yz intake cam vs wr cam + head porting


5 replies to this topic
  • stev0

Posted November 05, 2009 - 11:25 PM

#1

Im doing a full rebuild on my wr.

Im thinking of going the yz cam route? Should I port and flow the head too? Would it make a real difference? Ive decided to ditch the stock uncorked pipe and drop on the steel frame yz450 pipe.


any other idea's where I can look for some more power?

I was advised against the Hi comp piston as they need more frequent rebuilds then the stocker? And here i was hoping for 55hp :smirk:

  • tribalbc

Posted November 06, 2009 - 06:44 AM

#2

Well on my 07 I went the HC piston and YZ cam route. The bike rips now but the estart is sporadic from the YZ exhaust cam. Next spring if I still can't get my estart consistent I'll try just the YZ intake.
When I was doing my rebuild I contacted our reputable machine shop here in BC about porting. They claimed they could give me a 5hp gain on top with no loss to bottom or mid. But it was a little pricey and since I didn't need any valve seats cut or anything (valves still haven't moved since new) I decided I would wait untill my next rebuild when I need to do valve work.

As far as the HC piston needing more frequent rebuilds this would be true judging by how long these stock pistons last. Mine still looked good after 9000km's, somewhere around 250-300hrs. I plan on replacing my piston anually now, about 3-4000kms.

  • stev0

Posted November 06, 2009 - 07:08 AM

#3

I got 11000km and my big end went. I have an idea that the bike overheated as we had some training and there was alot of idling. Such a pity though. Now that the motor is open, i would like to just sort everything out. Another 10 000km and I would be over the moon.

Ill definitely look into porting now... every hp is needed!

Visit the ThumperTalk Store for the lowest prices on motorcycle / ATV parts and accessories - Guaranteed
  • tribalbc

Posted November 06, 2009 - 07:12 AM

#4

I got 11000km and my big end went. I have an idea that the bike overheated as we had some training and there was alot of idling. Such a pity though. Now that the motor is open, i would like to just sort everything out. Another 10 000km and I would be over the moon.

Ill definitely look into porting now... every hp is needed!





My bike was running fine. Just figured it was time for a piston and cam chain seeing this bike gets raced and had so many hours. So I figured I would go HC piston and change the cams while I was in there.
For the less than $200 cost they're cheap insurance to do every year.

  • stev0

Posted November 06, 2009 - 08:01 AM

#5

My previous motor (from new) only lasted me err a year....

its a late 06, i bought in middle 08 with 600km on. I used it for dualsporting and everything else and it lasted a year. I rode it pretty much every 2nd day. Plenty of wheelies... and it was nothing but reliable... I love my wr... I dont love the price of rebuilds.

  • stev0

Posted November 06, 2009 - 08:01 AM

#6

Now my only plan with the bike is sunday playing in the mountain passes and enduro's.

no more dual sporting. bleh




 
x

Join Our Community!

Even if you don't want to post, registered members get access to tools that make finding & following the good stuff easier.

If you enjoyed reading about "" here in the ThumperTalk archive, you'll LOVE our community. Come join ThumperTalk today!

The views and opinions expressed on this page are strictly those of the author, and have not been reviewed or approved by ThumperTalk.