Topic: Re: Bigsam302's 76 CB750F (915cc): Project Helen – Running Report!

[SOHC4 Cafe Racer Fan]

Well done, Sam. Just the vote of confidence to shake out the rest of the gremlins and rip up some twisties.

[Bigsam302]

A genuine congrats, Sam on the BOTM. Truly deserved. Also makes you a very viable contender for BOTY! Looking forward to some out on the road pictures... 

Cal,

I cannot thank you enough for all of your help and advice.  Don't worry, I will hopefully post some road pictures next weekend.  I am almost done with working out the bugs.  I had an issue with my rear axle sliders which could have been very bad.  I'll explain it later when my I receive my new set in the mail.

Sam

[Bigsam302]

Well done, Sam. Just the vote of confidence to shake out the rest of the gremlins and rip up some twisties.

Thanks again Don!  You have been a wealth of knowledge and support.  As I mentioned to Cal, I should be able to post an update next weekend.  I have my oil tank sorted out and I should be able to wrap up the rest next weekend.

Sam

[MRieck]

Your bike resembles the Munch Mammoth. Looks great.

[Bigsam302]

Your bike resembles the Munch Mammoth. Looks great.

Haha! Thanks MRieck and thanks again for the parts.

Sam

Sent from my Nexus 5X using Tapatalk

[Bigsam302]

I’ve been steadily working on my bike trying to get it back on the road and it has been one major headache after another.  I am very sad to report that I have only managed to put about 7 miles on my bike.  I haven’t even had a chance to really rip into it.  The few chances that I have had to pull a fist full of throttle have been amazing.  This bike pulls hard and is a blast to ride.

First, let’s talk about my oil tank.  I am beyond pissed about it.  It has followed the same suit as my gas tank.  The work on is was crappy.  When I went out for my first test ride, oil was shooting out of the fittings.  It covered my motor and then the engine heat cooked it.  So all my new paint is ruined.  So I pulled the oil tank and took it to someone who could fix it.  I ended up buying some high-quality AN fittings to replace the crappy ones that were already on it.  When my welder started welding on the oil tank, oil started shooting out of the screw holes.  This pissed me off even more.  Not only were the fittings crappy, the bottom screw holes that bolt the tank to my gas tank were tapped all the way through the oil tank.  Meaning, there is nothing stopping the oil from draining out of the screw holes.  I mean, who does that?  I guess that they figured the screws would plug the hole and it wouldn’t leak.  WRONG!

My welder made a bung for the screws and welded to the tank.  That fixed that problem.  We also decided to look at the plumbing for the oil lines.  Inside of oil tanks, the supply line is flush with the bottom of the oil tank, and the return line has a tube that runs close to the top of the tank.  Then the overflow/vent line ends close to the top of the tank as well.  This was the only line that was actually installed in the tank correctly.  We had to add a proper return line.  After my testing, I am happy to report that it works like is it suppose to!  Oil tank problem is solved!

Here is the original AN fitting that was on the tank.



New AN fittings and they seal like they are supposed to!



Oil tank painted and good to go!



While I had my oil tank out, I decided to make some improvements to my gas tank.  I figured that since cars used heat shielding on the firewall, it might be a good idea to use it on my tank.  So I ordered some heat shielding and fitted it to the inner part of my tank.

[Bigsam302]

The next issue was my chain.  Take a look at the picture below and tell me if you notice something out of place.



If you look closely, you will notice that the axle adjuster screw is bent a little.  Not good at all.  You may be wondering how something like this could happen?  Well, it is my own fault.  I didn’t really pay attention to it until I noticed that my chain had gotten really slack all of a sudden.  My bike has a wider swingarm from a 78 CB750.  So I bought a pair of axle sliders off of ebay that were supposed to be for a 78 swingarm.  Well, it wasn’t.  These things are about half a inch longer and a little wider than the OEM sliders.  So the axle adjuster screw didn’t fit straight.  It fits at a slight angle.  So when I put the bike under a load when I was out testing it, the force from the engine caused it to bend a little.  I also believe that I may have had my chain a little too tight as well.  When I think about it, I am very fortunate that I had the problem with my oil tank or I would have been riding this thing at full speed and something catastrophic could have happened if the chain had come off.



Here is a comparison between the two.  Clearly you can see that the one I had is larger than the OEM one.  I ended up picking up a new set of sliders from Vintage750.com.  This time everything fits like it is supposed to!


I was able to get my clutch to work.  It shifts just fine.  I don’t know if everything is a hundred % just yet.  It shifts ok up through the gears, but it’s hard to shift at times and it is real hard to find neutral.  If anyone has any insight on this, I would love to hear it.  I don’t know what else to do about it.  I’ve taken that clutch apart more times that I would have liked and I’ve replaced everything in it.  Am I missing something?

[Bigsam302]

And now for the most frustrating part!  I have been chasing oil leaks on this bike since I’ve started.  Most of them made me feel like the biggest idiot.  The first one was easy.  I had oil leaking out of the oil drain plug.  I think that the original plug was stripped.  I did have to tap the hole when I was assembling my motor.  So I ended up just buying a new one and it was fixed.





Like I said, the rest of the oil leaks made we feel like the biggest idiot.  I noticed that oil was draining out of a few screws around the engine case.  I was able to twist it with my fingers and then I had a “oh sh#t” moment.  I found out that half of my bolts were not even tight.  The only bolts that were tight were the case studs around the crank.  So how did this happen?  It happen because I used a cheap torque wrench.  When I was assembling the lower case, I used a one of the old school torque wrenches with the needle/lever.  Needless to say, it was way off!  After I put the lower case together, I decided that I should spend the money on a good torque wrench to assemble to rest of my motor.  I started not to trust the readings that I was getting on the old one.  I only bought it because I needed something to torque screws and bolts up to 10 ft lbs of torque.  So I broke down and spent the money on a good one.  Long story short, I had to go back and re-torque all my lower case bolts and the leaks went away.

So today, I think that I have all the bugs sorted out, and I take my bike for a test ride.  Two miles into it, my bike is smoking again.  This time there is oil coming out of the head somewhere in between #2 and #3 exhaust ports.  I can’t tell if its coming from below the cylinder head or down around the block and lower case.  I’m scratching my head.  I’ve torqued and re-torqued the head bolts.  I put gasket sealer around the 6 disks that go in the head.  This thing keeps leaking when I put the bike under load.  It’s fine when I’m just revving it in my garage.  Any help or advice that you can give me would be greatly appreciated.  I already know that I am going to have to pull the head and replace the gaskets.

I am so frustrated!  I just want to get out an enjoy this bike.  I don't want something that just looks pretty in my garage!

[unamusedd]

Did you happen to check your tach cable on the cover? Mine would leak oil going down the road and would smoke from around that same area.

[Bigsam302]

Did you happen to check your tach cable on the cover? Mine would leak oil going down the road and would smoke from around that same area.

Yes, I checked the tach cable and all the valve tappet covers.  The top fin is completely dry.  But everything up under it is not.

[calj737]

Did you torque your head with the same cheap torque wrench? If so, theres your problem... Clean the engine, then dust the area with baby powder, run the engine and locate the actual source of the leak.

[Bigsam302]

Did you torque your head with the same cheap torque wrench? If so, theres your problem... Clean the engine, then dust the area with baby powder, run the engine and locate the actual source of the leak.

Cal,

No, I used a good torque wrench for the head.  I'll try the baby powder trick.  How well do you think it will hold up to actually riding the bike?  When the bike is sitting on it's stands, I can crank it and rev it hard and there are no leaks.  The leaks come when I'm actually out riding it and putting the bike under load.  If you look at the front of the cylinder head, all the paint has bubbled.  I'm starting to think that it is coming from the pucks under the cam towers.  What do you think?

Sam

[SOHC4 Cafe Racer Fan]

What ft/lb values did you use in torquing down the head?  I recall you were using heavy duty studs. 

[Bigsam302]

What ft/lb values did you use in torquing down the head?  I recall you were using heavy duty studs.

I torqued them down to 22ft/lbs

Sent from my Nexus 5X using Tapatalk

[edwardmorris]

A bit pricey but maybe consider getting this adapter to verify your torque wrenches (if getting snap-on or pro recaliberation isn't an option)

http://www.amazon.com/Powerbuilt-940963-Digital-Torque-Adapter/dp/B009MBG4MG

Sorry I haven't read through the entire thread, but two Qs.

One thing I can think of that's close to #2 and #3 on the front are the oil return holes but OCICBW. Did you use some hondabond/sealant around those?

Is the oil pump rebuilt? If so, I hope the bypass valve spring was either replaced or was in good enough condition to reuse.

[Bigsam302]

A bit pricey but maybe consider getting this adapter to verify your torque wrenches (if getting snap-on or pro recaliberation isn't an option)

http://www.amazon.com/Powerbuilt-940963-Digital-Torque-Adapter/dp/B009MBG4MG

Sorry I haven't read through the entire thread, but two Qs.

One thing I can think of that's close to #2 and #3 on the front are the oil return holes but OCICBW. Did you use some hondabond/sealant around those?

Is the oil pump rebuilt? If so, I hope the bypass valve spring was either replaced or was in good enough condition to reuse.

Ed,

As I'm going through other threads about oil leaks, I'm starting to think that I didn't pay enough attention to my head when I installed it.  Meaning, I didn't use any hondabond/sealant when installing my head.  I only put sealant around the 6 pucks.  I saw that Dino had put hondabond around the oil return holes in his video, but I chose not to do that.  I also need to look at putting teflon paste in my cam tower studs.  I read that somewhere as well, but I didn't do it.

As for the oil pump.  It was in good condition when I took it off and tested it.  I just replaced all the o-rings and reused it.

Sam

[MCRider]

As to chain adjusters; they are not designed to hold the wheel in place under load. They are designed to adjust the chain. The axle nut is supposed to hold the wheel in place. If the adjuster bolts bend (assuming you have the correct sliders) then the axle nut is not tight enough. It should be 58 to 72ft lbs.

[edwardmorris]

Sam, those cam tower studs only need to be packed with high temp teflon paste IFF they were removed in the first place. That may not be where the leak is if they were left untouched, however no harm in doing it anyway if you're pulling the head.

Hondabond around the return holes is pretty much required, your's is the second bike I've seen recently that has had oil leaking after the rebuild. In Dino's vids, IINM, he also added Hondabond to the o-rings for the oil feed holes, which to me seemed risky. Proper thickness o-ring is all you need to prevent leaks around the oil feed line, so I didn't use any on those.

[Bigsam302]

As to chain adjusters; they are not designed to hold the wheel in place under load. They are designed to adjust the chain. The axle nut is supposed to hold the wheel in place. If the adjuster bolts bend (assuming you have the correct sliders) then the axle nut is not tight enough. It should be 58 to 72ft lbs.

Thanks MCRider!  Yeah, I think that it was a combination of both.  The wrong sliders and I didn't have it torqued to the right specs.  It was definitely a lesson learned and it is corrected now.

Sam

[Bigsam302]

Sam, those cam tower studs only need to be packed with high temp teflon paste IFF they were removed in the first place. That may not be where the leak is if they were left untouched, however no harm in doing it anyway if you're pulling the head.

Hondabond around the return holes is pretty much required, your's is the second bike I've seen recently that has had oil leaking after the rebuild. In Dino's vids, IINM, he also added Hondabond to the o-rings for the oil feed holes, which to me seemed risky. Proper thickness o-ring is all you need to prevent leaks around the oil feed line, so I didn't use any on those.

Ed,

I'm not taking any more chances.  When I sent the head off to Cycle X, it was completely stripped.  Everything was removed.  I put the studs back in myself.  Since I have to take it off again, I'm going to do it just in case.

I just got off of the phone with Ken from Cycle X.  I had to order new head gaskets and stuff.  I was telling him about the leaks and he told me that he just recently started putting Hondabond around the O-rings just like Dino did in his video.  I watched his video again today and I realized another stupid rookie mistake that I made.  I didn't use Hondabond on my pucks.  I used this Permatex liquid gasket stuff and I'm wondering if this was the main cause of my leak.   

Sam

[SKTP]

Link to the "DINO video" please? I am putting my cases back together soon. Thanks

[Bigsam302]

Link to the "DINO video" please? I am putting my cases back together soon. Thanks

Here is the link to one of his videos. 

He has over 20 videos on his page and it is under HackaweekTV.  They are very informative.

[SKTP]

Thank you very much. On my last (and first ever) rebuild I didn't seal the pucks AT ALL. I had special "oil pants" for my first 300 miles before I couldn't take it anymore...

[Bigsam302]

Thank you very much. On my last (and first ever) rebuild I didn't seal the pucks AT ALL. I had special "oil pants" for my first 300 miles before I couldn't take it anymore...

No problem at all!  Glad I'm not the only one! 

[SKTP]

I'm sure you've seen this thread...but, just in case

http://forums.sohc4.net/index.php?topic=107040.0