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Discussion in 'Motorized Bicycle General Discussion' started by jleadbetter, Aug 6, 2010.
Just got my kit...should I be concerned with this gap
Looks like your head bolts are loose.
My bike has that too, probably no biggie. Worth giving the head bolts a check though just to make sure.
Tighten the head bolts a little, if it doesn't make a difference, put 2 gaskets instead of 1.
forgive me but, do not ever use two gaskets. this is not the proper way to fix the issue. use some copper sealer from your local car parts dealer and the gasket you have. a little liquid copper gasket sealer and your gasket should do the trick. if it does`nt and you find there is no compression or weak compression. pull the head off and leave the jug. get a fine file and flat file the head and jug to match each other. do not!!! take to much off. this will cause the piston to possibly hit the spark plug on the up stroke. make sure you take just a little off at a time. too much and your piston will strike your plug. this should increase the compression and solve it. never run two gaskets. that`s not the way its done. that`s horrible advise!
Best way to dress the head (well other then on a mill) is to use a sheet of wet/dry sandpaper and a piece of double strength (1/8") glass as a flat surface.
It's too easy to screw up and make a gouge with a file, unless you can find a 4" wide file.
Is there a reason for that?
Doubling up on the head gaskets doubles your chance of blowing a head gasket out and also reduces your compression ratio.
Some of the kits are actually shipped out with 2 head gaskets installed. Why, nobody knows for sure. It is wrong.
Truing up the gasket surface with 250 grit wet/ dry sandpaper on a sheet of thick glass, just like Kevlarr suggested, is the best way to insure a good, flat sealing surface. If you can't find glass, use a known very flat section of your kitchen counter or a marble chopping block. Whatever you use it must be FLAT, no hills or valleys. I use my glass top dining room table. Use water from a bucket mixed with a little soap on the wet/ dry sandpaper to help prevent the paper from loading up with aluminum. It will cut faster and cleaner that way.
agreed, but i thought this guy might have some skill? sorry, just assumed someone could use a file properly. wez
Never assume anything...
Jleadbetter- How does the bike run? It does appear that the head may be loose, BUT it may be the way the gasket is, having curled up a bit after the head was tightened. If it runs O.K., and doesn't leak, leave it alone.
And be sure to get the approval of your wife/girlfriend/ line-in partner, before using the dining room table for motorbike work. That sounds like a sure way to get into trouble
The flat surface idea is the way to go. You can easily see if there are high or low spots that need attention. The head is easy...the top end of the cylinder is a little harder unless you remove it from the crankcase. A good flat surface is essential for proper head gasket sealing but I'd take Joe's advice before doing anything. If it runs good...in spite of what it looks like...leave it alone.
30 years ago ,I painted a Harley oil tank and used my wife's oven to bake it . Worked great for the paint but OOOOOOOOOOO did I hear about the stink in the house .
Don't clean oily parts in the laundry sink either. 11 years later and it still has a black ring in it.
Maybe you should try washing the sink?
You don't need to do anything to that engine. When I first saw that on my engine I thought something was wrong too. Once I took the head of I noticed that right around the cylinder there is a slight step up that can't be seen when looking at your pic so it apears that there is a gap in the gasket but there isn't.
Nothing to worry about. That gap is just typical Chinese 2 cycle manufacturing tolerances.
For the 1000 miles that the engine may last, that gap will be the least of your worries.
The glued down sandpaper is a safty thing for the good china on the holidays
Kevlarr is dead on here, the file is a bad idea for working on an aluminum head even if you know how to run one your chances of getting it as good as using the glass and sandpaper is slim.
If you dont have a piece of glass it is sold very cheap at home depot, If you dont have access to a milling machine this is the best way to surface the head and get a god level gasket surface, just be sure to always apply the pressure straight down centered on the head and move it in a circular motion, if you push down on one corner more than the rest even this method can work the head down unevenly just take your time and apply even pressure, and you will be in good shape.
DO NOT USE A FILE. Unless you are a robot, you can never be certain you have taken exactly the right amount of metal from a mating surface uniformly. If this other guy has done this successfully, he is likely more lucky than he knows. More power to him. I only tell you this because I want you, and others who read this, to avoid learning something bad the hard way. Most of us don't have a lot of money, and this "file" suggestion leads down a path to a costly error.