Jdub goes there 1981 650e rebuild

[jdub6092]

When waiting for parts or other engine building delays, I'm trying to keep busy polishing parts, touching up emblems, etc.
Not sure I like the chromish appearance of the case covers. Any tips for making them look more stock in appearance? 20240810_083304.jpg

[jdub6092]

Next step was to measure the cam lobe heights. All of them are below service limits by 0.2 - 0.4 mm/.01"-.02" Is this a deal breaker for continuing or would I just expect less than optimal performance?
I've found a used set of camshafts that reportedly came off a bike with < 13k and waiting for measurements. If that doesn't work out, I see that I can still purchase new ones, albeit adding to my already blown up budget.

[jdub6092]

Got the valves installed in the head and had some difficulty installing the buckets over the springs. Again learning that patience is the key, found that rocking them back and forth while very slowly pushing down at first is the key. Once they are squared up, they slide down easily with assistance from assembly oil.


20240810_083147.jpg

[jdub6092]

More delays and learning experiences.
Was able to get the cylinder installed on the pistons after trying several methods, forgetting to install the dowels, trashing a base gasket and lots of choice language.

Eventually, I found that it was actually a lot easier to use the DIY piston holder blocks and compress the rings by hand enough to insert them into the cylinder walls. The tapered entry really helps with this.

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[jdub6092]

The head and carbs look nice all bead blasted. With the head, make sure there is no grit inside the blind oil flow passages. Shoot carb cleaner in the passages, and collect the runoff and examine it for grit.

Thanks for the suggestion. I can see how bead grit could have gotten into the cam journal oil passages with no way out as I dont think the oil bolts were removed at the time. I didnt really see any grit come out, just some light color possibly from dried oil.
should have done this before I painted the head. I had baked it for a couple of hours and thought it would be cured. However, there are a few spots where it is peeling now. Hopefully, I can just do some touchup. Need to get this bike fired up to properly cure the paint.
Oh well, it's something that had to be done.

[Nessism]

The head and carbs look nice all bead blasted. With the head, make sure there is no grit inside the blind oil flow passages. Shoot carb cleaner in the passages, and collect the runoff and examine it for grit.

[jdub6092]

43 year old piece of art work. Internals look pretty good also.

20240726_062814.jpg

[jdub6092]

Finally have the pistons installed. Circlips gave me fits for the first few. I figured out how easy it was by the 7th and 8th installations.

20240720_130949.jpg Need to re-orient the ring gaps before dropping the cylinder, but I figured they wouldnt stay put.

[jdub6092]

Nice paint job so yes there was a goodly prep. Kudos.

Thanks Cipher,

Actually, I had the Valve Cover (plus head and cylinder) bead blasted, so prep was pretty easy. Basically a little scotchbrite and acetone. The crankcase was another story. A real test of my patience, but came out quite nice.

[jdub6092]

I think I see what the issue is. The seats for the K&L needles are not as deep as the original Mikunis.
However, the originals appear to be even a bit shorter in total height meaning additional tab down bending for proper float height. Something doesnt seem right.

[Cipher]

Fresh out of the easy bake light bulb oven. Test pieces to determine whether I should continue with the rest of the engine or hand it off to a professional.
Gonna give it a shot.
One issue I'm having is that the temps here in the Phoenix area this time of year are already 100+ by 10am. Trying to do painting early, but having trouble determining how long to wait between coats. Obviously flashing very quickly. Had some orange peel on the Valve cover and a small area of paint peeled away from the primer while removing masking tape several hours after painting.
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Nice paint job so yes there was a goodly prep. Kudos.

[jdub6092]

I tore down my carbs again to get them bead blasted. Prior to that all I really needed to do was adjust the float heights to 22.5mm. While doing that, I had to bend the float tabs down quite a bit from the original almost completely flat position. I knew I was measuring correctly and was just going to accept the excessive bend.

While building back up, I compared the K&L rebuild kit parts to originals and found that the K&L float needles look different and are shorter, accounting for the tab bending.

I would just use the originals, but the needle springs on three of them are really tight. Maybe additional cleaning could help. Are these K&L float needles acceptable?

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[jdub6092]

One more of the crankcase, session 1 20240629_212757.jpg

[jdub6092]

This is coming along nicely.

When I painted my engines, I just assembled it loosely, a few finger tight bolts to hold it together and used foam to fill the intake and exhaust ports and a few other areas as needed and then painted it, came out well and saved a bunch of time.

I agree that I could have saved a lot of time doing the full engine. I got a little antsy to get started and I wasn't ready to start painting the crankcase. Must have put in 40 hrs cleaning and prepping it. Also wanted to practice on smaller parts. Finally go started on the crank. Doing it in two sessions as I don't have an engine stand or cradle. So far so good.

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100F should be OK for painting, you must have low humidity there so should be good, 5-10 minutes between coats at those temps should be fine.

Humidity of 30% is considered high here, normally about 10-12% in June, so no problems with that, but it does flash pretty quickly, so I only waited a little over 5 minutes between coats.

You can use engine heat cycles to cure the paint once you have the the engine back together and running so no need for the light bulb oven on the engine.

Cheers,

Understood, and the Crankcase will employ that method. Was able to bake the rest, so hopefully it will not peel or scratch too much when I stuff it back into the frame.

[Kiwi Canuck]

This is coming along nicely.

When I painted my engines, I just assembled it loosely, a few finger tight bolts to hold it together and used foam to fill the intake and exhaust ports and a few other areas as needed and then painted it, came out well and saved a bunch of time.

100F should be OK for painting, you must have low humidity there so should be good, 5-10 minutes between coats at those temps should be fine.

You can use engine heat cycles to cure the paint once you have the the engine back together and running so no need for the light bulb oven on the engine.

Cheers,