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Post by 90GTVert on May 27, 2019 18:04:22 GMT -5
I am wondering if there just isn't enough gasket crush leading to failure. You want about 18% protrusion for proper seal on an o-ring. Actually went over that almost a year ago after the first issues. I think that was OK. The o-ring has a 2mm cross section. The groove in the head was 1.54mm deep before sanding and 1.52mm after. Roughly 25% squeeze. That didn't mean a whole lot to me, but I found THIS PDF from an o-ring manufacturer that has more than anyone should ever need to know about o-rings in it. It says this in section 3.6 : " When used as a static seal, the maximum recommended squeeze for most elastomers is 30%, though this amount may cause assembly problems in a radial squeeze seal design. In a face seal situation, however, a 30% squeeze is often benefi cial because recovery is more complete in this range, and the seal may function at a somewhat lower temperature. There is a danger in squeezing much more than 30% since the extra stress induced may contribute to early seal deterioration. Somewhat higher squeeze may be used if the seal will not be exposed to high temperatures nor to fl uids that tend to attack the elastomer and cause additional swell.
The minimum squeeze for all seals, regardless of cross-section should be about .2 mm (.007 inches). The reason is that with a very light squeeze almost all elastomers quickly take 100% compression set. " According to that same pdf, compression set is basically how close the seal is to compressed size after use even when not squeezed, with 100% compression set meaning the seal doesn't recover at all. Static seal is what this would be, as they call it static when the 2 surfaces aren't really moving in relation to each other aside from things like thermal expansion/contraction or vibration. So the ~25% squeeze seems good to me based on that. The blown o-ring is about 1.9mm cross section. Hard to get an exact measure because it deforms easily under contact with the calipers. Still, that's something like 20% compression set related to original deflection. Long story short, AFAICT the o-ring fit is healthy.
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Post by 90GTVert on May 30, 2019 9:28:44 GMT -5
I got the engine out and took a look. Sure enough, another head gasket failure. It looks like the weakest points are always where the stud sections meet up with the bore section. Even what hasn't totally failed has started failing in those areas. Since they're both here, a look at the modified head (right) vs standard. Seeing them side by side, I'd say I need to get the burette out and check combustion chamber volumes before anything goes together. One stud coated with crud and coolant. I don't know if the base gasket didn't like the coolant or if it's because I've done multiple head swaps without touching the base or a little of both. I was using Aramid with Buna-N gasket sheet coated with Permatex Ultra Grey. It has been the best gasket material that I've had for cylinder, reed and gearbox gaskets. I got 3/8" washers and 1.5mm x 7mm Viton o-rings to use for the top of the head. The washers are a bit large on the OD to work with the design of the head though. I made up an aluminum sleeve to fit over an M6 bolt that very closely matched the ID of the washers. I had to kind of push the washers on it because it was snug. I mounted that to the setup that I had made for holding the head by the stud holes at one point. That let me machine down 15 washers at once. That amde them a much better fit for the head. The problem is, these Taiwan parts don't have a great finish so something would need to be done to flatten them out if o-rings were going to be used there. Then I started thinking it would be a much better idea to just keep the coolant out of the stud passages totally instead of trying to seal the head/cylinder joint, cylinder/base joint, and the studs cut through the cases from porting. These o-rings still leave a decent chunk of material at the top of the cylinder. I made up a cutter from some 9/16" O1 drill rod that I had from the initial exploration of a 3rd support gearbox. I cut it down to 8.5mm on the very end to fit the cylinder stud holes snug as a guide. Then I cut a section to 11mm. I have 2x7 o-rings on the way, because I wanted to get something a little beefier and those will end up 11mm OD. Then I cut one end small enough to fit in my drill easily. Then I used a cutoff wheel in an angle grinder to carve out a cutting profile. It's pretty darn rough, but I didn't figure it really needed to be perfect to cut. I've got an old junk cylinder on the fail rack from the pin destruction, so I used it as a test. I had to drill it first, because it was a much tighter fit around the studs and my pilot section wouldn't fit in it. Same brand from the same seller. Drilling the holes larger got pretty "interesting" at one point. The bit wanted to grab and it grabbed hard enough to yank the cylinder out of the vise, leaving me with this big spinning chunk of iron to try to control. The cutter cut surprisingly easily. The profile of the cut isn't good though. It's rounded. I think I'd need to cut the end of the cutting section back flat in the lathe to get a better profile. Also, I know this is way too deep. I just wanted to see how well it was cutting. Remember you're looking at a smaller o-ring than the groove would be intended for (10mm vs 11mm). Another issue is that the 8.5mm diameter of the stud passage doesn't seem great for a 7mm o-ring and stud. I'd think I'd be better off to cut deeper with the 11mm bit and make inserts that would make the stud a tighter fit. ...And then I realized... that's all pointless. My modified head still has o-ring grooves so it wouldn't be able to seal against anything. Kinda seems like the best method to solve this would have been to have the head welded up and then face it off. Then cut grooves in the cylinder like this. You can see that the 11mm o-ring setup would leave about double the meat between it and the combustion chamber and could be contained in the cylinder instead of the head. Maybe not though, because I'm not sure if the o-rings should be thicker than 2mm to be more durable and then that gets right back to the limited space issue.
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Post by 190mech on May 30, 2019 12:05:30 GMT -5
I'll be glad to weld up a head if you want to go that route,some castings weld terrible though and there is no way of telling till the welding begins... Another thought,,,make up some 8mm studs with o-ring grooves,then turn them down to 7mm at the base for threading..Honds scoots use 6mm stuff
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Post by 190mech on May 30, 2019 16:38:36 GMT -5
Here is an example of oversize cyl stud fab to the extreme!Wobbly at KiwiBiker posted this pic,note the O-ring grooves,,
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Post by 90GTVert on Jun 2, 2019 10:48:03 GMT -5
I put the cutter that I made back in the lathe and faced off the actual cutting section. Now it can cut in like it should without the rounded profile. That's basically all that I accomplished regarding the cylinder issues since my last post. I want to get the o-ring groove in the head that I haven't modified welded up so I can face it off. I figured I'd try local welders so I wouldn't have to bug John with more of my silly projects. I am lucky enough to have a welding shop less than 2 miles from my house. Unfortunately, he had his "On Call" sign out every time I rode by. Fine. I'll go to the next closest, about 10 miles away. Caught them out to lunch. Total failure on that front so far. I also read a little bit about making studs and I think I just confused myself. That's not hard to do though. So it sounds like even if I could find 8740 chrome moly or something like that, people say not to make your own studs because the threads should be rolled instead of cut to maintain strength and not disturb the grain structure of the metal. Does that really matter though when you just want to torque an M7x1.0 thread in the 10-15ft-lb range? I'm guessing not really. So far, I've stripped multiple aluminum engine cases, but I don't think I've ever stripped a stock stud that I'm sure isn't high quality on a Chinese scooter. Practically, I'm guessing 4130 wouldn't be much different than 8740 for this application, but I was thinking about finding 8mm studs and then just cutting one end down and re-threading. Haven't checked the lengths that I'd need. I don't even know that I'll use o-rings on the studs though. To be honest, I'm so green to the idea of o-rings on studs, having never used them on anything that I recall, that I don't even know exactly where it would be best to place them. I'm probably overthinking some of the stuff that doesn't really matter and totally missing the crucial points. That's usually how it goes for me. lol Part of the reason it has been more stagnant is that I seem to have tweaked my knee once again, so I've been trying not to mess with T2 a whole lot. It got better for about 2-3 days around the car show or just after, then the usual BS wore it out again I guess. This is getting old fast, but what can you do? I don't mean to sound like I'm cryin' about it here. It is absolutely affecting how much I work on anything though. The tough guy attitude of just dealing with it makes it worse, to the point that it got all swollen and I was icing it and had some numbness in my toes. It improves slowly with rest... then I have stuff that I must do and it goes south again, feeling not so bad usually just as I have to do the stuff that hurts it again. I still couldn't leave it totally alone, and I have had new Michelin Power Pure SC tires sitting here for a long time now. I kinda wanted to go back to the totally on-road tires. The dual sport stuff is an improvement on dirt roads, gravel or fresh tar and chip surfaces and things like that... but the majority of my riding is on regular roads and I have always been able to feel a difference in turns. The dual sport tires are probably all I need, but I find it more reassuring with the feel of the on-road specific tires. You can see here that the rear tire (left) was in need of replacement. The front still looks nearly brand new, but it doesn't get the same stress... and I haven't figured out front wheel burnouts yet. Definitely gotta replace this valve stem. The piece on the core that let's you take it out is missing. I've said it before, but I'm so glad I put the small investment into good tire tools a little while back. My old irons and spoons and rim protectors got the job done many times, but these things are a big improvement all around. I went to clean the wheels when I got them off and I was pretty disappointed. The front is actually good, but the rear is suffering from being exposed to chemicals. Whether it's gas and oil dripping down from a spill or overflow or brake parts cleaner from a CVT service, it gets abuse that the front doesn't and that is ruining the paint already. The stickers were a bad idea apparently. They've been peeling off for a while, and taking some of the already yellowing clear coat with them. You can see in the other pic that even after cleaning, they look stained. I don't worry a lot about T2's appearance, but I have been tired of painting wheels every year or two, because it tends to take a considerable amount of effort to get a decent result and it never looks good for long. I'd like to just be able to wash off my wheels and not worry about them otherwise, and I don't think that's ever going to happen with me spray painting them unless perhaps I can totally avoid any harsh chemicals touching them... and that's not likely. So that has me back to thinking about powder coating. I talked about it over a year ago, and then drove to a powder coater that wasn't in the office after a 45 minute drive there. Kinda gave up at that point. I'm tired enough of my paint jobs that I'm ready to check into it again. I've sent messages to two businesses near Baltimore that would prob be 1.5 to 2 hours each way. If I get good answers, I may do it. I may even give the closer place another shot. Not sure yet. Still don't wanna spend the money, but don't want to constantly repaint either. I've got new wheel bearings, seals, speedo magnet, and Ride-On ordered and already have more valve stems. For now, T2 is stuck in a weird position. I did at least make T2 into a cartoon while trying to spend less time on my feet. I mean in more ways than it and my experiences with it have always been a cartoon. Missing some detail and modified to make it easier to do.
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Post by aeroxbud on Jun 2, 2019 14:49:08 GMT -5
That's a cool cartoon. You are a man of many hidden talents. 👍
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Post by pinkscoot on Jun 2, 2019 15:34:02 GMT -5
Brent, when I was living in Baltimore and working in Jessup we used these people to powder coat for us www.advancedindustrialfinishes.com. We were always happy with the results. They are right off of Rte32 on Rte 1 in Jessup.
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Post by 90GTVert on Jun 3, 2019 9:52:04 GMT -5
The welder down the road was actually in the shop just now so I took the head in. He looked it over and asked some questions and said he thinks he'd be better off soldering/brazing it instead of welding the groove. He said the weld may melt the thin inside portion of the o-ring groove to some degree and it puts it at a higher risk of warping. He thinks soldering or brazing it would be a better solution, though still with some risk. I told him that I was going to face the head off in a lathe and I could cut the edge of the chamber if he thought welding would be better aside from that, and he still said he thinks solder is the way to go. He works with welding and such all day every day so I'm cool with whatever he thinks. I don't think he remembers, but I had him weld an aluminum sprocket to a cast Chinese pocket bike wheel years ago and it was excellent work that looked perfect when it came back and never had a bit of trouble. He's gotta place an order for what he wants to put in there because he doesn't have that much and said he's booked all week anyway so it will prob be next week. I ended up talking to him for 5-10 minutes about the scooter. He asked if it was me that he sees going by sometimes. I said maybe. He said that thing moves. I said it's probably me then. He said, "What do you just ride it to the gas station and back?". The gas station is maybe 2.5 miles from my house and sells food and such as well so it's one of the few things close. I said, "Not exactly" and then told him I blew the head gasket after about 22 hours of riding it to OC the other weekend. His jaw about hit the desk. "Really?!?" Yup, I'm a weirdo.
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Post by 90GTVert on Jun 3, 2019 10:19:46 GMT -5
Bmore Kreative Customs that Jwhood recommended the first time I talked about this got back to me just now. "Your looking at about $300 to coat your wheels in super chrome. It is not a shinny and reflective as actual chrome. but its all we got in the powder world" I google image searched for "super chrome". Some of it looks really good and some of it looks like very shiny silver. Not crazy about the $300 price. IIRC the guy from much closer wanted about $200 for whatever chrome-ish finish he had when I checked. Ryan had his wheels done for $120 in PA, but that would put me right about the same as the more local guy by the time everything is shipped back and forth. Still waiting on a place that does true chrome and powder coating. Black chrome with true chrome looks amazing, but I have a feeling that stuff is really expensive. There's one other place about 45 minutes away that I may reach out to as well. EDIT : Nevermind. Just looked through their gallery and a black wheel in there looks rough and like overspray or not coated well in spots. If that's what they put in the gallery, I think I'll pass.
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Post by aeroxbud on Jun 3, 2019 14:06:07 GMT -5
Black chrome looks so good. It's much more expensive though. A couple of years ago they banned one of the chemicals used to make the black colour in Europe. You can't get it anymore. I guess there is probably a powder coat similar now. But it probably would not have that deep shine.
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Post by 90GTVert on Jun 4, 2019 12:48:11 GMT -5
I never have heard from the place that does True Chrome. I have seen that another place says True Chrome starts at $250 per wheel. Pretty much what I figured... too rich for my blood. With the other place near Baltimore coming in at $300, I decided to put the wheels in the truck and go to the place that's 45 minutes away since they quoted me $200 last year. It's called Perfect Finish, and they get excellent reviews. www.perfectfinishde.com/I got there and someone was outside helping a customer load work into their truck. Two old dogs greeted me first, then the guy loading the truck told me to go ahead in the office and he'd help me. He asked what I needed and I held up the wheels and said I was hoping to get them powder coated. He said OK and asked what color. I told him the colors that I was considering and he said we don't do anything chrome. Last year, I was told that they had a few finishes that were the powder versions of chrome, but that they wouldn't actually look like chrome. Tossed that idea away immediately and looked through a couple of color books. I picked something out, but the squares in the book weren't especially shiny. I said I like that, but I would want it to be glossy. He said it should be, but it could be cleared over to make it really pop. I told him that I have no experience with powder coat so I don't really know what to expect from it. I was expecting to be offered some sort of real sample, but instead he said "I think it would look really sweet with clear over that if we could do it right". "If we could do it right" is not what you want to hear. Last year the owner had told me to come up and see samples to decide, now there are no samples. I asked how much it would be with clear and he said he didn't really know because he doesn't do pricing. I asked for a rough idea and he said maybe $150. I said for both coats, and he said yeah. Cool, that works for me. He said the boss was in Dover, DE at the time (~30 minutes away) and he's the one that handles that. The guy that I was talking to was prob about 20, and I'm pretty sure he doesn't regularly talk to customers. Nice enough, but lacking any sales abilities. I left the wheels there with my color choice and info and the owner is supposed to call me back about any more details and pricing. I asked my parents if they wanted to ride with me since it was sort of a long drive and they're both retired now, so they were both in the office because I thought it would be a longer process. When we left, they said I think he meant $150 per wheel and my understanding was $150 for both and I figured prob another $50 for blasting or something... so I really don't know where it stands ATM. Hopefully I'm not driving back to pick them up untouched when I get the real info. Oh, and turn around time was estimated at ~2 weeks because they are busy. The odd thing is, they get high marks in customer service in all reviews. So far I have went there and couldn't find anyone and then went there and couldn't get answers. This is how my luck always seems to go. As usual, I'll keep ya updated.
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Post by Lucass2T on Jun 4, 2019 13:33:02 GMT -5
Good revieuws from probabaly all those harley owners with way too much money in their pockets. If you said its for a Harley the guy probably had call his boss right away and get you a nice fat juicy bill, crisp and clear and fully calculated through. #rant
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Post by aeroxbud on Jun 4, 2019 14:30:10 GMT -5
Never heard of clear coating powder coat before. You should be able to get a very similar shine to what you would expect from paint. When they bake the powder it sort of melts together forming a glossy coat.
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Post by 90GTVert on Jun 4, 2019 14:58:56 GMT -5
I didn't think you needed any extras to get a gloss finish, but the dude there didn't seem that confident.
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Post by 190mech on Jun 4, 2019 17:11:22 GMT -5
The clear goes over the color from what Ive seen..We took some aircraft control yokes to a local powder coater for a gloss black refinish,we stripped and soda blasted them before delivery,,They came back dark blue,dull and pitted!Owner reluctantly had us reinstall them...I could have done a waay better job with an industrial polyurethane paint since we did all the prep work!
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