compression readings - Snowmobile Forum: Your #1 Snowmobile Forum
http://www.snowmobileforum.com
Go Back   Snowmobile Forum: Your #1 Snowmobile Forum > Specific Snowmobile Forums > Polaris Snowmobiles


» Sponsors





Reply
 
LinkBack Thread Tools Display Modes
Old 12-23-2012, 01:47 AM   #1 (permalink)
Registered User
 
polaris_indy22's Avatar
 
Join Date: Aug 2011
Posts: 331
compression readings

Today i did a compression reading on my 1991 indy 650 rxl efi now i have a few questions.

1. As i was pulling the plugs from clutch side to water pump side i notice that the plug on the clutch side look normal but the other two look dark and oily. what could this be from?

2. I took the compression readings with WOT and the readings were from clutch side to water pump side 130-125-115. All the readings should be close to 130 right? also i have heard that the readings should be within 5psi of each other. is that right? Obviously mine arnt so what does that mean?


Clutch side to water pump side

polaris_indy22 is offline   Reply With Quote
Sponsored Links
Advertisement
 
Old 12-23-2012, 07:33 AM   #2 (permalink)
Super Moderator
 
RJ Gleason's Avatar
 
Join Date: Feb 2005
Location: Groton NY
Posts: 32,454
That would be 10% of each other, which you have.
Was that warm or cold test?
The one plug looks perfect color.
__________________
Old Cat Rider
'93 Wildcat 700EFI
w/ Comet 108 Pro-4 clutch & 01 ZR skid

'90 Wildcat Project in progress.

Vintage (sorta)
1980 Indy Trail 440 (for sale)
1980 AC Pantera (donor engine to the 90 wildcat)


http://www.dcdrifters.net/


Worshipful Master; F&AM Dryden Lodge# 472
http://www.masonicdryden472.org/

Rules of this forum are strictly enforced!
RJ Gleason is offline   Reply With Quote
Old 12-23-2012, 10:09 AM   #3 (permalink)
Registered User
 
polaris_indy22's Avatar
 
Join Date: Aug 2011
Posts: 331
so u think that those are good numbers? i thought they seemed kinda far apart. it probably wouldnt hurt to rebuild it next year would it? and that was a cold test. on the plugs what do u think is causing thoes two to be really black? i talked to my dad this morning and he said it sounds like it its getting oil fouled. he has never really looked at it and he doesnt know much about snowmobiles but he knows his engines.

Any ideas??
polaris_indy22 is offline   Reply With Quote
Old 12-23-2012, 01:33 PM   #4 (permalink)
Registered User
 
ClassicIndy600's Avatar
 
Join Date: Feb 2011
Location: Wisconsin
Posts: 218
are all three plugs the same?
ClassicIndy600 is offline   Reply With Quote
Old 12-23-2012, 04:57 PM   #5 (permalink)
Super Moderator
 
RJ Gleason's Avatar
 
Join Date: Feb 2005
Location: Groton NY
Posts: 32,454
What I would recommend is that you do a seal test.
Start it up and spray some carb cleaner or starting fluid at the crank seals and the throttle body mount flanges. If the rpms go up, there is an air leak.
__________________
Old Cat Rider
'93 Wildcat 700EFI
w/ Comet 108 Pro-4 clutch & 01 ZR skid

'90 Wildcat Project in progress.

Vintage (sorta)
1980 Indy Trail 440 (for sale)
1980 AC Pantera (donor engine to the 90 wildcat)


http://www.dcdrifters.net/


Worshipful Master; F&AM Dryden Lodge# 472
http://www.masonicdryden472.org/

Rules of this forum are strictly enforced!
RJ Gleason is offline   Reply With Quote
Old 12-23-2012, 07:04 PM   #6 (permalink)
Super Moderator
 
BC_Dan's Avatar
 
Join Date: Jan 2004
Location: oregon
Posts: 12,663
I agree, the left plug looks perfect. If I were jetting a carb sled, I would jet more like the right one, so there would be a bit of fudge factor when riding in colder weather. But for EFI, they should all be about like the one on the left.

The center one does look more oil-fouled than the right one. Not much you can do to change either the fuel or the oil. It's better to have a bit too much oil and fuel than not enough! As long as the sled isn't continually fouling plugs and runs fine, I wouldn't worry too much.

I would run a half can of SeaFoam with the next tank of gas, that may help clean out the fuel system a bit and give more precise metering. But I do a half can on the first tank on all my sleds, just because. I really should buy stock in SeaFoam and WD40
__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
BC_Dan is offline   Reply With Quote
Old 12-24-2012, 11:52 AM   #7 (permalink)
Registered User
 
polaris_indy22's Avatar
 
Join Date: Aug 2011
Posts: 331
yes all three plugs are the same only had two runs on them. i will get some carb cleaner from my dad and test the crank seals. we have a 79 enticer 250 thats going to need crank seels im pretty sure.

also i was wondering if i could remove the oil injection system and just premix the gas 32:1 that way it cant inject more oil than it needs. if i cant do that how would i fix the oil fouling. bc i really want the top end back.

i have already Put seafoam in the tank i use seafoam in all my toys

could having different plug wires cause anything?
polaris_indy22 is offline   Reply With Quote
Old 12-24-2012, 12:05 PM   #8 (permalink)
-LIFETIME MEMBER-
 
musicfreako's Avatar
 
Join Date: Dec 2009
Location: Allegan, MI
Posts: 347
Check your plug gaps also
__________________
The only cat I'll ever own will have a track and not require a litter box

Current rides

98 ZR600 EFI (03 zr900 skid, reverse, fox shocks, clutched)
97 Polaris Indy 500 (stock)
91 El tigre EXT 530 (01 Zr skid, clutched, MINT)
94 Polaris Indy trail deluxe (very heavy!)

New rides
90 El tiger EXT 530
98 Zr 600 Carb
00 Zr 600 EFI (trophy winner in the 700 class drag races)
musicfreako is offline   Reply With Quote
Old 12-24-2012, 12:08 PM   #9 (permalink)
Registered User
 
polaris_indy22's Avatar
 
Join Date: Aug 2011
Posts: 331
what should they be gaped at?
polaris_indy22 is offline   Reply With Quote
Old 12-24-2012, 12:18 PM   #10 (permalink)
Registered User
 
white lightning's Avatar
 
Join Date: Feb 2008
Location: Upstate NY
Posts: 567
.028 I think - WL
white lightning is offline   Reply With Quote
Old 12-24-2012, 06:37 PM   #11 (permalink)
Super Moderator
 
BC_Dan's Avatar
 
Join Date: Jan 2004
Location: oregon
Posts: 12,663
Keep the injection. At idle, it's giving you 150:1. At wide open, maybe 32:1. When the throttle varies, the oil delivery does, too. If you were to mix 32:1, your plugs would be even worse.
__________________
2007 Dragon RMK 700 155", 2008 RMK 600 155", 95 Prowler 550 2-up, Really OLD AC Cheetah

http://www.avalanche.org/accidents.php
BC_Dan is offline   Reply With Quote
Old 01-08-2013, 05:24 PM   #12 (permalink)
Registered User
 
meburdick's Avatar
 
Join Date: Dec 2011
Location: Northern Central CT
Posts: 1,991
Quote:
Originally Posted by BC_Dan View Post
Keep the injection. At idle, it's giving you 150:1. At wide open, maybe 32:1. When the throttle varies, the oil delivery does, too. If you were to mix 32:1, your plugs would be even worse.
Not to mention that at least some EFI machines specifically say to NOT pre-mix and run the oil through the fuel injectors.
__________________
2012 Rush 600 Pro-R: https://plus.google.com/photos/11364...CObw59TN6NWvJg
1998 Indy 440: https://plus.google.com/photos/11364...10516040672513

Thank You to all of the members of the US Armed Forces
meburdick is online now   Reply With Quote
Sponsored Links
Advertisement
 
Reply

Thread Tools
Display Modes

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


Powered by vBadvanced CMPS v3.2.2

All times are GMT -5. The time now is 10:49 PM.



Copyright SnowmobileForum.com

Search Engine Friendly URLs by vBSEO 3.6.0