pidjones rat bike project - '79 CB750F

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The cheaper the bike the more it will cost.
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[pidjones]

Rear wheel bearings on order. The bearing retainers came out easy by drilling 3/16 holes in an aluminum bar and dropping 3/16 drill bits through them into the retainers (after first drilling out the stakes). The bearing in the sprocket carrier came out easy, and a good thing because it was single shield with the shield installed toward the seal and the open cage exposed to anything that gets by the o-ring between the carrier and the axle area. It felt very rough, had rusty grease in it. I think (hope) the All Balls kit has all double-shield bearings. Haven't knocked out the two smaller bearings yet, but don't expect a problem (famous last words).

Still waiting for the coils to get in. Post Office is really dragging their feet, plus today is Veteran's Day observed.

Set up the controllers for heated gloves and jacket liner on my GL1800. Looks like temperatures will stay down until Spring, now.

[pidjones]

Coils (used from ebay) came in yesterday evening. Between the original wires and angled plug caps and one of the caps/wire on the replacement coils, and one plug cap pulled apart, cleaned, and reassembled I have all reading ~5K Ohms. Tried old plugs on each and have sparkies on all four. But, I have the rear wheel bearings out and Partzilla won't be shipping the new ones until tomorrow.

So, replaced the swingarm grease fitting (old one was broken), pulled the swing arm bolt and lubed it up before reinstall, and while doing it observed that the right leg of the center stand is broken ~1/2 way through at the joint to the pivot tube. So, I'll set the swing arms on jack stands (bike is presently on center stand and a dolly under the headers) and fold the center stand up for removal. I have one of those brake spring tools so will try that. Never had success with coins/washers in the spring coils.

Guess I need to pull that HF welder out and dust it off. Wonder if the auto-darken shield still works? The daughter borowed it for the eclipse year before last, and it worked then. I'll strike a lighter in front of it to test before I strike an arc.

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You do not need any special tools for the spring on the center stand. You place it in the down position and remove the tube that holds it to the frame and then pivot the stand forward, it will come right off. Reverse this procedure to install it.
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[pidjones]

I haven't struck an arc (intentionally) since ~1970. But, the center stand on the Rocket is broken on one side, so I'll give it a try. The removal was tricky because I already had the rear wheel off and bearings out of it so I had to support the swing arms on jack stands. Was able to get clearance for the pivot to come out by removing the two muffler mount nuts on both sides and pushing the muffler down enough for the studs to come out and rest against the mount. Did the penny trick on the spring because my brake spring tool just didn't have the mechanical advantage for this job.

The right side of the stand was almost completely broken away from the pivot tube. Someone must have smacked this pretty hard.

So, imagine the weld quality by someone that hasn't welded in well over 40 years - it was stick then - and them doing it on a rainy driveway with a Harbor Freight flux core welder with five year old HF wire. Scary enough? Worse than a Honda weld! Anyway, it's worse but "it is what it is". Went back together surprisingly easy. Then I knocked it on its side taking it off the jack stands. This thing feels light after picking up GoldWings.

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I like your penny trick.
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[pidjones]

The correct petcock is finally installed. Hopefully, it will be dry and not to cold tomorrow. If so, I'll back her out of the garage and make a few attempts at starting.

[pidjones]

Got to thinking it would probably be good to check on how you adjust the cam chains on these beasts. My GL1000s were just belt driven cams with tensioners that have springs you let pull the idlers into position and then just lock that down. So I look through the procedures and then go down to the garage to identify the adjusters. And what do I find?

So, I found one bolt on ebay and ordered it (although I probably could have made one on the lathe out of an 8mm bolt from Ace). Looks like the lock nut is just a flange nut with an o-ring relief. The fun will be in removing the rusted, broken-off-below-the-case bolt. Already soaking in PB Blaster. I do have some left-hand bits and some easy outs. I'm thinking about a dozen heat cycles to pull the lube in and loosen it up, too. Joy. In an awkward spot to drill, too.

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That SUCKS
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[pidjones]

Finally have enough parts assembled to at least start it and help show what else needs done. Some poor critter lost his home in the exhaust pipe, I'm afraid. Youtube video

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Awesome!!!!!
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[pidjones]

Success this morning! Rigged up the left-hand bit in a 1/4" chuck normally used in a battery-powered screwdriver that has a 1/4" hex drive and jambed it with a nut behind it so it wouldn't unscrew. Then mounted that in a 6" x 1/4" hex extension that came with a bolt hole cleaning brush set. Chucked that in the battery powered drill in reverse and drilled the bolt. Didn't catch and unscrew durring that, but the extractor bit and held to remove the broken bolt. Blew out the hole and it looks clean with undamaged threads. Ran a regular bolt with a smooth flange nut in it for now, until the ebay replacement comes in.

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Impressive!!!!
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[pidjones]

Found a problem with the accelerator pump (o-ring too fat at bowl/carb junction) and remounted the carbs. New front cam tensioner bolt came in, so I went through adjusting and (lightly) locking it down. Ready to re-mount tank but broke the inline fuel filter I had added so will have to wait for next week to fire it up again.

[pidjones]

Fuel filters came in this afternoon, so I hooked the fuel line back up and rolled the bike outside for another test run. Better, but #1 and 4 headers are still not warming up (well, #4 a little). I had gone through the plug wires and even replaced them. The plug caps are all 5k ohms. Checked #1 to #4 resistance and it is good. Plugs are all firing according to my tester. New plugs. Compression test done last week was 130, 120, 120, 130 psi (so you would think that 2 & 3 would be the cold ones). Have NOT checked timing on anything. Still where it was left, probably back in 1999.

Float valves now all working. And, it seems the accelerator pump is working, too. Was able to warm it up on the choke and then lower the idle to about 1k (if I can believe the mechanical tach).

Someone in its past removed the end baffle, so it is louder than I'd like. May have to hammer a new end piec out to weld some re-entrant tubes in. Does anyone know how long the final baffle tubes are on the 4-2 Sankei pipes? I know they are just about even on the outside, but how long do they extend in? And, are they just smooth straight tubes or do they have holes, fins, etc.? Gee, I wish that I had looked closer at that gorgeous '79 CB750F parked at the hotel when we went to Barber!

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#1 and#4 not running does indicate an ignition problem since they run off the same ignition circuit, but do not rule out the carbs. I have seen it.
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[pidjones]

Yeah, I have a couple other coils, but they both have cracks on the bottom side (although ohming out Ok). Might try one anyway, just to see. I know that the spark doesn't look quite as hot on them. I'll try swapping the modules, also. Haven't even looked at timing. Still setting where I found it, which has probably not changed since 1999, and is probably wrong if the rest of the bike is an indication. I think the carbs must be very close, as I went through them again carefully and they are very similar to the GoldWing carbs I've done.

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I would try swapping ignition components from side to side one at a time to see if the problem moves to the other cylinders.
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[pidjones]

Checked air gaps today. Front was .008", rear was .015" reset them both to .012" as suggested elsewhere. Checked static time and it was about a degree retarded. Moved it to between the marks and checked 2,3 the same. It will be to cold to test it for about a week now.

[pidjones]

Got a little more checked (or really, re-checked) today. Did the ignition test with screwdriver on the pickup coils - good hot spark on old plugs with the gap opened to ~ 3/16". Voltage test on spark units in spec. Buttoned that up and pulled the valve covers. checked the valve clearances again. Tightest is .003, loose one was .006 inch. Need a couple 295s to get any closer to the .004-.005 I'd like to have. Spent a lot of time getting RTV off of the valve cover from a PO putting it on the gasket. Now, I believe in tacking the gasket on the cover to make it more convenient, but not squishing RTV out everywhere. Anyway, cleaned that up and tacked the gasket to the cover with Indian Head.

Then, while digging out the RTV from the head I noticed something that I had not seen before. Right end intake cam holder is broken. This thing just keeps getting worse! Anyway, found a full set on eBay for $40 and ordered them.

Finished up my aux fuel cell. Presently using a 1/2 liter isopropyl bottle for the reservoir. Can go bigger if ever needed by just getting a bigger bottle to put the nipple in the bottom of. I like this one because I can just cap the bottle when I'm done with it and take it out to the shed, drain it in a tractor.