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Rebuilt, getting mixed reviews about the engine
- Limitlesstruth
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Anyways more to the point: I had to get the engine rebuilt, I took it to a shop (shop A for reference) and they told me that the engine wasn't in the best of shape and wanted to bore the engine to clean it up put in a new piston kit (1100 wiseco bore kit I believe?) and new intake and outtake valves along with another head that was in better condition. After a ridiculous back and forth I got the engine back in my possession in which I then after some aggravating attempts gave up on getting the engine back into the frame. While the engine was at shop A, I had been to shop B which specializes in KZ's and talked to the owner gotten parts that needed to be replaced. I took the bike in all parts to shop B to have them rebuild the thing because of the inability of me and my father to get it to go, plus busy schedules and this is where the problem begins more or less.
Before the owner at shop B were to put the bike back together he wanted to check the engine, make sure he thought it would at least run before putting everything in place and in such wasting time and money. He did a leakage test and compression test to the following results, here best portrayed from him to me to you: Cylinder 1 and 2 had no compression, 3 had a decent amount, 4 minimal. This all to my dismay I call shop A tell them what I have heard or come up with and what I would hope they would do to remedy the situation. With some stupid responses I eventually got them to accept the fact that they had to at least prove their work in some respect, I talked to the head manager and took the engine to them, they did a compression test in front of me to the following result: 150, 140, 110, 140 --psi-- respectively. Keep in mind these things (all new parts --intake, outtake valves, pistons, and bore-- and no oil has circulated through the engine. I told shop B what I had actually seen with my eyes and the response was that his tests were more accurate. He hand cranked the engine for the compression test using the bolt by the electrical points on the right side of the engine, and "did a leakage test" to which he said there was a 80% leakage out of the exhaust valves from what I understand.
I've gotten a few different points of view but the general thing I got was: it will be fine, you wouldn't see that kind of compression with that amount of leakage plus the engine needs oil to help seal and gain that extra compression plus the parts need to be broken in.
So I guess my question is what am I dealing with here, is it possible that with the supposed leakage I have through the valves will the engine actually show compression, and even if yes will it run anywhere near where it should?
1979 KZ1000 ltd.
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- silentchris
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Speed is only a question of money. How fast do you wanna go?
1978 kz1000 ltd
Hailing from the wild suburbs of our nations capital
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- Limitlesstruth
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Can I actually see compression off of an engine where there is any major leakage like I'm being told there is? What is the difference between using a battery to run the starter motor versus hand cracking the motor for a compression test?
1979 KZ1000 ltd.
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- 4TheKZ1000
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If you need someone you can trust, fair and no bullshit...contact Larry C...he is on this forum...let him know your story and see what he thinks needs done.
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- kawman66
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75 z1b
76 kz900ltd
76 kz900
76 kz900-1500
77 kz1000ltd
my drinking team has a racing problem
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- Patton
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Where compression test numbers are too low, a leak-down test helps find the cause of poor compression.
Good Fortune!
1973 Z1
KZ900 LTD
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- zukdave
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crank with a wrench.
Ask shop "B" for a reach around
and a dollor off chicken nugget coupon.
1980 KZ650 F1
ZX750A1 motor.
Wiseco 810cc kit.
Zukiworks racing ported head.
VM 29 smooth bore's.
Dyna 2000 Ign. w/Dyna mini coil's
APE cylinder stud's and nut's.
APE valve spring's.
APE Track King clutch.
V/H KZ1000 sidewinder.
3.5x18 laced to a KZ1000 disk hub.
150/60/18 Shinko 006 Podium.
63" wheel base.
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- silentchris
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Speed is only a question of money. How fast do you wanna go?
1978 kz1000 ltd
Hailing from the wild suburbs of our nations capital
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- wireman
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silentchris wrote: Hand cranking is just fine. It doesn't need to crank fast the piston coming up will generate a more accurate number if you do it with the starter your libel to have a valve start to open and reduce the number.
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What the deuce are you talking about? :laugh:
Put the electric start on the motor and crank it over without the carbs on before you stick it back in the bike.
That #3 compression number sounds totally screwed to me on a motor that was supposed to of been rebuilt,check the valve clearances before you go much further.
The other guy saying youve got 80% leakage rate is totally oppisite of the numbers other guy is giving you,were the exhuast valves all hanging open when he checked the motor? :woohoo:
posting from deep under a non-descript barn in an undisclosed location southwest of Omaha.
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- OldSchoolZ
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Here is the PROPER way to test compression.
1) remove all spark plugs
2)disconnect coil hot wires (if there is unknown gas in a cylinder
and it spurts out while cranking, your spark plug wires can not arc and cause a fire)
3) insert compression gauge into specified cylinder
4) open throttle wide open and crank engine with starter or kick engine hard with kick lever
until the gauge wont go higher.
THAT is the number you are looking for.
The problem with turning by hand is, the piston will not draw a full intake charge.
It requires the piston's movement going down quickly to draw in a full intake charge of air.
80% leakage means 80% of your compression would be gone, not possible with the comp numers you mentioned that are all above 100lbs. Personally I wouldnt take either shops comp numbers seriously.
1/2 the guys that work at dealerships, I wouldnt trust to work on my lawnmower.
Remember, don't work on your bike so much you never ride it.
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- bountyhunter
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Amen, and you can snap the bolt off trying. That is NOT what it's there for.zukdave wrote: Come on guy's you CAN'T do a compression test turnin the
crank with a wrench.
Ask shop "B" for a reach around
and a dollor off chicken nugget coupon.
1979 KZ-750 Twin
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- oldzed
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This motor is giving decent compression considering it is still "dry"
I wopuld be tempted to add a little oil to each cylinder and retest.
I think you would see an improvement in the readings.
A leakdown test is to see where air is escaping when compression is low.
Lots of engines I have tested over the years have failed leakdown tests until they have been run.
In the old days when we ground in valves we would finish by giving the valve a sharp tap to fully
seat it . If you did not do this they were harder to start till the valves go bangerd into the seat.
DO NOT TAP ANY MODERN 16v TYPE VALVES. THEY CAN BE DAMAGED DUE TO THE MATERIALS USED
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