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Discussion Starter #1
My bike is an '03 vn800B. I've only ridden it a few miles, and that was the day that I bought it (2 weeks ago). I knew it needed a lot of work, so I tore right into it that night, and won't be riding it again until everything is made right.
My question is about timing, as it relates to the F and R marks on the flywheel/rotor and TDC lines on the cam sprockets. I've spent hours trying to find a clear answer, but I've come up empty. Thanks in advance for any help, it's much appreciated. Here's the deal.....

The motor made a definite ticking sound when I bought the bike, so I figured I needed to do a valve adjustment. As it turns out, the gaps on 6 of the 8 valves were .10mm to .15mm too big, which is consistent with the excessive ticking I would think. But something has me confused. I followed the procedure to set my pistons to TDC. I turned the crank bolt counterclockwise until the arrow on the side cover lined up with the “F” marks on the flywheel, but when I looked at the line on the cam sprocket, it was still way off line with the top of the cylinder head. I understand what it is to be 180 degrees off, and that was not the case. I went back around many times to confirm what was going on, and it consistently lined up the same way. When I'm at TDC (the line on my cam sprocket is lined up perfectly with the top of the cylinder head) the arrow on the side cover is a solid 15 degrees past the second “F” mark on the fly wheel (the mark right next to the letter f). This is also the case with the rear cylinder. It's my understanding that there are magnets on the flywheel, which trigger the CDI and tell it when to fire the spark plugs. So, is my timing way off?

Outside of the excessive ticking, the motor seemed to run very strong. The day I bought it, I took it for a short ride after I got it home, before I started tearing it apart. She pulled hard through all 5 gears, and before I knew it I was doing 90+. Based on my experience working on cars, if the timing is set to fire 15 degrees before TDC, the motor will run like crap, or not run at all. So what am I missing?

I referred to the following video, among other things, while performing my valve adjustment. If you watch the video and skip ahead to about the 3:15 mark, you'll see him setting his front cylinder to TDC. Notice that when the marks for “F” on his flywheel/rotor line up with the mark on the side cover, the TDC line on his cam sprocket is almost perfectly lined up with the top of the cylinder head....
https://www.youtube.com/watch?v=7F3fONFkNZ8

FYI, I went ahead and did the valve adjustment. I trusted the lines on the cam sprockets for TDC and ignored the marks on the flywheel/rotor.

In this picture, my rear cylinder is perfectly set to TDC, according to the line on the cam sprocket. As you can see, the little arrow on the side cover is almost 3/4 of and inch past the "R" mark (The actual mark is above the "R" and you can't really see it in the pic)
http://i1167.photobucket.com/albums/q629/brandocain/518_zpszu8rsd3q.jpg
 

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How many miles on this motor, it sounds like the cam sprockets are off by 1 tooth. This would be consistant with what you are finding if the chain had jumped a tooth while running. Do you know if the motor has ever been apart before? In the hotrod world, advancing and retarding the cam can effect where the power is being made, more low end or top end power, but this is usually only by a couple degrees each way, any more and you risk the valves and pistons contacting each other. I would also recheck your valve adjustments after you get this timing issue fixed. Seems odd that they were that loose, they most always get tighter.
 

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Discussion Starter #4
Thanks for the reply Rick.

The bike only has 7k miles on it.

I guess there's no way to know if the engine has ever been apart, but I don't believe it has, and there's no sign of it.

Suppose the timing chain did skip a tooth.....
- I counted the teeth on one of my cam sprockets and came up with 42. 1/42=.0238, so a 1 tooth skip would result in a change equal to 2.38% of 360 degrees, which works out to 8.568 degrees
- Two rotations of the flywheel/rotor equals 1 rotation on the cam sprockets. So 8.568 degrees on the cam equals 17.136 degrees on the flywheel/rotor. I estimated that the marks on the flywheel/rotor were at least 15 degrees off (based on the diameter of the flywheel/rotor), so my original estimate seems consistent with a 1 tooth skip.
QUESTIONS:
- The front and rear are both the same distance off the mark. They each have their own tensioner, so wouldn't it be quite a coincidence for both chains to skip a tooth?
- Why would the tensioner be so loose after only 7000 miles?
- The timing belt tensioner on my honda civic was too loose and the belt skipped one notch on the cam sprocket. The car would not start. Not even close. I don't know whether this would be considered an 8.568 degree advance or a 17.136 degree advance, but either way, wouldn't the engine run like crap, or not at all?
- If my timing chains are both off by one tooth, then what would be the easiest way to set it right? Would simply loosening or removing the tensioners give me enough slack to reset the chains?

Thanks again for your help everyone. Please let me know if there's anything I need to be more clear about.
 

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When you rock crankshaft back and forth, does the second mark line up with true TDC?
Put a screwdriver down the sparkplug hole so you can detect piston rise and fall.

This is something you will have to sort as timing mark misalignment and loose valves cannot be ignored.
 

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Discussion Starter #7
I put a 1/4" drive extension down the spark plug hole to detect piston movement. My understanding is that true TDC occurs when the piston is at it's absolute highest point. If this is correct, then when I'm at TDC, the second "F" mark on the flywheel is lined up perfectly with the timing mark on the side cover. At the same time, the cam sprocket is still what appears to be about a tooth away from lining up.
Does this mean my flywheel is timed correctly with TDC, and my cam is about 8.5 degrees behind?
That would mean that my plugs are firing at the right time relative to piston/crank position, but the valves are opening and closing later than they should. About 8.5 degrees too late....

I can see how cam lobe wear would cause the valves clearances to become looser rather than tighter.....
Can I tell if the lobes have excessive wear just by looking at them? If so, then mine have it. I can easily see signs of wear on the lobes. Probably way more then they should have after just 7k miles. My assumption is that having the cam sprocket 1 tooth out of sync with the crank could cause this kind of wear....
 

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Discussion Starter #8
Here's what I'm thinking I should do....

1:Take tension off of the timing chains and reposition them by one tooth on their respective sprockets.
2: Reset the tensioners.
3: Recheck valve clearances to be certain that they are within spec.
4: Finish the rest of my repairs/maintenance and put her back together.
5: See how she runs.

Is it stupid for me to think I could be ok with worn cam lobes for a couple thousand miles, as long as the timing and valve clearances are correct? It would just be for the summer. I could replace the camshafts and rockers in the winter, when it's too cold to ride and I have more time and money.....

Any thoughts? Anyone want to set me straight?
 

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Discussion Starter #9
I managed to reposition the timing chains by 1 tooth, and now everything seems to line up nicely.

Just loosening the tensioners does not provide enough slack to reposition the chain. I also had to remove the camshaft caps, which allowed me to tilt the cams forward and create enough slack. I followed the procedure outlined in section 4-9 of the factory service manual, and it was a piece of cake.

My plan is to have it all back together on Saturday. I'll fire it up then, see what happens, and report back.
 

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It may have been tooth out of time and the valve clearances were slackened off so it would run?
I do not think valve train wear is a factor with such low mileage.

Good work to pursue this!
 

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Kawk,
I think you may be on the right track regarding the irregular cam lobe wear. Normal lobes look 'cleaner' than the untouched cam surfaces, but not shiny or worn - like emery cloth on a copper tube. A micrometer (with the cam outta the head) will speak volumes.

I am not sure the service limits but if you check the manual, shims can get pretty fat before Kaw does not recommend using them. Might get you thru the summer.

Anyway, I admire your dedication to the issue. You are clearly very sharp and well versed in common sense. A rare trait nowadays.
 

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Discussion Starter #14
Quick side note: Headlight not working. Believe I've traced it to the headlight relay. The relay, unfortunately, is an integrated part of the junction box (fuse box). Ordered a used and “tested” replacement on ebay for $20 including shipping.... we'll see
Side note to the side note: To access the junction box, you must slide it out from under frame crossbar on which the seat rests. Slide it toward the battery, and wiggle it up outta there! I had to remove the positive battery cable and shove it down out of the way to create enough space.

Ok, back to the point....
Thanks everyone for the info and encouragement. I appreciate the pics rick. Seems pretty hard to tell exactly how mine compare to a picture though. However, I did measure the cam heights several times and all were withing compliance by a few hundredths of a millimeter (according to my digital caliper). Thanks to sfair for the service limit data by the way....

I'll tell you what, I'd love to know how those timing chains got off by a tooth. I don't suppose I ever will, but I'm certainly interested in anyone's ideas/theories on the subject. What do I think? At this point, I think that someone just set them wrong while “fixing” the bike. Probably the same idiot who had the following setup in place..... Coolant breather/overflow hose running from the thermostat housing, not to coolant reservoir where it belongs, but right down the back. Connected to nothing. Like a breather hose. What was connected to the coolant reservoir? The breather hose from the air cleaner of course! W....T....F.... I discovered that lovely little configuration while I was siphoning the old coolant out of the reservoir. The point is, a dumb ass had their hands on this bike at some point. When, and for how long, I do not know. I'm just going to finish getting it together, and fire it up! We'll see what happens.....

There has been a setback. I've come down with a wonderful condition known as “cellulitus” in my right elbow/forearm (pic below if you're interested). Apparently it's not to be taken lightly, and it hurts like a mother f..... so I've been out of commission for a few days, just letting the antibiotics do their thing. I seem to be on the road to recovery now though, and did get some work done on the bike today. We'll see what tomorrow brings. I'll definitely post an update when I do finally pull the trigger on that beast!

http://i1167.photobucket.com/albums/q629/brandocain/photo_zpsy2o3oane.jpg
 
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