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You might be able to replace the head gasket on the rear cylinder, but the front cylinder will be very difficult as the head is nestled under the steering head. It will be tight!
I've never done it with the engine in the frame myself.

And for SP2's (since it's what I have), you don't have to remove the front ignition coil to remove the engine.
There's enough space for the head to clear the coil and wiring harness on the left side.
Better if you use two people since that engine weights 160 lbs.
Pulling the engine is far easier than installing it.

For installation, I found that tilting the engine forward on the lift, I can slide the tail of the engine back and up so I can then slide the lower rear mounting bolt and spacer into place.
Then it's just a matter using the lift to swing the engine up into position for the rest of the mounting bolts and spacers.
Then attach the swingarm and begin torquing the bolts and nuts in the specified sequence.

SP1 have the adjust bolts and locknuts for the engine, so it's a bit more involved, but not excessively different.
 

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Discussion Starter #3
So the SP2's do not require a special tool to loosen the swing arm nut? I haven't gone through the service manual in detail yet. Just trying to get some insight on what I'm getting myself into.
 

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You need a special tool. I'd call it a castle nut socket. You can see examples on eBay if you search RC51 swingarm tool, or RC51 tool.
 

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So the SP2's do not require a special tool to loosen the swing arm nut? I haven't gone through the service manual in detail yet. Just trying to get some insight on what I'm getting myself into.
No, both SP1 and SP2 both require a special tool to loosen and torque the lock nuts (castle locking rings) for each adjust bolt on the swingarm.
The SP1 also requires a 21mm allen socket to loosen and torque the right swingarm adjust bolt, and a 14mm allen socket to loosen and torque the left swingarm adjust bolt via the hex under the swingarm pivot bolt.

The SP2 uses specific distance collars with the engine mounting bolts to secure it into the frame.
The SP1 uses adjust bolts and locking nuts (requiring a special tool to loosen and torque) the engine to the frame.
 

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Discussion Starter #8
Well... I shall attempt to replace the head gaskets with the engine in the frame. According to the Service Manual, looks like the head has bolts instead of studs. Not to sure if the dowel pins will be a problem when lifting that head out. I'll keep you all informed if I'm successful or not.
 

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Discussion Starter #9
Well.... finally got some time off and wrenched on my "Arcee" today. I was able to remove BOTH front and rear cylinder heads without dropping the engine. Even had a little bit of breathing room on the front cylinder. Popped the head off and examined it, there was water in the cylinder itself and saw where the water was coming through on the head. However I don't see a spot on the gasket where it might have punched through? Wouldn't it be obvious? Didn't see any cracks on it either. Thoughts?
 

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Did your engine overheat beyond the 251 deg F critical temp for a length of time?
If so, it could possibly be a warped head.
You could have it placed on a flat measurement plate to check if it exceeded the tolerances.
If the head is warped, you'll have to find a replacement.
You can't mill off the head surface due to the cam gears.
 

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If the head checks out within tolerance, then it may simply be a bad head gasket.
Although that doesn't happen very often.

Were the heads removed recently? Maybe the heads bolts weren't torqued properly on reassembly.
If using used head bolts, the torque is higher than with new bolts.
 

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Discussion Starter #13
Had a Tech straight edge the Heads... all within spec. I'm just going to say it was a bad head gasket. SubSailor... I can tell someone has taken the bike apart... just don't know if they went as far as I did. I did notice that at least 2 head bolts were not as tight as the others on the front head where the issue was. Gonna clean everything up and start putting it back together this coming weekend and go from there. Noticed small issues here and there with wiring and mounting so gonna take my time. I have been researching thermostat mods... right now its failed in the open posistion and temp has been consistant in the mid 100's (up until the head gasket failure). Thoughts on taking it out all together and running it straight?
 

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On the surface, it sounds like the front head bolts were not torqued to spec.
Since both heads surfaces check out as flat, then replace the head gaskets and and torque the head bolts to spec.
For reused head bolts, it is 51 ft/lbs, for new bolts, it's 47 ft/lbs.
The heads bolts are coated in engine oil before the tightening process, and the heads bolts are torqued criss-cross manner in 2 or 3 stages of increasing torque values.
Since I reused my head bolts, I just divided 51 ft/lbs by 3 and used those values (it's not really stated what the intermediate values are in the service manual).

As for the thermostat, it's there to maintain water flow through the engine to maintain operating temperature when the engine is not under high load conditions (such as idling at a light, or cruising down the freeway).
Race bikes generally run without a thermostat as they are under fairly constant full throttle conditions.
On race bikes if they need to raise the engine temperature, they usually tape over a portion of the radiator to reduce air flow. Also easy to remove to increase air flow.
 

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Discussion Starter #15
Thought I would give a little up date on the top-end build. Both heads back together and torqued down along with the throttle bodies and related hoses and fuel lines. However, when re-installing the exhaust headers back to the head, i couldn't help to notice that the exhaust gaskets were missing... I don't recall them coming off in the first place? It's the OEM exhaust minus the Jardine slip-ons, so I know I need them. Other then that It's just refitting all the parts back on. I tried to crank it over to hear it run (fluids in it of course) but lo-and behold the battery was dead. She's gonna fight me the whole way. :)
 

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Discussion Starter #17
She lives! Got her running yesterday, brought her up to running temp with no overheating and fans kicked on normally and no leaks. Did a couple of oil changes to clean out the contaminated oil. Just have some smaller issues now to deal with, but got the hard part out of the way. She will be road worthy very soon.
 

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She lives! Got her running yesterday, brought her up to running temp with no overheating and fans kicked on normally and no leaks. Did a couple of oil changes to clean out the contaminated oil. Just have some smaller issues now to deal with, but got the hard part out of the way. She will be road worthy very soon.
Great news man, keep us posted.

James

Sent from Motorcycle.com App
 

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Discussion Starter #20
The Honda Gods are not smiling down on me............... went for a small test ride this evening. I rode around easing to get her up to running temp. All is great, sounds good, rides great, gobs of power! After a couple of hard accels I went to put fuel. On the way home I went for one last hard throttle....... The engine jumped to life... then went lifeless, locking up the rear wheel. I stopped on the side of the road ( just a block from my house) and put the trans in neutral, the engine fired back up... but with the loudest engine knock I have ever heard.... figure I spun a rod bearing....
 
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