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Post by AtariGuy on Aug 24, 2018 7:11:37 GMT -5
Just throwing this out there - 152qmi engines (gy6 125cc) also use the same intake manifold bolt spacing and gasket riser pattern that will mount to 139qmb engines but have a larger carb mouth to fit the 24+mm bore carbs used on 125/150cc engines. A few guys swap to these larger keihin cvk carbs for 50+mm bore builds. May have to look into those k&n style pod filters for these as the stock (or modified) airbox wont fit the carb's bells. Or make a velocity stack/bell mouth for it... Here's a "performance intake" that should fit.And a 24mm carb. In the related products below it should be a 26mm carb as well if you so choose...
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Post by jackrides on Aug 24, 2018 10:47:16 GMT -5
You guys are doing some real research. Thanks!
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ratdog
Scoot Enthusiast
Posts: 342
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Post by ratdog on Aug 24, 2018 14:21:38 GMT -5
Atari guy, thanks! That is some good info! No doubt that will open up a whole new world of parts for Walt to explore.
Jackrides, thank you for that. I was about to stop posting this thread as it seemed the only one thT was reading it was only doing so to tell me I was wrong.
A couple little updates.
First we have run into a problem with Walt’s bike. It will run great then suddenly act like it’s out of fuel. Set a little bit, starts right up runs great, the dies again. My guess is that it’s the fuel filter or a proublem with the auto shutoff pet cock. I had condemned it could be the valve adjustment was too tight, but I think it would have to cool down a lot longer for the adjustment to come back. On top of that, we seem to have had the head off about every other day, so I really don’t think it that. I’ll know more when he gets back with the bike in the trailer. This happens about 20 miles away wher we have a very long stright flat paved road and I haven’t seen the bike yet.
Second, we have decided to try modding a few cams to see if that helps. If there is interest, I,m thinking about letting some others try some of these cams. If I did that, they would have to have a highly modified engine and have some solid testing in hand. I’m thinking something like 0 to 30 time and distance, 0 to 40 time and disrance and of course top speed at what RPM. I’d like to add a couple, 0 to 60 ft, time and speed, and max speed after 1/2 mile. They would also have to send me a cam or two ( like undamaged stock cams or undamaged preformance cams they aren’t using. Not real sure I’m going to do that yet as this is a lot of work only to have someone vanish with one of my cams. If they did send a preformance cam, I’d like to know what cam it is so I can check the specs before I grind on it!
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Post by magoconnor on Aug 25, 2018 16:33:54 GMT -5
Have you guys tried taking some weight of the flywheel?
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ratdog
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Posts: 342
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Post by ratdog on Aug 25, 2018 16:53:59 GMT -5
No, if anything I might drill some holes and add weight to balance the heavier piston. Lighter weight would give quicker response, but we have CVTs so, imho lightening the flywheel would not boost HP. And to get higher speeds, we are looking for more HP.
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Post by magoconnor on Aug 25, 2018 18:06:28 GMT -5
Okay what size carburetor are you guys using? I was thinking maybe going with a 24mm, but maybe thats overkill. But my valves are 21,5 in 19 ex.
Do you what size your valves are ?
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ratdog
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Posts: 342
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Post by ratdog on Aug 25, 2018 19:52:07 GMT -5
21.5 18.1. Don’t know where the orginal head came from. Intake ported to 23mm. Metal intake 22 mm car 97.5 jet. Tried 23mm but no gain in top speed so went back to 22mm because we have the polit jet and needle set so it runs real clean from 0 to 56 mph! Currently using a no name A9 cam but will switch to the cam made in Taiwan soon.
Totally off subject... Walt turned. 13.4 on his first ever pass down the dragstrip ( on my 600). Best time after several runs was an 11.24. I think he will be in the tens tomarrow! He’s hooked. Wants to ride who’s chicken too tomarrow. Do the letters NFW mean anything to you? He’s going to build his own bike now. We are going to extend the swing arm on a soft tail frame he has and he’s building a 105 to put in it. He’s going to have a custom frame build based on who’s chicken too frame. More projects!
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ratdog
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Posts: 342
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Post by ratdog on Aug 27, 2018 7:54:11 GMT -5
Off subject (again)
We spent this weekend letting Walt make runs at the dragstrip on my 600. He learns fast and yesterday turned his quickest 1/4 mile yet, 10.94
Bad news is that was in the finals, and he busted out of his bracket! Now he has never dragraced before and I guess his teacher ( me) didn’t explain some things. Anyway he crossed the finish line a good 3 bike lengths ahead of his opponent. Ran the quickest (and fastest) time in his history ( all 2 days of it). But he was running a 11.01 bracket. So WOW! Great run! You loose.
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ratdog
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Posts: 342
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Post by ratdog on Aug 27, 2018 10:31:37 GMT -5
Mini update on the cam project.
Using a new set up and fresh battery these are the specs I thought you migh find useful on the stock cam
Max lift on the exhaust is .179 at the cam, and .175”at the valve. Max lift on the intake is .186 at the cam and .181” at the valve
Something that might be more interesting to those that are thinking about piston clearance.
When the engine is at TDC on the intake stroke, the exhaust valve is lifted .004”. And the intake is lifted .026”
Glixal
Max lift on the exhaust is .179 at the cam, and .175”at the valve.
Max lift on the intake is .186 at the cam and .181” at the valve
(gee, same as stock)
When the engine is at TDC on the intake stroke, the exhaust valve is lifted .004”. And the intake is lifted .021”
Now this surprises me big time!
The Glixal has more (not less) clearance at TDC (less valve lift)
This is very odd!
acording to my measurmrnts, the Gilxal opens 5.2 degrees later then the stock cam
I’ll get to the other A9 cams later. Comments?
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Post by magoconnor on Aug 27, 2018 12:57:12 GMT -5
It will sure be exciting to see how the a9 will compare. Not many "real" specs out there. Which a9 cam are you gonna use?
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ratdog
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Posts: 342
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Post by ratdog on Aug 29, 2018 1:37:37 GMT -5
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
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Post by fugaziiv on Aug 29, 2018 8:51:23 GMT -5
Just food for thought, there's only 1 QMB stroker crank available. Everyone selling one is selling the same thing. Matt
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ratdog
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Posts: 342
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Post by ratdog on Aug 29, 2018 8:57:52 GMT -5
matt,
do you know if its pressed together or welded up? I doubt the small increase in stroke will have much effect, but Walt will do it if he can take the crank apart and upgrade the bearings. He is sure that any min now the big end will come apart.
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ratdog
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Posts: 342
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Post by ratdog on Aug 29, 2018 8:59:02 GMT -5
WHOO HOO!
Taking advantage of the cool morning air, Walt broke the mile a min today! Actuary his 2 way run was 60.9 MPH (GPS)
latest addition is one of the coolest. Fully Programmable Digital ignition advance CDI With this little guy you can program the advance in one degree chunks for every 1000 RPMs On top of that, you can make two programs and switch between them without having to remove the box and reprogram it!
After he programmed it, we verified that it was doing what it said it was with a timing light and degree wheel
We also put the twain made “A9” cam in it
After the measurements I took on the 5 cams I have, I am more convinced then ever that we can modify one of these cams to do much better. So that project is underway. (but will take a while)
Walt wants to get his first version of the 105ci Softtail drag bike done for the weekend. This guy can weld! The swing arm has been extended 9” and we have already made the strut (to replace the shock) We are converting it to chain drive. Still waiting for the new (much lighter) forks. Walt decided to make his own gas tank (only needs to hold a gallon at a time) we have been building the rear set controls. Walt decided to start with a mild set of “torque grind” cams, but we are building it to be an E85 engine.
So anyway, we are going to be building him a drag bike for the rest of this week.
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Post by fugaziiv on Aug 29, 2018 9:32:19 GMT -5
matt, do you know if its pressed together or welded up? I doubt the small increase in stroke will have much effect, but Walt will do it if he can take the crank apart and upgrade the bearings. He is sure that any min now the big end will come apart. It definitely does have an impact. Additionally, pressed. He can upgrade the bearings if it makes him more comfortable, but the crank is spec'd with decent bearings as is. We don't have these things falling apart, and we've built QMB engines that are quite a bit more powerful than what you've got at the moment. Matt
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