[MrGrinch]

Hey all,
I had a thread a couple/few months ago about my vt500c not wanting to start and decided after a compression test to tear the engine down, well here is my update to that and my issue as it stands now.

My compression ratings were low in both front and rear cylinders, after tear down I found the rear cylinder had a nasty scar across the middle of the cylinder and the front had a broken piston (between rings), but had not scarred the cylinder. I had ordered a replacement cylinder and piston off ebay, piston was good, cylinder was cracked. Got a refund for the cylinder about the time I scored an 84 ascot locally for $250 that I could use for parts, it had a lot of usable parts for my shadow. Pulled the rear cylinder and behold it's usable. Honed it and the existing front cylinder and put it all back together with new rings and gaskets, put the engine back in the frame and tried to fire it up. No luck. I am hooking to my car battery and it turns over fine and occasionally will give a really explosive backfire out the rear exhaust pipe (I just have headers installed for now). I have everything installed on the bike except the full exhaust and the tank. I am using a bottle with the lid drilled out and a fuel line inserted so that I know for a fact that it is getting good/clean fuel.

Thinking that I may have screwed up the timing of the cams, I took the valve covers off (with the engine in the bike), and followed the sequence in the service manual and clymer manual to check the cam, cam chain, and cam sprocket alignments and it all seems right (unless I am misunderstanding it), since it really seems like a timing issue (the compression is good, it was the first thing I checked). My take on the cam timing is that you do front first, then rear:

- Turn the engine to F.T. mark, install front cam (lobes down), install sprocket in chain and put on cam (make sure timing marks are parallel to head surface), temp install bolt in exposed cam bolt hole
- Turn crank 180 degrees to F.T. mark again, install cam bolt in exposed hole
- Turn crank 180 degrees again to F.T. mark and tighten temporary cam bolt.
- Turn crank 232 degrees to the R.T. mark, install rear camshaft with lobes facing down, , install sprocket in chain and put on cam (make sure timing marks are parallel to head surface), temp install bolt in exposed cam bolt hole
- Turn crank 180 degrees to R.T. mark again, install cam bolt in exposed hole
- Turn crank 180 degrees again to R.T. mark and tighten temporary cam bolt.

Any ideas/insights, is my take on the cam timing right or am I doing something wrong, the clymer manual has a little different cam timing procedure that doesn't make a lot of sense to me. I am really considering just turning the rear cam 180 degrees and see how that works. Getting incredibly frustrated with it, but really want to get her running again, I repainted the whole engine black and the exhaust with black header paint and she is looking quite sexy, if I can only get it running, I can move to painting the body parts.

 

[still_bluenoser]

Yea, you may have not been on TDC compression (i believe thats the stroke of the cycle you want) which should put you out.

Dont just flip the cam, unbolt your chain sprocket from your cam while your on the FT or Rt (whichever cylinder you try first)

Than rotate the crank til you hit the FT or RT again. Tighten things up as normal.


Try again.

If your getting good compression you have done something right, its just firing on the on the wrong stroke.

 

[Jim O]

I read this and it was all Greek. Wish I had the skills you two appear to have!

 

[still_bluenoser]

I read this and it was all Greek. Wish I had the skills you two appear to have!

Do one valve adjustment and you learn almost all of it.

 

[JeffL1985]

Bluenoser is right the cylinder you're working on setting the cam timing for must be on the compression stroke. Do this by installing one spark plug in each cylinder then put you finger over the cylinder you're adjusting say the front to start with rotate the engine over with the 17mm socket and you'll either feel a sucking or pushing (pushing for compression) then line up the FT mark or RT for rear. If I remember correctly there is a small hole on I think the middle lobe that will face straight up when the cam lobes are facing down. The important thing to remember is don't try to start it if you even think the cam timing is off you could sink a valve into the piston. I just finished a rebuild of my 500c so I know where you're at let me know if there's any thing I can help with.

 

[still_bluenoser]

The important thing to remember is don't try to start it if you even think the cam timing is off you could sink a valve into the piston.

Thats right, I always spin the engine with a socket before I try anything with the starter after I've had the top end apart.

 

[MrGrinch]

I read this and it was all Greek. Wish I had the skills you two appear to have!

Honestly, it usually just takes getting your hands into it and it all starts to come together, I've been working on vehicles for around 20+ years. And yet those skills still wont get this dang engine to start. lol

 

[MrGrinch]

@ Bluenoser - I was planning to pull the cam sprocket and rotate the engine like you stated, that way I wouldn't have to fight with compressing the valve springs, but thanks for clearing that up in case someone else comes along and reads that. In order to set the cam timing I am turning the crank with a socket, but once I thought I had it right tried to fire it up.

@ JeffL - That process to check stroke would only work if the cam is already installed correctly, but if it's 180 degrees out would not work the way it should since the valves will be in the wrong position at the wrong stroke. An example would be if the piston is on the compression stroke, but the cam is 180 degrees out, it would be in the exhaust stroke position and the exhaust valve would be open so you would feel no pushing on the thumb or finger.

Thanks for the responses so far, I plan on changing the cam timing 180 degrees out on the rear this afternoon, hoping to post a success this evening.

 

[MrGrinch]

Latest update! I couldn't wait for this evening, so I worked on it at lunchtime (I work from home most days) and pulled the cam sprocket off the cam and spun the crank 360 degrees and re-installed (thus spinning the cam 180 degrees). Put it all back together, the entire process took me 1.5 hours. Tried to start and was loosing heart because it sounded like it wasn't trying at all, just spinning. Decided to give her one more shot and it sputtered for a second.....tried again and VROOMMMM! She fired right up and ran nice a smooth! No misses or anything, just a little de-cel pop due to having nothing but headers on for now. Ran her for about 10 mins or so to get her good and warm. Cut it off and letting it cool for now, will re-start her later this evening to make sure she starts easier now that she's ran once.
Time to move on to the body work. Thanks for all the input on this.
Just to celebrate I gave her a quick photo shoot until I get the body work done. I plan to do an olive drab tank, fenders, and side panels with the blacked out engine and accessories (going for a bomber/fighter theme)... Here is what she looks like now.

 

[FastXR]

Looks really nice, glad to hear you finally got it sorted out! It really does get disheartening sometimes when you think you have a problem solved and it doesn't go as planned. Glad this one worked out. Dont forget to keep updating us on your progress.

 

[still_bluenoser]

Looks great! Good job.

 

[MrGrinch]

Just wanted to post on my progress so far. Been cranking her up daily just to keep the engine moving, she's been hard to start after I finally got her running, but the more I run her, the easier she starts now.

- pulled handlebars and cables off the ascot parts bike.
- sanded and painted the handlebars, instrument canisters, and front end components flat black and re-installed.
- Swapped throttle and clutch cables out for ascot cables, shadow ones were too long and stick out too far.
- Stripped tank and patched a few spots, need to sand down patches and it's ready for primer.
- Started sanding off / stripping the rear fender.
- Took apart ascot master cylinder, going to get a rebuild kit soon, I am going to replace the shadow MC with this one because the shadow MC sits at an angle on the ascot bars due to the design from the old "buck-horn" style bars I took off.
- Got back my 2-1 exhaust adapter from my brother (he's a welder and welded on a cover from the ascot power-chamber I cut the 2-1 side off of) Repainted all the ascot exhaust parts with ceramic header paint (not sure I like it yet, may have to re-do with grill paint later).
- Headlight canister is out getting bead blasted, will repaint flat black when it gets back.

here are a couple updated pics showing the new bars/dash set up:

 

[MrGrinch]

Took her for a good test ride around the neighborhood today! Got my rear LED blinkers, grips, and bar ends today so put it together enough to ride around a bit. Still got a few kinks to work out and still have to paint the side covers and front fender, and make a sissy bar pad, but so close now.....