Restoration of Sandcast #97

[markb]

Before I swap the head I decided to split the cases to check out the kick starter. I used plenty of padding to protect from damaging the cases.


Something was causing it to lock up. I confirmed that it was assembled correctly and it worked with the cases apart. I took the assembly apart and comparing the parts to others I have everything looked fine. The only thing I could think of was I had not put any grease on the shaft where it goes through the clutch cover.


I put it back together with different parts and installed a new pawl spring. The only other thing I did was polish the ends of the shaft and lubricated them before reassembling. Then I put it all back together and installed the clutch cover and now it works fine. Could it have been that the shaft was binding in the clutch cover because it was dry?  I could have saved myself a lot of work but I had to be sure.

[markb]

Ok, I might have a change of plans. My next project was to swap the head and cylinder and put in the originals. I was going to put in the o-rings on the bottom of the cylinder and something didn’t look right. So I dug out the cylinder from E748 to compare. The bottom of the sleeves are different. E748 is on the left and E100 is on the right. Besides fixing the fin I had to have the cylinder resleeved and rebored because it had been bored to 1mm over. I’ve got to start paying closer attention.


Externally the E100 cylinder looks the same as the cylinder that’s on E100. So I’m thinking do I want to be correct or original? If this were the only original part on the engine that would be one thing. Clutch and transmission are not original. If you’ve seen earlier posts you know why. The other thing is I tried removing one of the rubber inserts between the fins. The nibs broke off. I think I have just enough to do the head but definitely not another cylinder. Maybe I could find some more. Maybe they would only cost $100. Bottom line is I’m thinking of only swapping the head. I have to do that to be correct.

[Sam]

If it were mine, i would use the cylinder block that the engine came with even if the sleeves look a bit different. No real reason other than knowing that the engine is "original" and not from another bike. I realize that this is pretty flimsy reasoning know that other parts of the engine came from other sources. It would not bother me to now that they sleeves were different; they are a part designed to wear down after all right?

[markb]

That's logical reasoning. If I had enough rubber inserts to "finish it off" I would probably use the original cylinder. I really don't think I'll be able to remove them from the old cylinder without damage. It's a pretty visible feature and would look incomplete without them. I am going to try to find some more, again. Anyone else have opinions about which cylinder I should use?

[Steve Swan]

imo, unless physically impossible, i'd do anything possible to keep all the parts original to the bike together.

[hondasan]

Check out item 202550314968 on eBay - part number is 286 middle number, so for 250/350 twins, though described as for 750 in listing. Not sure of difference if any. David Silver Spares sells repros for the 750 too, though not cheap at £3.25 or so each.

Chris R.

[markb]

imo, unless physically impossible, i'd do anything possible to keep all the parts original to the bike together.

After thinking about it I agree. I already have the old head and jugs off. What pushed me over the edge was I checked what I have for new inserts and I only have 4. Not enough for the head which was going to get replaced no matter what. So unless I could find some it would go without too.

Check out item 202550314968 on eBay - part number is 286 middle number, so for 250/350 twins, though described as for 750 in listing. Not sure of difference if any. David Silver Spares sells repros for the 750 too, though not cheap at £3.25 or so each.

Chris R.

So I'm taking a break and saw your post too.  They're the right color so I already bought them. Thanks Chris for the tip.  If for some reason they don't work I'll just keep looking until I find some.

[Steve Swan]

yup....  in my experience it is fidelity to achieving the finer details that requires more attention and is more tiring than correcting the larger 'problems'.

[markb]

So I got the jugs and head on and I’m thinking could things go any better. Well the answer to that was no. I torqued down the 16 head nuts and then when torqueing the 6mm screws under the pucks, one of them stripped out.  
That’s where I quit for the day yesterday so I could think about what to do. I decided to heli-coil it. I thought about trying to do it in place but decided the best is to pull the cylinder off and do it right. There isn’t a lot of room between the hole and the flange on the cylinder sleeve so it seems like the tap drill and tap may go into the flange. I think the sleeve is soft enough for that. My only other decision now is while I’m at it should I do all four?

[Steve Swan]

Mark, speaking only for myself, i would not use helicoil in that area.  i would go with a timesert which i am sure you are familiar with.  repairing all four of those holes is one of those things you just have to decide if not repairing them is worth the gamble.  when i restored E1973, on the initial assembly, i pulled threads out of at least 2 or 3 of those 6 mm holes.  luckily, on the 2nd assembly, i did not pull anymore.

[markb]

The main reason I'm thinking Heli-coils (besides having them on hand) is there isn't much room before hitting the sleeve flange. I'm not sure if the Time-serts are bigger or not. Maybe I'm thinking Keen-serts. I've never had any issues with heli-coils. Why do you prefer the timeserts?

[Steve Swan]

The main reason I'm thinking Heli-coils (besides having them on hand) is there isn't much room before hitting the sleeve flange. I'm not sure if the Time-serts are bigger or not. Maybe I'm thinking Keen-serts. I've never had any issues with heli-coils. Why do you prefer the timeserts?

i prefer timesert because it is an actual insert threaded into a hole and not a strand of wire wrapped into the thread; in my experience, timesert is a more durable and rigid repair.  unlike timeserts, i've had helicoils walk out when removing the fastener or pull out when tightening the fastener; in particular, cases where the helicoil had already been in place prior to my tightening or loosening said fastener.  not that i am against helicoils, i am not, i do believe in certain applications they have their place and work well.  my thinking about the variables of when to consider timesert vs. helicoil, in the case of the cylinder head, because of cold-to-hot-to-cold temperature variability of repeated cycles of expansion and contraction, accompanied with high frequency vibration, i would go with timesert.  the m/c repair shop i worked in as a mechanic for 3 years, when/where ever possible we used timesert.  there's a little more involved with installing a timesert vs. a helicoil, but imho, the extra steps to install a timesert are worth the minimally extra amount of time and effort.  and as you mention, there may be areas where there simply is not enough metal or space to install a timesert and a helicoil is the ticket.  my personal preference, i will always use a timesert over a helicoil when/where ever possible.  http://www.timesert.com/

[Steve Swan]

since i didn't know what a keensert was, i looked it up.  fwiw, here is some interesting reading on time vs. keesert that seems minus the bullshit one can find on DB's from time to time - https://www.apexspeed.com/forums/showthread.php?28829-Keenserts-vs-Timeserts

[markb]

Thanks Steve for your opinion and the additional information. After careful consideration I decided to stick with the Heli-coils mainly because of the small distance to the sleeve flange. Hopefully I will never pull the head off again and this engine will never get stressed like a normal rider.

I pulled the cylinder off to install the Heli-coils. I thought about doing the one in place but decided against it because of the accuracy and the chips. I looked at all of the 6mm holes and at least one more of them looked suspect so I did all four under the pucks.


They were pretty close to the sleeve flanges but the tap just barely went into the flange.


While I was at it I did the rear one too.

[markb]

Finally, the cylinder and head assembled. The original cylinder and head. The 6mm screws torqued down just fine. I’m happy I went that route in spite of the extra work.


Here’s a shot where you can see the two small o-rings under the towers instead of four on later heads. I did that to document that the original head was in fact installed.