How do I test my compression, 250 2 Stroke???

S

snb73

Member

Nov 30, 2003

770

0

• May 9, 2006

• #1

I have a 2003 RM-250 and I want to test my compression. What is the proper methode for testing compression on a 250 2 stroke? How many kicks for an accurate reading?

Thanks, Steve.

 

K

kawicam125

Uhhh...

Mar 14, 2006

195

0

• May 9, 2006

• #2

go out and buy a compression tester. next, remove the spark plug and insert( screw in) the tester into the spark plug hole in the cylinder. don't try to start the bike, just kick it until the reading on the tester won't go any higher.

 

T

toddb3

Member

Apr 20, 2006

86

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• May 9, 2006

• #3

Shouldnt you warm the engine before you do this? It seems like I get a higher reading with a warm engine than cold...

 

darringer

LIFETIME SPONSOR

Dec 2, 2001

1,029

0

• May 9, 2006

• #4

Also, push the kill switch while kicking. Warm or cold will vary only slightly. It usually will take quite a few solid kicks for it to top out.

 

Masterphil

DRN's Resident Lunatic

Member

Aug 3, 2004

1,003

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• May 10, 2006

• #5

Do a compression test when you get done riding the bike. That way you know it will be warm. When I tested my 125sx I got 170 cold, but 195 hot. There is a big difference.

Procedure to do a compression test:
Pull plug
Screw in compression tester
Open throttle all the way
push the kill switch
kick until the meter won't go any higher

Your bike should be in the 190+ range, and I wouldn't be suprised if it is over 200.

 

G

gillsm

Member

Apr 7, 2002

15

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• May 10, 2006

• #6

compression test

Why do you guys say you should push in the kill switch,just curious. thanks

 

S

snb73

Member

Nov 30, 2003

770

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• May 10, 2006

• Thread starter
• #7

I was riding in some very fine dirt this weekend and the motor sounded different. I lost some top end and over rev. I changed the plug and that helped, everything was back to normal. Then I took the bike around a small track, just putting around. The same thing happened. I will change the plug, but wondered itf some silt got past the air filter.

I wasn't sure how many kicks it took to get a valid reading. I have 220 lbs after about 10 kicks, it went down to 190 after 24 hours. Guess the rings are good.

Thanks, Steve

 

S

samham

Member

Nov 22, 2002

72

0

• May 10, 2006

• #8

I am curious as well,, no plug, no spark, no combustion, no need for a kill switch.......

 

Masterphil

DRN's Resident Lunatic

Member

Aug 3, 2004

1,003

0

• May 10, 2006

• #9

Saftey first!

The downside to a compression test is that it only tells you how well the piston/rings are sealing. It gives you no idea how much the piston is rocking in the bore, or how close the piston is to a stress fracture.

 

K

kshackleton

Member

Oct 12, 2005

109

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• May 10, 2006

• #10

gillsm said:

Why do you guys say you should push in the kill switch,just curious. thanks

Click to expand...

There is a small chance of damaging the coil without a plug installed...that is the only reason that I can see to hold down the kill switch.