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Post by 190mech on Oct 6, 2019 8:07:56 GMT -5
Here is a step cut mod head..
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Post by christopher on Oct 6, 2019 9:38:04 GMT -5
Aluminum cylinders are nikasil coated and the coating laps over the top of the bore,if you cut the 1mm from the cyl top you will have a good chance of the plating chipping,,Best option would be to step cut the head(loose the o-ring groove),that way the combustion chamber will remain the same,just sitting down inside the bore 1mm... Hadn't thought about that coating. Is there a resource I would be better off sending a head to because they are familiar with our scooters and the setup process? I could look locally but don't have an idea where to start, I'm not sure I want to be someone's learning curve. I have one of those it is 2.50 mm, way to much, the piston bumps into it. I was doing the math and I thought this isn't going to work, also it in place with my hand and rotated the fan, At tdc the piston moved the head up.
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Post by christopher on Oct 6, 2019 9:56:41 GMT -5
Is that mounted in a lathe, using the spark plug hole?
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Post by christopher on Oct 6, 2019 13:27:40 GMT -5
Went for a couple mile ride around town with the improved squish 0.85mm. To windy today to do any times for 0-35 mph to see if it helped. Still runs fine and kick starts on first or second kick.
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Post by chehystpewpur on Oct 6, 2019 13:35:49 GMT -5
on of the things my boss did to get around touching the cylinder coatings was to put the cylinder in a lathe and remove material from the bottom side where the gasket surface is. it would raise port timings slightly which is what he wanted anyways and lower squish/raise compression and keep from messing up the chamber shape/size for the different heads he used. not gonna say the man was smart for that but it was pretty clever. it killed a few birds with one stone in a few short minutes and was ready to go with a performance boost out of the box on almost any cylinder.
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Post by 190mech on Oct 6, 2019 13:44:35 GMT -5
Right,lathe cut using spark plug hole..Some arent drilled exact center and require a bit of "adjustment" to get a head to run true with the surface,,Thats a Stage 6 head in the pic and was crooked as a dogs hind leg!Ive cut a bunch over the years,be glad to cut yours if you give me the specs and some beer money... PS,basic cylinder setup is get piston flush with bottom of transfers at BDC(important for piston cooling),degree wheel the port durations,adjust to suit build,then set squish dimension..In that order
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Post by christopher on Oct 6, 2019 15:15:24 GMT -5
Setting the squish to 0.85mm was or should I say is worth it. My best 0-35mph time had been 9.98 seconds, repeatable. I just turned a 9.00 second 0-35mph, if anything I was riding into a head wind, definitely not a tail wind. For a basically free modification I would say it is worth it. I have always used premium fuel, I didn’t notice any pinging or detonation. Oh and I did have a 45mph gps speed, For those that care about top speed.
Exhaust was the biggest gain so far, really let’s the motor breath. I could barely get to 30 and was using 0-30 times. When I opened up the factory air box, really didn’t gain much, adjusted jetting etc. Changing the exhaust pipe I turned 42 mph the first time out. I started to use 0-35 times to get the CVT weights dialed in along with the jetting. This allowed me to compare to the videos I have been watching. My 0-35 times with dialed in settings were better than my 0-30 times.
I use a program called SpeedBox that uses my phone’s accelerometer for timing.
Went for a ride after mowing the lawn, was able to repeat the time, with a 8.99 second 0-35.
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Post by christopher on Oct 6, 2019 15:29:29 GMT -5
Next up, I should have a Stage6 70cc aluminum setup running before the week is out. Thanks to chehystpewpur, for selling me some parts cheap to give it a try. I have a new piston and rings on the way, also a soft nylon hone 320 grit to put in some hatch marks. I asked and that is what was recommended to deglaze the bore before installing a new ring. Maybe I can get to sub 8 second times.
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Post by christopher on Oct 8, 2019 5:55:01 GMT -5
Wahoo is going to be a 70cc, next time I post. Piston will be delivered before I get home today. Shouldn't take long to bolt him together with new parts. Pulled off the 50cc parts last night. Up jetted the carburetor main jet to a 95, should be rich hopefully. Still waiting on cylinder temperature gauge should be here Thursday.
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Post by chehystpewpur on Oct 8, 2019 11:38:37 GMT -5
glad to hear you liked what you seen. just dont hone it too hard as the aluminum bores are plated and if the plating chips or is worn off it will make the cylinder wear very fast as aluminum is very soft. if you hone it just do it very briefly and use lots of lubrication. tranny fluid works great if you have some laying around. couple seconds with drill spinning one way while moving hone up and down at a constant speed then couple seconds the other way tops with something like that if it was me. dont spin the drill fast either.
i felt the cylinder before i shipped it just to see if there were any bad high spots to warn you about but most of it went in rather than out so if it was me id just let the rings do their job lol. as id hate to remove the plating thats in there and kill the cylinder. its not very thick and if you get a crosshatch started in there over the one thats in there it means you went through the plating and the piston will be riding on bare aluminum. they bore and hone the cylinders before they plate them so the hatch you see is under the plating from the factory.
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Post by christopher on Oct 8, 2019 19:27:52 GMT -5
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Post by chehystpewpur on Oct 8, 2019 22:11:44 GMT -5
usually a few good miles like 10-15 can get a plug to change color pretty quick but glad shes up and running. hopefully pretty well. plug looks pretty dark but its always better to be safe than sorry. did you do any prep on the cylinder or just stick it on with the new sliding parts?
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Post by christopher on Oct 9, 2019 11:17:17 GMT -5
I deglazed with a fine 320 grit nylon bristled hone. I was told to do so because the grooves hold some lubricant for the new rings while breaking them in. I used some two stroke oil as lubricant also. That was the recommended method when I asked. Definitely didn’t do it very long only about 10-15 seconds at a very low rpm maybe 60 rpm.
That picture was the 95 main, rode a few miles with the 90 it it was better, need to get some miles on to see. Thinking about sticking in another new plug so I’m looking at a new plug. Will go for a ride after work and see what I get.
I still have the annoying 1-2 shift, need to get rid of that.
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Post by chehystpewpur on Oct 9, 2019 11:44:33 GMT -5
most likely youll be around an 85-88 main then. your most likely using a smaller carb than i was. it will really wake up with a 19mm or 21mm. but 21 will be more finicky to tune.
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Post by christopher on Oct 9, 2019 14:47:49 GMT -5
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