Author Topic: About to do the 650 into a 550 swap. 650 teardown (Read 3425 times)

CBGhia · « **on:** August 14, 2015, 03:46:47 pm »

I have a 650 engine laying around the garage and I am about to pick up another one. The one I have is the early style and I have a clean set of stock 650 carbs to go with it. The one I am picking up is the later style. It has carbs, but the condition is unknown. I just pulled the head on this one and I would like your opinion on the parts. I admit, I don't know exactly what to look for when it comes to wear.

Also, correct me if I am wrong, but isn't this engine supposed to have studs instead of bolts holding the head/cylinders?

scunny · « **Reply #1 on:** August 14, 2015, 03:51:27 pm »

650 has bolts not studs, 2 are longer

SOHC4 Cafe Racer Fan · « **Reply #2 on:** August 15, 2015, 12:04:01 am »

Some of those rockers look a little pitted. You may want to look at you second motor to cobble together a clean set.

Stev-o · « **Reply #3 on:** August 15, 2015, 09:48:40 am »

Hey Joe....measure the cylinder bore with calipers to see if you are within spec.
Do you plan to bore or just hone & re-ring?

You've got 60 days to get this motor rebuilt and bolted in before the Rally in Luchenbach!

CBGhia · « **Reply #4 on:** August 16, 2015, 02:32:49 pm »

Quote from: Stev-o on August 15, 2015, 09:48:40 am

Hey Joe....measure the cylinder bore with calipers to see if you are within spec.
Do you plan to bore or just hone & re-ring?

You've got 60 days to get this motor rebuilt and bolted in before the Rally in Luchenbach!

my digital calipers stopped working. changing the battery did not help, so I am going to have to run up and get a new one.
Non performance stuff. I am trying to just slap something together on the cheap.

I am hoping to pick up the other 650 engine today. We shall see what it looks like on the inside. I really want to use this head because I think you can use the 550 carbs on it if I need to. I guess we will see.

SOHC4 Cafe Racer Fan · « **Reply #5 on:** August 23, 2015, 12:59:20 pm »

The earlier (1979-1980) head allows you to use the 750 carburetors with it. The later 1981-1982 that uses the CV carburetors will not fit up with the 750 carburetors.

How does that second motor look?

CBGhia · « **Reply #6 on:** August 25, 2015, 09:17:12 am »

Quote from: CB750 Cafe Racer Fan on August 23, 2015, 12:59:20 pm

The earlier (1979-1980) head allows you to use the 750 carburetors with it. The later 1981-1982 that uses the CV carburetors will not fit up with the 750 carburetors.

How does that second motor look?

The second motor is still in the frame and the odo has 73k miles on it. It looks really clean from the outside, though. I have not yet torn it down to check the internals.

Sorry for the lousy pics.

SOHC4 Cafe Racer Fan · « **Reply #7 on:** August 25, 2015, 12:13:54 pm »

I don't know if I'd call that motor "really clean" when looking at the exhaust port side, but that is normal and pretty clean for that side of the motor being exposed to 73K miles of rain, dirt, etc, kicked up from the front tire. You'll want to check out the rockers (since some of your other motor's rockers were pitted), cam and all other internal parts. Most importantly, check the condition of the head to see if you can use it for you build and thereby use the 750 carburetors -- IF that's what you want to do.

CBGhia · « **Reply #8 on:** August 25, 2015, 01:24:40 pm »

Quote from: CB750 Cafe Racer Fan on August 25, 2015, 12:13:54 pm

I don't know if I'd call that motor "really clean" when looking at the exhaust port side, but that is normal and pretty clean for that side of the motor being exposed to 73K miles of rain, dirt, etc, kicked up from the front tire. You'll want to check out the rockers (since some of your other motor's rockers were pitted), cam and all other internal parts. Most importantly, check the condition of the head to see if you can use it for you build and thereby use the 750 carburetors -- IF that's what you want to do.

Yeah, I meant clean as in, not a lot of oil around the head or anywhere on the engine for that matter. Even when you pressure wash it, you leave residue in the middle fins and I don't really see it on this one. So it did not leak... probably.

Anyway, I will pull the head off this week and look at it. This is the later model, so this is the head that I don't really want to use. I would like to keep the earlier head. Based on the number of miles on this one, I doubt I will be using any of it.

I have not compared them yet, but I wonder if the 550 rockers will fit on the 650. I have a good low mileage set laying around.

SOHC4 Cafe Racer Fan · « **Reply #9 on:** August 26, 2015, 07:13:18 pm »

Quote from: CBGhia on August 25, 2015, 01:24:40 pm

Quote from: CB750 Cafe Racer Fan on August 25, 2015, 12:13:54 pm
I don't know if I'd call that motor "really clean" when looking at the exhaust port side, but that is normal and pretty clean for that side of the motor being exposed to 73K miles of rain, dirt, etc, kicked up from the front tire. You'll want to check out the rockers (since some of your other motor's rockers were pitted), cam and all other internal parts. Most importantly, check the condition of the head to see if you can use it for you build and thereby use the 750 carburetors -- IF that's what you want to do.

Yeah, I meant clean as in, not a lot of oil around the head or anywhere on the engine for that matter. Even when you pressure wash it, you leave residue in the middle fins and I don't really see it on this one. So it did not leak... probably.

Anyway, I will pull the head off this week and look at it. This is the later model, so this is the head that I don't really want to use. I would like to keep the earlier head. Based on the number of miles on this one, I doubt I will be using any of it.

I have not compared them yet, but I wonder if the 550 rockers will fit on the 650. I have a good low mileage set laying around.

I'm pretty sure that the 550 rockers are NOT compatible with the 650. They have different part numbers and I believe they are different sizes. The valve train is also different. The only parts on the valve train that interchange are valve seals.

See if you can harvest enough good rocker arms from both motors to give you a clean enough set.

bwaller · « **Reply #10 on:** August 26, 2015, 07:33:38 pm »

Not to disagree Don but I think the rockers can interchange. One difference between models is the use of a locating spring with the 650 rockers, otherwise as I recall they should work. I don't have spare 650 rockers at the moment to compare so someone should take the time to be sure.

SOHC4 Cafe Racer Fan · « **Reply #11 on:** August 26, 2015, 08:55:05 pm »

Good to know Brent. As we know Honda has part number differences without a true difference on some parts. I just assumed based on what Buzz at Dynoman told me.

CBGhia · « **Reply #12 on:** August 27, 2015, 06:52:04 am »

I will check them against the rockers I have. I am hoping to get some time this evening.
I am smoking a couple of briskets for work this evening, so I should be able to play with it while keeping the firebox going.

SOHC4 Cafe Racer Fan · « **Reply #13 on:** August 27, 2015, 08:17:37 am »

There you go. Multitasking.

CBGhia · « **Reply #14 on:** August 30, 2015, 01:03:03 pm »

OK. Finally took a few minutes to pull apart the second engine.
This it the fist thing I saw when I opened the top

Looks like it has every bit of the 75k miles that the odometer shows

close up of the cam lobes

bearing surfaces look like ass

So, I don't think I will be using the second engine.

The cam does not look bad, so that's a plus. and I have the tach drive to go with it.

RAFster122s · « **Reply #15 on:** August 30, 2015, 02:09:17 pm »

That's to bad, wonder what caused the wear? Oil starvation causing the cam journal wear? Are the cam shaft bearing surface showing similar results?

CBGhia · « **Reply #16 on:** August 30, 2015, 03:44:41 pm »

Quote from: RAF122S on August 30, 2015, 02:09:17 pm

That's to bad, wonder what caused the wear? Oil starvation causing the cam journal wear? Are the cam shaft bearing surface showing similar results?

Strangely, the cam looks really good. I think the wear is due to high miles and running hot sometimes. I think the strange hole in the bearing surface of the head is from a defect. Maybe Honda will warranty that?

SOHC4 Cafe Racer Fan · « **Reply #17 on:** August 30, 2015, 04:01:09 pm »

I expected the cam to show similar wear to the rockers. It seems to look ok.

CBGhia · « **Reply #18 on:** August 31, 2015, 05:57:03 am »

So, Back to the first engine...

Anything I can do about the bearing surfaces on the head?

Can I lightly sand that with fine paper? Maybe start with 800 and go up to 100, 1200 and 1500?
Or does this need to visit a machine shop?

SOHC4 Cafe Racer Fan · « **Reply #19 on:** August 31, 2015, 03:35:20 pm »

CBGhia,

Assuming you are planning to increase displacement, here are some options:

(1) Dynoman 674cc kit (62mm - 2.2mm over) $519.95; 10.5:1 compression (http://www.dynoman.net/engine/pistons/dp-CB550.html#cb650) with head gasket

(2) Cruzinimage 661cc kit (60.8mm - 1mm over) $110; standard compression (http://www.ebay.com/itm/79-82-HONDA-CB650-1-00mm-OVERSIZE-PISTONS-SET-4-PISTONS-INCLUDE-CI-CB650APS-2-/161569761113?hash=item259e4ee759) - Does not come with head gasket

RAFster122s · « **Reply #20 on:** August 31, 2015, 03:45:22 pm »

I think that question about the bearing surface would be best answered by MReich. He or Cal. Mike knows what is possible but, you might come out cheaper picking up another head.
Heck, if it were not for shipping bike costs, you could buy a running bike for not a ton of money in some parts of the US.

David

CBGhia · « **Reply #21 on:** August 31, 2015, 05:11:26 pm »

Not planning on increasing the bore, yet. This is a budget swap.

Both of these engines were "running". The second one was used by a buddy as a parts bike, but it ran when he got it.

My plan was to just clean up the engine and slap it in the 550 for a quick power boost over the stock 550.

SOHC4 Cafe Racer Fan · « **Reply #22 on:** August 31, 2015, 05:12:58 pm »

Quote from: CBGhia on August 31, 2015, 05:11:26 pm

Not planning on increasing the bore, yet. This is a budget swap.

Both of these engines were "running". The second one was used by a buddy as a parts bike, but it ran when he got it.

My plan was to just clean up the engine and slap it in the 550 for a quick power boost over the stock 550.

That'll deliver on that expectation.

Kemp · « **Reply #23 on:** September 11, 2015, 08:03:56 am »

Have used 650 cam and rockers and locating springs on one of my 550's with no issues. Wear seems normal and adjustment of rockers is the same

CBGhia · « **Reply #24 on:** September 11, 2015, 09:56:33 am »

Quote from: Kemp on September 11, 2015, 08:03:56 am

Have used 650 cam and rockers and locating springs on one of my 550's with no issues. Wear seems normal and adjustment of rockers is the same

Good to know, Thanks!

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Author Topic: About to do the 650 into a 550 swap. 650 teardown (Read 3425 times)