Fresh rebuild, crank but no start
Hey guys, looking for some help here. Fresh rebuild (head redone by Dave, balanced crank and z400 bearing, etc) but I'm getting a crank but no start. I tried a bunch of stuff today and got it running at one point, but when I put plastics on and went to actually ride it I'm right back at crank but no start condition. Things I've tried already -
Spark - looks good, tried swapping coils with spare but no improvement
Timing - key good, c lines up at TDC checked with a screwdriver down the plug hole
Fuel - definitely getting fuel, perhaps too much? After a few tries at cranking if I pull the plug there's a layer of gas on the piston and some on the plug too. I did pull the intake and the spray pattern looked ok
Compression - tried adding 1-2 tbsp of oil, it smoked a bit and did start up after 2 attempts with cleaning of the plug between, but I tried adding some again and it doesn't seem to help.
I'm not sure where to go next, seems like excess fuel might be an issue but I'm not sure - repeated attempts at cranking might just cause that to happen?
Spark - looks good, tried swapping coils with spare but no improvement
Timing - key good, c lines up at TDC checked with a screwdriver down the plug hole
Fuel - definitely getting fuel, perhaps too much? After a few tries at cranking if I pull the plug there's a layer of gas on the piston and some on the plug too. I did pull the intake and the spray pattern looked ok
Compression - tried adding 1-2 tbsp of oil, it smoked a bit and did start up after 2 attempts with cleaning of the plug between, but I tried adding some again and it doesn't seem to help.
I'm not sure where to go next, seems like excess fuel might be an issue but I'm not sure - repeated attempts at cranking might just cause that to happen?
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Yea, I'm gonna have to pick up a tester with the right size adapter - the standard rental from the Autoparts store didn't have the right size plug adapters :-(
TPS Seems to be reading well, I can monitor with my DM kit. I believe I got it set correctly, I followed the directions found on here.
I'll tackle it again after work today; I was pretty angry last night but I've calmed down a bit.
TPS Seems to be reading well, I can monitor with my DM kit. I believe I got it set correctly, I followed the directions found on here.
I'll tackle it again after work today; I was pretty angry last night but I've calmed down a bit.
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- Joined: Wed Mar 10, 2021 10:41 pm
Keyway should be good - I pulled the flywheel and the key is fine, no damage to it.
After work I went and picked up a compression tester that actually has adapters for small plugs - checked on my DR650, ~85 PSI. The cannon was at ~10 PSI dry, and I added some oil and got it up to maybe 30. Definitely low :-/ So, working on pulling it all apart again. Is it possible its just timing, or am I gonna have to pull the head and look at the rings and all that jazz?
After work I went and picked up a compression tester that actually has adapters for small plugs - checked on my DR650, ~85 PSI. The cannon was at ~10 PSI dry, and I added some oil and got it up to maybe 30. Definitely low :-/ So, working on pulling it all apart again. Is it possible its just timing, or am I gonna have to pull the head and look at the rings and all that jazz?
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- Joined: Wed Mar 10, 2021 10:41 pm
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- Joined: Wed Mar 10, 2021 10:41 pm
It seemed to run fine, it didn't sound very abnormal. I only let it run for 30 seconds or so - closed garage cause it's cold outside!
I was wondering how it's possible to have it start at all if my compression was so low, but I'm pretty dang sure the compression tester is good - checked on my dirt bike. I did add oil a bit before I got it to run, but I added oil during the compression test too. Kinda strange.
I was wondering how it's possible to have it start at all if my compression was so low, but I'm pretty dang sure the compression tester is good - checked on my dirt bike. I did add oil a bit before I got it to run, but I added oil during the compression test too. Kinda strange.
I turned the crank a bunch of times before engine install to make sure the valves were all good, didn't hear anything so I hope I got the piston installed correctly. I'll pressurize at TDC and see where she leaks.
Thanks for all the help - I've rebuilt this engine twice so far; failed once after the case cracked (still not sure how...) and then a circlip came off one of the small oil pump gears and got up in between the cam idler gear and intake cam; sheared the water pump impeller end off and trashed most of the intake side of the head - current head is a rebuild from a spare engine I had.
Thanks for all the help - I've rebuilt this engine twice so far; failed once after the case cracked (still not sure how...) and then a circlip came off one of the small oil pump gears and got up in between the cam idler gear and intake cam; sheared the water pump impeller end off and trashed most of the intake side of the head - current head is a rebuild from a spare engine I had.