I couldnt tell, did you have the throttle all the way open when doing the compression test? With the throttle closed it can cause low readings. I had a Vtwin that read fine on one cylinder but low on the other. With the throttle open the low cylinder started reading normal. The other cylinder had a big crack in the intake boot so the number didnt change on it.
I didn't realise you have to do the compression test on a warm engine, I am sure it doesn't matter! My ZX9r still had a consistent 200psi before changing the head gasket and doing valve clearances, I didn't feel the need to recheck after, but kind of whish I did to see if it was any different. The spark plug gaskets were gone on mine, surprising as it's now still only at 23k miles. You are brave just yanking all the wiring out 😂 I guess from how confident you come across that your background is as a mechanic?
I think it's more best practice to compression test a warm engine, but not essential. As you'll know, things expand when they get warm, so you'll get lower results with a cold engine. I think the other benefit of running the engine first is you'll get the oil around everything. I wondered if that was why cylinder 4 had higher results, I've not checked yet, but that cylinder could be closer to the oil pump, so could have had a better feed. No, not a mechanic, I'm actually a computer programmer so thanks for your comment 😀 I've tinkered and maintained cars for 30+ years, and more recently bikes. 200psi is a really good result, you must have been happy with that 😀
@@motocrad Yea that does make sense that you'd get a better result with a warm engine. Just doing the compression test will pump oil around and bring the oil pressure up though. You can definitely tell you know your stuff to some degree, my skills are probably on par or there abouts. I was a mechanic for a very short while from time to time in my younger days, but certainly not a seasoned mechanic, but always do my own bikes, and cars when I did have them. Yea I was well happy and a little surprised with the compression tests. This is going to be a fun project as it gets going some more 👍
Let me know if you’re not past the point of no return or if you have any questions. I’ve had my 2001 for years and completed much of this work. FYI with th3 valve maintenance complete I got 210/210/220/220 on my compression test. These engines have lined cylinders, they cannot to my knowledge be honed.
That sounds like you're getting great compression. I didn't know that about the cylinders, I haven't done it yet, life has got in the way a little and the project is currently on hold. I'll do some homework before starting the rebuild :)
Hi, what was the point of stripping the engine down, if the compression readings were in spec? If you planned on stripping it down anyway, why do the compression test. Unless it's a RUclips content thing? I was under the impression that these had chromed bores, is it a good idea to hone those? Sorry for all the questions, I have a 9 e1 I'm in the process of swapping out an engine, after a weird gearbox fault.
Hi, being a project bike I wanted to strip it down to the last bolt and rebuild it, for no other reason than I wanted the challenge. I did a compression test just to give me a steer on the condition of the engine, and so that I can also perform one after I've rebuilt it, hopefully the results are better :) I don't know about the chromed bores, this is kind of why the project has stalled a bit. I've got to a stage where I need to do things I've not done before and I need to start doing some homework. Weird gearbox fault, I'm intrigued, good luck with it.
@motocrad Shame I can't put pictures up for you. Basically, it looks like one of the shifter forks has tried to friction weld itself to one of the gearbox gears. Does look a bit weird, will be stripping down for a neb. Look forward to seeing more of your project too. Cheers.
Personally I think you're making ALOT of unnecessary work. You should have put oil in each cyl first overnight. That will give you a accurate reading. also, please throw your Ali-Express screw in comp tester away, the hose swells and stuffs the reading, as well as not sealing.
Thanks for the advice, I do have a habit of buying Aliexpress crap. Making unnecessary work is what it's all about, I wanted a bike I could strip down to the last bolt and then rebuild. Having said that I've been distracted for a few months and the chances of it all going back together are getting slimmer each day 😉
Good luck too, Ive recently done a zx7r with a jumpy gearbox, bent selector fork. zx9 is like exactly the same looking at its guts.
nice build brother! cheers
I couldnt tell, did you have the throttle all the way open when doing the compression test? With the throttle closed it can cause low readings.
I had a Vtwin that read fine on one cylinder but low on the other. With the throttle open the low cylinder started reading normal. The other cylinder had a big crack in the intake boot so the number didnt change on it.
Hi, I tried it both with and without the throttle open, it didn't seem to make much difference 😞 That is interesting about your VTwin 🤔 All the best.
I didn't realise you have to do the compression test on a warm engine, I am sure it doesn't matter! My ZX9r still had a consistent 200psi before changing the head gasket and doing valve clearances, I didn't feel the need to recheck after, but kind of whish I did to see if it was any different. The spark plug gaskets were gone on mine, surprising as it's now still only at 23k miles. You are brave just yanking all the wiring out 😂 I guess from how confident you come across that your background is as a mechanic?
I think it's more best practice to compression test a warm engine, but not essential. As you'll know, things expand when they get warm, so you'll get lower results with a cold engine. I think the other benefit of running the engine first is you'll get the oil around everything. I wondered if that was why cylinder 4 had higher results, I've not checked yet, but that cylinder could be closer to the oil pump, so could have had a better feed.
No, not a mechanic, I'm actually a computer programmer so thanks for your comment 😀 I've tinkered and maintained cars for 30+ years, and more recently bikes.
200psi is a really good result, you must have been happy with that 😀
@@motocrad Yea that does make sense that you'd get a better result with a warm engine. Just doing the compression test will pump oil around and bring the oil pressure up though.
You can definitely tell you know your stuff to some degree, my skills are probably on par or there abouts. I was a mechanic for a very short while from time to time in my younger days, but certainly not a seasoned mechanic, but always do my own bikes, and cars when I did have them.
Yea I was well happy and a little surprised with the compression tests.
This is going to be a fun project as it gets going some more 👍
Thank you and ditto about knowing your stuff. It was your video that helped me fully understand the breather and kleen air system on these bikes 😀
Let me know if you’re not past the point of no return or if you have any questions. I’ve had my 2001 for years and completed much of this work. FYI with th3 valve maintenance complete I got 210/210/220/220 on my compression test. These engines have lined cylinders, they cannot to my knowledge be honed.
That sounds like you're getting great compression. I didn't know that about the cylinders, I haven't done it yet, life has got in the way a little and the project is currently on hold. I'll do some homework before starting the rebuild :)
Hi, what was the point of stripping the engine down, if the compression readings were in spec? If you planned on stripping it down anyway, why do the compression test. Unless it's a RUclips content thing?
I was under the impression that these had chromed bores, is it a good idea to hone those?
Sorry for all the questions, I have a 9 e1 I'm in the process of swapping out an engine, after a weird gearbox fault.
Hi, being a project bike I wanted to strip it down to the last bolt and rebuild it, for no other reason than I wanted the challenge. I did a compression test just to give me a steer on the condition of the engine, and so that I can also perform one after I've rebuilt it, hopefully the results are better :)
I don't know about the chromed bores, this is kind of why the project has stalled a bit. I've got to a stage where I need to do things I've not done before and I need to start doing some homework.
Weird gearbox fault, I'm intrigued, good luck with it.
@motocrad Shame I can't put pictures up for you. Basically, it looks like one of the shifter forks has tried to friction weld itself to one of the gearbox gears. Does look a bit weird, will be stripping down for a neb. Look forward to seeing more of your project too. Cheers.
Where did you get your engine parts
Please let me know
A combination of eBay and Fowlers (fowlersparts.co.uk). Fowlers for the piston rings and shells.
Personally I think you're making ALOT of unnecessary work. You should have put oil in each cyl first overnight. That will give you a accurate reading. also, please throw your Ali-Express screw in comp tester away, the hose swells and stuffs the reading, as well as not sealing.
Thanks for the advice, I do have a habit of buying Aliexpress crap. Making unnecessary work is what it's all about, I wanted a bike I could strip down to the last bolt and then rebuild. Having said that I've been distracted for a few months and the chances of it all going back together are getting slimmer each day 😉