I have a turbo’d gen 2 with 9:1 pistons and a full rebuild in the engine. Started it for the first time for 5 minutes and it would not idle and no power over 5000 rpm. Decided to do a compression test and leak down to verify everything and check timing which i did prior to putting it in the bike. However, something is not right. Fuel pressure is good and no vacuum leaks lead me to verify timing and compression. What would be a normal psi for the compression test given the rings are not seated and low compression pistons? Thanks
New Build Compression Test
- Thread starter merrell30
- Start date
Kiwi Rider
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Are you 100% certain the valve timing and the valve clearances are correct and within spec?
I believe so. Just checked timing at TDC on cylinder 1 and it is right on. Leak down is good and all cylinders very similar in leak down and compression. Compresson is low at 120 but given 100% rebuild and rings are not seated and low compression pistons is that normal? But if it is, why will it not idle and will not rev over about 6000 rpm?
Kiwi Rider
Registered
OK, have you rechecked the valve timing marks on the cam sprockets (tappet cover removed) as per the service manual diagrams?
Is the fuel pump ok?
Is the fuel pressure correct, within spec?
Do you have the factory service manual?
If not, download it . . there are plenty of people here that can send you a link, @Berlin Germany has all the info and manual downloads you need.
The Gen 2 idle speed is controlled by the 'Idle Speed Control valve', or ISC as it is referred to in the manual.
Go to 1A-92 in the manual for a complete rundown on the ISC system and how it works, and how to test and re-learn it etc.
If the ISC connector is disconnected while ignition is on or even just within 5 seconds of switching ignition off, it will cause a fault and it needs to be cleared.
Just try disconnecting the ground terminal on the battery for 10 minutes, reconnect it and see if the engine will idle.
Yes, I verified the intake and exhaust marks per the manual at TDC for cylinder 1. Marks are even with the cylinder head surface at TDC pointing left side for intake and pointing right side for exhaust. Verified valve lash. I then rotated engine 180 degrees and both marks are pointing towards each other, even with cylinder head surface. I have another gen 2 engine that has never been opened. I put both engines at TDC on cylinder 1 and compared what cylinder 1 cam lobe position looks like just for reference and they are the same. I know i cant trust that but it is at least close and not 45 or 180 out. Makes me think it is not a mechanical problem but a fuel problem and TPS/IAC problem. Fuel issue could explain not being able to rev over 6k but fuel pressure is constant at 43psi and no hose kinks. All fuel components are new as is all engine parts and the RCC turbo kit.
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Berlin Germany
Registered
not reving over 4-6000 rpm sounds for me that the timing is not correct - only one tooth over / less is enough for that scene.
so, if not yet done , download the manual here and follow the counting instruction at the the chain-pins (pages 3-123 , 3-124)
to check the cams again if the arrow at out is plane to cyl. head and the 15th pin etc.
or did you fumble at the cranks chain sprocket and forgot to turn it 5 teeth clockwise over the position as shown in the manual, supposing you are using the 0,08" foot gasket ????
Busa Quick
Registered
How did the motorcycle run before you did the work? How long did the bike sit without being ran? Is there any possibility the gas sat in it long enough to go bad or clog the injectors?
Motor has never run after the complete rebuild. All new parts and gas. I took it apart down to the cams. Verified timing and re-degreed the cams. Exhaust at 108 (per webb cams) and intake was 109.75 so I fixed that to 108. I also degreed in the cams on a different stock gen 2 engine i have to verify what i am doing and the stock engine matched the stock specs. Putting it all back together and am going to verify the injectors are working correctly and then reset the TPS and try to run it again. Timing was right where it should be and cannot be the problem. Must be fuel or electrical.
Problem solved. Stupidity was the reason. Too much fuel. I spent the last year and a half doing a 100% engine rebuild (6 months waiting on APE) and inter-cooled turbo install and forgot I installed into the fuel rail, larger injectors. I suddenly remember that, installed the stock injectors and it immediately started running normal. Broke in the cams and briefly tested out the transmission and it seems fine and A/F seems good. Will be heading to a Dyno soon after tying up some loose ends.
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Busa Quick
Registered
Glad to hear you keep trying until you found the problem. Sounds like you are on the right track now!
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