[scurvykervy]

Issue: I seemed to have stripped the threads for the CCT bolt, inside the cylinder head aluminum casing. Once the tension bar is in the cylinder head with the spring, I tighten the CCT bolt into the bar, but, the bolt spins and spins and never locks the tension bar into place. It just shoots the bar and spring across the room instead.

Parts fiche to help you get an idea:
https://www.cmsnl.com/honda-cb175k5-super-sport-1971-usa_model421/partslist/E06.html#results

Can I helicoil or time sert the cylinder head casing? Does anyone know what size I would use?
Honda part # 90009315000

I have a spare engine for this bike, I could use the cylinder head off of... but, I JUST rebuilt this cylinder head with all new valves, seals, and guides.

Story:
Today, I finally got the motivation to strip down the old bike after 2 years of it sitting in the garage.
4-5 years ago, I destroyed the engine of this bike by taking it on highway. Burned a hole clean threw the piston. I had it completely rebuilt with NOS parts. I had a engine shop put the piston rings on.
Engine ran alright after the rebuild, but, billowed white smoke out of exhaust. (3-4 years ago at this point.) I took engine back apart. Found the engine shop put a piston ring on upside down.

I put it all back together after fixing the shops mistake (don't really blame them, they build modern 1000 HP V8's for race cars... not little old hondas! they were nice enough to buy special tools to do my valve guides)

I tried starting the bike for the first time (again) and after the engine turned and turned from the starter.. I heard just... parts flying around in the engine. I threw it back in the garage where it sat for almost 3 years until today.

Today I discovered those parts flying around in the engine were the cam chain tensioner bar and spring! found them at the bottom of the engine. Hurray! now i cant put it back together. Yarruh!!

 

[Gixxer-18]

Yes you can helicoil /timesert the head; but which thread have you stripped? A picture of both the head and the tensioner bolt would be helpful before you continue. The bolt has two threaded portions... different pitches...

 

[Simo]

You dont need a heli just drill it clean and re tap the head to m6 and then use an appropriate lenght bolt.
Highway driving isnt enough to hole a piston unless the timings off or the carbs are off

 

[scurvykervy]

Yes you can helicoil /timesert the head; but which thread have you stripped? A picture of both the head and the tensioner bolt would be helpful before you continue. The bolt has two threaded portions... different pitches...

Here is an actual picture of my engine and "the hole" also a picture of the bolt in question plus a better reference of where it sits in cylinder head. The bar tensioner sits inside that hollow tube just under my red circle, the bolt locks it in perpendicularly.


- For fixes my options are.
There is a reputable machine shop down the road from me, would I be better off taking it to them and having them timesert? Simo's recommendation to drill, tap to m6, and get a different fastener, sounds more rugged to me.

 

[scurvykervy]

You dont need a heli just drill it clean and re tap the head to m6 and then use an appropriate lenght bolt.
Highway driving isnt enough to hole a piston unless the timings off or the carbs are off

That's relieving to hear, I was hoping it would be that simple. I must have over cranked it... I have access to a reputable machine shop that could do a heli or drill and tap it. Tomorrow's sunday and they are closed... so buying an m6 tap set from the hardware store might be happening.

I put about 3,000 miles on this bike before engine did a bad. The PO had Carb issues, timing issues, spark issues, spark plug fouling. Bike had lots of money put into Honda Western Hills Dealership to get bike on the road by PreviousOwner so I had a pretty good start, all new carburetor goodies, new stock timing goodies, new spark plugs and wires, the coil pack is off like some '70's-80's Kawasaki KZ400 or something like that. So all I had to really do was fine tune it, and pick up where he left off.

The day the engine popped, I had ridden bike like 20+ miles at 40-50mph on back roads out to a bike show. I took this bike on lots of long rides at 45-60mph, indicated speed, bike always seemed fine as far as the engine was concerned.. On the way back from show, I had been on highway for maybe 3-4 miles at 60 mph+. I tried accelerating from that speed to pass a chopped up harley davidson on the highway... throttle pinned.. passing him, bike is maxed out, past him, then.. pop! My guess is stock small carb jetting, lack of fuel, plus stock timing-point-system set to stock timing with no advance or retard, at that speed, sustained, plus all the carbon build up in combustion chamber shown by terrible fouled spark plugs. Led to detonation.

I'm hoping it's case closed after all this. I'd love to ride this thing on the road again, but, I'd also love to pass this bike onto someone else to enjoy as much as I have.

PS: It's great to hear from you Simo, I remember you helped me out a bunch back when I first got this thing! Hope all is well