Valve adjustment woes - Page 2 - Star Motorcycle Forums: Star Raider, V-Max, V-Star, Road-Star Forum
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post #11 of 23 (permalink) Old 02-02-2016, 05:34 PM
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"The surest way to find TDC is to remove a spark plug and stick a plastic soda straw down through the hole so it rests on the piston. Turn the engine slowly in its normal direction of rotation (this makes sure the timing chain stays tight) and observe the straw. When the straw stops rising, the piston is at TDC."

This is probably a stupid question, but, why not just watch the rockers for max slack and then adjust per specs. I have done it this way for years. Am I doing it wrong all this time? Cheers, Wavelength.

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post #12 of 23 (permalink) Old 02-02-2016, 06:29 PM
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Originally Posted by Wavelength View Post
"The surest way to find TDC is to remove a spark plug and stick a plastic soda straw down through the hole so it rests on the piston. Turn the engine slowly in its normal direction of rotation (this makes sure the timing chain stays tight) and observe the straw. When the straw stops rising, the piston is at TDC."

This is probably a stupid question, but, why not just watch the rockers for max slack and then adjust per specs. I have done it this way for years. Am I doing it wrong all this time? Cheers, Wavelength.
Nothing at all wrong with that tactic. However, I was writing for a person who wanted to find TDC.
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post #13 of 23 (permalink) Old 02-03-2016, 07:10 AM
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Nothing at all wrong with that tactic. However, I was writing for a person who wanted to find TDC.
the thing is he was looking for TDC for valve adjusting purposes, which is totally unnecessary. the only reason the manual uses that method is so both valves can be adjusted at the same time. it's ridiculous to pull covers and disturb seals when you don't need to. TDC really is only needed for cam timing purposes.

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post #14 of 23 (permalink) Old 02-15-2016, 04:36 PM Thread Starter
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Update: Thanks everybody, I finished the project successfully and she runs fine. No valve noise at all, that is. I'm still dealing with one carb running rich and drawing a lot of vacuum and the other running normal/lean and running considerably less vacuum, but that's for another thread.
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post #15 of 23 (permalink) Old 02-17-2016, 06:58 AM
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Update: Thanks everybody, I finished the project successfully and she runs fine. No valve noise at all, that is. I'm still dealing with one carb running rich and drawing a lot of vacuum and the other running normal/lean and running considerably less vacuum, but that's for another thread.
In your first post you mentioned having done some carb work. Now, you say one cylinder is pulling more vacuum than the other. Check your manual for the procedure to synchronize your carbs. Without going into great technical detail, the cylinder pulling more vacuum has its throttle butterfly less open than the one pulling less. There is usually an adjustment on the linkage between the two carburetors to correct this.
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post #16 of 23 (permalink) Old 02-17-2016, 04:29 PM Thread Starter
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In your first post you mentioned having done some carb work. Now, you say one cylinder is pulling more vacuum than the other. Check your manual for the procedure to synchronize your carbs. Without going into great technical detail, the cylinder pulling more vacuum has its throttle butterfly less open than the one pulling less. There is usually an adjustment on the linkage between the two carburetors to correct this.
It's actually worse than that, I'm afraid. I'm actually about to post a thread on it.
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post #17 of 23 (permalink) Old 02-17-2016, 05:15 PM
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Originally Posted by Arnold_Kupferkopf View Post
It's actually worse than that, I'm afraid. I'm actually about to post a thread on it.
omg don't say it, you overtightened and bent a valve.

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post #18 of 23 (permalink) Old 02-19-2016, 02:59 AM Thread Starter
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omg don't say it, you overtightened and bent a valve.
Good Lord I hope not! I set them all right to minimum on the first go; after a conspicuous silence of valve noise (which I'm told is a bad thing) and my later issues with compression/vacuum I (out of an abundance of caution) went back in and set them at about 1/3rd of the minimum specifications instead of right on the line. Now I'm getting a fair bit of valve clicking (which displeases me), and more importantly, no improvement in my low 5-pound vacuum on the rear carb. Thus, it was never the valves. Better to be safe than sorry, but still...

Thus, it seems I'll have to go back in again at some point (after I've resolved the low vacuum issue) and put them back close to the minimum. That presumes I'll ever get this damn carb situation sorted out...
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post #19 of 23 (permalink) Old 02-19-2016, 03:11 PM
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Until you get the compression issue sorted out, you are wasting your time worrying about vacuum or carburetors. Unless the engine itself is in good condition, with good and fairly equal compression on both cylinders, the vacuum will never come out right. Loosen all the valve adjusters and make sure you can actually feel play between the lifters and the valves when the engine is more or less at TDC. At this time you are not worrying about clearance - even if you can stick a dime in there it will work. Turn the engine over and observe that the valves are actually moving at the proper times, then try the compression test again.
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post #20 of 23 (permalink) Old 02-19-2016, 04:00 PM Thread Starter
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Came up with 120 front and 140 rear this time.
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