ninjette.org

Go Back   ninjette.org > 2008 - 2012 Ninja 250R > 2008 - 2012 Ninja 250R Tech Talk

Reply
 
Thread Tools
Old February 6th, 2020, 06:39 PM   #1
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
Low Compression On A Cyclinder, Should I Replace Piston Rings?

Did a compression test on my bike.

Bike runs. It sounds like my cylinder may be misfiring but I'm not sure. Sending my carbs to be cleaned today.

Compression test after bike warmed up:

Cylinder #1 (Left side when sitting on bike)
Dry: 145 psi
Wet: 205 psi

Cylinder #2:
Dry: 110 psi
Wet: 195 psi

Valves just adjusted and are in spec.

I don't have a leak down tester, I may consider buying one, but not sure if a leak down test could tell me much more than the compression test.

Wondering if there is anything else I should check. If I do end up needing to replace piston rings, how many days should I reserve if I worked all day on getting the rings on? I've never torn down an engine, closest thing is doing valve adjustments myself.

Does this look like a probable piston rings replacement scenario?
I've heard of those products like Rislone Compression Repair additives, but do they actually work? Could this be a temporary solution (help for 10,000 mi)
Can I replace piston rings with the engine still on the bike?

Last futzed with by nocturncal; February 7th, 2020 at 01:16 AM.
nocturncal is offline   Reply With Quote




Old February 7th, 2020, 03:39 AM   #2
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: SF East Bay
Join Date: Dec 2011

Motorcycle(s): CB125T, Ninja250R racer, Ninja250R street bike, EX250F#1, EX250F#2, EX250E, VF500F, CBR600RR

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Don't use any magic-elixirs in bottle. They'll often cause more damage than cure.

Other possible cause of low-compression is burnt exhaust-valves and/or seats. A leak-down tester will give you confirmation if leak is going past rings or valves. Then you'd have better idea of which areas to inspect.

A lot of times, ring-leaks are caused by carbon from too-rich mixtures or burnt-oil clogging rings. One hail-mary operation before tearing engine apart is to do piston-soak to dissolve some of sludge which may be clogging rings and preventing seal. Do both cylinders:

1. spray in PB-blaster for 5-sec down spark-plug hole
2. crank engine 1-sec to spread it around
3. follow with 3-4cc of acetone
4. lightly lay spark-spark over hole to prevent evaporation
5. let sit for 3-4 hrs

6. follow with 3-4cc of 50/50 acetone/ATF mix
7. let sit for overnight (6-8hrs)

8. follow with another PB-blaster/acetone mix
9. let sit for 3-4 hrs

10. crank engine to blow out any residual mixtures
11. re-install plugs
12. warm-up engine and re-do compression test.

Depending upon how much improvement you get, it will be additional data for diagnosis.

DannoXYZ is offline   Reply With Quote


Old February 7th, 2020, 05:58 PM   #3
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
@DannoXYZ thanks for the write-up. I'll do the soak once I get my carbs back from cleaning.

I'll waiting on a leak down tester that's coming in the mail tomorrow, I'll post results after
nocturncal is offline   Reply With Quote


Old February 7th, 2020, 10:41 PM   #4
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
@DannoXYZ sidenote, does it need to be PB Blaster or could I use another penetrating lube like liquid wrench?
nocturncal is offline   Reply With Quote


Old February 8th, 2020, 03:44 AM   #5
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: SF East Bay
Join Date: Dec 2011

Motorcycle(s): CB125T, Ninja250R racer, Ninja250R street bike, EX250F#1, EX250F#2, EX250E, VF500F, CBR600RR

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
I’ve found PB Blaster to work best. Frees up rusted bolts & nuts better than anything else. So cleans cylinders & rings best too. Got my wife’s Corolla with one 60psi cylinder back up to 195psi. Similar car with same issue picture posted above. I was able to skip the teardown.

I think you can remove pistons with engine in frame by removing head and dropping oil-pan. But it’s a lot quicker and easier to remove engine 1st.

Last futzed with by DannoXYZ; February 8th, 2020 at 12:28 PM.
DannoXYZ is offline   Reply With Quote


Old February 8th, 2020, 09:12 PM   #6
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
I did the leak down test and got some results I don't quite understand.

With the leakdown regulator set at 100 psi, the cylinder pressures I got were:

Cylinder #1: 99 psi
Cylinder #2: 99 psi

No air leak from intake, exhaust, or radiator cap.
Air only coming out through oil filler cap, both cylinders tested had this problem.

I rechecked compression and got:
Cylinder #1: 155 psi
Cylinder #2: 160 psi.

Cylinder #2 was the cylinder which was originally testing at 110 psi. I'm guessing after I did a wet compression test described in my first post, even though I ran the bike to blow out the excess oil for 45 min, that maybe some oil is still there helping the piston rings seal and that's giving me my better numbers?

I also was kinda confused about trying to find TDC on cylinders when I didn't have the valve cover off to see the camshaft lobes, so I ended up trying both cycles of 1T and 2T and chose the one didn't have air blowing through the intake.

My carbs are in a land far far away right now being cleaned, so I can't run the bike

Last futzed with by nocturncal; February 9th, 2020 at 12:46 AM.
nocturncal is offline   Reply With Quote


Old February 9th, 2020, 08:35 AM   #7
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: SF East Bay
Join Date: Dec 2011

Motorcycle(s): CB125T, Ninja250R racer, Ninja250R street bike, EX250F#1, EX250F#2, EX250E, VF500F, CBR600RR

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Excess oil should be scraped off by rings within seconds when running engine.

Hmmm, you may have had some grit or carbon chunk holding valve open earlier? Couple months ago someone reported something holding their valve open and giving really bad numbers. Then it freed itself and blew through.

At this point, I'd do piston-soak anyway. These bikes run really rich in high-end and has lots of carbon build-up.
DannoXYZ is offline   Reply With Quote


Old February 11th, 2020, 11:41 AM   #8
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
Quote:
Originally Posted by DannoXYZ View Post
Excess oil should be scraped off by rings within seconds when running engine.

Hmmm, you may have had some grit or carbon chunk holding valve open earlier? Couple months ago someone reported something holding their valve open and giving really bad numbers. Then it freed itself and blew through.

At this point, I'd do piston-soak anyway. These bikes run really rich in high-end and has lots of carbon build-up.
Awesome, I'm gonna do the piston soak once my carbs come back. I'll post compression test results
nocturncal is offline   Reply With Quote


Old February 13th, 2020, 04:59 PM   #9
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
I did the piston soak. Couldn't warm the engine up yet, carbs don't come back till tomorrow, but I got some improved compression test-wise.

Pre soak:.
Cylinder #1: 155 psi
Cylinder #2: 160 psi

Post-Soak:
Cylinder #1: 164 psi
Cylinder #2: 169 psi

Gained 9 psi on both cylinders!
nocturncal is offline   Reply With Quote


Old February 13th, 2020, 07:06 PM   #10
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: SF East Bay
Join Date: Dec 2011

Motorcycle(s): CB125T, Ninja250R racer, Ninja250R street bike, EX250F#1, EX250F#2, EX250E, VF500F, CBR600RR

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
That's good results! With warmed-up engine, you should be in 180psi range, which is perfect!
DannoXYZ is offline   Reply With Quote


Old February 15th, 2020, 08:36 AM   #11
DannoXYZ
ninjette.org certified postwhore
 
Name: AKA JacRyann
Location: SF East Bay
Join Date: Dec 2011

Motorcycle(s): CB125T, Ninja250R racer, Ninja250R street bike, EX250F#1, EX250F#2, EX250E, VF500F, CBR600RR

Posts: A lot.
MOTY - 2018, MOTM - Nov '17
Btw, you’ll want to do an oil-change.
DannoXYZ is offline   Reply With Quote


Old February 16th, 2020, 07:09 PM   #12
nocturncal
ninjette.org member
 
nocturncal's Avatar
 
Name: Cal
Location: San Francisco
Join Date: Jun 2017

Motorcycle(s): '09 Ninja 250R

Posts: 177
Quote:
Originally Posted by DannoXYZ View Post
Btw, youll want to do an oil-change.
1 out of 1 members found this helpful
nocturncal is offline   Reply With Quote


1 out of 1 members found this post helpful.
Reply




Similar Threads
Thread Thread Starter Forum Replies Last Post
new piston rings without honing 3 2013 - 2017 Ninja 300 Tech Talk 36 December 22nd, 2016 09:03 AM
JE High Compression Piston Kit (13.5:1 compression, 356cc displacement) Timpo 2013 - 2017 Ninja 300 Tech Talk 8 October 12th, 2015 07:21 PM
Is there a DIY on piston rings? cookiebug79 1986 - 2007 Ninja 250R Tech Talk 33 April 22nd, 2015 01:17 PM
Where to find oversized piston rings? cuong-nutz General Motorcycling Discussion 19 January 9th, 2013 08:27 AM
Where to buy Piston Rings? iceman.kcmo 1986 - 2007 Ninja 250R Tech Talk 5 January 28th, 2010 11:59 AM


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

Forum Jump


Motorcycle Safety Foundation

All times are GMT -7. The time now is 05:11 PM.


remote server monitor
Powered by vBulletin®
Copyright ©2000 - 2020, Jelsoft Enterprises Ltd.
User Alert System provided by Advanced User Tagging (Lite) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Except where otherwise noted, all site contents are Copyright 2019 ninjette.org, All rights reserved.