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Post by captincvmn on Jul 20, 2021 20:20:02 GMT -5
So I’ve struggled some with the Corsa Polini cylinder but I think I have it now. Or maybe it has me? Either way Sonny and Cher are content. I’ve had run-on and detonation issues I believe from high compression. No I don’t know how high compression is. I use a lot of vice grip pliers. Anyway, I’ve switched away from 93 octane ethanol added gas. A station near me sells three grades of straight gas. I got a two gallon supply of 93. Then I added my oil at 4oz/Gallon and then added 4oz of Octanium. Octanium is a octane booster and additive. Supposed to add 32 oz to ten gallons so I’m a little rich at 4oz:gallon. Run-on went away. Doesn’t do it anymore. It adds $2 to a gallon so I’m around $6/gallon mixed this way including oil. Idle still creeps up from 3>4K when it idles hot. Throttle blip will knock it back to 3k. Next mixture I’m trying is Turbo Blue 110 race gas. This is available at a local gas station right out of the pump AND it’s a full serve station. It’s expensive. $7.80/gallon. I only got one to try. I added my 4oz of oil again and went for a ride. Tank was almost fully empty when I swapped to the Blue. First off it smells different when it burns. No mistaking it. Went for a short ride, maybe 8 miles. It runs good. Seems to idle very well, no weird rise in speed while sitting, and runs down the road about the same as the 93+8 mix. I’ll finish out this tank and go back to the non-ethanol +Octanium mixture until that’s gone then I’ll go to straight 93-non E for two gallons and see what that does. For all of this I’ve kept with the same oil, Maxima Castor927.
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Post by 90GTVert on Jul 21, 2021 11:30:22 GMT -5
I love the smell of race fuel, but there's no way that you should need to run 110 on your setup. There are people with 30HP on pump gas Minarellis. I'm sure you could get gains, but you would need to dial it in to the race fuel's knock resistance and burn speed. At that rate, you'd be better off just dialing it in for common pump gas that you'll be using, unless you always want to rely on a supply of 110 whenever you need a fill up (limits where you can ride to a great degree unless you're surrounded by these stations or carry a large amount of fuel).
Whenever I've had lean hanging, it has been corrected by richening the idle mix/pilot jet and/or needle. I would at least give the idle mix a little bump toward rich as long as the idle is reasonable when cool/warm. I wouldn't expect that to be the cause of your run-on, but a little extra fuel cooling shouldn't make it any worse.
I don't recall; have you done a compression test? How about checking the corrected or uncorrected compression? I know squish was mentioned, but that only tells you so much. I'd hope that an off the shelf kit should have an appropriately sized combustion chamber, but if I were chasing a run-on issue I'd consider it. It is a substantial amount of effort to do it accurately though. At very least, cranking compression tests. If you happen to have a timing light, it wouldn't be a bad idea to check timing. While I wouldn't expect anything to change, it wouldn't hurt to check timing cold and then again when it was hot and idling high. I guess there could be some ignition issue causing advance when something gets hot.
There has to be something going on for it to require high octane to stop run-on.
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Post by captincvmn on Jul 21, 2021 14:04:55 GMT -5
I agree I should not need high octane fuel. Between kids and working 7-5 I’m just glad to be able to ride around. I will eventually get a compression tester. I don’t intend to keep running boosted fuel. It’s a band-aid.
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Post by ryan_ott on Jul 22, 2021 10:35:52 GMT -5
If you are using the supplied parts and don’t have any intake leaks (reeds, intake, head and base or crank seals) it really leaves the carb. What carb and jetting are you using?
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Post by captincvmn on Jul 22, 2021 11:15:08 GMT -5
I don’t believe I have any intake leaks. It’s a 19mm Dellorto clone. I need to double check the numbers but I think it’s got a 75 polini brand main jet and I think it’s a 42 idle jet. Unlike Brent I’m horrible about writing down what’s current and what’s changed. Temps on a long uphill WOT pull never exceed 210°F
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