tristan18au

Member
Jun 3, 2001
186
0
i own a 1998 xr250 and it rattles something terable when it gets hot, and does a bit when cold.its had a new cam chain, valves and the valve clearance i have triple checked and there fine!
also are the rocker arms ment to have a tiny bit of play in them?
all 4 have play in them, the bike has plenty of compresion and is starting easy when cold but not when hot.
what the hell is going on!!???

please help:think

also could my staintune exhuast be makinb the noise louder?
 

Kawidude

D'oh!
LIFETIME SPONSOR
May 23, 2000
1,386
0
I recently had a similar problem with my '97 XR400. It was making a really strange rattling sound that seemed to get worse as it warmed up. I thought it was the cam chain or the valves out of adjustment. After repeatedly checking each of those items, I discovered that it was a loose core in my FMF pipe. The center core loosened enough to move and vibrate a little. It was frustrating because it really sounded like it was coming from the engine and not the silencer. I'd suggested disassembling your silencer and checking it out.
 

Kawidude

D'oh!
LIFETIME SPONSOR
May 23, 2000
1,386
0
I would still check the silencer just to be safe. When I first heard the sound on my bike, I was absolutely convinced that it was coming from the engine. I had two buddies listen to it and they were both positive it was the cam chain. I guess the sound of the loose core in the silencer was traveling through the headpipe and making it sound like it was coming from the engine. Fixing or swapping the silencer would be a much easier job than having to tear into the engine. Just a suggestion.
 

E-Ticket

~SPONSOR~
Dec 16, 2000
735
0
Believe it or not... but mechanical/vibration noises can sound horrendous and be in the weirdest places.

A friend's DRZ-400 was making "death-rattle" noises - sounded horrible - just like the engine was about make some very expensive internal modifications to itself.

The problem? A loose mounting bolt on the skid plate!!!

Yup. It was allowing a mounting clamp to vibrate and resonate against the bottom of the frame and engine cases. Sounded just grim.

30 seconds with a wrench. And the "engine" was "fixed."

So yah.... watch your assumptions and check *everything*....!

Cheers!
 

ochster

LIFETIME SPONSOR
Mar 11, 2000
690
0
Knowing someone had been in the motor... I would pop the headcover off and make sure things are ok. I have seen numerous cam sprockets loose, and even cam chain tensioners.
 

ACS

Member
Apr 17, 2001
242
0
Tristan first check the actual valve clearances. If the valve clearance is too small when the engine is hot it will be difficult to start. Im not sure about what u mean with the rocker arm play. Second the rattle could be a loose timing chain, either tensioner has had it or chain just streached too far. That will also make hot starting difficult. Do you just trail ride it or do road kms? The Staintune could be causing a lean jetting situation. Did you rejet it after adding the pipe. Lean jetting can burn valves stuffing things up.
 

DualSportr

Member
Aug 22, 2000
527
0
When you did the rebuild with the new timing chain etc. did you check the small end of the rod?

With high rpm use, the small end of the rod will oval out (causing the knocking sound). Normally, on newer engines with loose/worn timing chains, this is an indication the engine has spent lots of time at high rpms - so a worn rod would be my first guess.

Of course, like everyone else said, check to be sure nothing's loose in the head first.

Regarding the rocker play - the rockers will move side to side on their shafts, but you shouldn't be able to wiggle them up and down on the shaft - this would indicate worn shafts and/or rockers. And this could definitely be causing the knocking sound.
 

SFO

LIFETIME SPONSOR
Feb 16, 2001
2,001
1
Wave washers suck up the the rocker and sub rocker side to side movement

They can break and create knarley noises.
Define the frequency of the vibration and the source will be revealed.:D
 

tristan18au

Member
Jun 3, 2001
186
0
i have inspected morre and found that the right hand side exhuast valves has pulled through the head, which was caursing loss of compression and hard starting. also the left is not far off could this be that damn rattle?
 

SFO

LIFETIME SPONSOR
Feb 16, 2001
2,001
1
T alk to Geoff at Ballards xrs.
He is in your country.
He has the fix for your exhaust valve woes...:D
 

tristan18au

Member
Jun 3, 2001
186
0
the rattle is still there i replaced the valves cam chain is fine and tensioner and rockers ect!

what is goinbg on is this normal? :mad:
 
Top Bottom