VES adjustment - HCS Snowmobile Forums

XCR This is a brand-specific forum. Posts on this forum are assumed to be questions aimed at similar model owners, and are not looking for comments of a sarcastic or "bashing" nature. Please be aware that if you violate this policy you are in danger of losing your posting privileges on this website.The calling out or posting of another members personal information IE phone number or address is prohibited.

Reply
 
LinkBack Thread Tools
Old 09-23-2013, 05:24 PM   #1 (permalink)
Advanced Member
 
Join Date: Feb 2013
Posts: 39
Default VES adjustment

I have an 03 xcr 800 the motor is bone stock, How do I adjust the valves? I have stock springs how many clicks should they be in or out?
miggscc is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 09-23-2013, 05:34 PM   #2 (permalink)
Super Advanced Member
 
patrioticinnovations's Avatar
 
Join Date: Sep 2005
Posts: 10,128
Current Sled(s): 2000 XCR 800 turbo
Previous Sled(s): 2003 XCR 1100, 98 XCR racer, 07 Attak
Location: SE Lower Michigan
Favorite Riding Area: Cadillac, Gaylord
Riding Since: 1982
Default

For trail riding, set them flush with housing.

Racing, set them in almost all the way.
patrioticinnovations is offline   Reply With Quote
Old 09-23-2013, 07:23 PM   #3 (permalink)
Super Advanced Member
 
Meat Head's Avatar
 
Join Date: Sep 2004
Posts: 3,528
Current Sled(s): 800 Etec
Previous Sled(s): Pile of shit D8
Location: MI
Default

Quote:
Originally Posted by patrioticinnovations View Post
For trail riding, set them flush with housing.

Racing, set them in almost all the way.
Why hold them closed longer than needed by tightening the springs pressure up? I let mine open sooner for racing purposes. Just looking for your logic?
Meat Head is online now   Reply With Quote
Old 09-23-2013, 08:10 PM   #4 (permalink)
Super Advanced Member
 
patrioticinnovations's Avatar
 
Join Date: Sep 2005
Posts: 10,128
Current Sled(s): 2000 XCR 800 turbo
Previous Sled(s): 2003 XCR 1100, 98 XCR racer, 07 Attak
Location: SE Lower Michigan
Favorite Riding Area: Cadillac, Gaylord
Riding Since: 1982
Default

Quote:
Originally Posted by Meat Head View Post
Why hold them closed longer than needed by tightening the springs pressure up? I let mine open sooner for racing purposes. Just looking for your logic?
Not my logic. It's in the 2000 Polaris XCR Racing Manual.

Several of us XCR folks have discussed it and concluded it has to do with a cold engine and pipes producing more low rpm cylinder pressure/torque which pushes the valves open too soon at the trail setting. Thus, it's necessary to delay the opening of the valves till later to properly follow the torque curve. The ideal opening point for the valves is at the peak torque rpm for a closed valve. This varies with cylinder pressure and pipe temperature.

Incidentally, if you carefully study any dyno test with various pipes on the XCR 800 you'll be able to see exactly where that closed valve torque peak occurs. It usually happens at 6500-6700 rpms. Any change to the stock power curve, affects the optimum spring calibration. This includes raised compression, advance timing, different pipes, jetting, etc.
patrioticinnovations is offline   Reply With Quote
Old 09-23-2013, 08:16 PM   #5 (permalink)
Advanced Member
 
Join Date: Feb 2013
Posts: 39
Default

so how often should someone replace the springs? how would one tell if it is time to replace them
miggscc is offline   Reply With Quote
Old 09-23-2013, 08:28 PM   #6 (permalink)
Super Advanced Member
 
Meat Head's Avatar
 
Join Date: Sep 2004
Posts: 3,528
Current Sled(s): 800 Etec
Previous Sled(s): Pile of shit D8
Location: MI
Default

Quote:
Originally Posted by patrioticinnovations View Post
Not my logic. It's in the 2000 Polaris XCR Racing Manual.

Several of us XCR folks have discussed it and concluded it has to do with a cold engine and pipes producing more low rpm cylinder pressure/torque which pushes the valves open too soon at the trail setting. Thus, it's necessary to delay the opening of the valves till later to properly follow the torque curve. The ideal opening point for the valves is at the peak torque rpm for a closed valve. This varies with cylinder pressure and pipe temperature.
Interesting, Thanks. I have heard engine builders cut there springs to open the valves sooner, as well I have them cut in my xcr with positive results. But Im not be comparing apple to apples here, stock ported and piped engine may like the valve closed longer.
Meat Head is online now   Reply With Quote
Old 09-23-2013, 09:16 PM   #7 (permalink)
Super Advanced Member
 
mike@TZR motorsports's Avatar
 
Join Date: Sep 2011
Posts: 727
Current Sled(s): 04 prox2 700 iqr 860cc and proxr 800
Previous Sled(s): bout every polaris made, see my blog on profile pg
Location: niagara county in western ny
Favorite Riding Area: southern tier of ny state
12-13 Mileage: 1100miles
10-11 Mileage: 1500
Age: 40
Riding Since: 1984
Blog Entries: 14
Default

This is good info , I also trim springs depending how high I make exhaust port timing and also compresion n pipesive seen exhaust valves not open with the stock springs with high exhaust port timing, id like to here more discussion on this !! mike
__________________
point and just give er!!!!
mike@TZR motorsports is offline   Reply With Quote
Old 09-23-2013, 10:22 PM   #8 (permalink)
Advanced Member
 
Join Date: Feb 2013
Posts: 39
Default

So when should I replace the springs? my engine is stock, do I buy buy stock springs or different ones?
miggscc is offline   Reply With Quote
Old 09-24-2013, 08:35 AM   #9 (permalink)
Super Advanced Member
 
patrioticinnovations's Avatar
 
Join Date: Sep 2005
Posts: 10,128
Current Sled(s): 2000 XCR 800 turbo
Previous Sled(s): 2003 XCR 1100, 98 XCR racer, 07 Attak
Location: SE Lower Michigan
Favorite Riding Area: Cadillac, Gaylord
Riding Since: 1982
Default

Quote:
Originally Posted by miggscc View Post
So when should I replace the springs? my engine is stock, do I buy buy stock springs or different ones?
I'd use stock springs.

To best illustrate the effect of too early opening of an exhaust valve, consider the following:
I turboed a 98 Skidoo FIII 700 triple with Rave valves. It was very torquey at launch as a naturally aspirated sled. Once turboed, it lost a lot of the low end torque, because as boost climbed and cylinder pressure rose, the valves opened too soon. I went to a local hardware store and found several different stronger springs. A spring that was almost twice as strong worked very well.
Attached Images
File Type: jpg FIII&XCR600 005.jpg (330.2 KB, 17 views)
File Type: jpg FIII&XCR600 001.jpg (347.0 KB, 11 views)
patrioticinnovations is offline   Reply With Quote
Old 09-24-2013, 09:02 AM   #10 (permalink)
Super Advanced Member
 
patrioticinnovations's Avatar
 
Join Date: Sep 2005
Posts: 10,128
Current Sled(s): 2000 XCR 800 turbo
Previous Sled(s): 2003 XCR 1100, 98 XCR racer, 07 Attak
Location: SE Lower Michigan
Favorite Riding Area: Cadillac, Gaylord
Riding Since: 1982
Default

To add to this, DTR has done extensive testing of valve opening effects over the years. For example, they've locked the valve closed on the dyno to see exactly where that closed valve torque peak occurs with different setups. They've also locked the valve open and seen a significant loss of torque at low rpm.

It's interesting to see how various changes affect it.

To me, the best way to control the valves is to first establish an ideal opening position for the valve at every rpm, throttle position and pipe temp. Then monitor these items real time and program the valve to provide optimum engine performance over the entire rpm range. This could include racing modes as well as trail modes. I suspect that some manufacturers are already doing this to an extent. Skidoo for one.
patrioticinnovations is offline   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On



All times are GMT -4. The time now is 04:28 PM.



Powered by vBulletin® Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Search Engine Friendly URLs by vBSEO 3.6.0