Topic: Phaedrus: CB750 RestoMod - Update: 09/23/21 w/ new video

[754]

That scale has to be thicker than you said, I think at least 20 thou.. or more.
 The squish band on that piston looks like it may be contacting. .

[scottly]

I agree with Frank; the scale I measured a few weeks ago was .020", and the edge of the piston looks too clean, like it's had the crap knocked off it. If this is the case, the top piston ring land may have been pushed down, pinching the top ring. What do the other three pistons look like? How does the height of the #4 piston compare with #1?

[HondaMan]

Ron, should  I jump in with my arcane observations?
Oh- and, send me your address so I can send you some thicker O-rings for use with the modern head gaskets, like MLS.

[Terry in Australia]

Yep, that piston looks way too proud of the head, but why just that one piston Ron? You might wanna keep digging into that engine and make sure that your conrod nuts aren't coming loose? Cheers, Terry.

[MCRider]

Thx everyone, things to think about. I'll measure the thickness of the scale. The rest of the pistons were flush with the cyl deck.

Yes HondaMan pls jump in. Check your PMs.

No clear cut explanation, I hate it.

Can't imagine that its a rod or assembly problem, as its an APE Racecrank and they put the Crower (good for 400 hp) rods on the crank. But, anything can happen I guess.

[scottly]

Ron, I have a theory that the cylinder block has been decked at a slight angle, but you will need to make more accurate measurements of the piston heights to prove or disprove it. Say, for example, there is .021" of slope between the #1 and #4 pistons, then the #3 piston would be about .007" higher than #4, and #2 would be about .007 higher than #3, but .007 lower than #1. Since there is also a compression issue with #2, are there any witness marks in it's squish band, not as pronounced as on #1?

[HondaMan]

Is the head quench-banded to match the bore size? If not, it could be sweeping the flat edges of the pistons too hard, causing severe turbulence and breaking up the swirl that normally helps to ignite a wide swath of fuel in this chamber. This happens often with the 836 kits and the Webcam cams like the 41 grind, if the head is not modified.

...I have to admit to not following the thread lately...

[MCRider]

Is the head quench-banded to match the bore size? If not, it could be sweeping the flat edges of the pistons too hard, causing severe turbulence and breaking up the swirl that normally helps to ignite a wide swath of fuel in this chamber. This happens often with the 836 kits and the Webcam cams like the 41 grind, if the head is not modified.

...I have to admit to not following the thread lately...

Thanks for the thoughts Mark. The bummer is that it ran so good, had good compression on all 4, didn't smoke. If the #1 hadn't already tilted the gauge at 210, and now its 90... what could have happened? Today was spent touching and feeling everything, speculating (which I HATE to do), looking for some clue. Dyno'd at 80+ several times. Now its 49!

The mating surface of the head to the cylinder give minor maybe indications of something...

Well anyway, here's some pics.
1 & 2 surface very clean, darkening in area caused by surfacing:

3&4 MLS left markings around the studholes but not other places.

1&2 Cyl: no clues



3&4 cyls:


#1 Piston:


#4 Piston:


Something to chew on. I've got some hints from HondaMan, and may switch to old fashioned gaskets, but something is wrong and I hate to be thinking it might fix itself.

[CBJoe]

No indication of loose conrod bolts right?  If that piston wasn't proud of the cylinder deck when you put it all together the first time, it's hard to think what else would cause that to occur.

[MCRider]

No indication of loose conrod bolts right?  If that piston wasn't proud of the cylinder deck when you put it all together the first time, it's hard to think what else would cause that to occur.

Right, I palpated all the rods and pistons, seem fine to me.

[MCRider]

That scale has to be thicker than you said, I think at least 20 thou.. or more.
 The squish band on that piston looks like it may be contacting. .

Yes it is 19.5thou.

More thoughts on the "squish band"?

[Jerry Rxman Griffin aka MuthaF'er]

I thought that 210lbs was quite high UNTIL I saw those big ass domes!

How's the KA tensioner holding up so far? 

[MCRider]

I thought that 210lbs was quite high UNTIL I saw those big ass domes!

How's the KA tensioner holding up so far?

Yeah that was my criteria when I bot pistons: I want the ones with them big ass domes.   

No wear on the tensioner. Considering swapping it out for the CycleX one, seems to have more thought put into it.

[MCRider]

I'll be doing a very intensive look see and measurement of all parts this weekend. Esp: the pistons lands and grooves, various distances etc.

But what I really wanted to say is : what a nice guy Ken at CycleX is. Besides answering the phone with something like "I hope I can help you" or something like that, with real sincerity he listened to my whole story and made comments and told me to keep him in the loop as we sort this out.

I bot a CX-7 cam at the suggestion of Mike Rieck. Ken told me, "that's a good cam but I've got some real bad boys if you really want to go fast"

Can't wait for Sunday!

 

[slikwilli420]

I'll be doing a very intensive look see and measurement of all parts this weekend. Esp: the pistons lands and grooves, various distances etc.

But what I really wanted to say is : what a nice guy Ken at CycleX is. Besides answering the phone with something like "I hope I can help you" or something like that, with real sincerity he listened to my whole story and made comments and told me to keep him in the loop as we sort this out.

I bot a CX-7 cam at the suggestion of Mike Rieck. Ken told me, "that's a good cam but I've got some real bad boys if you really want to go fast"

Can't wait for Sunday!

 

Kenny is a wealth of hospitality and knowledge. He has been working closely with me on custom pistons for my racer. I went with the CX11 cam per his suggestion that it was the baddest, nastiest cam you can put in a road racer. His and Mike Rieck's guidance have made mine possible. Good to have an ally like Kenny out there.

[MCRider]

I'll be doing a very intensive look see and measurement of all parts this weekend. Esp: the pistons lands and grooves, various distances etc.

But what I really wanted to say is : what a nice guy Ken at CycleX is. Besides answering the phone with something like "I hope I can help you" or something like that, with real sincerity he listened to my whole story and made comments and told me to keep him in the loop as we sort this out.

I bot a CX-7 cam at the suggestion of Mike Rieck. Ken told me, "that's a good cam but I've got some real bad boys if you really want to go fast"

Can't wait for Sunday!

 

Kenny is a wealth of hospitality and knowledge. He has been working closely with me on custom pistons for my racer. I went with the CX11 cam per his suggestion that it was the baddest, nastiest cam you can put in a road racer. His and Mike Rieck's guidance have made mine possible. Good to have an ally like Kenny out there.

What displacement are you using?

[MCRider]

Phaedrus is now a 902cc up from 888cc. (often called a 915cc, but that's not how the math works out.) Kenny bored and honed what I had, and we're fitting his (WISECO) piston kit with the shellac on the skirts and deep pockets for the big cam we're fitting (CX7). Kenny felt like #1 and #3 pistons kissed their respective exhaust valves. I couldn't see it, but I don't trust myself. Not a satisfying conclusion, but since #3 seized and required boring, and the ARIAS pistons were the only thing left over from the original engine kit, what the heck? Its all new now. I don't know if we'll ever get a satisfying conclusion as to what really happened.  Cyl and pistons on their way home, quick turnaround.

Mike has the head for diagnosis.

[CBJoe]

Phaedrus is now a 902cc up from 888cc. (often called a 915cc, but that's not how the math works out.) Kenny bored and honed what I had, and we're fitting his (WISECO) piston kit with the shellac on the skirts and deep pockets for the big cam we're fitting (CX7). Kenny felt like #1 and #3 pistons kissed their respective exhaust valves. I couldn't see it, but I don't trust myself. Not a satisfying conclusion, but since #3 seized and required boring, and the ARIAS pistons were the only thing left over from the original engine kit, what the heck? Its all new now. I don't know if we'll ever get a satisfying conclusion as to what really happened.  Cyl and pistons on their way home, quick turnaround.

Mike has the head for diagnosis.

Good Deal Ron   Maybe we will get to do a Dueling Dyno's with Phaedrus and the Hot Rod after all 

[slikwilli420]

I'll be doing a very intensive look see and measurement of all parts this weekend. Esp: the pistons lands and grooves, various distances etc.

But what I really wanted to say is : what a nice guy Ken at CycleX is. Besides answering the phone with something like "I hope I can help you" or something like that, with real sincerity he listened to my whole story and made comments and told me to keep him in the loop as we sort this out.

I bot a CX-7 cam at the suggestion of Mike Rieck. Ken told me, "that's a good cam but I've got some real bad boys if you really want to go fast"

Can't wait for Sunday!

 

Kenny is a wealth of hospitality and knowledge. He has been working closely with me on custom pistons for my racer. I went with the CX11 cam per his suggestion that it was the baddest, nastiest cam you can put in a road racer. His and Mike Rieck's guidance have made mine possible. Good to have an ally like Kenny out there.

What displacement are you using?

Sorry, just saw this. Im at 760 as that is the class limit for my racing organization.

[MCRider]

I'll be doing a very intensive look see and measurement of all parts this weekend. Esp: the pistons lands and grooves, various distances etc.

But what I really wanted to say is : what a nice guy Ken at CycleX is. Besides answering the phone with something like "I hope I can help you" or something like that, with real sincerity he listened to my whole story and made comments and told me to keep him in the loop as we sort this out.

I bot a CX-7 cam at the suggestion of Mike Rieck. Ken told me, "that's a good cam but I've got some real bad boys if you really want to go fast"

Can't wait for Sunday!

 

Kenny is a wealth of hospitality and knowledge. He has been working closely with me on custom pistons for my racer. I went with the CX11 cam per his suggestion that it was the baddest, nastiest cam you can put in a road racer. His and Mike Rieck's guidance have made mine possible. Good to have an ally like Kenny out there.

What displacement are you using?

Sorry, just saw this. Im at 760 as that is the class limit for my racing organization.

Cool!

[MCRider]

Well, its been a while. My procrastination has been enhanced by my disease. I spend a lot of time in therapy and I sleep a lot more. But there's lots to be encouraged by.

There has been so much back and forth, phone calls, emails, speculation and hypothication. Nothiing answers every question completely. Lets just say I'll have pretty much a new top end (cyls, WISECO 915 kit, Cycle X7 cam are here) just waiting on the head. Everything's been tweaked and honed and breathed on and prayed over. That's all I'll say about it till its running again. This weekend coming up is the VJMC National meet at Springmill State Park, so no wrenching. I won't be showing Phaedrus, but there will be others.

I've scored a hi-tech fold-able electric wheelchair so I'll spectate in style. I don't absolutely need it in close quarters, but distances of 20 yards or more are difficult, hence the chair. Its 52lbs, folds to a medium suitcase size, and really moves out.

I'll make a post of the VJMC Natl with pics. Then it will be back to work on Phaedrus.   

[Ichiban 4]

Well, its been a while. My procrastination has been enhanced by my disease. I spend a lot of time in therapy and I sleep a lot more. But there's lots to be encouraged by.

There has been so much back and forth, phone calls, emails, speculation and hypothication. Nothing answers every question completely. Lets just say I'll have pretty much a new top end (cyls, WISECO 915 kit, Cycle X7 cam are here) just waiting on the head. Everything's been tweaked and honed and breathed on and prayed over. That's all I'll say about it till its running again. This weekend coming up is the VJMC National meet at Springmill State Park, so no wrenching. I won't be showing Phaedrus, but there will be others.

I've scored a hi-tech fold-able electric wheelchair so I'll spectate in style. I don't absolutely need it in close quarters, but distances of 20 yards or more are difficult, hence the chair. Its 52lbs, folds to a medium suitcase size, and really moves out.

I'll make a post of the VJMC Natl with pics. Then it will be back to work on Phaedrus.   

Hi Ron..

We haven't chatted in a while.  Just wanted to say "hang-in-there".  I've had a number of friends incapacitated to point where they had to use wheelchairs..over the years.  It's amazing to me how functional and mentally sharp we can be..even with serious physical limitations (some friends mentioned..were quadriplegic BTW..for many years).  But don't want to get off on some bummer trip here.  Just wanted to say that I still follow your posts..enjoy your pics of Phaedrus..and hope you have many more years of enjoyment working on it (her?)

Later my friend

Al/Ichi

[Jerry Rxman Griffin aka MuthaF'er]

Ron, Good luck getting it back together. I'll bet you will notice great improvement this time around. Something just didn't seem right previously.

[MCRider]

Ron, Good luck getting it back together. I'll bet you will notice great improvement this time around. Something just didn't seem right previously.

Thanks Al and Ichi. Right, I'm looking forward to this rebuild.   

[MCRider]

Back from VJMC National. Lots of cool things. A nearly bonestock CB750K with a turbocharger. Pristine CT90 and CT125. Friendly, laid back event. State Park Inn great venue.  More later.

I've got 2 boxes of what I expect to be delicious motorcycle engine parts on my floor.