Kill Switch Won't Work When The Engine Runs Aaway

yuckfoo

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So whats the problem now? Your plug is looking pretty good. Is it still lean surging?
I don't think so, but after about an hour of riding for about 10 mins, letting cool, riding again, I came to a stop sign and the engine revved up super high. The kill switch would not shut it off, closing the choke wouldn't shut it off. I had to grab the brake and let the clutch fly. This has happened before on previous runs. The kill switch always works except when this runaway revving takes place.

I saw a video of a guy on a two stroke motorcycle who had the same problem. He said he had an air leak but that the reason the motor revved uncontrollably was because the head or the spark plug were so hot that the engine was dieseling.
 

Karl Snarl

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Plug says you're not that hot. There is an air leak though. Don't let it get that hot. Lol. Usually air leaks are carb mount, base gasket, intake gasket, head gasket and exhaust. Take some pictures of your gasket areas from all angles. Let me see if I can find the leak. Lol.
I don't think so, but after about an hour of riding for about 10 mins, letting cool, riding again, I came to a stop sign and the engine revved up super high. The kill switch would not shut it off, closing the choke wouldn't shut it off. I had to grab the brake and let the clutch fly. This has happened before on previous runs. The kill switch always works except when this runaway revving takes place.

I saw a video of a guy on a two stroke motorcycle who had the same problem. He said he had an air leak but that the reason the motor revved uncontrollably was because the head or the spark plug were so hot that the engine was dieseling.


I get off work soon so I can look at them on my pc if you take them.
 

yuckfoo

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Plug says you're not that hot. There is an air leak though. Don't let it get that hot. Lol. Usually air leaks are carb mount, base gasket, intake gasket, head gasket and exhaust. Take some pictures of your gasket areas from all angles. Let me see if I can find the leak. Lol.



I get off work soon so I can look at them on my pc if you take them.
You'd never seen anything in a picture. I've tested those areas multiple times. If I have a leak it's heat related and it only leaks after it's pretty hot. By that time the head is too hot to be spraying water or solvents onto it. The map torch doesn't put out enough pressure to be reliable. I'd have to have zero wind speed to have any hope of it showing results. I bought a heat gun thermometer. Once it gets here through the new slower-than-ever postal service (which will also soon cost more) I'll be able to see just how hot this is getting.
 

yuckfoo

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You'd never seen anything in a picture. I've tested those areas multiple times. If I have a leak it's heat related and it only leaks after it's pretty hot. By that time the head is too hot to be spraying water or solvents onto it. The map torch doesn't put out enough pressure to be reliable. I'd have to have zero wind speed to have any hope of it showing results. I bought a heat gun thermometer. Once it gets here through the new slower-than-ever postal service (which will also soon cost more) I'll be able to see just how hot this is getting.
Plug says you're not that hot. There is an air leak though. Don't let it get that hot. Lol. Usually air leaks are carb mount, base gasket, intake gasket, head gasket and exhaust. Take some pictures of your gasket areas from all angles. Let me see if I can find the leak. Lol.



I get off work soon so I can look at them on my pc if you take them.
Exhaust leak. How would I check for that?
 

Karl Snarl

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When I did use jetted carbs, How I jetted was " I found the best power jet, then went up one and tuned it in." While it will give more 4 stroke, especially when cold, it saves the engine. I get down and dirty on my bikes. Never worry if I'm going to kill it. I'm riding for fun. What the extra richness, and it's just slightly, does is pull heat from the engine when I am hammering her brains out. When I first got into this hobby I jetted for power, and learned that is bad if you don't plan on rebuilding ever month or so. She would run great for the first 20 mins, then slow down. Heat sucking all my power away, which then makes it even hotter, because I'm trying to flog her even harder to get tht power back. Now I beat the crap out of her, and she stays the same power level. She's not making maximum power, I'll save tht for race engines, She's making great power and living long, and riding without loss of power. If you ever lose power after riding for a few, you're most likely to lean and running hot. A lot of guys jet like that here, it's wrong if you want longevity. I have engines with 2-3k plus, and one with well over 4k on it. Never done anything to them but change the plug every so often, and that was only because I could. They didn't really need changed.
 

yuckfoo

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When I did use jetted carbs, How I jetted was " I found the best power jet, then went up one and tuned it in." While it will give more 4 stroke, especially when cold, it saves the engine. I get down and dirty on my bikes. Never worry if I'm going to kill it. I'm riding for fun. What the extra richness, and it's just slightly, does is pull heat from the engine when I am hammering her brains out. When I first got into this hobby I jetted for power, and learned that is bad if you don't plan on rebuilding ever month or so. She would run great for the first 20 mins, then slow down. Heat sucking all my power away, which then makes it even hotter, because I'm trying to flog her even harder to get tht power back. Now I beat the crap out of her, and she stays the same power level. She's not making maximum power, I'll save tht for race engines, She's making great power and living long, and riding without loss of power. If you ever lose power after riding for a few, you're most likely to lean and running hot. A lot of guys jet like that here, it's wrong if you want longevity. I have engines with 2-3k plus, and one with well over 4k on it. Never done anything to them but change the plug every so often, and that was only because I could. They didn't really need changed.
Yeah I don't care about speed really, I want this thing to last (once it's working properly.) I tell you what though. Last time I rode it I was so tempted to go full throttle. At times it feels like it really wants to go. I was reaching 23 mph at what I think was half throttle and that's with it running poorly. If I could hit 40 I'd be happy as I'd never really go that fast. I'd be happy to go 30 MPH (25 MPH is the legal limit here) and know that I'm not winding it out.
 

Karl Snarl

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Yeah I don't care about speed really, I want this thing to last (once it's working properly.) I tell you what though. Last time I rode it I was so tempted to go full throttle. At times it feels like it really wants to go. I was reaching 23 mph at what I think was half throttle and that's with it running poorly. If I could hit 40 I'd be happy as I'd never really go that fast. I'd be happy to go 30 MPH (25 MPH is the legal limit here) and know that I'm not winding it out.
ok get tht " I'm not going to go full throttle during break in" out of ya head. Its all wrong. You want to do quite a bit of full throttle blipping. Just not holding it, or revving it to the moon. You want to find hills to load the engine, and jam up them. The rings need to seat. As long as you aren't rapping it out, full throttle is what you need on break in( varied throttle, but you need some large loads). Get some speed, have some fun, just limit it to 20-30 mins max, the first few rides. I do 10-15 mins, let cool, check, beat some more, let cool, check, three times and I'm done. She's ready to crank out the ponies.


The jackshaft will let you run richer without excessive 4 stroking more ability to control how much load is on the engine.
 
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