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Post by Deleted on Jul 17, 2010 14:15:49 GMT -5
When i accelerate with my 72cc kit, i alway hear "DETONATION NOISE" from the motor!?
Is it normal?
What cause detonation noise?
Thank's!
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Post by 90GTVert on Jul 17, 2010 14:34:37 GMT -5
Spark knock is not good or normal. It can be caused by too much compression (stock head + BBK), low octane fuel, too much ignition advance. It usually gets worse as the engine gets hotter and under more load. The easiest option to check here is to use higher octane fuel. If you are already using premium you've got more work to do.
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Post by Deleted on Jul 17, 2010 17:07:55 GMT -5
Spark knock is not good or normal. It can be caused by too much compression (stock head + BBK), low octane fuel, too much ignition advance. It usually gets worse as the engine gets hotter and under more load. The easiest option to check here is to use higher octane fuel. If you are already using premium you've got more work to do. I use SUPER for gas all the time... If my spark plug look lean again with jet#95 do you think it cause this? "It can be caused by too much compression"People said the BBK was made for the original head of the 49cc motor...? |
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Post by Reign on Jul 17, 2010 17:18:22 GMT -5
I always have the same issue with my Triton. It always sounds like a tapping noise as I'm accelerating. And then as I get into the higher RPM's it sounds more like plastic rattling, but it's coming from the engine.
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Post by 90GTVert on Jul 17, 2010 18:25:57 GMT -5
The problem with what everyone says about engines is that Chinese stuff has different tolerances and most likely your Taiwanese made engine has different tolerances than those and not all big bore kits are created equal. My 72cc BBK worked with a stock head, but the piston was pretty far below deck so it was still kinda low compression. If the piston is about flush with the deck, that's pretty high compression. It may be fine running that way, but it's not good. I've ran engines this way as long as it's mild, but I also understood the risk I was taking by choosing to live with the ping. You might be able to cure it with a larger jet, but unless it's way lean that may not really be the problem.
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Post by Deleted on Jul 18, 2010 8:37:46 GMT -5
If i put a other gasket on the base, is it going to help to reduce the compression? |
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Post by 90GTVert on Jul 18, 2010 11:23:46 GMT -5
Yes. It will have the same effect as a larger combustion chamber, or more accurately a piston farther below deck. In other words, you'd be lowering the compression ratio. Be careful with that. I've never used multiple gaskets on 4 strokes because of the added risk of oil leaks. Others report good results. I just modify the head to increase the combustion chamber volume and lower compression. That way I can put the engine together every time just using 1 head and 1 base gasket. Simple, and cheaper in the long run.
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Post by Reign on Sept 10, 2010 10:25:54 GMT -5
Just a little update. I've recently gotten around to working on my Triton again, and I still had that noise issue anywhere above about 37 MPH. It would go up to about 47 top speed, and would get worse as you accelerated.
I've since put in an 82.5 jet, and switched to mid-grade gas. No more noise, and my top speed has risen to almost 55. It's worth the $4 jet and the extra 10 cents per gallon.
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Post by 2strokd on Sept 10, 2010 12:33:19 GMT -5
mid-grade :lol:  you should be running the bestest fuel you ca get out of the pump silly |
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Post by 90GTVert on Sept 10, 2010 12:59:59 GMT -5
Yeah, I use 92-93 in all of my scoots. You have to push the limits to get much power, so premium is a necessity IMO.
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Post by Reign on Sept 10, 2010 13:54:36 GMT -5
I only bought 2 gallons of it. I figured I'd try mid-grade and then when I run out, I'll try premium. So far it's been running great on mid-grade. Can't wait til I run out ;D
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Post by Goosey on Sept 10, 2010 19:15:08 GMT -5
I've always used premium. Even before I knew I was supposed to use stabilizer when i stored for the winter, and my scoot started up every spring without ever cleaning the carb. I finally got around to cleaning the Baron's carb just out of curiosity this summer, and still clean as a whistle after 5 years.
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Post by scooterrebel on Sept 11, 2010 0:09:25 GMT -5
Contrarian opinion here.
Ping is the motors way of letting you know it needs a higher octane fuel. If the pinging has stopped with a mid grade fuel you are just fine. Buy premium if you have money to burn. You can also retard the timekeeping just a little and probably do OK too. But if you want to get all the performance possible, advance the timing and then put premium in the tank.
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