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Post by Deleted on Dec 11, 2011 20:02:44 GMT -5
yeah dont give up yet try a smaller main. if its the stock cam and exhaust like mine a 105 is toooo much. i bought the same thing off CL that came with a 95, 105 and 115. ended up using a 95. i can run a 98 in winter if its real cold but on warm days its on the rich side and bogs a little.
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Post by Fox on Dec 12, 2011 22:49:31 GMT -5
I've tried several different carbs and jet sizes. Could it be that I'm using 87 octane?
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Post by Deleted on Dec 12, 2011 23:04:05 GMT -5
i had one once that did a similar thing turns out the cam was pretty worn out. no i dont think the 87 octane is doing it. is the exhaust flowing freely?
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Post by Fox on Jan 28, 2012 16:46:49 GMT -5
Okay so I swapped out the entire engine with a used stock engine from a parts scoot and got it running today. Installed 4.5 gram sliders and it pulls great.
The one issue I'm having trouble figuring out is that it runs great with an open carb but with an air box installed it bogs. I installed the smallest jet I had (#77) and it still bogs with a filter. So I took the outer cover completely off the air box and tried it and it still bogs. So I removed the foam element and tried it with just the back of the air box empty and it still bogs. Removed the air box altogether and it runs great. I'm stumped. I don't have a UNI pod to try on there but I suspect it would bog with one of those too. Somehow just the tube from the air box is disrupting air flow. It's weird.
Anyone have any idea why it's acting like this?
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Post by stepthrutuner on Jan 28, 2012 17:00:10 GMT -5
I bet it wouldn't bog with an oiled cotton K&N. Check throughly for intake leaks past the carb.
Edit: Also make sure carb itself is free from any unwanted air admittance.
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Post by Fox on Jan 28, 2012 17:11:05 GMT -5
I think maybe you nailed it. I just went out there and looked and there is gas leaking from the bowl gasket. I have a box of old carbs and I mixed and matched parts to make a "good" carb and I guess it's not a good idea to mix carb bodies and bowls. I'm going to take off the intake elbow and check the seal on that too.
Thanks!
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Post by Deleted on Jan 28, 2012 17:16:58 GMT -5
My stock 72cc motors come with #77 - #80 mains. I bet a smaller main would fix it if its a true 49.5cc motor. or solder it up and drill it...if the bowl leak is not the problem that is.
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Post by stepthrutuner on Jan 28, 2012 17:24:49 GMT -5
Since the bowl is vented excess air shouldn't be a factor there I would think. And the fuel level normally resides below the part line of the body/bowl. Fuel gets out from vibration if the gasket lacks integrity. You could have a float level problem or admittance valve problem.
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Post by Fox on Jan 28, 2012 19:36:21 GMT -5
I assembled a completely different carb and it still acted up. All my old carbs must just be bad carbs or it's something else. By "admittance valve" did you mean the intake valve on the cylinder head?
I'm starting to think it's not the carburetor issue at all but some kind of electrical demon or spark timing issue because I've tried two engines in this frame now and neither want to run right. I like a challenge but this is getting old.
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Post by stepthrutuner on Jan 28, 2012 20:40:06 GMT -5
Sorry. I meant the "float needle valve" or whatever most people call it. I just couldn't think of the proper name.
If it's electrical, tying that in with a more restrictive or less restrictive air filter is a stretch for me but as I get older I,ve just about learned to never say never more and more.
Using the same enricher? This is a good one.
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Post by stepthrutuner on Jan 31, 2012 17:40:08 GMT -5
You really got my curiosity up on this one, Dave. Ever get to the bottom of it? We could all learn from this one I figure.
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Post by Fox on Feb 3, 2012 19:02:12 GMT -5
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Post by stepthrutuner on Feb 3, 2012 20:26:22 GMT -5
Preciate the update and I'll keep an eye on this thread and maybe learn sumphin....
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Post by Fox on Feb 3, 2012 20:50:32 GMT -5
If the new carb works then all we learned is that I have a bin full of f-ed up carbs.  It's funny you know. I've worked on a quite a few scooters over the years that sat for a while and after I cleaned the carb two or three times with no luck I installed a brand new carb and they ran perfect. Not sure why but carbs seem to just go bad sometimes. The diaphragms look fine and you spray the crap out of the whole carb in every orifice liberally and they still refuse to work right for reasons unknown. My bin is full of carbs like that that I took home after replacing them with new ones. I figured I could make at least one good one out of all of them but apparently they are all bad or I'm missing something. :confused:  I need to buy a timing light but right now I'm friggin' broke as a joke. |
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Post by stepthrutuner on Feb 4, 2012 10:28:55 GMT -5
That's curious about those old carbs. I've read that old automotive carburetor professionals claimed that the only way to restore all the small passages to like new condition was to put the dissassembled carb in an agitator with the proper cleaning agent for a good while. Perhaps some varnish is remaining in your carbs somewhere.
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