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John, Thank you for digging out the Mono and taking some photos, that is a super cool saw! Clint

Agree 100%, those springs can be tricky! At least I’ve had the privilege of benefitting from all the expertise of others on here!

Nice find!

Ha, yep.... I’m starting to get the hang of it though. Still learning some of the little differences in design over the years.

I’ll have to add this to the list of items to keep on the look-out. Is the one you have in nice condition, I’d like to see photos

Wow, now that’s a cool looking saw!

Finally got the spool free last night and have started cleaning everything. I think I’m back in business again. Thanks again David!

Yeah, I may contact them again and see if they would put all three listings together for a best offer. Seems odd to separate into different listings.

David, This is great, thank you for all the detailed photos and guidance! As you noted, my engine is missing the felt and thrust disc, this does seem to be a common occursnce. I’ll give this a go... Thanks! Clint

Is there a trick to removing the recoil rope spool from the earlier O&R engines? This is the first engine I’ve worked on that doesn’t have the large retaining ring that clips into the little recesses on the housing. I can’t figure out what seems to be preventing the spool from sliding right out but it doesn’t seem to want to budge. I have not yet let the tension out of the recoil spring so I’m thinking that is probably my issue but wanted to ask before I mess anything up.

Interesting. Not sure I’ve come across an engine yet that has no replaceable seals. I wonder what they use instead. I just opened up another engine so I’ll tank some measurements and see if any of these new seal candidates will fit. The were so very close to being a fit on the last shaft I tried.

I’ll check back with the seller again if they haven’t sold already. Is the Mini Twelve fairly uncommon?

Very interesting. I was going to return these seals but I think I’ll keep them and see if I run into any of these larger shafts.

I was tempted at this after looking at the listings last night. I sent the seller a couple questions about a package offer/deal for both. I haven’t responded yet to his proposed offer.

David, I did not realize there are different size shafts. That’s good to know, perhaps they might fit one of them. I’ll have to keep these on hand and check next time I have an engine opened up. Do you know the OD measurements on the different size shafts?

Well the small U-cup seals that I ordered arrived and I was initially excited as they looked like they were going to be perfect solution but unfortunately they were just slightly out of spec for ID. So close... back to researching.

Cool, thanks for the link- I’ll have to get some of that! Yep, dirty gas isn’t a pain. I have a 2.5 gal gas can fill that I’ve collected over the years, time to take in to the local disposal center which is always a hassle.

Ha, sounds like we have a similar arsenal of cleaning utensils. I’ve been buying Q-tips in bulk now and I go through a fair amount of carb cleaner, works great. Not sure why I hadn’t really used gasoline up till now but it’ll be a go-to for soaking these gear box and carb parts for sure.

I found a possible source for small U cup seals so I took a gamble and ordered a couple different sizes. I’ll let you know once they arrive and I have a chance to see if they fit.

I’m with you, the U cup is probably needed for properly managing the case pressure, shaft friction, etc. The o-ring approach might work for very short runs but would likely wear out fast or cause other problems unless you could get just the right balance of exact dimensions so as not to be too compressive on the shaft and against the inner wall of the groove.

Just looked at the rebuild thread again, thanks! Hmmm, you’d think someone would make little seals like this for chainsaws or something... more searching I guess. I still wonder if a X-profile o-ring might be an option. I don’t know enough about how the seal functions but I’m guessing that since it’s a pressurized system it’s best to have the U-cup rather than a more compressive type seal like an o-ring or the x-profile o-ring.

I finally got this engine all put back together yesterday. I didn’t attempt to replace any of the shaft seals with o-rings just yet. I thought I would first see if the old seals had a little life left in them. Well, I got the engine to run for 1-2 seconds at a time, basically it will fire off the little bit of gas from priming the carb. Does this sound indicative of a seal leak or a fuel problem? I completely rebuilt the carb and cleaned the fuel tank and also added an in-line fuel filter (I do that on pretty much all my engines now) so I think the fuel system is working properly. By the way, the little “Crap Trap filters by Sullivan No 187 are great). As soon as I got the engine all back together I remembered the engine/shaft seal leak tests from previous threads. I was kicking myself for forgetting to try those techniques before buttening it all up. But, I guess I’ll get a second chance now If an alternative replacement U-cup seal in this particular weird size range for O&R continues to be non-existent, what are your thoughts on a X-profile o-ring? I was wondering if this style o-ring might offer sort of an in-between solution of a U-cup and a standard O-ring. I haven’t ever actually pulled one of the induction shaft seals out of the little groove. Is it also a U-cup style or something completely different? It doesn’t look like a U-cup to me but without actually getting it out it’s hard to tell. Does anyone have a NOS seal that can post some close up photos? Given their scarcity I don’t want to accidentally damage one pulling it out just to study it

Wow - that’s a nice tidy set up for spare parts That’s a great little cabinet of drawers. Nothing like NOS parts... Ha! I like the photo of the cat!

Yeah, I’m not sure why either. From here on out though I’ll definitely be using gas - that made fairly quick work of it! That thickener is amazing stuff, I’ve never messed with anything so sticky.

Made some progress, finally had to use some gasoline....