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Post by bumtrain on May 31, 2018 17:31:19 GMT -5
Oh no, sounds like your con-rod bearings are done. 2 locals here had the same noise (almost sounds like variator rattle) and both times turned out to be a bad crank. What's the next thing to do then?
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Post by dexameth on May 31, 2018 17:39:11 GMT -5
Oh no, sounds like your con-rod bearings are done. 2 locals here had the same noise (almost sounds like variator rattle) and both times turned out to be a bad crank. What's the next thing to do then? Well... To verify you could pull your top end off again and check the play of the crank. If it's done, you could either replace the crank or buy a new complete motor.
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Post by scootnewb on May 31, 2018 20:33:43 GMT -5
Are the valves hitting the piston?
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Post by scootnewb on Jun 1, 2018 17:02:47 GMT -5
I run a 24mm carb with a 115 jet on a 52mm stroker build, and did on a regular 50mm build and 108 jet. They run great with that carb setup... Did you gap/clock the rings correctly? Can you explain the issues more clearly? May I ask which carb / manifold were you using on the 50mm build oh.. and jets? Thanks
its in the spread sheet
My bad. I thought I was in a different thread.
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Post by bumtrain on Jun 2, 2018 11:05:07 GMT -5
Are the valves hitting the piston? How can I check to see. will there be marks on the piston?
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Post by bumtrain on Jun 2, 2018 11:06:18 GMT -5
What's the next thing to do then? Well... To verify you could pull your top end off again and check the play of the crank. If it's done, you could either replace the crank or buy a new comp lete motor. Could the problem happen right after the install? The engine only has 700 miles.
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Post by scooterted on Jun 2, 2018 17:58:30 GMT -5
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Post by bumtrain on Jun 2, 2018 18:15:19 GMT -5
opp After checking to see if that's the issue should I put in a higher quality crankshaft?
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Post by scootnewb on Jun 2, 2018 19:55:48 GMT -5
If I'm not mistaken it usually takes some use before the crankshaft or crankshaft bearings bork. A day a week maybe never. If this happened right after you installed it, I think there was either something already wrong with the bottom end or the parts in your BBK were out of spec/bad install.
If you pop the head off you'll see marks on the top of the piston. Also could see if your valves are bent and no longer moving freely.
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Post by GrumpyUnk on Jun 4, 2018 9:39:17 GMT -5
Sounds like poorly adjusted valves to me.
I would remove the cam follower/rocker arm cover, and set the cam sprocket so it indicates TDC.
With the piston at TDC, both valves should be completely closed. There should be some clearance between the tip of the valve stem and the tip of the rocker arm. If you can rock the rocker arm back and forth, and feel more than a very very slight amount of movement, the clearance is likely too large. You could also have rocker arm tips that have wear 'cups'. The tip of the rocker arm is manufactured with a more-or-less flat surface, which touches the tip of the valve stem. If the stem has worn indentations into the tip of the rocker arm, adjusting the valves may prove difficult. The feeler gauge will measure between the highest part(non-cupped/non-indented) of the rocker arm tip and the end of the valve stem. If there is any rocker arm wear, the 'cup' will allow more clearance than indicated by the feeler gauge, and you will get noise. The actual clearance is almost imperceptible, being on the order of .002". It is difficult to feel the 'gap' unless it is larger than specified. If you measure the clearance with the rocker on the cam lobe 'ramp' or other than the 'heel' of the cam lobe, you will get excessive clearance, and tappy-tap-tap will occur. When adjuste properly, there will be little valve noise. Pull the cover and check for rocker arm motion before condemning much more expensive bits & pieces. tom
Added: If the valves were hitting the piston crown, the valves would likely be bent, and no longer seal, and the engine would no longer run. The noise of a connecting rod bearing would occur with EVERY rotation of the crankshaft. The noise, to me, is at valve cycle rate, not crankshaft rate. IOW, it is slower, by half, than crankshaft rotation. Rod bearing clank/rap would be at crankshaft rate.
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Post by bumtrain on Jun 4, 2018 19:31:56 GMT -5
Sounds like poorly adjusted valves to me. I would remove the cam follower/rocker arm cover, and set the cam sprocket so it indicates TDC. With the piston at TDC, both valves should be completely closed. There should be some clearance between the tip of the valve stem and the tip of the rocker arm. If you can rock the rocker arm back and forth, and feel more than a very very slight amount of movement, the clearance is likely too large. You could also have rocker arm tips that have wear 'cups'. The tip of the rocker arm is manufactured with a more-or-less flat surface, which touches the tip of the valve stem. If the stem has worn indentations into the tip of the rocker arm, adjusting the valves may prove difficult. The feeler gauge will measure between the highest part(non-cupped/non-indented) of the rocker arm tip and the end of the valve stem. If there is any rocker arm wear, the 'cup' will allow more clearance than indicated by the feeler gauge, and you will get noise. The actual clearance is almost imperceptible, being on the order of .002". It is difficult to feel the 'gap' unless it is larger than specified. If you measure the clearance with the rocker on the cam lobe 'ramp' or other than the 'heel' of the cam lobe, you will get excessive clearance, and tappy-tap-tap will occur. When adjuste properly, there will be little valve noise. Pull the cover and check for rocker arm motion before condemning much more expensive bits & pieces. tom Added: If the valves were hitting the piston crown, the valves would likely be bent, and no longer seal, and the engine would no longer run. The noise of a connecting rod bearing would occur with EVERY rotation of the crankshaft. The noise, to me, is at valve cycle rate, not crankshaft rate. IOW, it is slower, by half, than crankshaft rotation. Rod bearing clank/rap would be at crankshaft rate. Thanks for the help I will take a look at everything and see if anything arises. Ill check the valves and the crank shaft and see which is damaged or needs adjustment.
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Post by bumtrain on Jun 4, 2018 23:19:14 GMT -5
Okay, well I torn everything down again. I found no play in the crankshaft when jiggled and moved. The piston head had no marks or indication of hitting the valves. The valves have no indication of hitting the piston. They're not bent or the valve springs are not damaged. When I did open the case, the intake rocker arm was loose, so I believe this should be the issue. I also made sure that the cam was aligned with tdc, made sure the chain was tight and didn't move.
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Post by bumtrain on Jun 5, 2018 10:11:42 GMT -5
m.youtube.com/watch?v=sYYPj84YbekHere is a video of me going over everything I did. Please let me know if you see anything wrong. Also sorry for not turning the phone to the side haha.
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Post by humanshield on Jun 5, 2018 12:02:44 GMT -5
I'm with GumpyUnk's post above. What he says is also my thoughts.
Did you find the source yet? I wonder if you're checking the valve gap at the right place and time? ANYONE can make a mistake. I've made some doozies.
You sure you're getting the chain tensioner set properly?
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Post by bumtrain on Jun 5, 2018 12:49:26 GMT -5
I'm with GumpyUnk's post above. What he says is also my thoughts.
Did you find the source yet? I wonder if you're checking the valve gap at the right place and time? ANYONE can make a mistake. I've made some doozies.
You sure you're getting the chain tensioner set properly?
I put everything back together and The chain tensioner is always fully extended when I take it out, so I think that is fine. I've set the piston at top dead center before adjusting the valves. I'm waiting for an exhaust stud (because I snapped it like an idiot) and an exhaust gasket. So I only started the engine for a few seconds to be sure it started after putting everything together. So I am awaiting the arrival of those items before I can hear the noise (hopefully not),
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