ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Aug 13, 2018 20:09:56 GMT -5
Dem, I don’t take very good pictures with this tablet, but I snapped these. In another thread, I talked about fixing a bike a kid a couple streets over he had screwed up while putting in a BBK. Well the head he got was horrid. So I did a quick clean up before putting the bike back together. He was using a stock carb and exaust, so I wouldn’t take much out, and this was kinda a quickie cause it wasn’t for me and ofcourse the kid wanted his bike back right now. The pics look a whole lot different then real life. You can kinda see the multi angle valve seat, but it just dosent show well in the pics
|
|
|
Post by dexameth on Aug 14, 2018 8:52:17 GMT -5
Most heads I've worked on had multi-angle seats like that, but be lucky if the valves did. Most of the time I just throw a little lapping compound in there and spin it up for good measure, then clean and install hoping that the seal will be better than from factory.
|
|
|
Post by humanshield on Aug 14, 2018 15:15:07 GMT -5
If you REALLY wanna make some serious power in a scooter just remember....you gotta remove ALL the valves
|
|
|
Post by AtariGuy on Aug 15, 2018 2:04:12 GMT -5
If you REALLY wanna make some serious power in a scooter just remember....you gotta remove ALL the valves Except the reed cage. And do some porting on the cylinder.
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Aug 15, 2018 7:49:24 GMT -5
Well if you have the pair system intact, you do actuly have reeds. Of course what you seem to be really saying, is you need a two stroke to get Max preformance. At any rpm, a two stroke will have twice as many power strokes so the power potential of a 50 cc two stroke is greater then a 50 cc 4 stroke
|
|
|
Post by katt on Aug 15, 2018 15:55:28 GMT -5
Well if you have the pair system intact, you do actuly have reeds. Of course what you seem to be really saying, is you need a two stroke to get Max preformance. At any rpm, a two stroke will have twice as many power strokes so the power potential of a 50 cc two stroke is greater then a 50 cc 4 stroke Its not like twice as powerful though because strokes on 2t are not as efficient as 4t, but perhaps 30-40% more powerful.
|
|
|
Post by AtariGuy on Aug 15, 2018 18:22:12 GMT -5
With a tuned pipe at 49ccs, a 2 stroke is double the hp output of a 4 stroke. Completely stock however, 2 strokes run 5-6hp, 4 strokes are about 3-3.5hp.
|
|
|
Post by katt on Sept 4, 2018 6:39:04 GMT -5
Okay peeps aside from porting that i don't want to do, from what i understand 47mm heads come in 2 flavors big valves and regular valves, bigger valves fill with air/fuel faster so higher RPM = more juice, but lower compression because wide valves require higher cutaway in addition to extended 47mm cutaway in head, so low end will sorta suck? Also from what i read big valve head needs ~18-20mm carb to feel the difference. Did someone used big valve heads on 47mm or 50mm what are results compared stock to 39mm head?
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 4, 2018 7:20:46 GMT -5
We have tried number of different combos now. Earstlitingloudenboomer currently has a big valve ported head i with a 23 mm carb and a 1 inch no taper exaust into a reverse cone megaphone. If you have followed my project thread you know that he is now running over 60 mph with that bike. Our next big project is to make up a real racing cam. It currently has an “A9” cam (best of the 4 so called preformance cams I Measured)
Red bike has a 50 mm BBK with 22 mm carb and ported head but stock vale size (I did do a mutliangle valve job on it). This has different ( custom made) 1 inch SS lead pipe and a “preformance “ muffler. While loudenboomer is running 205 lbs of compression red bike is running 178. Red bike does about 50 mph
Blue bike has a 52 mm BBK, 23 mm carb, and a large valve head. He also has a “A9” cam. The ports are matched to the manifold, but no internal porting and a stock vale job. The other two bikes have a metal intake manifold, blue bike has a plastic (stock) manifold. Like both the other bikes, we have decked the jug and done a very slight milling of the head to “ clean them up”. To lower the compression so it can run all day on the street, we made a very thin copper “base gasket” which is sandwiched between two paper gaskets Blue bike does 47 to 48 mph on a regular basis. Red bike is running 181 lbs of compression
Someone else said that porting was more important then valve size, and I tend to agree. Until I have something that repents a bit more of a “racing “ cam, I’ll stick with the small valve head on Red bike. Before I starting doing machine work on red bike, I went from a stock head to the big valve head and lost 2 mph! That’s why I stick with the small valve head on red bike.
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 4, 2018 7:46:58 GMT -5
While I never tried it, i think the big valve head might actually do better with the stock cam. The "A9" cams are a "torque grind" cam, not what I would consider a performance cam.IMHO you need more duration to take advantage of larger valves. I know this may be too much info, I copied this cam info from a different post so you can see what I mean OK. long post about cams, hope you can stay awake to the end Cam #1 stock from a new icebear 50cc falcon “CX” on the gear. “6002/p6” on the bearings. Two small holes one large hole Cam #2 Glixal A9 AT-A9 on gear, 16002 and 'XS” on bearings. 9 holes plus the two small timing holes Cam #3 OCC Performance cam A9 3 hole like stock 6002/p6 on bearings Cam #4 Fly Pig performance cam A9 oval with “S” thru it on gear 6002/P6 on bearings three hole like stock cam Cam #5 cam made it Taiwan Sorta a teardrop inside of teardrop graphic on gear three holes like stock Cam #1 lift, .187” on intake .179 on exhaust lift at TDC on intake stroke .008 intake .026 on exhaust duration intake @.001 162.2 @.005 122.7 exhaust @.001 161.2 @.005 152.8 cam #2 lift .187 on intake .179 on exhaust lift at TDC on intake stroke .004 intake .021 on exhaust duration intake @.001 156 @.005 135.2 exhaust @.001 150.8 @.005 119.6 cam #3 lift .187 on intake .182 on exhaust lift at TDC on intake stroke .009 intake .030 exhaust duration intake @.001 176.8 @.005 171.6 exhaust @.001 145.6 @.005 140.4 cam #4 lift .182 on intake .176 on exhaust lift at TDC on intake stroke .020 on intake .010 on exhaust duration intake at .001 156 @.005 119.6 exhaust at .001 145.6 @.005 119.6 cam #5 lift .186 on intake .179 on exhaust lift at TDC on intake stroke .006 on intake .022 on exhaust duration intake at .001 159 @.005 139.3 exhaust at .001 153.2 @.005 121.2 On Paper Cam #3 would seem to give the best results. This is the cam now in Red bike. Read more: 49ccscoot.proboards.com/thread/23399/new-project-excited-on#ixzz5Q8VPCAg2
|
|
|
Post by dexameth on Sept 4, 2018 9:27:44 GMT -5
I really wanna see these bikes ratdog
|
|
|
Post by SMALL CC TEK on Sept 4, 2018 11:31:08 GMT -5
"full potential of 47mm BBK" : I would go small valve just clean the bowls up and the ports don't change the port size a by more than 1 maybe 2mm and lap in your valves ..Your attempting to keep the volume of the flow up in the ports at all times and throttle positions ! A quality 47mm big bore kit with good rings a properly honed cylinder will produce more power in my experience even with a 39mm head ! A 10th surface will do wonders in some cases remember they produce 100th heads they tend to be way off after the first 10th or so and they are never Quality controlled again they just keep producing therm if we are talking Chinese parts ..
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 4, 2018 12:10:39 GMT -5
I agree 100% if these engines were attached to a Manuel clutch and Manuel trans. But remember with the CVT, you are always basicly running in the 7500 rpm range. The CVT pretty much elimates worrying how the engine runs at low RPM
|
|
|
Post by gsx600racer on Sept 4, 2018 16:45:20 GMT -5
Well if you have the pair system intact, you do actuly have reeds. Of course what you seem to be really saying, is you need a two stroke to get Max preformance. At any rpm, a two stroke will have twice as many power strokes so the power potential of a 50 cc two stroke is greater then a 50 cc 4 stroke Its not like twice as powerful though because strokes on 2t are not as efficient as 4t, but perhaps 30-40% more powerful. Wanna race ? Your modded scooter and I will run a bone stock Honda Elite 50cc thats been derestricted. Adding a bbk, up jetting the carb, and other mods, your 49/50cc scooter's efficiency has been downgraded some. You don't make more power without adding more fuel for a larger displacement, hence lost efficiency. Also if they were really efficient, you would never hear a backfire(unburnt fuel igniting in the hot exhaust system) The only true efficient scooters are fuel injected, have a O2 sensor, and a ECM to mange its performance and efficiency.
|
|
ratdog
Scoot Enthusiast
Posts: 342
|
Post by ratdog on Sept 4, 2018 20:10:58 GMT -5
Good points, but I don’t think anyone on here is looking for efficiency. Maybe I’ve skipped over it, but it just seems to me that most of these posts are about getting more speed and sometimes getting better acceleration..
My 600 almost certainly is no where as efficient as your 600. I’d be willing to bet I burn as much as 3 times as much fuel going 1320 feet. But frankly I don’t give a crap how efficient it is
as far as you bone stock Honda Elite 50. Well it been a while since I worked on 2 strokes ( like back when I was racing go karts and motocross) but I think you may be overstating it speed a bit. We know from racking dirt bikes that they feel 250 cc two stroke is in the same class as a 450 cc four stroke. But that’s two strokes with a pipe. You take an otherwise stock Elite with a pipe on it and I’m guessing you would be in the 45 mph speed bracket. But frankly that is pure guess as I have no experience with them. Now if we are going back to your discussion of efficiency, I very much doubt that your Honda is anywhere as efficient as a 50 cc 4 stroke. I mean no matter what you do, a two stroke has to fire twice as many times at any given RPM. They stopped putting two strokes in cars a long time ago. There are very few 2 stroke bikes left, and I don’t think the all time king of two stroke, the out board motor, has but a very few two strokes offering left
|
|