Jdub goes there 1981 650e rebuild

[jdub6092]

I moved the gas and vent hoses on the other side of the rail. Not that it matters, but because two sets of photos in the sevice manual show it that way.

After four rounds, including thread repair, I finished shimming the valves. Results as follows:
#1 exhaust: 2.50 - 0.05
#2 exhaust: 2.45 - 0.07
#3 exhaust: 2.40 - 0.09
#4 exhaust: 2.45 - 0.07
#1 intake: 2.35 - 0.09
#2 intake: 2.50 - 0.07
#3 intake: 2.55 - 0.07
#4 intake: 2.45 - 0.09

Understand that .09 is technically out of spec., but saw in several places that this OK and even preferred. I don't actually have a .07 or .09 feeler blade, but the .06 and .08 blades slid in easily and the next blades up (.08 and .10 respectively) did not clear.

Back to installing the carbs and air cleaner, followed by exhaust and valve cover. Getting close to seeing what I have.

[jdub6092]

I'm getting close to firing this thing up for the first time in over a year. Made the bonehead mistake of installing the carbs and airbox without installing the fuel and vent lines first This was one of the most difficult jobs that I previously did due to the tight spacing. However, using a little silicone lube and a heat gun, it was surprisingly not too difficult. Then I noticed that the fuel line that I had purchased was the reinforced braided type and rather stiff making it really difficult to bend and add a filter. I got some more flexible hose and now I'm trying to figure out if the lines should be routed inside or outside of the carb rail before reinstalling the carbs.
Went to Bikecliff's "Where do these hoses go" article, but the pics are not available. Other searches showed several variations.
In the end, it probably doesn't matter, but what is the proper or best way to route these lines? This is what I've pieced together.
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[jdub6092]

Some good things have come from my head dilemma.
First I realized that the manual was correct as far as the cam chain links. It actually is 19 link spacing even though the intake cam sprocket arrow does not point straight up. Every bike I researched from the era, including the 650g and gl that share the same head, but different number of sprocket teeth, had 20 link spacing.
Found this confirmed in a thread from 15 years ago from a member in NZ who did a 550 to 650 engine conversion.

I also learned a trick (common knowledge to a mechanic or vet) on how to get the exhaust cam #1 sprocket arrow lined up flush to the gasket surface at TDC. Just start with the sprocket one link turn down and when the cam caps are torqued down, the arrow ends up perfectly flush. It may also be due to my camshaft journals not resting flush on the bearings in that position, which may also may be a result of my shims being too large.

Speaking of shims, I ordered a dozen from Z1 to cover the size range and quantity that I expect to be needed. At $5.25/shim it was economical to get the job done in one session and end up with several spare shims.

20241223_070735.jpg

[jdub6092]

Thanks for the tip Dom.
I was amazed at what a fine wire wheel and some polish and buffing could do a dull piece of dull aluminum.
Ill give it a shot.

[DomsKat550]

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

You probably figured out how to make the highly polished aluminum look more stock, but I hit the faces with horizontal 1,500 grit wet, then sides with vertical sanding.

[jdub6092]

I have decided to give the original head a try for a couple of reasons. I was able to get the cams to move freely after grinding the journals, bearings and caps down with valve grinding compound. I was quite surprised that the measurements between bearing and journal diameters were so consistent.
The head I purchased clearly had a sloped mating surface. I took it to my machinist to blast, cut valves and seats and resurface. He was apologetic about the mistakes he made decking the top surface of my original head and only charged $50 for this work. Unfortunately, it looks like he had to take too much material off the head to flatten it. It may still work, but since my original head surface is in great shape, Im more confident with it.
We'll see.

[jdub6092]

After searching far and wide on how to restore chrome, especially dull and hazy chrome, I realized that re-chroming is really the only answer if you want anything close to the original finish.
Since I wasn't going there, I instead went with the multiple rounds of sanding with WD-40. From 320 up to 5000 grit. Then buffing and polishing. Finally, I used a worn down, clean, dry piece of 3000 grit paper and went to town in a small area. I noticed shallow scratches disappearing and shine reappearing. So I repeated this on the rest of the pipes, then a final buff with lambs wool disc. Certainly no where near showroom quality, but I'm satisfied with the outcome.
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[Grimly]

I only have the manual for the 850, but from it you can see (using Plastigage) there's not much clearance allowed - 0.15mm or 0.0059".
I have no reason to think the 650 engine will be any different, but I could be mistaken.

image upload

[jdub6092]

Have been cleaning up the new head and taking a shot at grinding down the original. It has been a very slow process with several rounds of lapping compound to remove the absolute minimum amount of material, but I now have the cams spinning freely.
I have been tempted to just start re-shimming every valve and button things up and get this thing started and tuned up.
However, Im concerned that there is a level of precision that i first need to figure out. I have polished up the journals, bearings and caps to a fairly smooth finish (up to 3000 grit sand paper soaked in wd40), but as you might imagine, the journal widths are not perfectly uniform - lower in areas where they contact the bearings. I don't really know what kind of measurements I need to be taking to ensure proper operation. Do I need to account for expansion when the engine gets hot, how to prevent knocking, etc.

The used head that I purchased has good valves that fit nice and tight. However, the lower surface looks almost like it was decked at an angle with the mating surface a bit higher on one side.

[jdub6092]

I did go ahead and purchase a used head with cams and caps as I anticipate removing the required amount of material from cam journals and caps is going to be a crapshoot. The mechanic I spoke to said it would likely require a flapper sanding disk to remove the required amount of material.
Now I get to go back to my machinist and see if he will prep the replacement head for free after trashing the original.

FYI, while searching for the replacement head, I came across an NOS GS850 Cylinder and head for $380 OBO + tax and $60 shipping.

[jdub6092]

Back after a 3 week tour of Eastern Europe.
Was set up to purchase a new head on EBAY after making an agreement with the seller to delay the shipment.
Then my small shoulder bag with wallet, cards, cash, drivers license, passport and spare phone was stolen in Lithuania. Included the credit card I would be using.
Then someone purchased the head as I had to cancel my credit and debit cards.

I ended up stuck in Vilnius, Lithuania for four days waiting to get an emergency passport while my family continued on to Estonia and Hungary. Was Labor Day weekend, so embassy staff took off early on the Friday it happened and took the three day weekend as well with no staff available.
What a cushy job. They work 2 hours in the morning, take a 90 minute lunch, then 2 more hours in the afternoon.
Luckily, I was able to get the emergency passport on Tuesday before they left for the day. Then straight to the airport to Budapest, Hungary through Frankfurt, Germany to meet up with my family. Could have used the $2k hit to make my bike show ready.

Anyway, I'm going to first see if I can grind down the cam bearings with lapping compound. If that doesn't work, there are a couple more heads available on the bay.

[jdub6092]

There was absolutely no reason for him to machine the entire top of the head, all that was needed was to dress up the course of the sealing face, but that would have taken time and effort. The milling machine, the way he did it, was just left on its own to get on with the job, utter laziness, and moronic.
As a matter of interest, just how bad were the dings and marks? I'd bet they were easily filed smooth and filled in with steel putty.

There was one bolt hole that required welding and another couple where i attached a vice grip to see if i could remove the broken bolts. I scratched it up, but really just surface scratches and nothing too deep.. i think the extra material from the weld was the main reason he did it. Probably could have carefully filed it down and sanded to blend in.

20240826_094156.jpg What still can be with my old tank. Have an NOS tank taht will be added.
If I look at this while Im taking my break, maybe it will motivate me to get over the cam issue and get this thing done.

[Grimly]

There was absolutely no reason for him to machine the entire top of the head, all that was needed was to dress up the course of the sealing face, but that would have taken time and effort. The milling machine, the way he did it, was just left on its own to get on with the job, utter laziness, and moronic.
As a matter of interest, just how bad were the dings and marks? I'd bet they were easily filed smooth and filled in with steel putty.

[jdub6092]

Unfortunate, this guy had a reputation for quality work.
He recommended a mechanic who said he has had success at using valve lapping compound and spinning the cams by hand. However, he said he hasn't had to grind off as much as .16mm before.
Since I'm looking at a new head, I figured I'd give it a try myself. Doing it in increments. Seems to work. I can tighten the caps down a little more each time before it binds. The journals remain quite smooth.

Anyway, I got the wiring completed and everything except for the untested charging system checks out. Likely to need a turn signal relay as it is hit and miss on blinking.
Front brakes bled and grab very nice just rolling down the driveway. Suspension (front) seemed a bit soft.
Must have made a mistake on the rear master rebuild, so will try again. Internal parts are new. Think I may have forgotten to lube the rubber as it doesn't push back smoothly.


Going to take a break for a few weeks and refresh.

[Grimly]

I now think I know why I have binding on the camshafts.
The machine guy I had repair the damaged valve cover bolt threads, said he decked the top of the head also because of scratches resulting from attempts to remove the broken bolts.

Your machinist is a moron.