Author Topic: Phaedrus: CB750 RestoMod - Update: 02/23/20 w/o new pics  (Read 484557 times)

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Offline MRieck

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Re: Phaedrus: CB750 RestoMod - Update: 9/19/19 w/new pics- DYNO run
« Reply #4550 on: February 04, 2020, 03:02:21 pm »
After reinstalling the cam and rockers, we took it apart again for various reasons and pulled the threads out of at least 2 maybe 5 holes. So we signed up for helicoil 101. Any comments?
It happens Ron....to you, to me and many others. I have put many Helicoils in heads with no problems. There are some tricks. Finish tapping with a bottoming STI tap after using the tapered tap to avoid pinching the insert. I use some cutting fluid on the tapered tap. I also put a small amount of hi temp threadlocking compound on the inserts.
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Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 9/19/19 w/new pics- DYNO run
« Reply #4551 on: February 09, 2020, 06:44:52 am »
After reinstalling the cam and rockers, we took it apart again for various reasons and pulled the threads out of at least 2 maybe 5 holes. So we signed up for helicoil 101. Any comments?
It happens Ron....to you, to me and many others. I have put many Helicoils in heads with no problems. There are some tricks. Finish tapping with a bottoming STI tap after using the tapered tap to avoid pinching the insert. I use some cutting fluid on the tapered tap. I also put a small amount of hi temp threadlocking compound on the inserts.

Thx Mike and for the PM. Gonna experiment this AM on an old head... if I still have it.  :P
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 9/19/19 w/new pics- DYNO run
« Reply #4552 on: February 09, 2020, 01:12:37 pm »
Had a nice morning in the shop today. We (Me, Bruce, and Ed Spengeman showed up, long time no see) were going to practice setting some helicoils. Remember we stripped 2 holes on the notorious cam bearing block hold down to the head holes.  But we realized that CBJoe took the helicoil kit home with him last week and called in today that he needed some home time after a rough week. So we decided to try an old farkle for stripped threads. I know I heard of this 25+ years ago, but can't swear that I ever did it. But I think I did, but used a 1/4-20 bolt. It worked, but I realized that one should really use a 1/4-28. For what you say? Fast forward 20+ years to today.

A 1/4-28 of the appropriate length, is almost a match for a 6mm x 1 bolt. It is slightly larger diameter, but still fits in the holes, and slightly coarser thread pitch. So since the 6mm threads are already removed, came out with the bolt, one doesn't need to drill anymore. Just take a 1/4-28 tap and make new threads in the old hole. Worked like a champ! (Let's hope).  The hole in question was the front main cam block holder downer. Was so easy we went ahead and did the back one as well. Both tightened down to 100 in/lbs.

We still have one to  do. Its the right rear cam bearing cap bolt. It has the dowel in it as well. The 1/4-28 fits through the dowel OK. But the head on the bolt is an 11mm (7/16 actually) and there isn't enough room to drop a socket on it. Maybe an open end will work. Or we'll use a helicoil.
« Last Edit: February 09, 2020, 01:15:02 pm by MCRider »
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Terry in Australia

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4553 on: February 13, 2020, 01:55:05 pm »
Ckuld you use an "allen bolf" Ron? The head won't be any bigger than tbe stock nut, and can be torqued properly with an adapter. ;D
I was feeling sorry for myself because I couldn't afford new bike boots, until I met a man with no legs.

So I said, "Hey mate, you haven't got any bike boots you don't need, do you?"

Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4554 on: February 13, 2020, 02:37:16 pm »
Ckuld you use an "allen bolf" Ron? The head won't be any bigger than tbe stock nut, and can be torqued properly with an adapter. ;D

Genious! That could work fine.   :D
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4555 on: February 13, 2020, 07:14:50 pm »
Hey Ron, I did the 1/4-28 trick on one or two cam tower bolts the last time I had the top end off my motor in 1979, and it seems to have held up fine. ;D
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Offline 754

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4556 on: February 13, 2020, 10:09:23 pm »
Just turn or grind down a 7/16 or 11mm socket, it's only going to about 8 ft lbs..
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Offline MRieck

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4557 on: February 15, 2020, 01:53:59 pm »
 Are you using a grade 8 fastener Ron? I have replace the stock tower bolts with maximum length 12.9 grade Allen heads. That is done after installing 12mm long 6mm Helicoils....pretty strong after that treatment.
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Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4558 on: February 16, 2020, 09:05:24 am »
Are you using a grade 8 fastener Ron? I have replace the stock tower bolts with maximum length 12.9 grade Allen heads. That is done after installing 12mm long 6mm Helicoils....pretty strong after that treatment.

Geez, throw me a curve ball.  ;) No, the bolts we used and were going to finish with are Grade 5 mush.
We decided to go 1/4-28, but use Grade 8+ Allen heads. We ordered up a set of 6mm helicoils too, just in case we decide to go that way.

So we got those on order, and called it a day.
« Last Edit: February 16, 2020, 10:53:11 am by MCRider »
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Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Don R

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4559 on: February 16, 2020, 10:01:01 am »
 I have a head and cylinder that were held together by 5/16" allen bolts under the cam pucks. The cam hold downs are also 1/4" fine. Someone in it's past didn't own a torque wrench. I haven't decided whether to helcoil or timesert them. Even though it seriously annoys me, it's apparently not hurting anything.
 Once I passed up a sandcast head, it was ported for a mini sprint and every thread had been heli coiled. What was I thinking?
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Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 02/09/20 w/o new pics
« Reply #4560 on: February 16, 2020, 10:54:50 am »
I have a head and cylinder that were held together by 5/16" allen bolts under the cam pucks. The cam hold downs are also 1/4" fine. Someone in it's past didn't own a torque wrench. I haven't decided whether to helcoil or timesert them. Even though it seriously annoys me, it's apparently not hurting anything.
 Once I passed up a sandcast head, it was ported for a mini sprint and every thread had been heli coiled. What was I thinking?

Good story! Key is "apparently not hurting anything". Doesn't leak oil? 
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline MCRider

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Re: Phaedrus: CB750 RestoMod - Update: 02/23/20 w/o new pics
« Reply #4561 on: Today at 12:04:03 pm »
Had a good session in the Busted Knuckle Garage. Me, Bruce, and CBJoe. HeliCoils 101. CBJoe procured a serving of everything we would need, an install kit, some spare taps, some 1/4-28 Allen head bolts of the Grade 8  etc. CBJoe has been instrumental in seeing that this project doesn't get stalled out.

I had an old head that has a real story behind it, too much for now. Has virtually every hole repaired with helicoils or KeenSerts. KeenSerts are really beefy but need some room for drilling the prep hole. So they were just used on the 4 hold down bolts. The bearing cap hold down holes had been rudely repaired with helicoils but the coil stood proud of the surface. Or they weren't installed cleanly. So we ripped them out and did some real clean installs, for practice. Joe had never done one and my experience is nearly 30 years ago.

With some positive vibes, Joe took to Phaedrus's head. Drilled the holes necessary, coiled them with the longer 12 mm coils, (I held the vacuum hose), and they look great and strong. We measured the depth to put the coil in the hole that takes the locating dowel. It seems to set right on top of the coil, nice and perty.

He wanted to go ahead and refix the 2 we did last week with the 1/4-28s. And I sympathize. But its all just a test bed now, so I vetoed the refix idea in favor of keeping the 1/4-28s. So if it ever gets sold, we'll need to tell the buyer ahead, the fixed holes on the right are 6mm x 1, and on the left 1/4-28s

Cleaned up and went home, literally and figuratively.  Next week we should get the cam back in.
Ride Safe:
Ron
1988 NT650 HawkGT;  1978 CB400 Hawk;  1975 CB750F -Free Bird; 1968 CB77 Super Hawk -Ticker;  Phaedrus 1972 CB750K2- Build Thread
"Sometimes the light's all shining on me, other times I can barely see, lately it appears to me, what a long, strange trip its been."

Offline Tintop

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Re: Phaedrus: CB750 RestoMod - Update: 02/23/20 w/o new pics
« Reply #4562 on: Today at 04:26:02 pm »
Glad to hear things keep moving long.  Always pick up a tidbit, or your posts pull another dusty file card from the old brain. ;)
1977 CB550/4 Cafe - Speed Warrior / BOTM 03/11
1980 CB750F (project)
Whittaker GBF Vintage Racing Sidecar (XS750 power) - ITG / 151's / CMR Racing Products (SOLD)
1976 CB400 SS - stock / BOTM 04/11 (SOLD)
1973 CB750 K - basket case (SOLD)
77 CB550 Cafe build
550/750 Filter Thread
Sidecar Rebuild Thread

 

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