Author Topic: first start after rebuild (Read 1427 times)

scottly · « **Reply #25 on:** March 19, 2015, 06:42:28 PM »

Bill, IIRC, this is a big-bore motor?

theslayedsaint · « **Reply #26 on:** March 19, 2015, 06:58:30 PM »

Ok here's so pictures of the rotor When I took the nut off the rotor just came right off not sure if that's a good sign or bad. What should I be looking for?

As for the kick, it is a big bore (849) could it just be the points need timed? Or the carbs not being synced yet?

scottly · « **Reply #27 on:** March 19, 2015, 07:07:04 PM »

Crank doesn't look too bad; was it wiped clean before the pic? If not, do so and post pics again. Check the bore of the rotor for burrs or gouges.
Kick back is more likely due to advanced timing than carb sync; until you get the bike running well enough to do a proper tune-up, you may want to slightly retard the timing by rotating the point plate clockwise a little bit.

theslayedsaint · « **Reply #28 on:** March 19, 2015, 07:22:21 PM »

Saw what looks like s little "grove" line that goes around about at the half way mark, other then that nothing. And the crank had nothing other then a little wear line maybe in the same spot the roter line was.
Another qustion why is the roter taped at the closest to you when a screw doesn't go there?

theslayedsaint · « **Reply #29 on:** March 19, 2015, 07:25:15 PM »

Not sure if it matters but the crankshaft was balanced and lighted

DaveBarbier · « **Reply #30 on:** March 19, 2015, 07:38:20 PM »

Have any pictures before you took off the rotor? The rotor was sitting properly on that gear collar, right? Those lockable, one direction bearing things gave me a hard time when dealing with the primary shaft on my bike.

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1978 Honda CB550K

theslayedsaint · « **Reply #31 on:** March 19, 2015, 07:45:14 PM »

Dave I'm not really sure what your talking about? I can't understand the rotor going on but one way? Can you explain? My thougt at this point is somehow the rotor isn't sitting far enough into the taper so not allowing for a could seal?

scottly · « **Reply #32 on:** March 19, 2015, 07:48:54 PM »

Quote from: theslayedsaint on March 19, 2015, 07:22:21 PM

Another qustion why is the roter taped at the closest to you when a screw doesn't go there?

Those threads are for the rotor puller that's normally required to pull the rotor off the crank. The pics look OK; can you feel anything poking up in the bore with your finger, or does it feel smooth?
Lightened crank might add to the kick-back.

DaveBarbier · « **Reply #33 on:** March 19, 2015, 07:55:17 PM »

Quote from: theslayedsaint on March 19, 2015, 07:45:14 PM

Dave I'm not really sure what your talking about? I can't understand the rotor going on but one way? Can you explain? My thougt at this point is somehow the rotor isn't sitting far enough into the taper so not allowing for a could seal?

(Disclaimer: I don't know a lot. Just reaching for ideas.)

It only will go on one way. With the +screws facing the motor. Those roller bearings slide on the collar on the starter gear. It's pretty obvious but on my 550 they won't go on if you just push. You have to push while turning rotor the opposite way, those rollers will then open up allowing the rotor to slide on the collar properly. (The 550 doesn't have this type of rotor, I'm just relating it to a part on the primary shaft which has the same mechanism.)

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1978 Honda CB550K

theslayedsaint · « **Reply #34 on:** March 19, 2015, 07:59:52 PM »

Thanks Dave! But unfortunately I've got it on right.
I've reached my limt of ideas checked everything it looks great. Only thing I can think of is its not getting jammed enough into the taper but why or if that could happen no idea. Maybe I'll try to put it back together and see what happens.

DaveBarbier · « **Reply #35 on:** March 19, 2015, 08:28:27 PM »

Have any pictures from before you took off the rotor? This may be a stretch, but this is what I'm thinking. I think your starter issue is related to this. Does your starter make a sound when you push the button but not make the engine turn over?
I think your rotor isn't pushed on the taper all the way. I think there is a gap between the gear and your rotor. Like my picture I just drew up:

I'm thinking the rotor isn't fully enveloping the starter gear so that it's not fully on the taper of the crank, thus loosening it up while you run your bike. And I also think your starter is working fine but it's spinning the starter gear freely and not engaging in the rotor to actually crank the motor over.
Can you take a picture of the gap between the gear and rotor when it's installed?

Close??? No? Ok, I tried, haha.

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1978 Honda CB550K

theslayedsaint · « **Reply #36 on:** March 19, 2015, 08:53:41 PM »

Thanks for info and the time! Really love this site.
Ok I cleaned the whole thing put it back together with the 70ft-lb torque, and at this point it's working!! Turnibg engine and starting right away. I'll keep testing it and let you guys know.

scottly · « **Reply #37 on:** March 19, 2015, 09:15:08 PM »

The starter is the real test of how firmly the rotor is seated onto the crank taper; the first time it happened to me, I hit the starter button and heard the starter spinning, but the motor didn't turn. This was after I owned the bike for only a week or two, and hinted at all the other stuff the PO messed up.

theslayedsaint · « **Reply #38 on:** March 20, 2015, 08:50:46 AM »

Ok guys... Back to square one first try to start the bike this morning and it started spinning again. At this point I've got no idea what to do. Why didnt they make this a reverse screw so it went tightened will runing not losen?

DaveBarbier · « **Reply #39 on:** March 20, 2015, 09:01:25 AM »

Quote from: theslayedsaint on March 20, 2015, 08:50:46 AM

Ok guys... Back to square one first try to start the bike this morning and it started spinning again. At this point I've got no idea what to do. Why didnt they make this a reverse screw so it went tightened will runing not losen?

Dude, PLEASE humor me and post a picture of the gap between the rotor and starter gear! In my mind this could totally be the problem. I had a feeling that you'd come back with the same problem.

Maybe I'm crazy and I really have no business trying to diagnose this issue, but I can't help myself, haha.

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1978 Honda CB550K

DaveBarbier · « **Reply #40 on:** March 20, 2015, 09:08:57 AM »

I may be wrong but I think the rotor spins CCW so a REVERSE screw would actually loosen as it spins. I think it's coming undone by momentum and the starter.

My 50¢

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1978 Honda CB550K

theslayedsaint · « **Reply #41 on:** March 20, 2015, 09:15:48 AM »

Here you go kinda hard to see.
Have another idea on what it could be, the gear (picture attached) looks like and feels like it's got little dips in it. I'm thinking this could be the issues but just a theory, so maybe I'll order it and give that a try.
Could I pull the gear off and run kick only to test it? Or does that throw the balance off.

DaveBarbier · « **Reply #42 on:** March 20, 2015, 09:29:32 AM »

Ok, I was way off, haha. I was expecting a bigger gap between those two parts. Thanks for humoring me!

I'll leave it to the professionals.

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1978 Honda CB550K

theslayedsaint · « **Reply #43 on:** March 20, 2015, 09:49:35 AM »

its all good thanks for trying! just found my answer to running without the gear. http://forums.sohc4.net/index.php?topic=20931.0
looks like i'll be waiting for a new gear! of course i have the whole weekend to work on this bike and tune it and now its unable to start hahah

scottly · « **Reply #44 on:** March 20, 2015, 05:32:22 PM »

Quote from: theslayedsaint on March 20, 2015, 09:15:48 AM

Here you go kinda hard to see.
Have another idea on what it could be, the gear (picture attached) looks like and feels like it's got little dips in it. I'm thinking this could be the issues but just a theory, so maybe I'll order it and give that a try.
Could I pull the gear off and run kick only to test it? Or does that throw the balance off.

Wear on the hub of the gear may cause problems with the starter clutch slipping, but isn't the issue with the rotor coming loose from the crank. The proper torque spec is 72.3 ft/lbs. Both the tapered end of the crank and the rotor bore should be clean and dry when you assemble them, and it may help to firmly push the rotor onto the crank with a twisting motion before inserting and tightening the bolt. How did you originally remove the rotor before the rebuild? How are you preventing the rotor from turning when torquing the bolt? What sort of torque wrench are you using; cheap "clicker" type?

theslayedsaint · « **Reply #45 on:** March 20, 2015, 05:48:37 PM »

heres where i'm at right now.
pulled the gear that goes to the start and left the gear that is on the crank. retorqued it and ran the bike letting it warm up and kicking it a bunch of times did that for a while then i pulled the cover and checked it, still torqued and to the 70 lb. using back brake set all the way on to hold the bike down while in gear. as for the torque its a CDI same company that makes snap on tools. I ordered a "new" gear and i'll try that when it arrives. I also took the bike for a test ride ran "fine" still needs work but nothing to do with this issue i'll try and write a detailed post about it next, can't seem to get it to run right. anyways thoughts?

scottly · « **Reply #46 on:** March 20, 2015, 06:21:10 PM »

Kicking the bike puts no load on the rotor, so you may as well reinstall the gear. Torque the bolt to at least 75ft/lbs.

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Author Topic: first start after rebuild (Read 1427 times)