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Post by lunatuck on Jun 29, 2020 18:53:09 GMT -5
I’ve noticed that when my scoot loses power when the spark plug temp crosses about 310F. I started adding premix to suppliment my oil injection and it cooled it down about 10-20F after long WOT runs, but basically if I run it WOT up a 500’ climb, it hits 310F and starts to lose power. If I let off the throttle, it drops to 270F pretty quickly and gains all of its power back.
I didn’t do a compression test, but I did check the head for any leaks and didn’t see anything out of sorts.
I think my main jet is on the rich side. I had some issues with plug chops. I think my 30s WOT runs just aren’t long enough to get a smoke ring around the base of the plug. But the top of the threading is dark and the ceramic is a bit darker then I’d expect. Does it sound like a rich main? I’ve been trying to err on the rich side, but may have gone a bit too far. 90-92 were pretty perfect, but I’m now at 94.
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Post by Zino on Jun 29, 2020 20:39:59 GMT -5
Since you have a temp gauge . Use it as one more tuning tool. Throw the 90 or 92 in and watch temps up the same wide open runs and 500 ft hill climbs. If you are still low 300's and your scoot flattens out for temp after 4-5 mile wide open runs .
For example both my vinos are running street pipes with 70 kits stock upjetted carb I flew home today from work 12 miles it basically is full blast Wide open the whole way There are only 4 stop signs .One area is 6 miles straight away . My temps just kind get in that 310 ish range and level off and depending on the Humidity of the day. Now if I am under Jetted they rise real fast and keep climbing since the scoot cannot cool itself. Fuel mixture provides 80 % of the cooling for these scoots.
Don't get hung up on what your absolute temp as long as it flattens out . The big key with Cast Iron Stay under 350 degrees.
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Post by Zino on Jun 29, 2020 20:49:07 GMT -5
To get safe Jetting . Here was what I did this weekend I start way too rich so it gurgles then I go down a jet and measure top speed and feel. 95 jet gurgles very poor takeoff deep sound 53 mph 90 jet no gurgling stopped take off better 56 mph 84 jet great take off 56 mph 82 great take off sounded zingy 56 mph
Most of the time I need to go at least a mile for a plug chop. The 84 had the light pencil line ring. And Then I monitor from that day forward with the temp gauges looking for temp spikes as I ride and when I come to a stop to see what cruising temps are.
From what you say about the color on the ceramic and the top ring you are safe too rich as a overall tune .
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Post by lunatuck on Jun 29, 2020 21:16:12 GMT -5
Part of my problem is my hills. I have no strait WOT runs. The max is about 1.5mi uphill. The temps climbed to about 325F at the end. 500’ climb. I upjetted because it seemed a little high. But I’m balancing temps and top speed. My best top speeds were 90-92, but then I gave up some concerned I was lean. Tomorrow I hope to see exactly what is going on now that I ruled out air leak or head leak.
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Post by Zino on Jun 29, 2020 21:21:36 GMT -5
Hills actually work really well for Plug Chops . You have to have the scooter under Heavy Load to bake in the Smoke Ring. Take that Scooter up that 1.5 mile hill Start at the bottom with a Fresh plug after the scoot is warmed up and swap back at the top .
325 degrees is not High for Cast Iron .
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Post by lunatuck on Jul 1, 2020 6:27:16 GMT -5
First, somehow when I opened the carb, I had the 96 jet in there. Don’t know if I had a brainfart, but thought it was lower. I put the 94 in, then did a kind of stress test. Ran a long hot run then did my uphill. I dodn’t lose power. I was able to push the head temps to 327F. I think I was just too rich. I even think I could go a step leaner, but going to take it slow.
I may try another plug chop, but my uphill has too much traffic. Need to find a better place.
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Post by Zino on Jul 1, 2020 8:13:32 GMT -5
I think you found the Jet that you should run .
Jetting kinda goes from gurgly no power ,slighty rich lower power ,to rich but safe ,perfect ,a little lean but plenty of power dont run for long distances Racers will play around in here temps wont hold ,Unsafely lean Temps spike real fast .
You sound like you are in the too rich but safe area . It is hard to be perfect because of humidty, elevation ,tempatures . So just get in a range that works for your riding style.
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mybad
Scoot Enthusiast
Scooter Enthusiest from Salem Massachussetts USA, SR50 Malossi Replica ,Derbi Predator,and bunch of
Posts: 130
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Post by mybad on Jul 1, 2020 19:31:53 GMT -5
After reading this post I think I'm going to get a temp gauge. It's amazing how these engines stay cool at all . Is there even a better fan or something for better cooling ? When I did my big bore I was going to swap to water cooled but really no room on my scoot to fit radiators so I stayed with air .
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Post by Zino on Jul 1, 2020 20:11:31 GMT -5
You can get a bigger fan Jog 90 style for example but it really cuts down on your horsepower . Proper fuel mixture does 80% of the Job of cooling .
Temp gauges protect your investment just watch for major temp changes .
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Post by Mech Warrior on Jul 10, 2020 12:13:58 GMT -5
Without a doobt you are way too lean.
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