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Post by Florida Antique on Jun 23, 2015 21:47:05 GMT -5
I think Niz is just trying to gross us out
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Post by sai on Jun 23, 2015 21:55:37 GMT -5
As I stated,the sides of the piston are dark from blowby during combustion,they should be silver(as the rest of the piston) or a light brown..7000 miles is a lot of piston strokes and rings do wear out even with the best materials and oils.Didnt I post in one of your threads about 'hand honing' a cylinder?I hope you did that during the ring install.. I didn't hone it because the cylinder wall feels very smooth. Not a single scratch. And also... I think I might have missed or forgot your post about it.
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Post by niz76 on Jun 23, 2015 21:57:07 GMT -5
Here's a cylinder I 'hand honed' using 190mech's teaching just last night! I used 220 grit sandpaper at 45 degree angles (just doing it by hand- no hone/ball hone necessary!) to make a "crosshatch" - I have done this literally dozens of times and it works like a friggin charm! Notice how the cylinder is pretty smooth and shiny... BEFORE: Hand Hone method AFTER: Kinda hard to see but the 45 degree "scratches" go both ways making tiny little "X's" or- crosshatch! The crosshatch is important (you can usually see it pretty prominently in a brand new cylinder) because the little "X's" actually hold the lubricant oil which is what lubricates the rings as they constantly slide up and down the cylinder metal to metal. Without lubrication the rings would simply weld themselves to the cylinder wall from the heat of friction! (SEIZED ENGINE!!) Someone correct me if I'm wrong here- but I'm assuming the crosshatches also help to 'seat' the rings- that is- kinda "forms" or "sands/grinds" them to all the imperfections of the cylinder wall so they fit and seal perfectly. Anyway- give the oil a place to cling to (crosshatches) for a happy engine!!
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Post by sai on Jun 23, 2015 22:09:30 GMT -5
Do you have to hine the cylinder even though the walls are still super smooth like its out of the box?
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Post by niz76 on Jun 23, 2015 22:19:18 GMT -5
Do you have to hine the cylinder even though the walls are still super smooth like its out of the box? You should- it'd be mo better. You actually don't want the walls to be super smooth shiny polished looking. It's preferrable to be able to actually see a nice crosshatch... You don't have to... a pita to take the whole thing apart again I know, but it seems like you're serious about keeping your scoot running top notch and that's great!- I'd want my cylinder and brand new ring(s) to be mo better
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Post by sai on Jun 23, 2015 22:21:12 GMT -5
I would not lose compression this way eh? Ok. Might as well do it right!
So is it a 1 pass 1 way with the sandpaper or do you keep rubbing it to the wall up and down many times?
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Post by niz76 on Jun 23, 2015 22:32:50 GMT -5
I would not lose compression this way eh? Ok. Might as well do it right! More likely you will actually gain compression! Woohoo! Here's a tip when you do it; Push down really hard on the sandpaper when you're sanding and don't be afraid to really make those scratches! You can see from the pics that my crosshatches are kinda 'wimpy' compared to the scratches that a stone will make... BTW- Here's 190mech's hand hone technique (it is in the tech library). From your thread a long time ago haha. Here are a few pics of the "hand hone" method Ive used to refurb 2T stuff since the 70's; Here is a drawing of the pattern we want inside a piece of PVC pipe; This is how it should look after the hand hone work(sorry this is a junk cylinder);
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Post by sai on Jun 23, 2015 23:04:02 GMT -5
Honestly I'm rather scared doing it...
Will it still work on a cylinder that seized and has 4 corner scoring mark?
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Post by niz76 on Jun 23, 2015 23:41:16 GMT -5
Lol it's actually very simple and takes less than 5 minutes. I will make a quick video tomorrow and upload it showing how to do it. It's really easy! You'll see!
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Post by sai on Jun 23, 2015 23:59:38 GMT -5
Thank you very much. that's really nice of you.
The one thing I'm mostly tired of is cleaning the black goo off my finger nails...
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Post by sai on Jun 24, 2015 15:36:22 GMT -5
I just put a combo of 6 and 5.5 rollers, I can feel the power drop from 20mph and up. Is this a roller thing or do I need to replace piston head too now?
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Post by sai on Jun 24, 2015 19:50:53 GMT -5
Ok this is ridiculous. I already reppac d piston heads and done all kinds of things...just I'm losing even more power.
It screams from 0-20, but after that I lost power and can manage up to 30mph only... but then on a flat and no head wind I can get up to 40-45mph.
So fed up.
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Post by 90GTVert on Jun 25, 2015 7:39:00 GMT -5
If your power changed with the roller change, put the old weights back. If it's better then you know that's not the direction you needed to go with the weights. If it feels like good power at any point, than you may just be dealing with some CVT tuning now. I wouldn't expect a low compression engine to run strong at any time.
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Post by sai on Jun 25, 2015 8:56:41 GMT -5
I put the old 6 grams back in and it feels a little better but it's still the same.
Here's the funny thing: on a stretch of a block, I can go from 0-45mph FAST. Then I turned around, I only got to 38mph, rode 3 blocks and barely got 41mph. (this is fresh start when I woke up just now)
The engine still sounds a little muffled and the plug is still rather black. Dark brown in the ceramic area. (waiting for the FMF muffler packing still)
What do I do now? I'm really lost.
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Post by 90GTVert on Jun 25, 2015 9:05:31 GMT -5
Often if it runs well when it first starts it's rich or springs are fading with heat. The engine needs more fuel till it warms up, which doesn't take too long if you run it hard. If it's tuned rich that may make it run stronger at first. If springs are fading, you should notice an RPM change. Clutch springs shouldn't change your speed, but the contra spring could.
Can you give us a more detailed updated list of exactly what you've done now? It may be helpful to know where you're at. This stuff gets tough to diagnose online and more so if we aren't certain of details.
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