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Post by ThomasTPFL on Feb 5, 2019 10:52:08 GMT -5
Some carb and intake setups want a bit of intake restriction to run nicely, but at wot want all the air they can get...
I'm thinking a big reed valve on the airbox with reeds that don't want to open until high flow is happening. I might have junk laying around to test this scheme if I get a chance later this week. I have this yeller tgb that's being dumb about tuning.....
They don't need to snap closed nicely like the engine valves, so a flap of plastic may do the job.... Or maybe just a little door on a spring...
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Post by gsx600racer on Feb 5, 2019 18:11:02 GMT -5
Interesting concept, might be worth experimenting with. Keep us posted with your findings.
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Post by repherence2 on Feb 5, 2019 21:03:43 GMT -5
This made me think of Boyesen reeds.
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Post by harleyracer59 on Feb 6, 2019 6:42:39 GMT -5
I like the idea. however, if you're having tuning issues now, I could only assume opening more air flow at any throttle position while closing it at another would only open more variables to an already hard to tune situation. like I said. I like the idea, but the "valve" would need a specific amount of force to open and close. also while it might not need to be completely air tight when closed. it would need to still close a fixed amount at a certain time or there would be another changing or variating amount of restriction to add to the tuning equation. it would have to open at a set point and close at a set point or you might be opening a whole can of lean "worms" that show up and go as they please. leaving you chasing lean conditions that are there one minute and gone the next. I don't think it will make tuning any easier and might actually make it completely non tunable altogether. I'm interested to hear your findings, good and bad...  I think this might be better suited for a slow poke 4 stroke, that isn't as air sensitive as a 2 stroke.  |
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Post by jeppetheswede on Feb 6, 2019 10:19:43 GMT -5
Wery interesting
Been fiddling around with variable hood scoops with different results.
It is defenetly worth a try.
So ceep us updated with future results.
And as harleyracer says it could bee very hard on a two stroke.
But what do ikmow this is unknown terrytory for me.
Only been fiddling with big fourstrokes before.
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Post by snaker on Feb 6, 2019 10:49:34 GMT -5
Dan Martin over at Dans Garage Talk forum was messing around with Air Fuel Ratio sensors and whatnot with good results.
Unfortunately that site seems to be closed.
I think something like that would be useful for your project.
You could open and cover various spots, try different things and be able to see definitive results.
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Post by repherence2 on Feb 6, 2019 10:51:53 GMT -5
Thomas, I think I resolved such an issue by installing a splitter plate on my carb mouth. The idea was copied from a shop that installs a carb modification, seen it on the net. Basically the plate splits the carb mouth 50/50, like an equator. So below 1/2 throttle, all the air pulls in from the bottom half. As you go past 1/2 throttle the slide comes up above the splitter plate and air is drawn in from above and below the splitter. I think it made it easier for me to smooth out the tuning of my OKO 28. Just a thought.
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Post by harleyracer59 on Feb 6, 2019 10:56:38 GMT -5
Thomas, I think I resolved such an issue by installing a splitter plate on my carb mouth. The idea was copied from a shop that installs a carb modification, seen it on the net. Basically the plate splits the carb mouth 50/50, like an equator. So below 1/2 throttle, all the air pulls in from the bottom half. As you go past 1/2 throttle the slide comes up above the splitter plate and air is drawn in from above and below the splitter. I think it made it easier for me to smooth out the tuning of my OKO 28. Just a thought. got any pics of this splitter? |
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Post by ThomasTPFL on Feb 6, 2019 11:30:14 GMT -5
This was a brain fart I had at work yesterday, lol. The more I dwell on it the more I think it'd just be a complicated way to get around a bad carb tune. I can't think of anything that could be accomplished with my airbox valve idea that wouldn't be more appropriately addressed with jetting or change of metering needles.
That said, If I can't sort this engine out better I'll be sending a scosh off the tip of the needle as I don't have a collection of such things and it's a $15 Chinese clone carb anyway. I just haven't swapped it for the small dellorto I have laying around because I don't want to fool wih a manual choke on this bike.
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Post by repherence2 on Feb 6, 2019 20:33:39 GMT -5
Thomas, I think I resolved such an issue by installing a splitter plate on my carb mouth. The idea was copied from a shop that installs a carb modification, seen it on the net. Basically the plate splits the carb mouth 50/50, like an equator. So below 1/2 throttle, all the air pulls in from the bottom half. As you go past 1/2 throttle the slide comes up above the splitter plate and air is drawn in from above and below the splitter. I think it made it easier for me to smooth out the tuning of my OKO 28. Just a thought. got any pics of this splitter? Google: Rich's Taylor'd Porting Service. www.richstaylordporting.comHe refers to it as a "venturi divider". He has a small write up in the Venturi Divider Modification subsection. |
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