MX Tuner

Russell McInnes

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Feb 14, 2001, 8:32:01 PM2/14/01

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Well there is no indication that the piston has come into contact with the
powervalve. After lots of thought I reckon that it is caused by vibration.
It must open and close pretty violently judging by the wear that the pins on
the middle layer inflict on the slots in the top and bottom (particularly
the top) layers. A bit of damping probably wouldn't go astray. When I put
the new one in I'll be liberal with the Moly-grease.

Russ.

"dsc" <Dudley....@eku.edu> wrote in message
news:2001Feb13.0...@acs.eku.edu...

Aaron Swarvar

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Feb 15, 2001, 9:22:26 AM2/15/01

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Going by what my bro had to say about it and I just took a quick look at it and
didn't see any good way to get it apart at a quick glance and went about my
business on my YZ...he broke it to get it off and couldn't see any other way to
do it. I wouldn't trust some little worn out piece of plastic in there anyway,
it was only 26 cents so I'd just figure that little clip into the price of
taking the top end apart. Regardless, suzuki should put a little more quality
into their bikes...

Aaron
2001 YZ125
#691

MX Tuner

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Feb 15, 2001, 7:08:34 PM2/15/01

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I agree. That's one reason I ride a blue bike. When I owned my RMX, I
kept a couple of those clips on hand "just in case".

MX Tuner

alex

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Feb 16, 2001, 1:13:35 PM2/16/01

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funny thing, i still use the clip. o broke a little peice off and it snaps
in and out just fine. i have also used a little zip tie just in case.

about those blue bikes? i might ride one too but the dealer in Vincents
Yamah in northern michigan sucks, i wouldn't buy you a bike there. i think
he sells them just to have something on his floor in the summer. try to get
something repaired and you get put to the end of the PWC or snomobile line.
dam dealers think their shit don't stink.

"Aaron Swarvar" <mxrac...@aol.com> wrote in message
news:20010215092226...@ng-cg1.aol.com...

J Payer

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Feb 17, 2001, 1:14:34 PM2/17/01

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Tuner wrote:

> I agree. That's one reason I ride a blue bike.

<snip>

While Yamaha might not use those cheap-o clips, I'd think twice before
bragging about their quality and reliability.

Just for the record, I ride green, so, no, I'm not offended by the
anti-yellow comments. :-)

J&K

www.smackovermotorsports.com, www.eric-gorr.com, www.appliedrace.com,
www.tssgraphics.com

MX Tuner

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Feb 17, 2001, 7:54:32 PM2/17/01

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On Sat, 17 Feb 2001 13:14:34 -0500 (EST), Pay...@webtv.net (J Payer)
wrote:

>Tuner wrote:
>
>> I agree. That's one reason I ride a blue bike.
>
><snip>
>
>While Yamaha might not use those cheap-o clips, I'd think twice before
>bragging about their quality and reliability.
>
>Just for the record, I ride green, so, no, I'm not offended by the
>anti-yellow comments. :-)

Unless a Yamaha is neglected, I've found them to be quite reliable.
But I don't do much YZ 80 work at all, so that may influence your
opinion. Is Kim still riding her YZ?

MX Tuner

J Payer

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Feb 18, 2001, 7:52:56 AM2/18/01

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Tuner wrote:

> Unless a Yamaha is neglected, I've found them
> to be quite reliable. But I don't do much YZ 80 work
> at all, so that may influence your opinion. Is Kim
> still riding her YZ?

Yeah, she's still riding it. She won the women's championship this year
in both the MX and HS divisions in the association we race in. I
haven't heard the end of it either...<LOL>

I've heard bad stories from many people about the YZ80, but hers
<knocking on wood> has been very reliable, except for the times Kim
decides to throw it down or let someone run over it. ;-)

I have a friend with a 2000 YZ125, and the bike is very well maintained.
He about got killed one night when his clutch plate broke and locked up
the tranny. If it would have happened a few seconds earlier he would
have been doing the biggest jump on the track. The bike was only a
couple weeks old at that point. A few weeks after that his clutch hub
cracked. They caught it and replaced it before it broke.

Another buddy with a YZ250 (1999 edition, again, very well maintained)
blew out 3rd gear, then 2 rides later after fixing it blew out 4th gear.
This kickstarted return spring also broke and cracked the case in the
process.

Granted, these are only 2 bikes out of many, but then I see stories on
here about 426 clutch hubs exploding, 426 rear hubs being tore up, (not
to mention Ty Davis can't even finish a race now days) it just doesn't
give a real sense these bikes are any better than the rest, save Honda.

My $.02 YMMV. Offer void in Texas.