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Engine basics => Engine set up tips => Topic started by: Mark Mc on December 13, 2017, 09:58:59 PM
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I have an O.S. .25LA RC engine I got used. I have a C/L venturi and NVA to go in it, but the screws holding the carb in are stripped. apparently the previous owner used the wrong screwdriver to try and remove the screws, and now they're stripped beyond hope. What would be the best way to remove the screws without filling the case with metal filings?
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I have an O.S. .25LA RC engine I got used. I have a C/L venturi and NVA to go in it, but the screws holding the carb in are stripped. apparently the previous owner used the wrong screwdriver to try and remove the screws, and now they're stripped beyond hope. What would be the best way to remove the screws without filling the case with metal filings?
Remove the backplate, and drill the screw heads with a , just under 3mm drill bit dead center, or if you have a mill use it
If you get metal in it you can use air to blow it out, then clean it with something like WD40 or brake clean. If you like you can fill the crank port and bottom case with a paper towel.
The other thing you could try is to take a dremel thin cut off wheel, and cut a slot across the bolt head, heat the head with a solder gun, then try to remove with screw driver. I would much prefer the heat and try the screwdriver after slotting
Randy
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Needle nose vice grips on the screw head can work. You could also grind flats with a dremel on the side of the head and use a wrench.
Goodluck.
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What Randy said, use a dremel cut off wheel and slot it ,then heat it ,.if it has lock tite a slight tap on it first will help
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If you can drill the screws a small easy-out may also work.
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I have that problem every time I buy an old OS.
Heat. WD-40. Cutting a slot in the bolt-head. Bigger Vise Grips.
When I buy a new OS, I promptly replace all the bolts with metric Allen heads.
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I have that problem every time I buy an old OS.
Heat. WD-40. Cutting a slot in the bolt-head. Bigger Vise Grips.
When I buy a new OS, I promptly replace all the bolts with metric Allen heads.
Get real screwdrivers, and they will work better than Allen wrenches.
https://www.amazon.com/Hozan-JIS-4-JIS-Screwdriver-3rd/dp/B00A7WAHTU/ref=sr_1_1?ie=UTF8&qid=1513299538&sr=8-1&keywords=hozan+screwdriver
Brett
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Get real screwdrivers, and they will work better than Allen wrenches.
https://www.amazon.com/Hozan-JIS-4-JIS-Screwdriver-3rd/dp/B00A7WAHTU/ref=sr_1_1?ie=UTF8&qid=1513299538&sr=8-1&keywords=hozan+screwdriver
Brett
Brett is correct you need JIS screw drivers, however many times this will not help as on used ones, the heads are already mangled, I get them all the time in my shop
Randy
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Chris, I’ve never had much luck with the needle nose vice grips in the past. I was trying to avoid that. I’ll put that in the “possibly’ column.
Rich, I don’t have an easy-out that small, unfortunately…
Randy, Bob, and Paul. I’ll try a Dremel to cut the slot and a torch to heat it up before trying a flat blade screwdriver. I’m assuming a heat gun will not give me enough heat for this evolution.
Brett, I have that exact set of JIS screwdrivers. The previous owner stripped out the screws, not Moi. But I’m stuck trying to fix his error.
Mark
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Chris, I’ve never had much luck with the needle nose vice grips in the past. I was trying to avoid that. I’ll put that in the “possibly’ column.
Rich, I don’t have an easy-out that small, unfortunately…
Randy, Bob, and Paul. I’ll try a Dremel to cut the slot and a torch to heat it up before trying a flat blade screwdriver. I’m assuming a heat gun will not give me enough heat for this evolution.
Brett, I have that exact set of JIS screwdrivers. The previous owner stripped out the screws, not Moi. But I’m stuck trying to fix his error.
Mark
Mark I would use a solder iron before a torch, let it get hot first then put it on the head of the screw
Randy
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:-\ :-\ :-\
Why didn't that occur to me. Thanks Randy.
Mark
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Sometimes using exactly the right screwdriver, and pushing hard into the screw as you try to unscrew it, will work.
If not -- what everyone else said.
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Woo-Hoo! They're out!
Doing a little filing of the bolt heads and applying a little heat allowed the screws to come out. The engine now has the stock O.S. nozzle and venturi on it. I kept the rear remote NVA instead of a venturi NVA for this one. I had a couple of nozzles from when I converted a couple of 25 LA-S engines to the venturi NVAs. I'm going to use this one upright in a plane, so it shouldn't have the issue of the fuel running back into the needle assembly like when I mount them in profiles.
Thanks for all the help, Guys!
Mark
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Impact driver after heating area and applying penetrating oil. Tap lightly. Support opposite side of Venturi. If you happen to have an impact driver or know someone who digs 70s era Japanese bikes.
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Dennis brother... I worked a LOT on Jap and domestic Bikes and fully agree with First proper drivers and the impact wrench
BUT I question the wisdom of an impact wrench here....maybe you are aware of a smaller dinky version... my Impact driver is a 3/8th drive cumbersome 3 lb tool to smack with a hammer monster that must be perfectly held in alignment and I would NEVER use on a SMALL diameter fastener... OS carb screws are small and short and NOT hardened steel....they were stripped by someone using the wrong tool and technique
AND Impact driver still would requires a proper sized JIS BIT... I have 3/8th and 1/2 inch impact drivers... never can find any JIS bits for them....all I find are the typical JIS for 1/4" hand drivers
Heat
Good straight smack to shock the threads
Proper tool to start
JIS/PHILLIPS rounded out?... vise grip out side grasp and loosen or cut new slot for blade bit.... used after a heat cycle
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impact of any kind is way over kill. a lite tap with a small peen hammer is all that is needed
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I have personally not used this yet, but saw it online to remove stripped screws. Get a rubber band that would cover the screw head, then use the correct screwdriver and push and turn. Looks interesting, and worth a shot if all else fails.
https://www.youtube.com/watch?v=MaCYyL4UJAA
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My real ' Vice Grip ' vice grips :o have a SERRATED tip to the JAW , so weeny screws such as those ( Though youll mark the case as they swing / rotate , unless you mask it ).
These Suckers will GRIP the screw head on the nasty little loctited os 25 cases , whereas a plain end ' copy ' will just screw and skew off .
So , shopping for Vice Grips , check theyve got the serrated jaw ends , for such finery as the carb screws .
Putting the case , supported by a bearer offcut / on a solid bench , and leaning on a correct fit screwdriver , is the first option .
Seem s to be some clear locking compound on the LA 25 ones .
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Seem s to be some clear locking compound on the LA 25 ones .
Tears?
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Don't hit the impact driver hard. Give it a tap. After backing up opposite side of Venturi. The small screws are not used when engine is converted to CL. Yes heat and use penetrating oil first. Phillips drivers are useful on stripped Japanese Standard screw heads. Wider points sometimes get a grip on stripped screws. I've used a twist push driver successfully on the screws. Don't know if they're made anymore. Recently I used one like a low impact impact driver on a stubborn screw. Banged on the top of the grip same as an impact driver. It worked. Careful. Be careful. Venturi might crack.
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Dennis, are you talking about this type of screwdriver? I have had one forever, but have never used it since I first got it.
https://www.amazon.com/Jobar-Easy-Push-Reversible-Ratchet-RET6980/dp/B00TGIAFU2/ref=sr_1_17_sspa?ie=UTF8&qid=1514180667&sr=8-17-spons&keywords=twist+push+driver&psc=1&smid=A19NVE4G6SOT2C (https://www.amazon.com/Jobar-Easy-Push-Reversible-Ratchet-RET6980/dp/B00TGIAFU2/ref=sr_1_17_sspa?ie=UTF8&qid=1514180667&sr=8-17-spons&keywords=twist+push+driver&psc=1&smid=A19NVE4G6SOT2C)
Mark
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this is a bleedy impact driver . !
(https://shop.advanceautoparts.com/wcsstore/CVWEB/staticproductimage//N3409A/large/25960296_kti_kti71700_pri_larg.jpg)
Though theres prettier / dandier ones these days , of course . and probably always was . At a price . Nowadays being made in china . . . . :## HB~> S?P
Cheap & nasty ones have a fair bit of SLACK . Require pre loading in required direction . Or just cuts across the slack . Need bits that fit the screw , too .
A Sort Tap with a Large Clout seems preferable to a hard light thing ?? .
Really needs ' job ' suporting under at impact point .
Which describes the risk of flattening it . :( :(
Vice Grips I used ' end on ' perpendicular . 1/2 ? in. jaw . ( Handle rotated / in line with screw axis ) as qweeney little screw things .
The real vice grips are invaluable for ' one piece stuck ' as our forign freins say . :o :o[/img]
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Yes. That’s it.
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Dennis, are you talking about this type of screwdriver? I have had one forever, but have never used it since I first got it.
No, and those are of little utility. What Dennis is referring to is this:
https://www.amazon.com/TEKTON-2905-8-Inch-Manual-7-Piece/dp/B000NPPATS/ref=sr_1_3?ie=UTF8&qid=1514388020&sr=8-3&keywords=hammer+impact+driver
Which is also of little/no utility in removing screws from model engines. You don't want to use a hammer on any model engine. Get a proper JIS screwdriver like this one:
https://www.centralhobbies.com/prod_detail.php?cat=14&subcat=95&id=1726
and stop screwing around with "workarounds". And in fact, once you strip the head with a Craftsman or similar, these frequently WILL still remove it, because the Phillips-head will damage the center of the "cross", and a proper screwdriver will engage the entire slot to the edge - where it requires both less force, and has not been stripped off.
The "impact driver" approach is the crude way to attempt to use improper Phillip's-head drivers on Japanese motorcycles. It's not necessary in that case, either, but if all you have is conventional Phillips, it will sometimes work - and frequently, strip it out in a tiny fraction of the time it took to strip it by hand. I cannot find any place to get JIS bits for such a driver, so the solution in that case is ALSO to get proper screwdrivers as reviewed here:
https://www.webbikeworld.com/vessel-jis-screwdrivers-review/
Of course, you can grind a conventional Phillips to get the right shape, if you know what your are doing. The angle needs to he slightly shallower and the point needs to get knocked off, and all the edges should be straight and sharp.
With proper screwdrivers, JIS cross-head fasteners are superior in most ways to Allen heads - they certainly have less tendency to strip out because the local forces on the parts that meet are much lower. The only advantage to the Allen screws is you can get them in higher grades, and are almost universally available in the sizes you need. There is no issue removing the screw holding on OS carburetors, I have done it many times, it just comes right out with a "pop" when the Loctite or whatever lets go.
Additionally, people tend to use a driver that is too small. The biggest one that fits is the right one, and it usually looks absurdly oversize. Too small, and it will strip out anyway.
JIS drivers tend to work well on regular Phillips because it engages the outer edges of the slots, but not the other way around. The Phillips drivers tend to bottom out on the JIS screws, leaving it only touching the inner corners of the "cross".
Note also that JIS screws are identified with a little dimple on the head, telling you not to use a Phillips driver.
Brett
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I spent maybe first 20~30 years on Japanese bikes ( only one 77 AMF Harley) and had to use-- at the time--- the proper tool....an 3//8th inch impact driver to do any work on them
Note all my later bikes were Harleys....but I did own some very cool state of the art Jap bikes....at the time
It was common to buy a hex head replacement screw and bolt kit for most jap bikes as we ALL commonly stripped out each and every "Phillips" screw with our USA Phillips #2 or #3 driver...
NONE of us having and internet and KNOWING that Japanese Industrial Standard (JIS) was different...we just cursed the stupid Japs for using soft steel screws and happily slammed a hammer to the fact for the impact driver to get rid of the inferior Jap Junk
I eventually found out about the JIS screw drivers.... fortunately for automotive motorcycle use
So when I started acquiring Asian Hobby engines and some domestic I has a variety of tools
The only fasteners I deliberately changed to hex head were on buggered used engines and I had a stock of the hex screws
Right tool for the job is always best...or so my dad tried to teach his impatient young son
As I said above... trying to smack a impact driver to remove the very small Carb screws on an small engine of 5~7 oz is NOT a good plan... on the side of a 540LB motorcycle engine case...no sweat
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It was common to buy a hex head replacement screw and bolt kit for most jap bikes as we ALL commonly stripped out each and every "Phillips" screw with our USA Phillips #2 or #3 driver...
NONE of us having and internet and KNOWING that Japanese Industrial Standard (JIS) was different...we just cursed the stupid Japs for using soft steel screws and happily slammed a hammer to the fact for the impact driver to get rid of the inferior Jap Junk
Same here. the Suzuki shop I worked at (and later raced for) use the same "impact driver and a 5-lb sledge" approach. We knew the things didn't fit properly but not why, and assumed they were just too soft. Towards the end of my motorcycle tenure I saw some Yamaha factory mechanics popping them on and off with great ease, so I asked them how, so I worked up the courage to go over and ask, and they said "they aren't Phillips, and you can't get these screwdrivers in the US, go grind a Phillips like this (and held it up). Sure enough, after a few tries we got something that worked. BTW, I think we found that the giant Craftsman #4, reground, fit the case screws on the Suzuki GT series very nicely.
The most interesting point was that they were still using the JIS cross-head screws on the Yamaha factory bikes, at least for the low-stress applications like engine side covers. They could certainly *afford* Allen head screws.
Brett
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Hello What has been said about JIS screws explains why so many of my second hand OS engines had stuffed heads and back plate screws and those 702, 703 and 704 mufflers with the one screw to tighten them on were always stripped out leaving mufflers to go loose. Left me always looking for socket head cap bolts in weird metric threads!
One thing I really like is quality cap or grub screws with socket heads making life a lot easier.
Also remember before the Japanese stuff we had British stuff with 'challenging' threads and weird hex head sizes on bikes and cars and old engines like ED, D.C, Mills and my old ETA 5cc that is still in need of a 8BA(?) head bolt.
Thanks for all those helpful tips people :)
Regards Gerald
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The most interesting point was that they were still using the JIS cross-head screws on the Yamaha factory bikes, at least for the low-stress applications like engine side covers. They could certainly *afford* Allen head screws.
Brett
That's definitely interesting.
I have seen a lot of "philips head with dots" on Japanese electronics from Furuno in the last couple decades at work.
I always thought the dot was indicated that machine threads were under the head, not sheet metal threads, but am happy to know the real meaning.
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Problem is with stripped head screws. I assume they were already widened by use of a Phillips. Issue is to remove screw without damaging case. Screws are not used when engine is converted to control line. No need to preserve them. Frequently these screws are virtually “welded” in
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Hi depending on the design and size of the head sometimes you can slot them with a dremel or hack saw. If there is not enough room to do this can you get a replacement head as the next measure will probably damage it if you drill out the tops of the screws then remove the remains of the screws if enough protrudes with vice grips. Another way if you are very good with a mig welder with fine wire is to weld a screw driver to the head of the screw. The heat of doing this helps removal. Good luck Regards Gerald #^
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Hi depending on the design and size of the head sometimes you can slot them with a dremel or hack saw. If there is not enough room to do this can you get a replacement head as the next measure will probably damage it if you drill out the tops of the screws then remove the remains of the screws if enough protrudes with vice grips. Another way if you are very good with a mig welder with fine wire is to weld a screw driver to the head of the screw. The heat of doing this helps removal. Good luck Regards Gerald #^
For destructive removal in this application, vice-grips are probably the easiest and safest. Once you start with cutting a slot, it had better work because if you also strip out the slot, too, there's not much left to grab.
I don't mean to flog a dead horse, but very frequently, you can strip the head out with a Phillips driver, and then still get it out with a proper screwdriver, because proper screwdriver engages the ends of the slots the Phillips driver can't reach.
Brett
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I don't mean to flog a dead horse, but very frequently, you can strip the head out with a Phillips driver, and then still get it out with a proper screwdriver, because proper screwdriver engages the ends of the slots the Phillips driver can't reach.
Dead or not, the horse deserves another thwack. I've done this, too, more than once, with good success. But only, only, only if you use the proper screwdriver.
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Allthough I rarely have problems with Allen head screws (learned in a hard way to replace them early enough), I wonder why Torx screws are not more popular.? L