Jump to content
Sofiedog

Time for valves...

Recommended Posts

2005 CRF450X...I estimate it has over 5,000 off-road miles or around 350 hrs on original top end...numbers are estimates based on my maintenance log.

I've shimmed the valves a few times...last time one of the intakes was using one of the thinnest shims...it's time.

Its gotten more difficult to start and idle cold...starts and idles better when it is warm...just about can't get it started now.

IMG_5072.JPG

I'll try to get it done now...

Share this post


Link to post
Share on other sites

Put the stainless steel valves in and you may never need to shim again. I have been running the same valves in my 05 since the originals went.

  • Like 2

Share this post


Link to post
Share on other sites
Put the stainless steel valves in and you may never need to shim again. I have been running the same valves in my 05 since the originals went.

thx...yeah...that's the direction I'm leaning.
  • Like 1

Share this post


Link to post
Share on other sites

had some time to disassemble the camshaft holder.

IMG_5260.JPG
IMG_5261.JPG

released chain tensioner pressure...removed gear
IMG_5264.JPG

camshaft holder assy, buckets, and shims out
IMG_5265.JPG

Share this post


Link to post
Share on other sites

What is the significance of the left intake wearing faster than the rest? 

I'm assuming the discussion about shiming pertains to the rocker stem or shaft whatever the arrangement, due to seat wear, and not shiming springs.

Either way, how long does it take for a person that is familiar with the process to run through the valves?

I'm not an x owner but I'm looking at them closely. I'm coming from the xr platform which pretty low maintenance, at the cost of more weight.

 

 

Share this post


Link to post
Share on other sites
What is the significance of the left intake wearing faster than the rest? 
I'm assuming the discussion about shiming pertains to the rocker stem or shaft whatever the arrangement, due to seat wear, and not shiming springs.
Either way, how long does it take for a person that is familiar with the process to run through the valves?
I'm not an x owner but I'm looking at them closely. I'm coming from the xr platform which pretty low maintenance, at the cost of more weight.
 
 

I've seen some discussions on why its the left intake that wears the most...maybe because of the way the head is cooled that valve gets the hottest? and their larger dia than the exhaust valves?

Adjusting the valves (changing shim thickness) is required for these when the titanium valve wears...much sooner than the seat. The shims sit on top of the valve stems, under the buckets on the intake side...under the rocker arms on the exhaust side.

It takes me an hour to check the valve clearance...gotta pull the seat, tank, valve cover...find TDC on compression stroke with timing marks.... then use a narrow feeler gauge...its clear in the manuals.

if you have to reshim, then you have to take tension off the cam chain, pull the cam, and swap shims.

Re-shimming doesn't last long (10-20 hrs) once the valve starts wearing...they may have a Ti oxide surface treat that wears.

The rev capability of the modern CRF engines are very different than the XRs. The CRFXs are great off-road bikes...Honda should have used more durable stainless steel valves on the CRFXs like they did the TRX engines and left the titanium to the CRFRs...IMHO.

Share this post


Link to post
Share on other sites

Where are you sending to? Whats it running you if you don't mind me asking... Getting it ported 😏 What about a piston? Are you dong a top end at the same time?

Share this post


Link to post
Share on other sites

Well...I just shipped it off today to AS Racing in Santa Clarita, CA...they have had a good rep on here.

We exchanged a brief message yesterday...I'm going with the steel Honda TRX valves. He should get it in a few days and I'll post up again when he contacts me and I have all the details.

The cylinder is just sitting on there...I'm going to pull it off and look at it and the piston/rings...I don't expect any issues...the bike didn't seem to burn oil.

Probably, what makes sense, is new piston, rings, cam chain?

I heard they do a nice porting job...but this isnt a racer...I would probably buy a CRF450R head with larger valves and a different cam if I was also porting for high performance.

IMG_5267.JPG

Share this post


Link to post
Share on other sites

Nice! Yea I would do the piston, rings, and cam chain. Also maybe a light hone and measure cylinder after and check specks to verify cylinder condition. Thats what I plan on doing after this season to mine. That's why I'm so curious about where your sending it. 

Makes sense if it's not a racer so no porting. But... I think some people use the X head with a R cam. Not exactly necessary to buy a R head. I could be wrong. 

Cool thanks for the info! Look forward to watching the process continue. 

  • Like 1

Share this post


Link to post
Share on other sites
Nice! Yea I would do the piston, rings, and cam chain. Also maybe a light hone and measure cylinder after and check specks to verify cylinder condition. Thats what I plan on doing after this season to mine. That's why I'm so curious about where your sending it. 
Makes sense if it's not a racer so no porting. But... I think some people use the X head with a R cam. Not exactly necessary to buy a R head. I could be wrong. 
Cool thanks for the info! Look forward to watching the process continue. 

I thought I may go in this direction...IMG_1978.JPG

But, in all the years I've ridden my 450X off-road, I don't ever recall wishing it had more power. The intake box is derestricted, it has been rejetted and it has an aftermarket exhaust. Nice, linear power.

I do recall wishing it were lighter, turned quicker, and had a lower seat...
  • Like 1

Share this post


Link to post
Share on other sites

I thought I may go in this direction...IMG_1978.thumb.JPG.9c3c052abace41a8213e51e7d5508983.JPG

But, in all the years I've ridden my 450X off-road, I don't ever recall wishing it had more power. The intake box is derestricted, it has been rejetted and it has an aftermarket exhaust. Nice, linear power.

I do recall wishing it were lighter, turned quicker, and had a lower seat...
I did mine with that head couple years ago and the valves haven't moved at all. It has more snort.
  • Like 1

Share this post


Link to post
Share on other sites
I did mine with that head couple years ago and the valves haven't moved at all. It has more snort.
I traet her like crap too.20190212_074202.jpeg
  • Confused 1

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:


×