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Post by speedy1125 on May 4, 2011 19:10:39 GMT -5
Ok so the new HOCA piston got here. No problem with the edge of the piston hitting the head BUT its a dome shaped piston and I had to use 2 thick HOCA base gaskets to keep the valves from hitting the piston. Always something. I am glad I got 3 gasket sets. We will see how long it runs this time. I might just get the entire HOCA kit where everything was made to work together, and better quality than the chinese stuff for sure.
Also the other 2 bikes got here, I am going to pull the heads off tomorrow and see if they are 72cc like mine was.
I have 2 people interested in them already so hopefully they will both sell this weekend. I even have some chick bugging me about getting her a pink one lol.
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Post by speedy1125 on May 4, 2011 20:07:03 GMT -5
oh and the 1000 rpm spring doesnt feel any stiffer than the stock one but we will see.
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Post by speedy1125 on May 4, 2011 23:58:30 GMT -5
It would start after pumping the gas about 10 times. would idle lower and lower and die. Give it any gas and it would shut right off. Switched idle jets from one of the new bikes that came today and it fired right up and runs great albiet a little less power. I think having to use 2 base gaskets robbed me of some compression, but it runs.
seems the stock contra spring is the 1000 rpm one because there is no change at all there.
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Post by 90GTVert on May 5, 2011 20:51:49 GMT -5
Better to sacrifice compression than a piston or valve.
My 1000RPM contra was definitely stiffer than what came stock. Wonder if you got a beefier contra stock or a dud 1000?
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Post by speedy1125 on May 6, 2011 4:37:01 GMT -5
I think it has a stock 1000 spring because it was a factory 72cc both these new bikes that i have for sale just like mine are 72cc as well. I believe we can now safely assume that all of these from this particular company are 72cc  If anyone wants one I can ship one to you new in the crate for $750 |
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Post by speedy1125 on May 6, 2011 14:30:50 GMT -5
Anyhow, after some riding, it feels about the same as the 72cc. Maybe a little more but not much at all. The 2 base gaskets have really lowered the compression and also I dont think the cam bearings are going to live long with the cam chain so tight because of the 2 thick Hoca base gaskets. I am going to get a good kit soon. Was thinking of another kit like I used and just use a die grinder to mill down the head where the piston and head were making oh so slight contact. Boy it sure was fun for that 400 miles! Had awesome power, I could cruise with 55mph traffic easy. An Airsal kit is made to use the stock head which would put the compression at about 11.8:1, I dont think the crank bearings would live long though.
Your thoughts?
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Post by 90GTVert on May 6, 2011 22:09:23 GMT -5
It's not that big of a deal to open the cylinder head up how you'd need to do it if you choose to go that way. Mark it and Bevel or blend it into the rest of the combustion chamber. Just watch the valves.
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Post by speedy1125 on May 7, 2011 2:56:51 GMT -5
It's not that big of a deal to open the cylinder head up how you'd need to do it if you choose to go that way. Mark it and Bevel or blend it into the rest of the combustion chamber. Just watch the valves. True. Here is another solution: It came to me lying in bed in the dark and thinking about the downfall of this kit, why I didn't think of this before I don't know. Sometimes we cant see the forest for the trees. If you get this kit, get some better gaskets to use with it. The base gasket included with this kit is little more than a punched out piece of notebook paper. Too thin. The Hoca 50mm gasket set from PartsforScooters is thicker and better material. The piston in this kit was just barely touching the head using the included gasket, not hard enough to destroy it outright, but enough to have a life limited to about 400 miles. A better quality thicker base gasket would solve this problem. The Hoca 50mm domed piston isnt a good match with the 50mm head that came with this kit so I emailed scrappys to see if they have just the piston specific to this kit. I ordered 3 sets of Hoca 50mm gaskets on my last order from PFS so if scrappys comes through with the correct piston I think I will have solved the problem here. Using the Hoca domed piston I bought as a replacement and 2 thick Hoca base gaskets in order to have valve clearance is putting stress on the cam bearings and also lowered the compression such that it doesn't have any more measurable power than the 72 did. Its just not a good combo. Correct piston and better base gasket and this kit would be good to go so thats the plan. Once you have the right tune and power, its hard to go back down lol. Read more: 49ccscoot.proboards.com/index.cgi?board=builds&action=display&thread=1657 |
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Post by 90GTVert on May 7, 2011 5:55:31 GMT -5
That sounds like a good plan. Simple and should get the job done. Since you're exploring all of your options, it's also not terribly difficult to cut your own valve reliefs if you ever end up wanting to use the domed piston. Just gotta make sure the piston is thick enough that it'll be fine for the clearance you need. I used a flat grinding stone and a dremel to make valve reliefs in my 4T when they didn't line up. 49ccscoot.proboards.com/index.cgi?action=display&board=builds&thread=20&page=33#8499 |
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Post by speedy1125 on May 7, 2011 6:11:25 GMT -5
yeah thats a damn good idea too, I think im gonna do that.
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Post by speedy1125 on Oct 29, 2011 9:44:40 GMT -5
the cylinder head was for 47mm not 50mm. thats evidently why it happened. the valves werent hitting but the edge of the piston was.
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Deleted
Deleted Member
Posts: 0
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Post by Deleted on Feb 19, 2012 17:05:04 GMT -5
Anyhow, after some riding, it feels about the same as the 72cc. Maybe a little more but not much at all. The 2 base gaskets have really lowered the compression and also I dont think the cam bearings are going to live long with the cam chain so tight because of the 2 thick Hoca base gaskets. I am going to get a good kit soon. Was thinking of another kit like I used and just use a die grinder to mill down the head where the piston and head were making oh so slight contact. Boy it sure was fun for that 400 miles! Had awesome power, I could cruise with 55mph traffic easy. An Airsal kit is made to use the stock head which would put the compression at about 11.8:1, I dont think the crank bearings would live long though. Your thoughts? This is the motor i put the LV exhaust on. Its been almost a year and almost 4000 miles on this motor. Still runs strong. |
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