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Topic-icon R75/5 Running rough after stupid mistake

  • jpalin
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2 months 1 day ago #3764 by jpalin
Okay so, I decided to check my valve clearances, got the flywheel to OT, and adjusted the one side. Good so far. NOT!
Mistake #1
I set the valves on the wrong cylinder and went ahead and set the other side without turning the flywheel 360 degrees. Thought I was done and tried to start the engine. It sounded awful and real noisy on the one side. I almost immediately turned the engine off.
Mistake #2
So thinking the one side was out I went ahead and set the other side and set my valve clearances also not on the compression stroke of that cylinder. I tried to start it but it wouldn’t.

Then after research and realizing my errors, I went and set the valve clearances like this:
1. Remove both pugs and open the valve covers.
2. Turn the engine over until I see the intake valve open on one cylinder and keep turning the flywheel until I see the “OT” in the inspection window.
3. Then knowing that that cylinder is at top dead center (TDC), I adjust both valves (.10mm intake, .20mm exhaust).
4. Then I move to the other side and rotate the flywheel one rotation back to TDC and adjust the valves on that side.

But now the engine runs really rough, and it sounds like it misses, or one of the valves opens at the wrong time because I hear it almost backfire. I went back and opened the valve covers to see if the rods are bent by rotating them (after loosening the rocker nuts and readjusting the clearances) and they look fine.

Have I bent or damaged a valve? The timing was fine before I did this, so I don’t think it that. What do y’all think?? I can post a video it it’ll make it easier to diagnose.

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2 months 1 day ago - 2 months 1 day ago #3765 by Wobbly
Replied by Wobbly on topic R75/5 Running rough after stupid mistake
You certainly could have.

First, let's check the valve adjustment. Plugs out, gearbox in high gear, valve covers removed. Turn the rear wheel slowly until you see both rocker arms moving on either cylinder. Now adjust the opposite set of valves ! Turn the engine 360° until the rocker arms you just adjusted are both moving, and transition to the other cylinder's valve adjustment.

► Step number 2 is to borrow a compression gauge. Screw it into each plug hole one side at a time. With the plugs in the wires and plugs laying on the cyl head so they are free to spark, hold the throttle WIDE OPEN, and allow the electric starter to turn the engine over until the compression ceases to climb. The 2 maximum compression readings should be within ~15% of each other. If they are not, then the heads need to come off.

Good luck.

Don't hide 'em, Ride 'em !!
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Last edit: 2 months 1 day ago by Wobbly.

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2 months 1 day ago #3767 by jpalin
Replied by jpalin on topic R75/5 Running rough after stupid mistake
► I’ll do the valve adjustment first and see if that is correct.

► On Step #2 I have another aniclary problem. The bike will not turn over with the starter button now. I’ve found that only my red battery charging light goes on and no other lights when I push the key in. I have the battery on a charger to see if it is a low battery issue.

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2 months 13 hours ago #3769 by jpalin
Replied by jpalin on topic R75/5 Running rough after stupid mistake
Alright so I figured it out! The window has a dot for alignment as well as the “OT” mark. I aligned those two dots and made sure I looked perpendicular to the window. I went trough the whole process and the bike runs like a champ. With the electrical, I changed the battery and everything turns over just fine. Thanks for the quick reply!

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2 months 4 hours ago - 2 months 4 hours ago #3774 by Wobbly
Replied by Wobbly on topic R75/5 Running rough after stupid mistake
When you set the ignition timing, you need to be right smack dab on the mark. Looking square in the hole and searching for the divot or line next to the appropriate timing mark.

However, it is not the same with valve adjustments. The valves are only open for about 90° of the 720° cycle. The rest of the time the lifters are following the base circle of the camshaft. So there are probably 30 crankshaft degrees on either side of the OT mark during which the valve pair can be adjusted without penalty.

So if you think that setting the flywheel exactly on the OT mark somehow solved your problem, then you are mistaken. I'm not saying this to condemn or chastise you, but merely to point out that your error lies somewhere else and has NOT been discovered. No doubt you'll be adjusting the valves again in the next several months. All I'm saying is that you'll have this exact problem again unless you make an effort to refine your valve adjustment process.

OK ?

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Last edit: 2 months 4 hours ago by Wobbly.

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1 month 4 weeks ago #3793 by jpalin
Replied by jpalin on topic R75/5 Running rough after stupid mistake
You are correct. I have since also figured out that I had a bad connection to my horn which is tied to the starter as well as the rear brake light. I have that fixed as well.

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