Author Topic: First timer top-end rebuild gone wrong, yippee! Ugh... (Read 21995 times)

markreimer · « **Reply #75 on:** October 10, 2015, 10:42:46 AM »

I was just wondering if it could be the dyna and not the coil! It's about 4-5 years old now. I still have the points system somewhere. I've actually never ridden points. I swapped it out dr the dyna when I bought it. Ill try installing that and see if that narrows things down. Tha ks

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markreimer · « **Reply #76 on:** October 10, 2015, 11:27:58 AM »

Ok, will do. I picked up my points just now and am just heading out of town for two days but I'll do it right when I get back. Limited number of riding days now, so I'd love to get this solved before snow.

As an aside, I'm dripping oil out my valve cover breather tube and it's splattering against the side of my rear tire. I'm also leaking at the front of the valve cover gasket. Makes me wonder, is that a sign of unusually high pressure in there? I never had oil dripping from the breather before I rebuilt the top end, but now I have a fair amount, as well as white smoke that doesn't dissipate as the engine heats up (I thought it might be condensation since it's getting close to freezing over night and the bike is covered in dew, but even after 45 minutes of hard riding it still puffs smoke).

I've ordered a new gasket and will try replacing it with the engine in the frame, hopefully that solves the leak. But it doesn't address the oil from the breather. How much is acceptable?

Old Scrambler · « **Reply #77 on:** October 10, 2015, 08:38:45 PM »

Check your breather tubes on the oil-tank...........you may have the tranny to the mid-breather on the back of the tank crossed up with the top-breather to atmosphere. You also may have something blocking an oil-return and / or the breather in the valve-cover. You said oil ran out of the inspection caps on the valve cover.............that should never happen

Did you properly seal the exhaust-side cap-bolt threads in the cam-tower?

I agree about the Dyna-S.........current inventory seems to be good.

I like your tenacity......When all is sorted, try riding the bike for several days in a row..............and maybe a little longer trip when you can trust it. Its sort of like letting the bike know that you want to depend on it

markreimer · « **Reply #78 on:** October 11, 2015, 11:09:48 AM »

I checked the breather tubes and they are routed correctly. The two hoses that are puffing smoke and dripping are straight from the valve cover and the other larger diameter hose that vents from the top of the reservoir tank. Not lots, but consistent. I recall a bit of white smoke is common after a top end rebuild. Maybe it'll clear up. I've only got about 250km on it since the build since the ignition problem has kept me from longer rides.

Regarding the inspection caps and oil, it wasn't actually leaking from them, what I meant is that I removed them while it was running to confirm oil was making its way up to the top on all sides and I could see it splashing around in there. A few drops were even flung clear out of the inspection holes.

Can you elaborate on the exhaust side cap bolt threads in the tower? I was very methodical when I assembled the top end, torquing everything to spec in stages. I'd be really surprised if I missed something there.

Thanks!

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Old Scrambler · « **Reply #79 on:** October 11, 2015, 05:06:59 PM »

What you missed was the advice in the branden-thread about a leak-proof motor assembly................the cam-tower fasteners are threaded to air along the sides of the spark-plug reaches. If you did not seal the threads, they will weep oil that runs down the front of the motor. If they leak badly enough, the oil will move around the ends of the heads from air-pressure while riding. My K3 only has one breather from the top of the valve-cover. None of the breathers should drip oil.

markreimer · « **Reply #80 on:** October 12, 2015, 06:18:52 PM »

Quote from: Old Scrambler on October 11, 2015, 05:06:59 PM

What you missed was the advice in the branden-thread about a leak-proof motor assembly................the cam-tower fasteners are threaded to air along the sides of the spark-plug reaches. If you did not seal the threads, they will weep oil that runs down the front of the motor. If they leak badly enough, the oil will move around the ends of the heads from air-pressure while riding. My K3 only has one breather from the top of the valve-cover. None of the breathers should drip oil.

Right, now I understand what you're talking about. I'm pretty confident it's not leaking from there though, for this reason - I wiped all the oil off the front of the engine and all the fins in the head. Then I started the bike and hit it with a bright light. It didn't take long before I saw the oil leaking at the valve gasket. Right around the 2/3 spark plugs there is a fairly long gap between bolts for the cover, and it's leaking there, running along the tiny bit of gasket that sticks out, and dripping onto the very top cooing fin. Some additional oil drips right at the source of the leak, falling past the spark plug boots and onto one of the cooling fins toward the centre of the head, then running forward and dripping onto the oil filter cannister. After a short ride, the entire middle of the engine is soaking in oil, making it impossible to see where it is originating from. But based on what I saw after cleaning it, it seems it's only leaking at the cover.

Hopefully my new gasket will be in within the week. Tomorrow evening I'll be putting the points back on and will report back after going for at least a half-hour ride.

markreimer · « **Reply #81 on:** October 13, 2015, 06:04:30 PM »

Well this is interesting! I popped the ignition cover off to replace the dyna with points and there's a mounting bolt flying around. Could this be causing a shirt somehow in here and killing 2/3?

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markreimer · « **Reply #82 on:** October 13, 2015, 10:37:39 PM »

I decided to remove the dyna anyway and try points. I've done two rides so far, no failed 2/3 yet. It idles well and accelerates hard, but if I'm cruising at around 4K or higher the engine sounds like it's stumbling a little. Almost like how it sounds when your float bowls get low right before you run out of gas. This has been happening for a while and I had assumed it was related to the dead 2/3, But again, no dead cylinders on the first two rides with points.

So my guess is that the points swap has (hopefully) solved my 2/3 issue. The slight stumble at higher rpm cruising may be unrelated and more to due with carb/fuel delivery, or something else. I did notice my crappy exhaust wasn't sealing on the spigots in the 2/3, not even close. Perhaps that's the cause.

So next steps: valve gasket, double check carb floats and jets for adjustment and cleaning if needed, seal up exhaust, maybe even double check carb sync, and ride a bunch to confirm no more dead 2/3 issues.

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70CB750 · « **Reply #83 on:** October 14, 2015, 03:32:11 AM »

I doubt that bolt would do it. It would cause a mechanical failure more likely.

markreimer · « **Reply #84 on:** October 20, 2015, 10:27:28 PM »

Well I fixed a few small problems and created one big one.

- I replaced the valve gasket with the engine in the frame. I had used hondabond on the front of the valve cover around the journals, which made removing the old gasket a chore. but about 25 minutes later patience paid off. Old one off, new one in (dry this time) and after a 25 minute ride there are no leaks.
- Ground down my exhaust finned clamps a bit so they can tighten more, my pipes are no longer loose on the spigots and sealing nicely.

Then...things got ugly.

Last repair of the night - my oil pressure switch has been sticking. I tried cleaning it, but it never stays working properly for long. So I bought a replacement aftermarket switch from 4into1.com. It looks the same to me. I threaded it in and started tightening it down with a ratchet. Just before it bottomed out it started to feel a bit tight, so I gave it another couple turns and CRACK. Um...wtf was that.

I cracked my engine case where the switch threads in. I started the engine and sure enough oil pours out of the crack. I removed the switch and found that there is a taper at the top which my old one didn't have - it sat flush. So as i tightened it, it cracked the case.

So now what am I supposed to do... I put the old switch back in and gently tightened it. It seems to be working so far, no leaks, but the crack is pretty large. I'm thinking it needs to be welded, yes? Just a tack or two over the crack so it doesn't grow? I'm just hoping it can be done with the engine in the frame. Think that's likely?

markreimer · « **Reply #85 on:** October 20, 2015, 10:28:16 PM »

Here's the crack. That oil came out within seconds.

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bytio · « **Reply #86 on:** October 21, 2015, 04:57:48 AM »

The oil pressure switch is counter sunk/ tapered so does not need to bottom out, use torque setting published or a small tighten (1/4 turn) once threaded in. Not helping now I k ow, but for next time

70CB750 · « **Reply #87 on:** October 21, 2015, 05:06:10 AM »

You could also close it for good - or till you get the engine out of the frame - and use oil pressure gauge on the galley plug.

KayOne · « **Reply #88 on:** October 21, 2015, 06:52:22 AM »

JB Weld is amazing stuff. Clean area very well with a degreaser (I use lacquer thinner). Use air to help clean oil our of casting crack and apply JB. Use a thin layer of JB on the sensor threads and screw in so the case and sensor epoxy can cure as one repair.

markreimer · « **Reply #89 on:** October 21, 2015, 08:20:39 AM »

Quote from: KayOne on October 21, 2015, 06:52:22 AM

JB Weld is amazing stuff. Clean area very well with a degreaser (I use lacquer thinner). Use air to help clean oil our of casting crack and apply JB. Use a thin layer of JB on the sensor threads and screw in so the case and sensor epoxy can cure as one repair.

Thanks guys, some good ideas here.

RE: JB Weld - Wouldn't that end up solidifying the sensor in the engine and make it impossible to remove? I've had two switches start acting erratically on me in five years so I don't want to permanently leave it in there, if I'm understanding this correctly.

I have wanted to use a pressure gauge on the galley plug for a while. The comment about sealing up the switch port entirely - how would I actually do that? Or did you just mean if I was getting it welded, I could cover it up completely rather than repair with the assumption I'd still want the threads in tact?

Sure wish I had known about this taper before. Ah well. At least my valve cover stopped leaking so far and it's not a rolling smoke machine anymore!

70CB750 · « **Reply #90 on:** October 21, 2015, 09:09:58 AM »

My thought was that the power sensor is somewhat limiting, dedicated screw in plug could be longer or have a flange or whatever to make sure it keeps it sealed. And the galley oil pressure gauge would keep you informed till you pull the engine and have it welded and repaired correctly.

Plug would be the short term solution while I would definitely plan to have it fixed properly in the long term - see Cal's post above.

The galley contains high pressure oil and having leak there is really not a good juju.

markreimer · « **Reply #91 on:** October 21, 2015, 09:58:41 AM »

Ah makes sense now.

I put some feelers out for local welding contacts to fix the engine. With snow coming within a week or so I may not be able to do this till the spring. If I can't find someone local to repair this, I may just JB weld a plug bolt into the switch location and seal it up for good, then mount a gauge in the galley on the side. It'd be cheaper than having it welded anyway. But I'll make that call once I hear back from a few welders I've contacted.

Also a bummer because I was asked if I'd like to ride the 750 in a TV commercial shoot today, hah!

markreimer · « **Reply #92 on:** October 28, 2015, 10:37:01 AM »

Dropped the bike off at the shop today for welding. Same shop that did my cylinders and head work actually. Should be ready by Friday. Fingers crossed it all works out.

Good news is that I haven't had dead cylinders in seven straight rides and it's running much smoother overall. I guess you can add me to the dead Dyna S club.

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markreimer · « **Reply #93 on:** October 29, 2015, 09:14:40 PM »

Well the weld has failed. It repaired the crack but hadn't sealed it from oil. The oil now flows out the side of the weld bead. I've asked the welder to take another look but as of now the bike isn't rideable.

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markreimer · « **Reply #94 on:** October 29, 2015, 09:18:04 PM »

You'll notice I have a crush washer in here - that was placed there when I thought it was leaking at the base of the switch. But in fact it's out the side. With the switch not seated as deeply into the case due to the washer it leaks even more. When I remove the washer it doesn't leak as badly, but still is a steady leak. Tempting to just stuff a JB weld bolt in there and seal it up for good at this point. But I'll give the welder one last look

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markreimer · « **Reply #95 on:** October 30, 2015, 07:24:12 AM »

He had indicated he wanted to cut through the crack and fill it while welding but didn't think he could get in there with the engine in-frame and assembled, so instead welded along the edge of the crack. The crack is like an upside-down 'T', and it seems the crack was sealed everywhere except the lower righthand side of the 'T'. I haven't been able to find anyone else willing to take a look at this point. Either the do-over works, or I'm taking the engine out of the frame for the third winter in a row

markreimer · « **Reply #96 on:** October 30, 2015, 07:54:28 AM »

Oh no insult at all. The welder himself wasn't confident it would work and described the situation as beyond ideal, hah.

Thanks for explanation, I'm no welder by any means and that helps me understand that challenge here.

So if the weld fails a second time, what options am I looking at. I guess I could...

a) pull the engine and see if the weld can be done properly as you described. Wish I hadn't sold that frame kit I bought last year...

b) plug the whole completely with a bolt/sealant. Now I believe that port is attached to the main oil galley, so putting a bolt in there couldn't be too long or it would potentially block the oil flow to the galley, right? It shoudl be as close to the length of the pressure unit I'd think

c) find another engine, at which point I'd probably swap the block/head onto the replacement since I just redid everything on mine.

markreimer · « **Reply #97 on:** October 30, 2015, 08:08:42 AM »

Quote from: calj737 on October 30, 2015, 08:03:16 AM

Quote from: markreimer on October 30, 2015, 07:54:28 AM
b) plug the whole completely with a bolt/sealant. Now I believe that port is attached to the main oil galley, so putting a bolt in there couldn't be too long or it would potentially block the oil flow to the galley, right? It shoudl be as close to the length of the pressure unit I'd think Correct and probably the route I'd go.

c) find another engine, at which point I'd probably swap the block/head onto the replacement since I just redid everything on mine. An option, but "B" is easier in my opinion
Unless you are over-the-moon for originality, B provides a simple solution to a few problems. I prefer solutions that are clean, elegant, and durable. Plugging the hole with a good sealant on the interior should work, then relocating the switch is pretty simple and available too.

I've never had any good luck welding these cases up assembled (for all the reasons I mentioned above). Its just super tricky to do... Even welding up cracked covers and what not, I have a very diligent routine prior to:

- Degrease really well
- Preheat to purge the impurities
- Degrease again
- Carbide bit to open crack
- Re-heat
- Degrease
-Cross fingers and weld

Never bead blast your pieces prior to welding them (aluminum). This only drives the impurities deeper into the surface. I've seen that mistake more than once. Owner thought he was doing me a favor. Little did he know he just added about 2 hours or work

Ah, interesting. Definitely not over the moon for originality. I don't care of there is a pressure switch there or somewhere else, as long as I have some way of monitoring it. Relocating the switch I suppose could be done via the right-side galley plug, where a lot of people mount gauges, right? Without having a warning light on the dash, I could run the gauge up to the instrument panels on the bars so at least it's up in plain view I guess. Unless you know of another spot to put an actual pressure switch and keep the light?

For sealant, do you have a suggestion ? I was thinking JB weld on the threads of a bolt, put a crush washer on the bolt and torque it down.

markreimer · « **Reply #98 on:** October 30, 2015, 08:21:51 AM »

Ok, I think I understand - you're saying you like the idea of using the oil galley on the right side, but not simply mounting an analogue gauge in there. You're saying there are other gauges available which would tap into the dash light somehow? Perhaps an electronic sending unit of some kind I'm guessing? That sounds like a very good solution to me if I'm understanding it correctly.

Thought I don't understand your suggestion of a complementary set screw - can you explain please?

markreimer · « **Reply #99 on:** October 30, 2015, 09:46:00 AM »

So scanning these forums, I cannot figure out what the thread pitch of the oil pressure switch is. Some say M10 x1.0T, others say BPT 1/8, and others NPT 1/8. All of them are 100% sure, of course

For the purposes of sealing the hole, what would you suggest?

If I use a shouldered bolt I'm not sure I can do that with pipe thread, it'd have to be the M10 bolt. At least I've never heard of a shouldered pipe-thread bolt before

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Author Topic: First timer top-end rebuild gone wrong, yippee! Ugh... (Read 21995 times)