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Post by 90GTVert on Aug 5, 2019 8:11:04 GMT -5
I checked into the stud issue that jackrides mentioned. The stud nearest where I think the failure was did come out far enough that the threads end before the head. The stud is smaller than the threads though, so it wouldn't actually bottom out. I checked to be sure.  I took the stud out anyway and went over it's threads and the threads in the case, but it didn't change anything. I measured and it was just bottoming out, not a thread issue. Then I stuck the stud in the lathe and shaved off a bit of the case end before cleaning the threads again. That was enough that the threads at least meet up with the head. A thick washer under the nut would have solved it pretty much the same way. I don't really think that issue should have caused it to fail. It certainly wouldn't help. Now, if there has ever been such a thing as a lucky fail... I think this was it. When I pulled the cylinder and piston off to work on the case threads, this is how the wrist pin bearing came out.   Talk about a close call. I'm guessing a few more miles feet and I would have to figure out my plan beyond the 103 immediately. That was a brand new Wiseco bearing when I put it back together from the cracked cases. Prob ~100 miles on it. There was one more needle in there BTW. I lost it in the floor, but everything that should be a part of that bearing came out AFAICT. |
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Post by ryan_ott on Aug 5, 2019 9:04:39 GMT -5
The 2 stroke gods are against you for riding that large CC 4 stroke.
Good catch!
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Post by 90GTVert on Aug 5, 2019 12:25:12 GMT -5
If a gasket is used on the bore area,then we need an outer gasket too,,or maybe make it all one piece,then deck the whole mess to get proper squish. What do you think should be done with the outer o-ring if a gasket is used? 0.3-0.5mm alone wouldn't worry me, but I already shaved off some of the head while trying to get it all flat from the central o-ring filling. Prob to the point that I'm pushing it anyway. Run the o-ring and see what happens I guess? Taking that whole groove out would require a lot of cutting to the head and re-doing the squish/combustion area. Not that it prob couldn't be done if it had to be. I'd prob cut the other head that I modified if it came to that since this one has a big sealing area as-is if that didn't work out. Trying to decide if I should give this another shot with sealant or if it's pointless and I need to worry about redesign again. The whole thing already seems more complicated than it should ever need to be to get a seal that holds. I also wouldn't think it should break wrist pin bearings with any regularity, so I don't know if there's some kind of crazy stress happening that I'm unaware of at this point. I've got a 1'x1' sheet of 0.020" (0.51mm) copper on the way just in case. |
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Post by Kenho21 on Aug 5, 2019 12:47:02 GMT -5
Seems to me since you did make a change to the problem area (gasket and stud with issue or same location, correct?) it would be worth a shot to see if that fixes it. That would be that path of least resistance/PITA compared to machining a head right away I would think.
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Post by jloi on Aug 5, 2019 15:51:25 GMT -5
all I know is them things will never fit around your wrists.
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Post by 190mech on Aug 5, 2019 17:45:27 GMT -5
Yeah,like many builds the project expands into a complicated mess that the space shuttle engineers would walk away from!Decking the top of the cylinder would keep the head O-ring groove intact...020" would come off pretty fast with a 40 grit cheap sanding belt on a piece of glass,then finer for finish..  PS,bet the top end bearing cage was damaged in shipment... |
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Post by 90GTVert on Aug 5, 2019 18:39:50 GMT -5
Yeah,like many builds the project expands into a complicated mess that the space shuttle engineers would walk away from!Decking the top of the cylinder would keep the head O-ring groove intact...020" would come off pretty fast with a 40 grit cheap sanding belt on a piece of glass,then finer for finish.. My first thought was the cylinder deck, but then I thought... this is the last 54mm that I know of. I have another head that maybe I can mess with or I can buy a 52mm head for $80 and mod it if this is a flop. That's why I was thinking it may be better to put the work into the head. More work, but less risk... I guess. PS,bet the top end bearing cage was damaged in shipment... That's not terrifying at all since the other B1042 Wiseco bearing that I have here came in the same envelope IIRC.  BTW, regarding why I don't immediately slap it back together... I'm tired of failing. I've had enough coolant shooting on me, overheating, bleeding out pressure on the side of the road, pushing, calling for trucks, etc... It's bound to happen again, but it does get old when all you wanna do is ride and I can't push worth a damn since the crash, or at least not without repercussions that last quite a while. I'm just taking a minute to ponder if doing this over is an almost certain re-fail or not. I'm kinda on board that it ain't hurting much at this point... but then I think about more pushing, hot coolant baths, overheating... |
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Post by 90GTVert on Aug 5, 2019 19:05:01 GMT -5
The Yoshimura exhaust springs came in today. I mentioned earlier that I wasn't clear on how they were measured since some companies seem to label them differently and because Yoshi's 2.6" spring says 82mm while 2.6" converts to 66.04mm. Looks like they label them by total length an if they give a number in parentheses it is probably the distance they can be stretched across. They're all pretty stiff, so I don't think you'd want to plan on stretching them much.   |
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Post by 190mech on Aug 5, 2019 19:20:05 GMT -5
If you want to keep it going,reverting back to AC may be the only route possible at this time..Other than casting up a new cylinder and head....
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Post by 90GTVert on Aug 5, 2019 22:37:49 GMT -5
If you want to keep it going,reverting back to AC may be the only route possible at this time..Other than casting up a new cylinder and head.... I don't really want to let it beat me. I want to own an LC setup that doesn't leak every few rides. It may not be this one, but I feel that it must be done. At this point, I'm considering the stock 52mm cylinder for the Apex/DRR ATVs, though they're made for 42mm cranks. That would make an 89cc. That may also put me right into the same situation I have with this 54mm kit. There's also a Malossi cylinder that G-Force says this about : "This aluminum high performance cylinder kit bolts right on to your Apex or DRR mini quad cases/crankshaft. No need to split your cases and buy a $500 crank - Just bolt this on and a minor tweak to your cvt and jetting and you have the foundation for faster things in the future! Whats nice about this cylinder is that it works on stock applications, but also will run at the National level if you add an exhaust, ignition and over range as time goes on." Sounds amazing, but then reading Malossi's info, I'm not getting how it works on the stock crank with a 13mm pin (AFAIK the DRR/Apex is 12mm) and it doesn't sound like it would be something to use with a stock exhaust. "THE WILDEST KIT YET OFFERED. 90cc performancBOLTS ON TO STOCK DRR AND APEX 42mm Stroke 90cc Cranks!!!! The new MHR Bigbore 90cc now Available. Attention! Crankshaft Malossi MHR Team 42.3mm stroke/85mm conrod required, or can be also used with 42.3mm stroke/90mm conrod with 5mm cylinder base spacer! The cylinder is based on the smaller 77cc big bore kits, however with the difference that the 90cc version can only be used with the special big bore crankshaft with 42.3mm stroke and 13mm gudgeon pin. Due to the extreme increase in capacity, 26 hp are possible." www.malossiusaonline.com/product_p/3116919.htmThe Malossi is a $400 cylinder kit, and if it needs a crank then I think it was another $400-ish. It's also sort of tempting to see if the Peace Pipe were used on the TPR 86cc if it would actually calm it down enough to be usable and not require an inner rotor and a 28mm carb while still making good power. That's what has been floating around in my head, but I'm not sure how bad these ideas are and when exactly I'd actually do anything. I think I'm going to give it a go one more time essentially as-is. I don't believe that I solved anything with the stud mod. I'm gonna try ThreeBond 1184 instead of Permatex Ultra Grey on the cylinder seal. Perhaps it's an exercise in futility, but ThreeBond has been a good sealant for the 2Ts in many scenarios and it says this : "The synthetic rubber absorbs vibrations and impacts without failure, especially when coolants are involved." As bad as I've wanted to ride to the beach for the last month, that won't be my first ride. |
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Post by 190mech on Aug 6, 2019 1:36:57 GMT -5
I looked at a TPR 86 kit back in the drag race days,was going to use an autotech 45mm crank,that would make durations higher than the 44mm stroke crank,,Had them on closeout in Germany cheap but didnt order it,always wished I would have though...
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Post by 90GTVert on Aug 6, 2019 8:08:05 GMT -5
I was going to ask what the durations were, but I found this page. It says 190/130, which is the same as what I have the 103 setup at for great results. It is for an AM6, but I'm guessing they'd set it up about the same across platforms. www.rrd-preparation.com/en/maximum-kit-complete-crankshaft-minarelli-am6/94-maxikit-top-performance-racing-tpr-aluminum-86cc-crank-minarelli-am6.htmlThey also note this : "We recommend it for competitions, protos, drags, preparers, to know that this kit does not have the same solidity or longevity as the cast, here it is really the power that is sought." When I was searching at some point, I saw someone talking about the cylinder kit only lasting 1,500km. That's ~930 miles, or basically 2 typical car show weekends for me. No idea how accurate that is though. With me, it may last 10 miles before I melt it. |
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Post by 'O'Verse on Aug 6, 2019 8:12:55 GMT -5
Well if its MHR that's Malossi's hyper race. I'd definitely get the crank too. But then your gonna need a pipe that probably hits in the 13,000+ rpm range. I'm pretty sure that 90cc kit won't be staying in the 10,000 rpm range. The good thing with Malossi is you won't have any casting issues. That's a bad a$$ cylinder. What I'd give to see you venture into the hyper race category..... Your a high mileage guy so... I think it's a good fit. I'm putting some serious mileage on Spaz's 77cc and the only problem so far is vibration rattling screws loose all over the scooter everywhere except the cylinder. Cylinders bullet proof. 👍
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Post by 90GTVert on Aug 6, 2019 8:53:15 GMT -5
The 13,000RPM part is what I don't think I can deal with. That will blow apart a stock flywheel eventually. I guess MVT claims it can charge a battery and run lights, but I'm not left with all that much excess with the stock stator that I'd think would put out more than racing kits. I like my DC setup, but I don't think I'd have the cojones to try to convert the expensive ignition over. I already had a HOCA kit that didn't work. Plus, at that stage it's revving like crazy just to move and seems like there's not much going on below 10,000RPM. I don't really want that for the street. My hope would be that I don't actually get the full race fury. As much as I'd like to be fast, I would like it to be rideable for full days. I was actually watching one of your vids the other day 'O'Verse, and the throttle seems like it is a light switch. I know your stuff is nastier than anything I'll ever own, but I can't see how that would be pleasant to ride for a full day. When I come home from 8-16 hour rides, I'm beat as-is. If I/we really think that the TPR 86cc would kinda calm down, that's prob what I'd try. It seems like if you take the same durations that I have now and run it with the same pipe that I have now, it shouldn't want to rev to the moon... but then the 90cc+ (non-high end) stuff seems to be limited to 10,000-10,500RPM for peak power anyway so it may not act the same with the 86cc. I really don't know what to expect from such a setup. Doesn't sound like anyone else is trying to tame them, but rather buying whatever parts are supposed to make the most HP... which admittedly seems kinda how it should go if you're going to buy a high end/hyper race kit. |
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Post by 90GTVert on Aug 6, 2019 13:15:08 GMT -5
The engine is back together. I still used Permatex Ultra Grey on the base gasket because it has worked and it is easier to clean up. Just used grease on the o-ring again, but switched to ThreeBond 1184 for the center head and cylinder seal.
I used a new B1042 wrist pin bearing and literally looked it over with a magnifying glass (don't have a microscope). Looked OK to me, but I don't know how much that means.
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