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Discussion Starter · #1 ·
I really would like some input from the expert wrench turners on this forum. The scenario is as follows. I own a 1968 Bonney that had a professional top end job about 3000 miles or five years ago. (You can see the bike is ridden very little but will stay in my collection forever.) Lately the bike has been getting very hard to start and makes a gurgling sound when you crank her over. After she kicks she tends to puke a good puddle of oil through the overflow. Of course if you start and run the bike frequently the regurgitation disappears. After warmed up the bike still runs like mountain ape with its butt on fire. There is a substantial oil leak around the cylinder base gasket and one of the bottom push rod tubes has a bad rubber ring contributing to the oil mess when she gets warm. Here are the variables I am dealing with. I have checked the head bolts with the torque wrench and they are within spec's. The bike is already 40 over and with a cold compression check with no oil added to the cylinders reads 125 on the right and 130 on the left. I have a new set of rings on the work bench and all new gaskets for the top end. What would you guys do? Just replace the push rod tube seals and carry a rag or pull the cylinder barrels check tolerances and hope for one more refresh ring job. As for allot of us right now, money is the contributing factor for a bike that is ridden very little and kept garaged with siblings that also need attention. Comments appreciated.
 

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hey jbc...not everyone here is going to agree with this but, on my 71 bonnie...i have no pushrod thub seals..as in none...nadda....when i put mine together, i used hi temp silicone...only...and let it dry a good amount (24hrs)...b4 firing up...3000 miles now...no leaks.....Tom
 

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Pull the head, chnge the pushrod tube seals and use some RTV to seal them, let dry overnight.

Meanwhile, pull the timing cover, pull the oil pump and check what's up with the checkvalve balls & seats; you either have grunt stuck in there, or a nicked ball and/or seat. That's allowing oil to flow out of the tank into the crankcase.

Meantime, you can just dump the sump plug at the bottom of the engine before you start it, and it will cut WAY down on the mess till you get to pull the top end.
 

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Discussion Starter · #4 ·
One More Question

I pulled the timing cover and did find the bottom crank seal was somewhat distorted. Would this in anyway contribute to the sumping problem. I soaked and cleaned the oil pump and did the leak test recommended in my shop manual, it appears to fine. No nicks or burrs and good pressure. I am at a crossroads here. I really would hate to buy a new pump if not needed, but since everything is openned up now is the time to fix the problem. I will be ordering new seals and gaskets in the morning, opinions anyone?
 

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A distorted seal could leak past enough to build too high a level in the crankcase indirectly, through the window in the timing chest.

BUT, that's wierd, becasue you said it clears up after you ride it a while; goes contrary to my above theory that is probably just flat wrong.

You need to ensure that your breather system is all clear from the bottom tube way up underneath the engine, above and in front of the drive sprocket, on up to the "Y" fitting near the battery, over to the oil tank, and out the tailpipe underneath the rear fender.
 

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Discussion Starter · #6 ·
Thanks Paul

A distorted seal could leak past enough to build too high a level in the crankcase indirectly, through the window in the timing chest.

BUT, that's wierd, becasue you said it clears up after you ride it a while; goes contrary to my above theory that is probably just flat wrong.

You need to ensure that your breather system is all clear from the bottom tube way up underneath the engine, above and in front of the drive sprocket, on up to the "Y" fitting near the battery, over to the oil tank, and out the tailpipe underneath the rear fender.
I really appreciate your advice. I went ahead and purchased a new oil pump with the seals and gaskets just to be sure. (The wife will just have go down and get fitted for the little blue jacket and start practicing how to say "Welcome to WalMart" part time.) Actually the price was better than I expected and it never hurts to have an extra part laying there for the next project. My luck it will be a Honda, but such is life. Anyway I am going to check the entire system clean and blow everything out. Hopefully this will correct the problem. The push rod tube seals and a new head gasket are also on the workbench. I am hoping by next week the old girl will be back to her old self and keeping most of her juices contained. Thanks again for all of the help you and others provide on this forum.
 

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Discussion Starter · #7 ·
I'm Back One More Time

The new oil pump is installed and the balls seated with a good tap. New seals and the Boyer back in and firing. (I didn't have a timing ring so I was darn careful about marking and the reinstall of the EI.) I pulled the head tonight and found one loose top on a push rod and slight wetness on the top of the piston on the right side probably from a little blow by. I had noticed some slight smoking on that side when the bike was first started. The jug walls look great and of course there is some carbon build up. Since I am 40 over already I am hoping a good honing and a new set of rings will buy me some time without having to go through the expense of a size overbore, new pistons, and rings. I truly understand I won't know anything until I pull the jugs and check gaps but man it would nice to hear from a couple of you who been doing this allot longer than me, that you can get by with just a ring refresh the second time around. Also on the Honda site I belong too several guys said they have had luck with buying rings one size over and filing the gaps down to spec's. Any opinions on that. Like most of us these days, money isn't all that plentiful and my job is still there for this week at least, so I am trying to get the most bang for my buck. Thanks again to all who take time to help the less mechanically endowed and don't forget everyone, Sunday is Mothers Day.
 

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At 3000 miles, I seriously doubt you need too bore. Just measure everything and see if it's within spec. If so, just do a light hone and throw some new rings in. I lucked out when we took my top end apart last year and clearances were still good. I just did a hone and ring job ... although, I did do a full head rebuild ...

best of luck!
 

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DO NOT get the next oversize rings.

First, LIGHTLY hone the cylinders and re-fit the rings to check the end gap. If less than .012 (should be .010), new rings aren't going to make much difference.

More importantly, if your piston skirt clearance is much greater than .006, you might end up scuffing them; new rings won't tighten up the slap in the bore all that much.
 

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Discussion Starter · #10 ·
We will soon know

Hopefully this weekend I will get the jugs off and do the dreaded tolerances checks. I hope I can use the feeler gauge and not a yard stick. If I do have to go the overbore route, 60 over strikes me as really getting to the limits on a 650 cylinder, right or wrong, but I really don't want to think about sleeves. Anyway wish me luck.
 

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Discussion Starter · #12 ·
Actually, you can go .080 on the 650 jugs.

.060 is not bad at all.
Paul,

I see what you mean. We were extremely slow today at work and I did some web pricing at several different suppliers. As always I am the expecting the worst and hoping for the best. Looks like the Taiwanese sets are the most readily available. Anyone had any quality issues using these?
 

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Discussion Starter · #14 ·
It has been a good day

I was up early this am armed with a hot cup of coffee and a McDonald's biscuit to pull my jugs. (That sounds almost obscene.)They were soaked and hot washed, given a light honing, and washed again. Here is the results. The barrels are good and clean, the pistons show no signs of scuffing and the carbon deposits were easily cleaned away. The ring gaps are from 14 to 15 on the high side, so they will be replaced. I am ordering either Hepolite or Hastings rings 40 over. I returned the set I had because they were off brand and not marked. I am 60 years old and I just can't see that infamous bevel on the inside and outside that is used for determining the top even with a good magnifying glass. The piston shirt clearance is close with .005 to .006 but pretty much even up and down the bore. I am just going to hope for the best and give it a shot. I know you really can't determine allot by looking into the crankcase, but it does look good and clean.
 

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Discussion Starter · #15 ·
Final Installment

I have put about 6o to 70 miles on the motor since the top end job and oil pump replacement. The bike runs like new with tons of compression and no more puking. There aren't even any oil droppings on the garage floor. Life is good.
 

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Discussion Starter · #17 ·
Final Final Installment

Excellent!

How 'bout some pix?
Here are a couple of shots of the renewed 68 Bonney and her Evil Step Sister, a 69 period Chopper. Thanks again to all, particularly Paul who contributed info and expertise during this adventure. Here are a couple of hints and observations I recommend to anyone else who is thinking about doing this procedure;

1. Document & photograph the disassembly. Freezer bags are great for parts and easy to record info on.
2. Have a good manual available for your make and model bike before your turn the first wrench.
3. Hint-plain old hose clamps make great ring compressors.
4. Hastings rings are superb in quality and customer support. (I had a question about ring position and their tech section returned my call immediately with the correct info.)
5. Make sure you have the tappets installed before you set the barrels. (There always has to be at least one good screw up.)
6. Take your time, go a step at a time, and don't rush. It is a great feeling when she fires up on the third kick and that assembly oil starts to burn away.

Thanks again all, now I am going for a ride.
 

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