Topic: My accidental 1982 Nighthawk 650

[cheddarGoblin]

Based on how much soot would end up on the exhaust pipes of cylinders 2 and 3, it seemed like that was the spot where I was losing power. So I focused on the ignition side of those cylinders.
Since they use the same coil and ignitor, I got to wondering if one of those was the issue. Additionally, I had not changed the plugs or wires at this point, and though I was getting spark everywhere, some of the connections seemed suspect (loose fitting plug caps, coil connections corroded, etc). The coils seemed to work just fine, and I 've always thought that they would either work or they would not. But, I was starting to run out of ideas at this point.

Plus, the exterior of the coil seemed to be discolored more than the unit for 1 and 4. Assuming they were both original, maybe that meant the 2 and 3 coil was getting hot or something.



So I just figured I would take care of all of these things with new coils, wires, caps and plugs. So I got this kit:
https://4into1.com/ignition-coils-caps-and-wire-honda-cb650-gl1100-1200/
While installing it, I realized that the caps that were on the bike were not resistor caps, so I hoped that I had found the issue. One of the symptoms of not having the correct caps is misfires.
Caps that were on the bike


New NGK caps


Additionally, I know that checking the timing would be a factor here. However, with the electronic ignition, there does not seem to be a way to adjust it, as the plate that has the pulse generators on it appears to be staked.


I did however, ensure that the lobe on the advancer, lines up with the lobe on the pulse generator when the timing mark is on the F for each coil. It seems like this is alll I can really do with this.

 

[cheddarGoblin]

After installing the new plugs, coils, wires and caps I took her for a ride again. It was a little better but not much.
At one point I did also swap the ignitors around in an attempt to see if it would cause the pipes of 1 and 4 to get more sooty but there was no change.

At this point, I think I needed to look at compression a little closer.

[cheddarGoblin]

A TALE OF TWO COMPRESSION TESTERS

Disclaimer - I have never used a compression tester before this project.

Alrighty, so when I started this project, I did buy a compression tester. It was an el cheapo from Amazon. When I used it at the time I just wanted to make sure I was getting similar compression between cylinders, which I did seem to have. Now that I know a little better now. I think I have found where I went wrong.

The service manual says I should be getting 170 PSI.

Here is a comparison of what I would get using my tester with a thread in attachment, my tester with a shorter attachment that you just press into the plug hole, and a borrowed quality tester that has a Schrader valve at the inlet. I did hold the throttle open during these tests.
Cylinder 1
With hose that does not have valve and that adds a ton of volume:

With push in cone attachment

With push in cone attachment and after adding oil to help the rings seal

With good tester when the engine was warm

Cylinder 2
Apparently I forgot to snap a photo of this cylinder with the long hose attachment
With push in cone attachment

With good tester when the engine was warm

Cylinder 3
With push in cone attachment

With good tester when the engine was warm

Cylinder 4
With hose that does not have valve and that adds a ton of volume:

With push in cone attachment

With push in cone attachment and after adding oil to help the rings seal

With good tester when the engine was warm


In summary, I seem to have low compression and that is my issue. My initial compression test was not done well or with good tools, which made me waste time looking at other stuff. The tester I purchased is not useful for this application. At a minimum the piston rings are worn. I will perform leakdown in next post.

[cheddarGoblin]

Leakdown test - sad face

I borrowed a leakdown tester. I am not 100% sure that I did it correctly, as I was expecting different behavior from the gauges than I observed. I was expecting the first gauge to stay at 80 PSI where I set it and the other to be lower when it was leaking but that is not what I saw.

Cylinder 1
This one seemed to have only a small leak. Which I would have expected as it seemed to have the best compression


Cylinder 2
Seemed to be leaking slightly more - But there is a video below that suggest this is leaking worse.


Cylinder 3
Appear to be pretty bad on cylinder 3 as expected


Cylinder 4 seems ok - But again the video below makes it seem worse


It was easiest to check the exhaust valves. I just did cylinder 2 as that seemed easiest at the time

I also checked cylinder 4 to the crankcase

So, I think I found my issues. Cylinders 2 and 3 are seem to be leaking bad at the valves. So it looks like I need to do rings and a valve job. This is more work than I was planning for but it really isn't surprising as the bike does have almost 50k miles on it. I just hope that things aren't past the service limit as I wont know what to do then.

[cheddarGoblin]

While I figure out what to do about my compression, I wanted to get something painted. I did find the factory paint at VMR but its pretty pricey so I am just gonna try to get close with some Duplicolor. To see what it looks like, I figured I would paint the underside of the tank first.

The first can had a cracked nozzle that I did not notice. Glad I was started with the underside.


Pretty light coat at first


I ended up doing 3 coats before using some clear that I had on hand. It is a little to metallic for me, so for the rest I am gonna do a gloss black base coat first and end with the metallic. Hopefully that turns out better. I will also use some 2k clear for what will be visible.



I had the top protected from overspray. It still needed some sanding and glazing as well.


Kinda just glad to finally have some paint on something and am somewhat happy with how it turned out.

[cheddarGoblin]

I let the underside cure for a week or so before handling. Then I taped that up to protect it. I left a little bit to be able to blend the edges.

I am gonna try to get this painted soon.

[cheddarGoblin]

Part of me just wanted to wait until I get the body parts painted before diving into the engine. But the rest of me wanted to get it apart so I could know exactly what I had to deal with so I could start working on finding the needed parts.

So this is mostly a pic dump of the first time I have ever disassembled an engine to this extent.

The rocker box does have a couple of stripped threads on the valve cover. So this might be a good time to address those as well


I think I am committed if I go past this point.


When I got the bike I was a little disappointed that it was a 650 instead of a 750. But then I found out the motor would have to come out to do this on a 750. So now I am happy it is a 650.


I already know that getting the cam timed correctly is going to be the tricky part.


Someone managed to leave a part of a spark plug cap over the top of a head bolt.


The thing I was concerned about was figuring out how to time the cam. But getting the notch in the came to point to 9 oclock when #1 is at TDC doesn't see overly complicated.




Head is off. It's real now.


Not sure if that is a ding in the valve or not.


Guess I will use the old gasket to keep track of the bolts. Clearing some of the crap out from around the bolt heads in order to get a socket on them was more time consuming than I expected.


The cam chain tensioner kinda sucks. It also has a crack in the rubber. Not sure if it needs replaced or not. Seems like it will be a trick getting that back in correctly.






I know these were leaking .



Didn't take as long as I was expecting to get here.

Yes, I put some shop rags around the pistons.

[cheddarGoblin]

As sort of a confirmation that the valves were leaking, I filled the combustion chambers with some lantern fuel.



As expected, cylinder 2 was the first to drain completely.


You can see the exhaust valve getting wet.


And fuel is leaking out of where the carb would attach.


I repeated the test with 3 and 4


3 did drain faster, though it wasn't quite as bad as I was expecting.

[cheddarGoblin]

Time to do some body work.

I've never painted anything that looked good when done. You know like other than interior walls. So not sure how well this is gonna turn out.

Though I wanted to keep the bike as stock as possible, I did not buy factory paint. Though I did find it at VMR paints, it was like $60 a can and given my lack of experience painting, I wasn't ready to spend that. So, I just tried to get it close, and used a black and metallic black from Duplicolor.

Here is what the side covers and tail piece looked like when I started. These came from different bikes and I had to get them from eBay.





I had to remove the decals first. They had clear coat over them, so once removed there was a depression that needed filled. I was too slow with the Bondo on the first one. So sanding sucked a lot. With the next one I just used a filler primer. That was a lot easier.




I also had to fill in some extra holes as the PO used fasteners to hold this thing together after the studs broke off.



Sanding sure sucks when you put too much bondo on


Getting it primed


I had already painted the bottom of the tank. Time to do the top.
I started with just black.



I was painting two different bikes that day. But I could only paint one piece at a time and they were different colors. So after I finished this tank, I had to hide it while it cured while I painted the other stuff.


Laid down the base as well as 2K clear. I thought I did a good job with the prep work but those imperfections really pop once you start painting. I am happy with how they turned out for my first undertaking of this magnitude Show here with the parts for my CB200T that I painted the same day.


Even though it isn't stock paint, I am planning on getting the decals, I think it will look good with them. Gotta buff it first though.

[cheddarGoblin]

It's been a while since I posted. So I got the warning that this hadnt been updated for 90 days when I started to post this reply. I had to get some machining done and I also moved halfway across the country since my last post, so I have a lot of catching up to do.

[cheddarGoblin]

I had a machine shop do a valve job and hone the cylinders. But now had to paint the head and cylinders before assembly. I wish I would have cleaned them better before they went to the machine shop but I thought they were gonna be toast but even thought the bike was high mileage, but they were still serviceable.

It is a Nighthawk so gotta get these black again. Getting them prepped and taped was quite a pain.









Can't wait to see if this high temp engine paint holds up



Apparently I forgot to snap a pic of the cylinders while I was painting them.

[cheddarGoblin]

Once I got the machine work done and the head an cylinders painted, it was time to reassemble the bike and get it going. However, I was also in the middle of moving from Nebraska to Virginia at this point. I really didnt want to rush through it and I still did not have all the parts that I needed. I was taking the bike with me, so I reassembled it so I wouldn't lose or damage any parts during the move. It was gonna be awhile before I got back to it.

[cheddarGoblin]

I started getting my new house in decent shape, so was anxious to get back to this project.

I did buy a new gasket kit before I moved and had that. But a new set of rings was something that I did not have and had a heck of a time finding.

This was the ONLY place that I could find them. The seemed good quality but I honestly don't have much frame of reference here.


They are standard rings. I did not have the cylinders bored. Maybe I should have but I am new at this.

I got the engine apart a second time and removed the pistons. I know they are just gonna get dirty again but these seemed especially cruddy.


I took my time and got all the piston cleaned up by letting them soak in vinegar for awhile to loosen up the crud. I was a little curious if these scratches would be an issue.


I got the new rings on without issue and was almost ready to get this thing assembled for real this time.

But first, I had to clean off some old gaskets. A little scotch should help with being patient.

[cheddarGoblin]

I got the gasket surfaces cleaned up and thought that I was ready to start assembling. However, I found that the gasket kit I ordered did not include the O-Rings that go between the cylinder base and the crankcase, so I had to order those separate. I received them and made sure all the passages were clear and started getting it put back together.


It is a little tricky to get the pistons into the cylinder and keep everything aligned. I had to employ the wife to help get the cam chain through while putting the cylinders on.

I was quite concerned about the condition of the cam chain tensioner. There is a significant crack in the rubber. Though I really did not want to assemble something in this condition, I really could not find a suitable replacement as the tensioner itself still seemed to work fine.



I went ahead and continued assembling. I hope I don't regret it.

[cheddarGoblin]

There wasn't much to take pictures of while getting the head on.

This might have been the only other pic I took while getting the motor reassembled. Getting the new seal on the rocker box was quite a challenge. I used some dabs of silicone and clamps in a few places to keep it in place.

[SOHC4 Cafe Racer Fan]

That tensioner looks pretty shot. They are difficult to find, but they are out there.  I'll PM you a contact who collects and sells these parts.

[cheddarGoblin]

That tensioner looks pretty shot. They are difficult to find, but they are out there.  I'll PM you a contact who collects and sells these parts.

Thanks. I'm sure it will come in handy.

[cheddarGoblin]

I finished assembling the motor and checked compression (with my el cheapo tester that I dont trust anymore) before I put the carbs on.
I did not have good compression but realized I did not check the valve lash, it was doing this late at night. But once I adjusted the valve lash, it had compression. Some valves did not have any clearance so I didnt think they were closing.

I put a decent compression tester on my tools to buy list and finished putting it together. And to my surprise...

It started!

I was even able to take it for a ride around the neighborhood!

It was a short ride because it was leaking oil from between the head and the rocker box on the right side. But it was running without any issue so that gave me a lot of encouragement.

When I was putting the rocker box back on, I wasn't able to tighten the rightmost bolt. It was staying in but I could tell it was stripped. I was pretty sure I did not do anything to strip it and there were 2 other holes in the rocker box that were for the 1# and #4 valve covers that were also stripped when I got it. So I guess I will be fixing those now.

I ordered from helicoils from Amazon and started taking it apart again, but only as much as needed.

I removed the rocker box so that I could practice on the two helicoils that it needed before drilling into the head.
Both of the outside valve covers each had 1 bolt hole that had stripped threads.



I put some tape under the hold to keep the metal bits out of the rockers and was super careful while taping and installing the helicoils.
They went in great.


Had to do this on the garage floor though. Really need a proper work bench in the new place!



Here is the stripped thread on the right side of the head. I taped it up as well as I could to protect the camshaft and held a vacuum over it while drilling.


I wondered why it wasn't leaking previously. Then I realized that the oil passages between the cylinder and the head were pretty clogged when I was reassembling and I had to clean them out. So it made me think that either not a lot of oil was getting there before or that the seal was just fused to the metal enough to keep it from leaking.

I was super careful and got the helicoil installed in the head. I blew it out with compressed air an hoped that no shavings got anywhere they should not be.


This time, the rocker box bolts tightened up nicely as did the valve covers. It sure is nice when something goes according to plan!

[cheddarGoblin]

So, I had the engine reassembled and it seemed to be an improvement from what it was at least. I had not taken it out for a very thorough test yet as I still needed to get plates on it. Sidebar: I think the DMV in Virginia is what inspires bad stereotypes for DMVs.

Anyway, while I was working on that, I need to address the paint. I had already painted the tank and plastics but did not care for how it turned out as it was a bit too metallic. Plus I still needed to put decals on and clearcoat those.

So...I ended up painting them again. I learned a lot last time, so it should be much easier this time. Plus, my recent test ride was the first time I had put fuel in the tank, I hadn't sealed up the edges of the paint, so it bubbled and needed fixed. Lesson learned.

You can see the too metallicy-ness here as well


I started on the plastics first. I sanded them smooth and this time, hit them with 2 coats of gloss black and a single VERY light coat of metallic. Then let that dry, applied the decals and cleared them all the same day. It turned out much better this time.











Here you can really see the difference between the complete plastics and the tank. I am really glad I decided to repaint.

[cheddarGoblin]

Time to get this tank finished!

First I had to repair the filler neck. I got that smoothed out and will seal up the seems with some JB Weld this time.


I sanded it smooth and will try it again.

The paint went on pretty well. I brought it inside to cure for a few hours before applying the decals.


The tanks decals were going to be the tricky ones.


Just getting them to lay flat is hard enough. I think one side is a tad bit off but I could not tell until after it was on the bike.


But I am happy with how it turned out so I will take it.







I think the clear does have some orange peel. I might wet sand and buff it out at some point but its gonna stay for now.

[cheddarGoblin]

The badges that were on the tanks were in rough shape. So much that I wasn't eve sure if I could make them look decent.

I scored a set for a different bike on ebay for cheap, so I thought I might give them a try. The badges are the same size but I didnt realize initially that the new badges were basically flat while the badges I had are curved. The new ones fit but do not conform to the tank. They look better but I am not sure if I could warm them up and curve them somehow.






I am digging how it is turning out.

[cheddarGoblin]

It was such a relief to get the engine rebuilt and have the paint and decals done!

Now I wanted to fix the seat. I ordered replacement seat cover from eBay. Time to get this done. Full disclosure, I've never done this before.

The whole time I had it, I thought this was the factory cover.



It wasn't until I started taking it apart and found it was an aftermarket cover that just had the same stitch pattern as the factory cover.

But the real cover was in much worse shape.




The all look close enough




Removing a crap ton of staples


At least the foam seems ok



I got the new cover on. Im not very happy with how it sits. The cover was for a 750, I thought the 650 would be the same size but it seems a little big so fits loose. It fits OK but not great. Also, I had to buy a pneumatic stapler to get this thing fastened, a manual stapler just doesnt do it. I am going to see how it goes and figure out what to do about it.

[cheddarGoblin]

Now that my tank was on, I needed a better way of holding it on.

The bike was missing the rear tank rubber when I got it. It had a screw and washer that were not correct for it either. I was using a piece of conveyor belt to cushion the tank for the time being.



But I scored a NOS tank rubber from eBay for too much money but I did not know where else to look. But I have somewhere else to look now thanks to Cafe Racer Fan

So now I have the proper rubber

[cheddarGoblin]

The bike was missing a petcock when I got it and the thread is and uncommon one. Initially I could not find a Honda replacement but did find one with the same thread for a BMW that got me this far. However, the clearance of the lever between the head and the carb was very tight and the side outlet made managing the fuel hose a challenge.




So I wanted to get the correct one and was able to get this original on eBay for a decent price. However, it was gonna need cleaned first. I was expecting it to be full of gunk but DANG!








At least the screen was intact though.


But if I can get it to work, it will be the better option I think.


I cleaned it up and wanted to give it a try. It did not come with a seal that went on the tank side, so I used the one I have for the BMW petcock.
I installed it, put a little gas in the tank and tried it out.

It leaked everywhere....

And when I was taking it back off I managed to break the filter that came with it.

It definitely leaked on the tank side but it seemed like it was also leaking around the cup area. I went to a local shop to see if they had some O-rings that would work but the parts dude directed me to Harbor freight where I picked this up for $10.


I tried 2 seals out of it for the tank side and cup side of the petcock and in a shocking turn of events...

They worked!

Cool, I was worried that it was going to leak around the valve area since that is not servicable but that seemed to be fine.

So I then used a dab of JB Weld to fix the screen that came with it. Not sure how well that will hold up.


Since I did not have the in tank screen for the Honda petcock, I tried to use another O-ring from the kit to get the BMW screen ti fit tight enough to use with the Honda petcock. Surprisingly, that seemed to work too.



Factory petcock fits much better

[cheddarGoblin]

I think I am getting close to just having normal maintenance type stuff on this one but we'll see. In the meantime, here are a few older miscellaneous pics that I hadnt posted before.

I managed to break one of the mirrors awhile ago while trying to adjust it.


I replaced these exhaust gaskets awhile ago but I am not sure that it did much good.


I tried this out on the leaky mufflers. It was a waste of effort.


These two bikes have taken up quite a bit of my time over the past year.