Deephaven Posted July 14, 2023 Share Posted July 14, 2023 Bought the boys a Honda 250ex. Our woods are really tight in our yard and wanted to have them learn to shift without having to worry about the clutch hand. Will replace it in 2 years probably with a full shift machine after they are competent. So on to my dilemma. Ripping it apart to clean it and make everything right. Once the gas tank was off, can see the cylinder head has a bolt that is not all the way down. In the past, I'd muscle it and snap it off...would like to avoid that. I assume it is cross threaded or something is jacked, but would like to make as little work for myself as possible. What would you all do? All I tried so far was to put a 10mm socket on it and give it a little turn. It didn't want to budge in either direction but I purposely did not force it. Can't say this bodes well for the whole machine and considering it needed all new brake cables, leaks oil on the shift shaft, was obviously buried in mud at one point, the carb had more shit on the inside of it than I've ever seen on any engine....but it has good compression and the rest of the parts I need are already en route. So how would be best to remove this and not make more work for myself? Quote Link to comment Share on other sites More sharing options...
Gold Member 800renegaderider Posted July 14, 2023 Gold Member Share Posted July 14, 2023 Heat, pb blaster, slowly back and forth and cross your fingers. 1 Quote Link to comment Share on other sites More sharing options...
Doug Posted July 14, 2023 Share Posted July 14, 2023 Spray some pentatrating oil down and let it sit overnight. Use some mild heat with a hand torch on the cylinder and see if can get it to turn. If it turns spray additional oil and work the bolt back and forth until it hopefully comes out 1 Quote Link to comment Share on other sites More sharing options...
Gold Member 800renegaderider Posted July 14, 2023 Gold Member Share Posted July 14, 2023 (edited) You could also try putting an air hammer to the head with a round bit and some pb. I think they sell actual bits for this I’m just cheap and use the round one though. Smack with a normal hammer do to. I don’t know how I feel about this on a head bolt but I’ve had ok luck with it on other bolts usually because of rust though not cross thread or galled bolt but maybe worth a try. Edited July 14, 2023 by 800renegaderider Quote Link to comment Share on other sites More sharing options...
toslow Posted July 14, 2023 Share Posted July 14, 2023 looks like just a rocker box bolt, leave it alone if it's not causing a problem Quote Link to comment Share on other sites More sharing options...
polaris7541 Posted July 14, 2023 Share Posted July 14, 2023 (edited) imo cut the bolt head off , get a die, make it a stud, might have to fab a die , if someone stopped there , its welded for sure Edited July 14, 2023 by polaris7541 Quote Link to comment Share on other sites More sharing options...
toslow Posted July 14, 2023 Share Posted July 14, 2023 3 hours ago, polaris7541 said: imo cut the bolt head off , get a die, make it a stud, might have to fab a die , if someone stopped there , its welded for sure Or it’s just backed itself out. Quote Link to comment Share on other sites More sharing options...
Deephaven Posted July 14, 2023 Author Share Posted July 14, 2023 Considering the other lovely zip tie work on the machine my guess is they cross threaded it and left it. Soaking in PB atm. No way it just backed itself out as it wouldn't budget putting some force on it. Quote Link to comment Share on other sites More sharing options...
toslow Posted July 14, 2023 Share Posted July 14, 2023 (edited) 6 minutes ago, Deephaven said: Considering the other lovely zip tie work on the machine my guess is they cross threaded it and left it. Soaking in PB atm. No way it just backed itself out as it wouldn't budget putting some force on it. pull another bolt and see how long they are and how much thread is left on the bolt that's stuck. It might only be a half dozen threads before it bound up. Make sure to blow the thing out with air before you start trying to loosen the bolt Edited July 14, 2023 by toslow 2 Quote Link to comment Share on other sites More sharing options...
Crnr2Crnr Posted July 15, 2023 Share Posted July 15, 2023 23 hours ago, toslow said: pull another bolt and see how long they are and how much thread is left on the bolt that's stuck. It might only be a half dozen threads before it bound up. agree, pull a couple other bolts out and check the overall length. try turning it in a bit first before trying to back it out. since you have access now, soak it with PB blaster, put a vice grip on the exposed portion of the bolt and when you go to move it use a wrench and the vice grips at the same time in case the head of the bolt decides to break off. if it does, with the other bolts removed you should still be able to pull the head and have more bolt to work with. my only concern would be there's an old piece of broken off bolt underneath the bolt sticking up. Quote Link to comment Share on other sites More sharing options...
jdels Posted July 15, 2023 Share Posted July 15, 2023 On 7/14/2023 at 4:38 AM, polaris7541 said: imo cut the bolt head off , get a die, make it a stud, might have to fab a die , if someone stopped there , its welded for sure X2. Had success with this before. Try a few things but that looks like can o' worms for sure. Quote Link to comment Share on other sites More sharing options...
mnstang Posted July 15, 2023 Share Posted July 15, 2023 I would soak some kroil down there. Sit overnight. Ride the machine pretty hard for a good 20 minutes to get a lot of heat in everything. Then try to remove it. Then tap the hole or helicoil/timesert if necessary but I'd bet just a tap would do since it's half out already. Quote Link to comment Share on other sites More sharing options...
toslow Posted July 15, 2023 Share Posted July 15, 2023 (edited) 1 hour ago, mnstang said: I would soak some kroil down there. Sit overnight. Ride the machine pretty hard for a good 20 minutes to get a lot of heat in everything. Then try to remove it. Then tap the hole or helicoil/timesert if necessary but I'd bet just a tap would do since it's half out already. Heating it up isn't going to work, the head is cast and the bolt is steal. The only thing that will do is swell the bolt Edited July 15, 2023 by toslow 1 Quote Link to comment Share on other sites More sharing options...
Doug Posted July 16, 2023 Share Posted July 16, 2023 2 hours ago, toslow said: Heating it up isn't going to work, the head is cast and the bolt is steal. The only thing that will do is swell the bolt Aluminum expands at a lower temp than steel. There is a sweet spot while applying heat that the Aluminum will expand more than the steel that it my break the bolt free. Quote Link to comment Share on other sites More sharing options...
toslow Posted July 16, 2023 Share Posted July 16, 2023 4 minutes ago, Doug said: Aluminum expands at a lower temp than steel. There is a sweet spot while applying heat that the Aluminum will expand more than the steel that it my break the bolt free. I get that, But it also cools faster than steel. Might work but i would not lay money on it Quote Link to comment Share on other sites More sharing options...
mnstang Posted July 16, 2023 Share Posted July 16, 2023 2 hours ago, toslow said: Heating it up isn't going to work, the head is cast and the bolt is steal. The only thing that will do is swell the bolt Wrong. 1 Quote Link to comment Share on other sites More sharing options...
toslow Posted July 16, 2023 Share Posted July 16, 2023 10 minutes ago, mnstang said: Wrong. sure try it and see if it works Quote Link to comment Share on other sites More sharing options...
toslow Posted July 16, 2023 Share Posted July 16, 2023 38 minutes ago, Doug said: Aluminum expands at a lower temp than steel. There is a sweet spot while applying heat that the Aluminum will expand more than the steel that it my break the bolt free. Is the head aluminum or cast? either or it's a cross threaded bolt. Quote Link to comment Share on other sites More sharing options...
Doug Posted July 16, 2023 Share Posted July 16, 2023 6 minutes ago, toslow said: Is the head aluminum or cast? either or it's a cross threaded bolt. Head appears to be aluminum. Guess would somebody pulled the bolt out and got crap down the hole and either crossthreaded the bolt or gauld up the threads. Quote Link to comment Share on other sites More sharing options...
Deephaven Posted July 16, 2023 Author Share Posted July 16, 2023 59 minutes ago, Doug said: Head appears to be aluminum. Guess would somebody pulled the bolt out and got crap down the hole and either crossthreaded the bolt or gauld up the threads. That's my guess as well. It's been soaking in pb for a few days. Not in a rush as the other parts we need are still some days out. Quote Link to comment Share on other sites More sharing options...
polaris7541 Posted July 16, 2023 Share Posted July 16, 2023 (edited) heat can be your friend or enemy , pends how hot you get it , seen gaskets else wear damaged , seals , stuff get warped,, and when your really happy with the torch melt stuff, hell not knowing how much magnesium is in a alloy POOF good luck moral of this WISH I DIDNT DO THAT Edited July 16, 2023 by polaris7541 1 Quote Link to comment Share on other sites More sharing options...
Doug Posted July 16, 2023 Share Posted July 16, 2023 (edited) 57 minutes ago, polaris7541 said: heat can be your friend or enemy , pends how hot you get it , seen gaskets else wear damaged , seals , stuff get warped,, and when your really happy with the torch melt stuff, hell not knowing how much magnesium is in a alloy POOF good luck moral of this WISH I DIDNT DO THAT You don't need much heat to get aluminum to expand so yes don't over heat it. And if you do get it to move and then it stops let everything cool back down to ambient temperature then repeat. To get the bearing to drop out of a water pump housing on a XCR 800 simple place the cover suspended bearing side down and use a heat gun on the top side. Small amount of heat and the bearing drops right out. Works good. Edited July 16, 2023 by Doug Quote Link to comment Share on other sites More sharing options...
krom Posted July 17, 2023 Share Posted July 17, 2023 On 7/15/2023 at 7:11 PM, toslow said: Heating it up isn't going to work, the head is cast and the bolt is steal. The only thing that will do is swell the bolt aluminum expands faster and further than steel. you aren't going to melt it without oxy Quote Link to comment Share on other sites More sharing options...
teamgreen02 Posted July 19, 2023 Share Posted July 19, 2023 My buddy Taryl Dactal taught me the heat and quench method. You could try a smaller torch and quench it with PB blaster before going full caveman on it with a garden hose. Quote Link to comment Share on other sites More sharing options...
ICG Posted July 19, 2023 Share Posted July 19, 2023 It's not scientific....but their is a torque spec for that bolts..... Remove at KOabout 10 percent over the factory torque counter clockwise...... If nothing try to get the base metal to about 300 degrees with a propane torch.... Use an infrared none touch thermometer.... Repeat above step. Quote Link to comment Share on other sites More sharing options...
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