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Post by steve on May 16, 2015 21:49:53 GMT -5
So the key broke off on my crankshaft. The one that sets the flywheel. I have a backup engine, with back wheel attached, so I transferred the new BBK over to that engine. I did not have the gasket that goes between the cylinder, and the crankcase. I don't think that's the head gasket. Anyways, now the starter won't turn the engine over. It's a brand new starter. Is the compression too much, because I didn't use a gasket? I just put some RTV silicone on it. I have a sheet of gasket material. If I cut a gasket, and put it in there, will that reduce the compression enough for the starter to turn the engine over?
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Post by ramblinman on May 16, 2015 22:05:09 GMT -5
as long as you didn't block oil passage then i think you are fine without a base gasket. it shouldn't effect the starter anyway. did you make sure the piston isn't hitting valves? can you rotate the engine by hand?
it could be any number of possibility's. for months i would occasionally have symptoms of a weak battery. i tried to diagnose but finally gave up. it still started so i figured why frustrate myself with this problem. then i replaced a camshaft with worn out bearings and it solved my slow (sometimes click) starts.
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Post by steve on May 16, 2015 22:10:55 GMT -5
I got it started with the kick start. It just won't turn over with the starter. It would turn over on the other engine, which is identical. Only difference is no gasket. I know shaving a mm off of the head will increase compression a lot. I have no choice. I'm going to put a gasket on it. Will report back.
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Post by geh3333 on May 17, 2015 0:46:13 GMT -5
First off , you should not just switch a cylinder and piston with the same rings , and without honing the cylinder, onto another engine . you will have big problems , oil blow by , burning oil, etc. Once your rings are seated , you cannot just remove them and reuse them. Well you can , but you will have issues. Best thing is to either buy a new kit , or buy new rings and hone the old cylinder. .
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Post by steve on May 17, 2015 9:40:35 GMT -5
It only has about 30 miles on it, and I put a new piston, and rings on. I just didn't hone the cylinder. I don't know what that is. Should I order a new cylinder, or do you think it's OK, with a new piston and rings, and only about 30 miles on it?
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Post by onewheeldrive on May 17, 2015 13:10:19 GMT -5
Well it's a good thing it didn't electric start, imo. With a 50mm and no base gasket, your engine probably would have been toast in about 500 miles, lol. So consider it a blessing.
The compression reading on that thing would have to be dangerously high.
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Post by ramblinman on May 17, 2015 13:35:25 GMT -5
Well it's a good thing it didn't electric start, imo. With a 50mm and no base gasket, your engine probably would have been toast in about 500 miles, lol. So consider it a blessing. The compression reading on that thing would have to be dangerously high. guess i been doing it wrong. are all base gaskets the same? the two i have installed were paper thin.
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Post by onewheeldrive on May 17, 2015 14:16:57 GMT -5
Most likely not all the same, but probably pretty close.
The bbk alone increases the compression, especially with the bigger bores on a stock head-- to the point to where some people add 2 gaskets. Even though the gaskets are thin, it definitely makes a difference.
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Post by geh3333 on May 17, 2015 16:24:07 GMT -5
It only has about 30 miles on it, and I put a new piston, and rings on. I just didn't hone the cylinder. I don't know what that is. Should I order a new cylinder, or do you think it's OK, with a new piston and rings, and only about 30 miles on it? If it were me I'd order a new cylinder. You may be able to get away with what u are using, but I'm not sure. It all depends on if the old rings begin to seat . if you use the old cylinder , just keep an eye on it. Make sure your not burning or using oil .
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Post by rcq92130 on May 17, 2015 18:50:37 GMT -5
I agree with GEH but just on general principals (new cylinder). The gasket at the base of the head will NOT increase your compression - it has nothing to do with the compression --- except for a tiny bit that would be like a tiny stroker crank. If you had skipped the HEAD gasket - different matter. But the paper gasket will NOT noticably increase compression.
HOWEVER:
1. 30 miles is WAY too much to just swap the BBK. The rings are 80% set within 20 miles. New rings are cheap.
2. Without a paper gasket you are either guaranteed to have an oil leak (if you used too little silicone) or you will have blocked the oil passage to the top of the head (if you used too much). Everyone warns to only "wet" the paper gasket with silicone (or, use none at all) since any more silicone is likely to block the little oil passage.
3. You can use the old cylinder with new piston rings IF you hone the cylinder. But they are so cheap ...
4. With a BBK you are likely to not have very good luck with the stock starter motor. They are simply too girly-man. You also usually need to put better wiring in between the battery & the solenoid, between the solenoid & the starter motor, and also between the battery neg terminal and engine chassis. Stock wiring simply doesn't carry enough juice. And if you still have weak starting try a new solenoid - also cheap.
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Post by onewheeldrive on May 18, 2015 3:12:26 GMT -5
If you add 2 base gaskets (total) the compression changes a bit-- from what I've read it's been about 10-20psi less. Think I read one that had about 30psi less.
Do you agree with that?
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Post by steve on May 18, 2015 8:51:12 GMT -5
Thanks for all the responses!
Just to be clear, I did replace the piston, and rings. I did not replace or hone the cylinder.
I am going to take it all back apart, and install as gasket. I am going to look in to how to hone a cylinder. I spose I'll either do that, or buy a new cylinder.
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Post by rcq92130 on May 18, 2015 13:41:44 GMT -5
Thanks for all the responses! Just to be clear, I did replace the piston, and rings. I did not replace or hone the cylinder. I am going to take it all back apart, and install as gasket. I am going to look in to how to hone a cylinder. I spose I'll either do that, or buy a new cylinder. Honing is very simple ... but the cylinders are sooo cheap. To hone: 1. Go to O'Reilly's or Autozone and get a free loaner hone 2. It attaches to your drill - should be run at LOW speed (lower the better 3. With drill OFF insert hone into cylinder so the 3 stones (spring loaded) press against the cylinder walls. 4. Start drill and IMMEDIATELY begin moving the stones down to the bottom of the cylinder, then back up to the top, then back down - over and over. The GOAL, when you are down, is to have the scratch marks forming a crosshatch pattern of about 45 degrees all along the cylinder wall. 5. You are NOT trying to remove metal, really - just scratch the walls so the rings will be "sanded" when you start the engine, seating them. It's all very, very simply. Five minutes. THAT SAID - A NEW CYLINDER IS SOOO CHEAP IT'S ALMOST NOT WORTH THE TIME.
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Post by steve on May 24, 2015 7:32:13 GMT -5
Alright, thanks to all. I have learned several things during this ordeal. 1. It'stheride members are a very knowledgable, kind group. 2. Ask BEFORE you do something. Engine work is not like dealing with women. It is NOT better to ask for forgiveness, than ask for permission. 3. Blowback is real, and it, well, blows.
I ordered my BBK from one of the lower priced places. They are not "bargains", they are cheap. I ordered just a cylinder, that cost as much as the entire BBK I installed, and the quality difference was remarkable. The cylinder on the cheap-o was as thin as a coke can. Order from NCY, Scrappydog, Scooters-to-go, and some of these others that have banner ads on here. Trust me.
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Post by rdhood on May 25, 2015 10:14:18 GMT -5
Good idea. Me: I purchased a used scoot with a new top end (cylinder/piston/rings) that was smoking out the tail pipe. Previous owner said he put a new top end on but that the rings did not seat. As much as I wanted to NOT get a gasket set and NOT hone it before putting on a new set of rings, I only wanted to be in there once. So I bought a gasket set and rings, and borrowed a hone from O'reilly auto parts . The hone is done with a hand drill at very slow speed for only about a minute. That was enough to erase any previous wear marks. Then, new gaskets, new rings (clocked and spaced correctly) with everything torqued down to spec. The scoot now has 30 miles on the new rings and , so far, all is good.
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