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Post by one1 on Oct 15, 2012 0:10:18 GMT -5
Was riding yesterday and hear a hissing sound like a blown out muffler, but was experiencing loss of performance and stalling so I knew it was around the head. Today pulled the seat and reached down to find a loose spark plug. The threads on the head/button are looking pretty thin. I guess it rattled itself loose and stripped them out fairly well. I'm not really getting a LOT of traction trying to screw it in. If there was something to lock the threads once in there it would stay in pretty well I guess since it does get SOME traction, it just strips. What do you guys recommend for something like a thread locker that will likely hold it without falling back out? Only good news is that this plug has been in a few hundred miles and looks great. LOL.   |
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Post by 90GTVert on Oct 15, 2012 10:10:59 GMT -5
I'd suggest replacing the head or putting in some type of insert like a heli-coil or timesert. kaseaparts.com has a new one for $40 + ship or you can usually search eBay for something like polaris 90 head and find a deal. Just look at the pics, not all of the 90cc ATVs were this 2T, but you can tell pretty easy what's what.
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Post by one1 on Oct 15, 2012 16:44:00 GMT -5
Well if i have to replace it im just going to build a new engine. This one has been great for 4500 km and still runs perfect, but i can do a squish head and a few other piston upgrades, new bearings throughout, etc. Make it a winter project because i feel like ive taken my last ride of the season. This is when i sold it last year.
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Post by 90GTVert on Oct 15, 2012 17:37:37 GMT -5
I doubt it needs too much internally at 4500km, but I can't argue with a build. ;D
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Post by aeroxbud on Oct 16, 2012 3:29:46 GMT -5
Sounds like a good excuse for a project  |
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Post by one1 on Nov 21, 2012 13:52:35 GMT -5
Mailman made me happy today.  |
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Post by one1 on Nov 21, 2012 18:10:53 GMT -5
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Post by 90GTVert on Nov 21, 2012 19:04:46 GMT -5
You need smaller sockets or maybe the Geely uses larger than a 12mm hex? I've never had and issue with a socket fitting any head I've tried for a 50 or 90 using standard 3/8" drive. Impact sockets prob wouldn't fit.
Be sure to check your squish clearance before you get too far. Also remember you can use copper spray instead of a gasket to save some milling if you'd like.
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Post by one1 on Nov 21, 2012 19:05:42 GMT -5
Fixed  |
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Post by one1 on Nov 21, 2012 19:13:54 GMT -5
You need smaller sockets or maybe the Geely uses larger than a 12mm hex? I've never had and issue with a socket fitting any head I've tried for a 50 or 90 using standard 3/8" drive. Impact sockets prob wouldn't fit. Be sure to check your squish clearance before you get too far. Also remember you can use copper spray instead of a gasket to save some milling if you'd like. I'm not using thick walled sockets, this is just a really incredibly tight wall. I have beveled edges on the other head, that I have circled. I imitated them and everything went well from there. On the squish, I'll be honest I haven't built enough engines to know how to check. I was looking at the head pics above and thinking perhaps the walls are thicker from the hole to where the chamber starts. It looks like that may be the case. That area that is countersunk on the geely head where it is lipped seems to be solid on the polaris head IF I am seeing it right just looking at the pics. If you look at the last pic in the series of pics the distance from the holes to the inner rim of the chamber seem like there is more on the polaris head. The outline on the polaris head where there is a faint lip is where the Geely is countersunk. |
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Post by one1 on Nov 21, 2012 19:18:33 GMT -5
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Post by one1 on Nov 21, 2012 22:23:20 GMT -5
It's clear now how much power I was loosing with that bad plug hole. I now have scootie's god power back. I thought it was lost for good. I went from being able to pull power wheelies in the start of the summer to barely getting up a hill by the end of summer. Now with the new head and everything gone over and tight it's back to it's old tricks seen below in my sig. I am certain the head is actually as good if not better compression with that smaller overall diameter across the chamber that I shown above..... provided my eyes aren't playing tricks on me. It is ABSOLUTELY giving me the god power again though. ANYONE want to look above and see if it looks the same to you as me? |
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Post by skuttadawg on Nov 22, 2012 0:39:04 GMT -5
So we can get inserts with harder threads ? I have never had a plug come out but I have seen it online and on a scooter a guy had that I met at a gas station . I ALWAYS R&R by hand and only give it a gentle snug . Be careful if you use thread lockers as it may work too well and strip the threads when removing it . I replaced the plugs on my x wives car and two had seized in there and got stripped when I took them out . On a Honda with aluminum head which is easy to damage unlike tough iron . I replaced the plugs on a Volvo that had been in it for eons and dang it the last one was stuck in there so tight I pulled off the handle off a floor jack to have more torque since I was afraid if I put too much effort I would do damage . It had grey stuff like anti seize compound but must have been thread locker .
The permanent LockTite I have ripped the heads off of bolts and had to use an EzOut which is a backwards drill bit to get them out .
Always wipe off the hole and threads with a clean rag before installing and only use your fingers to prevent cross threading like you can with a wrench .
I only like to use 6 point sockets and wrenches since 12 points can round off the facets
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Post by 90GTVert on Nov 22, 2012 13:46:06 GMT -5
Maybe that's a 50mm head and yours is 52mm? As long as you've got sufficient clearance between it and the piston crown, it'll be fine.
You can get inserts to replace the threads. Time-Sert is one name brand I've used on cars before without issue. You can get them in steel or aluminum I know. Steel is of course a bit tougher, but they say putting steel in the head can create a hot spot.
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Post by one1 on Nov 22, 2012 16:12:22 GMT -5
Given the slight size difference in the chamber that's exactly what it is. Also, I got to ride it today and it's got a lot of juice so I think it raised compression slightly, just a bit. After it was warmed up and at full temp it was still pulling power stands and assertively getting up to speed. The Linhai/Yamaha guys told me 97cc and that's what I have always had in my sig, and the polaris auction was for a 90.
So this is like the equivalent of running a high performance head then, isn't it?
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