DIY Tech Tip: Perform A Compression Test on your Motorcycle
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- เผยแพร่เมื่อ 2 ต.ค. 2024
- In this DIY Tech Tip from Lowbrow Customs, Todd shows you how to test your motorcycle's compression, and what it means. A simple compression tester which is available at most any auto parts store is all that is needed for this useful task. Check out more at www.lowbrowcustoms.com/tech
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Great tutorial, thorough and straight to the point without any bullshit. Thanks a lot!
I like the style of your video. It strikes a good balance between too much talking and not enough talking and action. Some of these tutorials are painful to watch, but you do a great job of keeping it engaging. Now, let me go actually do this...
Excellent video as usual from Tom at lowbrow - I read somewhere make sure to turn off the petcock too...not sure that makes a difference tho.
"Ok, somehow we got her to run with no compression. Don't ask me how we did that." Todd cracks me up.
Best video on a compression test on youtube.
Yup!
Love it!😁👍
Wow, big difference between hot and cold.
Great video! Very informative, Thank you. One quick question - what is the reason to have the throttle wide open? What is does from the technical point of view? Thanks for the answer.
If the throttle is closed, the cylinder fills with less than a full charge of air -- that's what the throttle is there for. So there's a vacuum (i.e. lower absolute pressure) in the cylinder. Then the piston compresses the vacuum, so the peak pressure in the cylinder is less than it would be if the cylinder had been allowed to draw in its full volume.
Oh! I see now. That makes sense, didn't realize that. Thanks! :)
thank you. best video of compression test on youtube 👍
why video makers (any type) dont do videos like u ?? :/ will go check my both Yamaha-s xt 600 (84) whats the result ... buyed them few weeks ago ... P.S. one thing u didnt show ... :( :/ that warm up ! like to hear it looks lovely ! :) but ... u got a A+ here :)
So it nearly doubled after letting the bike warm up. If my bike is running fine and the compression numbers seem within spec, should I still put some oil into the cylinders to see if I get a higher number?
I'am Your Newest Subscriber Great Videos. I'am Interested In Knowing Compression On My 2007 Honda Rancher ATV TRX400FGA
great video! thanks
Excellent knowledge, thanks for the help
coolest peg board I have ever seen
if you have an opposed head engine will the squirting of oil make a difference?
Brother i thank you very much for alllll of your advice and videos. When my father passed ,i inherited a 68 trophy, and has been a bear to get going again. Especially without his knowledge and never ridden or worked on a motorcycle before! You guys are amazing! Keep up the great vids! Peace out!
Good vid, be lost without you guys in TH-cam land. Pleased to say you guys will soon have my old Bonny back on the road and running sweet as a nut,,
Thank you! ;)
Great video. Never knew it was this easy. The test with the motor oil is a nice plus as well. Thanks a lot!
Thank you for this broskie! ... BTW, luv your garage! I have serious garage envy right now!
saved me so much time...oil in the spark plug hole.....of course !!!! Cheers
thats a old bonny true english bike you love them or hate in the 70s they where the best handling bike out there
my xj600s has 65 75 75 75 , do you think I need new segments? also it drained almost all the oil through the breather
Nice video. What is a good compression for a Harley 883 motor? (maybe a 2000 to 2013 Harley)
probably best bet is to find a manual or hit up a forum. I was able to find the service manual online for mine through a yahoo group and printed it out.
Thanks, I'm gonna looking for it
good day sir, is it possible to compression test to open carb or no air filter carb? newby here from ph. tnx
Yours was the first vid that came up on motorcycle compression test. So glad it did, straight to the point, plain language. Tip on the oil down the bores is brilliant. Keep it up.
Thank you for the informative video!!
So with oil added if pressure increases the rings are bad, if it doesn't change, there's a valve seating issue. That means regardless of reading, there's a problem, right?
yeah - that's weird - I guess that would be true if you have a bad reading on your compression: if the compression is out of specs, then the oil in cylinders would give you indication if its the cylinder or the valves that are in cause.
Finding the tech tips very helpful,just picked up 2 old triumph's and need all the help I can get!
all engines rise a bit on the wet test, it doesn't mean the rings are bad unless it's big jump
paul 466 how big of a difference
@@wilanderson1218 I'd say anything over 20psi of compression difference after you've added some oil to make'r a full wet test. Oil is great for sealing them down to the oil ring. Oops didnt watch before replying lol
If mine doesn't have a kickstart, do I just crank the ignition switch?
They better come down more than just "a few", with no compression...
in manual say 135 psi its mean with hot engine???my model is xtz 750 super tenere
Many thanks pal. Keep up good work. Best regards james
take out spark plug screw in tester turn on key start crankin.
Excellent video! Thank you!
Full throttle copied, what about the choke?
Thanks for your Video
Hey bro after a big rain my Suzuki C50 run for 10 minutes and stall I though no have gas but .. yes have half tank... so now when I started start ok but when I give gas just die !😩please helpme idk anything about motorcycles ... thanks
If it’s an electric start, do you just attempt to start the engine?
Yes
I have a 1999 Kawasaki ninja ZX6E it has 90-100 pounds of compression in all cylinders its supposed to run at between 135-215....my ninja will run fine for awhile but then it acts like it fouls a spark plug and then it is a sucker to get it to idle proper and to keep it running at idle. but i believe i need to get new valves and seats in the carbs. and i have set the floats properly. could i add engine restore to my ninja to restore my compression? valves have been checked for clearances and all seem proper. what is your take on it lowbrowcustoms???
if you spin that motor fast enough you can make some engines run if it's not to bad
Does the volume of the hose matter ? Bill
soo question(s) did it turn out to be the piston rings indeed? and does having the choke open or closed matter in terms of doing a compression test?
I'm curious too.
Did you pull the head and barrels off the engine? How worn were the rings and bore?
Great tutorial........I am helping my sun do a rebuild of a Suzuka Savage 40. The bike ran well when he bought it and we should have checked compression then but we have the bike torn down with the engine on the floor. Is there any way we can check this engine's compression now that it is out of the frame? Also, this bike does not have a kick starter........we are going to be building a Ryca Cafe Racer.
Buzey with a rebuild.No kick start and no wireing harness.Usted a torch wrentch and jammed the butter fly open and crank over engine.Easy way of checking any engine in or out of frame with a compression tester
thanks alot 👍
Sure glad I'm stuck in the 80's, cause that kicking to test sure looks like a major PITA! Or, maybe its just my age! Peace!
my 32 year old 2 stroke outboard still put out 90psi. thats pretty shit compression for a 4 stroke motor (i was always taught to do a compression test with the engine at operating temp and wot)
Does a compression tester work on my XR250 which has a decompression valve? Will it give a false reading?
Thank you very much, really helpfull. By hand when I turn the engine stator fast I need to apply very much force, but when I do it slowly the engine offers almos no resistance. Can be that a sing of compression leak? thank you in advance!
so you're supposed to do this test with the motor oil drained from the engine, yes? and when you squirt oil into the engine, is there a specific way you need to do that, or can you just pour it down through the sparkplug hole? when you squirt oil into the engine and the pressure stays the same, then it's good, right? provided the valve clearances are in spec? how much further up does it need to be to indicate that you need replace the gaskets?
thanks
Good one
Thanks 👍
Ive seen dyno results for a 250rr 40% down on compression but still making 38kw
Wow, thanks. Great video.
THNX for the information, so helpfull.. now, couple of questions: 1.- when the engine is warm enough to perform the "warm test"..? after 5, 15 minutes running..? 2.- it's ok to take out the sparkplugs of a warm engine.?
It's okay to remove plugs when warm. Time period for engine warm up: if it feels warm, it probably is warm.
Great video. Just tested my "68, 650cc BSA chopper. 125--130 Dry. 145--140 Wet.
Runs pretty good though.
Could low compression test maybe be the cause of a bike smoking?
Thank you for this! Makes perfect sense. Dig your style.
So cleverly done ...easy lesson.
Wish you safe riding from the U K.
what if its an electric start?
push the starter button then
Hello, I assume the spark plug shouldn’t be in the cylinder while testing it, but I have a carburetor, should I take that out or leave it?
Thanks I appreciate the video
Says it at 01:23 if a Twin remove both spark plugs. You can see the carbs are still on the bike so leave them on.
Great vid thank you for sharing!!
Awesome explanation...just what I needed👍
Nice vid
Should the engine be warm or can I get a fairly accurate reading from a cold engine?
Do on both and notice the difference
is the starting procedure the same on an an electric start bike ie. wide open throttle and crank?
Also need to plug choke
Thank you, very informative!
Great job with this video! Nice job explaining how it should be done! Thanks!
What’s could be the problem if the compression stays the same after the oil in the spark plug hole ?
Valves
What if you have just an electric start? Could I start the motor that way for a compression test?
Yes.
Thanks very helpful on my old Ural
Subscribed!Brillianr!😁👍
Good video. but why can't you remove one plug at a time leaving the other in? v star 1100
Because the you will be fighting the compression of the other cylinder, causing resistance.
did you keep the fuel line open ?
WISH I HAD A TEACHER LIKE THIS IN SCHOOL
Nice Vids, thank you to Lowbrow and Todd.
Very impressive, it's my first time to see that oil can increase compression
Awesome video! Thanks for your time!
Thanks, appreciate you taking the time Todd
Excellent, cheers
awesome video thanks for the lesson
Really enjoyed that thanks,should you use o ring grease on the the comp tester seal or is any grease ok? Also not sure if it’s on your channel but could you do a valve leak down test. Cheers 👍🏼
thanks brother im looking into getting a CB750k needed to know how to do this
great thank you for the tip, for sure i learned something new with this video
I don’t get it.
So do we go off the first readings of 60psi when engine was cold?
Or do we go off the 115psi when engine was hot?
The reading on the hot engine.
Is there anything we can tell from the cold reading?
@Albert G.
Is there anything we can tell from the cold reading?
@@114wildfire it should just be a rough measurement to see how bad a shape it's in... 60 cold would tell you it definitely needs work, but it wouldn't allow you to know the correct hot reading unless you turn the bike on and let it warm up. In his case it jumped from 60 to 115 which is a big jump, but 115 is still on the low side.
@@114wildfire you can also compare cold readings across cylinders just to make sure they're not drastically different from one another.