compression testing

jay87lx

jay87lx

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Hi, I am new here and have read all 12 pages of SRX, viper threads. Everyone agrees on one thing when looking at a sled for possible purchase and that is to do a compression test. I know you would do it with the throttle wide open, ign off. The comp should be w/in 10% of each other and about 120 would be good
1. are the other 2 spark plugs to be removed when doing the test , it really shouldnt matter right?
2. Do you buy a compression tester or can you make one?
I hope I don't get flamed for asking what may be stupid questions

Jay
 
I havent tried doing a comp test with all spark plugs off... imo... I would do one at a time....


Dont think you can really make one... they come cheap... just need to find a addator at the worst to have it fit in the tapered hole...\


keep pulling the cord until the dial stops going up...

I dont know about pushing the throttle either.... I didnt have to with mine...
 
Welcome to TY Jay...... Pulling all the plugs at once makes the motor spin easier.. Usually 2 or 3 good pulls will suffice.. Don't try and make one,,,just go to an auto parts store and you could BUY one relatively cheap.... We can get into doing it to a WARM engine and taking WET and DRY readings,, also CYLINDER LEAKAGE using a BIG DOLLAR leakage tester and CONFUSING the HECK out of you,,,,but,,,, A sled with 3000 miles usually gets a ring job and if a guy uses SYNTHETIC OIL throughout the sleds life,,, you could EASILY wait till 5000 miles before it needs a ring job.. f you are looking at a sled with 5000 - 6000 miles that has been running CONVENTIONAL oil and has NEVER HAD A RING JOB,,, just WALK AWAY from the sled,, because there are TOO MANY sleds out there that has LOW MILES and has been taken care of.... We are talking TWO STROKE SLEDS,,,vipers and SRX'S....
 
Thats how you get intelligent,,, by asking DUMB QUESTIONS!!!! I've been doing it my WHOLE LIFE!!!
 
Hello Jay-S,

Don't waste your time trying to build a compression tester, you can get an inexpensive compression tester from almost any auto parts store that will work fine. I always remove the spark plugs from all cylinders before starting the test. Make sure the ignition and/or kill switch is in the off position. Hold the throttle wide open and turn the engine over. If it is a recoil start engine, pull it over with several good hard pulls, usually 3 are enough to get the compression gauge to reach a maximum reading. I repeat this process 3 times for each cylinder and use the average of each cylinder for comparison.

Good luck and keep the questions coming!!

Jim
 
hi jay, if you want a whole bunch more reading change the display setting at the bottom of the srx/viper page to show threads from farther back, those 12 pages you read were just for the last month, that should keep you busy for a while
jeff
 
staggs65 said:
hi jay, if you want a whole bunch more reading change the display setting at the bottom of the srx/viper page to show threads from farther back, those 12 pages you read were just for the last month, that should keep you busy for a while
jeff
Click to expand...

AHHHH- Thank You!!!!! that will surely keep me busy for a long time
I will also pick up a compression tester at my next trip to the parts store.
Thanks again for the info. I have been reading NON STOP- LOL- Be safe

Also am I correct in assuming that the only way to check the condition of the power valves is to pull them apart?
 
So wouldn't the odd the PTO cylinder on a viper read differently on a stock sled since the head is 25cc versus 21cc for the middle and mag cylinders?
 
I'm picking up my first SRX tomorrow(WED.) It's a 2000 with 5300 miles. At what compression reading would you recommend re-ringing ? I'm assuming at re-ring time you're also honing, checking bores and pistons ? Are you replacing bearings etc. too ?

Thanks
 
compression gauges can vary greatly so there isn't really a preset # that will say you need a re-ring, if one is drastically different than the others or it's really low that could point to a problem, if you do do a rering, yes check your piston and bore specs, yes deglaze the cyls, shouldn't need crank bearings @ 5300 but check if you have any up and down rod play while it's apart, could need crank seals
 
Ride.Race.Live said:
Dont think you can really make one... they come cheap... just need to find a addator at the worst to have it fit in the tapered hole
Click to expand...
I just checked with NAPA tolls and the kit I looked at that had a gauge, 8" hose and 3 different threaded adapters and it was $199- OUCH. Does anyone have alink or P/N to a more economical one- scratch that- I just found a nice kit at sears for $64
 
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hotbeek said:
I'm picking up my first SRX tomorrow(WED.) It's a 2000 with 5300 miles. At what compression reading would you recommend re-ringing ? I'm assuming at re-ring time you're also honing, checking bores and pistons ? Are you replacing bearings etc. too ?

Thanks
Click to expand...

Not compression,,, MILES...... I usually RERING at 3000 miles.. Synthetic oil and you can rering at 5000 miles.. 5300 miles ABSOLUTELY NEEDS a rering NO MATTER WHAT!!! Bearings LAST A WHILE,, and if you need bearings (usually from BAD summer storage practices) you will KNOW IT!!!
 
I was looking through my Yamaha service manual for triples, when I came across this step in the instructions for performing a compression test.



2. Remove all the spark plugs, then attach the plugs to the caps at the ends of the spark plug leads and ground both plugs to the cylinder head.
CAUTION! I f the plugs are not grounded during the compression test, the CD ignition could be damaged.



​
How many people do this? I know I haven't
 
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To be honest with you, I'm not sure. I bought it on eBay. The CD has the YAMAHA logo on it (pirates!) and the title says that it is a Yamaha 3 cylinder repair manual 1997-2001. There is no other signs of who actually published it. I thought that sounded funny. Seems to me that if you had the swicthes off it wouldn't be firing anyway.
 
sockeyerun said:
To be honest with you, I'm not sure. I bought it on eBay. The CD has the YAMAHA logo on it (pirates!) and the title says that it is a Yamaha 3 cylinder repair manual 1997-2001. There is no other signs of who actually published it. I thought that sounded funny. Seems to me that if you had the swicthes off it wouldn't be firing anyway.
Click to expand...
Lol...thats a aftermarket manual.
 
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