Reducing Compression


12 replies to this topic
  • walshy

Posted November 23, 2006 - 12:19 AM

#1

This one is probably a bit out of left field!

Considering lowering the compression ratio on 03 WR450! :bonk:
Is this possible with maybe an extra base gasket?
Would this cause other issues, such as jetting and or ignition timing problems? :p :cheers:

  • SPLATT

Posted November 23, 2006 - 01:19 AM

#2

Just out of curiosity what do you hope to accomplish by doing this? It seems to me that you'll lose some of the bottom end snap but it'll be able to rev easier at high RPM and you'll be able to use lower octane fuel.

Steve

  • Wasabi

Posted November 23, 2006 - 01:58 AM

#3

Why would you want to do that Walshy?
It shouldn't cause any problems either.

  • pkcof

Posted November 23, 2006 - 02:20 AM

#4

well, you could always drill a small hole in the piston - or take one of the valves out - put in 6 or 7 head gaskets or grind the cams almost flat ?? -- perhaps buy a 250 ???

  • walshy

Posted November 23, 2006 - 03:21 AM

#5

Well to answer some of your questions, I figure that it would be an under stressed motor>
Smoother power down low
eg. less wear on the bottom end!
less wear on the whole gear train, starter assembly etc
As already stated, lower octane fuel, which is all I can get in the middle of nowhere.
Basically I want a light weight bike with good suspension that you don't have to rev the guts out of that is reliable!
I luv the power of this thing as it is, but its not necessary for basic bush riding.
Sorta like a TTR BELGARDA 600 "which I owned and luved" but lighter!

So, will this be a waste of time?:cheers:

  • Wasabi

Posted November 23, 2006 - 03:42 PM

#6

So, will this be a waste of time?:cheers:

Try it and find out! :p

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  • BlueBlood Rider

Posted November 23, 2006 - 05:43 PM

#7

Well to answer some of your questions, I figure that it would be an under stressed motor>
Smoother power down low
eg. less wear on the bottom end!
less wear on the whole gear train, starter assembly etc
As already stated, lower octane fuel, which is all I can get in the middle of nowhere.
Basically I want a light weight bike with good suspension that you don't have to rev the guts out of that is reliable!
I luv the power of this thing as it is, but its not necessary for basic bush riding.
Sorta like a TTR BELGARDA 600 "which I owned and luved" but lighter!

So, will this be a waste of time?:cheers:

The biggest engine stressor is the nut connected to the throttle.:p Seriously, except for having to accommodate poor quality gasoline, you can do more to extend your engine's life by how you operate it rather than by lowering its compression ratio. In fact, reducing the compression ratio will result in your not having the needed power in certain riding situations and having to stress the engine harder. That will put more strain on more than just the engine. If engine longevity is your real concern then simply develop riding habits that don't subject it to extreme stress. That means avoid frequent and/or sustained over-revving, lugging in too low a gear, sustained high speed operation, and poor maintenance. Keep in mind, these are high-performance engines that are pretty over-built for the kind of operation most riders throw at them. The vast majority of serious engine problems are related to abuse or neglect of some kind.

  • walshy

Posted November 23, 2006 - 08:05 PM

#8

YEAH I HEAR YA AND YOU ARE PROBABLY RIGHT !
Will be stripping the motor over summer, check things out, then make a decision.

  • Wasabi

Posted November 23, 2006 - 08:09 PM

#9

How many k's? I just did mine and it was all fine @ 5,000 kms.

  • walshy

Posted November 24, 2006 - 02:33 AM

#10

How many k's? I just did mine and it was all fine @ 5,000 kms.


Somewhere between 10,000 and 11,000 Ks.
I pulled the head off at about 5,000 Ks to check the valves, it was all good then.
Don't want to push my luck, the inlets have tightened up since then.
Time to give her a good check over me thinks!

Did you replace anything when you did yours?

  • simon@vic

Posted November 24, 2006 - 11:46 AM

#11

IMHO that will not make it any smother or more reliable.

the only benefit would be you could run 87 oct fuel..............

  • Wasabi

Posted November 24, 2006 - 01:56 PM

#12

Somewhere between 10,000 and 11,000 Ks.
I pulled the head off at about 5,000 Ks to check the valves, it was all good then.
Don't want to push my luck, the inlets have tightened up since then.
Time to give her a good check over me thinks!

Did you replace anything when you did yours?

Yeah, I threw in a piston and rings just because I had it apart. I threw in some cams too while I was at it. All were still good though. I just needed an excuse for a power up. All I needed was one shim!

Might be a good time to get the valves done (if needed) and bottom end inspection?

  • walshy

Posted November 25, 2006 - 04:51 PM

#13

Yeah, I threw in a piston and rings just because I had it apart. I threw in some cams too while I was at it. All were still good though. I just needed an excuse for a power up. All I needed was one shim!

Might be a good time to get the valves done (if needed) and bottom end inspection?


Yep will be interesting to see the extent of wear and tear!
Whatever I replace will be stock standard!
Gotta leave enough cash to freshen the suspension!




 
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