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Post by zumasterling on Jun 25, 2011 12:35:31 GMT -5
This is my first time posting on this scoot forum after "lurking" for some time now. I have a motorcycle shop in Richmond, VA and have been successful with the sportbike/streetfighter game for 17 years. About six years ago I started messing with scooters after a large purchase of theft recovered Zumas from PA and have been smitten with these little guys since then and aquired quite a few Vento's and such since then. Lemme also say that I am not 100% as far as working on 2T's but feel I hold my own well enough. I just recently bought five scooters (mostly TNG's and one Vento GY6) from a local shop that doesn't wanna mess with them. One of them is a TNG Venice with 17 KM on it and I did a thorough carb clean and de-restricted variator and exhaust, drained old fuel and put new fuel in (with about 1.5 oz of two stroke oil considering it is under 100km and may need some extra lube), checked all hoses for leaks and cleaned out the serviceable fuel filter. Up to 1/3 throttle it seems to go along smoothly but above that bogs severely and will surge after going back to 1/3 throttle after full as if a burst of fuel is unleashed. Wondering about possible float settings and adjustments that may be contributing to this problem. Needle is clipped in the number three position. Also got a couple L's49 scoots and will throw another post concerning the flywheel on one. Thanks in advance!
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Post by stepthrutuner on Jun 25, 2011 12:44:57 GMT -5
Sounds lean. Confirm the absence of vacuum leaks. I'm sorry but #3 position on the needle? I don't know which end to start counting from?
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Post by zumasterling on Jun 25, 2011 12:58:19 GMT -5
Sounds lean. Confirm the absence of vacuum leaks. I'm sorry but #3 position on the needle? I don't know which end to start counting from? Sorry, there are five clip positions on the needle so it would be the third position from top or bottom. It's a Mikuni carb on this scoot (one of the others has a Leader) and the main is a 70. Replaced fuel and vacuum lines with better ones (same size and all fuel rated).
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Post by zumasterling on Jun 25, 2011 14:19:04 GMT -5
I also forgot to mention that it looks like the airbox may have been modded. Appears that the snorkel has been removed and perhaps the hole widened. I may have a zuma airbox (looks identical) laying around so perhaps it'll change some of the running issue. After tuning a zuma with an Athena 70cc kit to near perfect reliability I have to say that tuning dialing in scooter is the HARDEST tuning challenge in existence. So many variables....
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Post by stepthrutuner on Jun 25, 2011 15:24:49 GMT -5
I wouldn't think a minor airbox mod like that would make much difference to compensate for. Plus a few main jet sizes.... maybe four max.
Well, it is pretty hard to get it perfect in all running conditions and throttle positions. That can get kind of expensive.... multiple needles, jets, slides, etc. that need to be kept on hand.
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Post by Fox on Jun 25, 2011 15:36:16 GMT -5
I think you need more oil in the gas. I run 4 oz. per gallon. Castrol 2 stroke synthetic. It's blue and doesn't smoke much.
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Post by zumasterling on Jun 25, 2011 17:07:18 GMT -5
I think you need more oil in the gas. I run 4 oz. per gallon. Castrol 2 stroke synthetic. It's blue and doesn't smoke much. Can't you get into an actual problem of running lean with too much two stroke oil? I am still running the oil injection and just added a bit of two stroke oil to the full fuel tank as I usually do with brand new 2t scoots. I am premix only on my Zuma and Vento Zip R3i (mildly modded stage one). Are you premixing or doing both at the same time?
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Post by zumasterling on Jun 25, 2011 17:17:23 GMT -5
I agree with you on that Stepthru, I have a bunch of different jets and such for streetbike carbs and have robbed some from honda 900rr carbs (the mikuni ones, some were Keihin's) and it would cost a fortune in parts alone to have all one needs on hand for comprehensive tuning, not to mention the damn labor involved. You certainly have to have patience when just trying to get it running pretty decent, and you have to be a Saint to get them perfect across the board.
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Post by Fox on Jun 25, 2011 17:17:46 GMT -5
Yeah I was told that too much oil can/will cause a lean condition because the oil displaces the gas.
I told you add more oil because I thought you had the injector disabled and added 1 1/2 oz. to a tank full.
I pre-mix
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Post by zumasterling on Jun 25, 2011 17:22:35 GMT -5
Fox, I dig Castrol Synthetic a lot. It is a good clean burner but this one has a red two stroke oil in it from the factory so I am thinking it may be Amsoil? Any thoughts? I have had people come into my shop running marine two stroke fluid and I always advise against. Marine two stokes are water cooled and I am not sure if the composition of the marine fluid is the same as air cooled. I feel there is a reason they sell marine and air cooled badged fluids?
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Post by zumasterling on Jun 25, 2011 17:25:05 GMT -5
Thanks for clearing that up Fox. What ratio are you running? (I know you are adding four oz to a tank of fuel but not sure how big your tank is)
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Post by Fox on Jun 25, 2011 17:34:01 GMT -5
4 oz per gallon = 32:1 I take a gallon can to the gas station and put exactly a gallon in it and then I take it home and add exactly 4 oz. of oil and then I fill my tank up. Brent posted a cool ratio calculator here: 49ccscoot.com/calculators.html
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Post by zumasterling on Jun 25, 2011 17:37:43 GMT -5
Another thing I have noticed about these scoots is that most of them were put into storage after most gas pumps were starting to host around 10% ethanol. Before ethanol was being mixed into fuel you would see dirty carbs from sitting but NOTHING like ones that had the current ethanol/gasoline fuel sitting in them. I loathe ethanol mixed fuel and the effects it has on small engines of any type. Ahhh, the good ol' days.
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Post by zumasterling on Jun 25, 2011 17:44:09 GMT -5
Thanks for the link Fox!
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Post by jmkjr72 on Jun 25, 2011 18:23:20 GMT -5
actauly if you use seafoam to stabilize the ethonal fuel its not an issue at all here in wi we have been dealing with e10 for the last 15 or so years without any real issues but again you have to use the right stuff to store the gas with it and when it does gum up it takes more to clean and if you put stabil in (i havent used the new so called ethonal safe crap) it will make things worse with the ethonal
im wondering if the petcock is being a pia not getting enough vacuum to open all the way up
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