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Post by chris7420 on Apr 6, 2022 16:21:13 GMT -5
I have a 2006 Yamaha YW50, It has the horizontal 50cc minerelli engine and I’m installing a polini 72cc big bore kit link below. Just wondering if anyone can tell me if I’ll need to install anything else to make the big bore kit work/get the most out of it. Different spark plug, different jets in the carb etc? Also my scooter has oil injection so I just keep the oil tank topped off but I read somewhere that when you go with the big bore you should add a about a capful of oil to every tank of gas. Can anyone confirm? www.scooterworks.com/Polini-Contessa-Big-Bore-Kit-72cc-Yamaha-Zuma-50-2T-P12918.aspx
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Post by 90GTVert on Apr 6, 2022 18:25:31 GMT -5
Welcome to the forum! You should always check the carburetor tune. It may need a different main jet, needle clip setting change, idle mixture adjustment or all of the above. Idle mix adjustment and idle speed setting are routine maintenance anyway. Some Polini instructions just say to richen the needle, but usually I have to change the main jet. Not always. I like to have jets on hand so I can do a few test runs and make sure it's good to go. You may also need to change out roller weights to make it work better with the big bore kit. Again, it may be alright, but it may need different weights. For me, changing to just a 70cc sport kit like that without other mods may require a little heavier weights to keep RPM in a good range. Good news there. You can actually stuff aluminum foil in weights if you have a scale with at least 0.1g resolution so you can do it evenly. That may save you from buying weights if it's close. 1-1.5g is about as much as you're going to stuff into a 15x12 roller. Here's some info for you... BBK Install : 49ccscoot.proboards.com/thread/556/install-big-bore-kit-1e40qmbModding Rollers : youtu.be/YkNhqEFeWVQCarb Tuning : www.49ccscoot.com/faq/carbtune.html
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Post by Zino on Apr 6, 2022 18:37:34 GMT -5
That is a nice solid kit that will run for thousands of miles with some extra speed and takeoff. You need the extended plugs most run the Br8Es . I have run the stock oil pumps with no oil added to the tanks with BBK Kits and Pipes for thousands of miles . Just make sure you buy a quality injector oil .
Stock Jetting with Stock Air Box The needle most likely needs to be a notch richer by lowering the clip because you will be able to run at higher speeds at mid throttle. The main is probably rich enough until you add a pipe . The Stock main is a 80 Tekei You could swap In Mikuni 11/22 size 85-90 to go up a couple sizes richer if needed.
The Stock Cvt will be very close to right Fine tuning you could look at medium clutch springs or 1/2 -1 gram lighter Variator weights to make your ride spunkier .
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Post by chris7420 on Apr 8, 2022 12:47:03 GMT -5
That is a nice solid kit that will run for thousands of miles with some extra speed and takeoff. You need the extended plugs most run the Br8Es . I have run the stock oil pumps with no oil added to the tanks with BBK Kits and Pipes for thousands of miles . Just make sure you buy a quality injector oil . Stock Jetting with Stock Air Box The needle most likely needs to be a notch richer by lowering the clip because you will be able to run at higher speeds at mid throttle. The main is probably rich enough until you add a pipe . The Stock main is a 80 Tekei You could swap In Mikuni 11/22 size 85-90 to go up a couple sizes richer if needed. The Stock Cvt will be very close to right Fine tuning you could look at medium clutch springs or 1/2 -1 gram lighter Variator weights to make your ride spunkier . Thanks so much for the reply, good info. Are these the right size jets? www.scootertuning.ca/en/carburettors-main-jet/5108-main-jet-set-polini-dellorto-6mm.html#/choose-6mm_10_pieces_80_98
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Post by Zino on Apr 8, 2022 18:15:32 GMT -5
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Post by chris7420 on Apr 8, 2022 19:21:53 GMT -5
Thank you, I’d like to order from this website if possible though cause I’m in Canada and they’re based in Canada as well and have fast cheap shipping, do you see anything on here that would work? If you scroll down past the carburetor’s there’s a list of different kid of jet kits - www.scootertuning.ca/en/57-carburettors
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pili
Scoot Enthusiast
Posts: 209
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Post by pili on Apr 8, 2022 19:28:52 GMT -5
You can also buy bigger OEM pilot and main jets from Yamaha. Part number 14T-14343-41-00 for the 82 and 14T-14343-42-00 for an 84. I found mid throttle greatly improved by raising the needle as mentioned, and increase the pilot jet one size to a 46 with a Yamaha 5BM-14353-23-00. The jets are affordable, about $6 each. If you don't have a Yamaha dealer nearby, Partzilla is a good source.
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Post by Zino on Apr 8, 2022 19:42:26 GMT -5
I only have experience with the mikuni and the yamaha jets that pili recommends. You can get mikuni 11/22 jets on amazon also .
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Post by chris7420 on Apr 9, 2022 18:15:34 GMT -5
I only have experience with the mikuni and the yamaha jets that pili recommends. You can get mikuni 11/22 jets on amazon also . Okay thanks so much. Also on a side note do you suggest I should replace anything else? My scoot has almost 11,000 kilometres on it, at full throttle it only goes 60 and takes forever to get there, I only ride it in 60km/h zones max so don’t really care to go much faster but I would like to be able to get up to speed easily. I cleaned the carburetor and replaced the spark plug when I got it but it didn’t really make a difference I’m installing the bbk kit so it’ll have a new cylinder and piston, I’m going to get some lighter rollers and medium strength clutch springs like you suggested. Do you think there’s anything else that’s due to be replaced? I was thinking maybe new clutch and variator as it’s only 72.99 total for both here - www.scootertuning.ca/en/variators-replacement/7077-replacement-variator-teknix-minarelli.html- www.scootertuning.ca/en/clutchs-replacement/8069-clutch-teknix-standard-107mm.html
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Post by Zino on Apr 9, 2022 21:26:52 GMT -5
First rule of tuning change only one thing at a time . If you were only do one big thing It would be The bbk kit . It will give you extra power everywhere take off to top speed and a few more mph up top. I would enjoy that for a little bit and tune that it in
A better clutch and variator can give you better shifting and a few mph up top because of larger gear ratio . I have never used the teknix so I could not tell you if they were much of an upgrade . I have had very good results with the polini and malossi transmissions .
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pili
Scoot Enthusiast
Posts: 209
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Post by pili on Apr 9, 2022 22:39:46 GMT -5
First rule of tuning change only one thing at a time . If you were only do one big thing It would be The bbk kit . It will give you extra power everywhere take off to top speed and a few more mph up top. I would enjoy that for a little bit and tune that it in A better clutch and variator can give you better shifting and a few mph up top because of larger gear ratio . I have never used the teknix so I could not tell you if they were much of an upgrade . I have had very good results with the polini and malossi transmissions . Excellent advice. The BBk's better acceleration will make you smile. Great bang for the buck. I found that and an upgear upgrade to be just the ticket for commuting. You can go from there if you want more.
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Post by chris7420 on Apr 11, 2022 22:13:50 GMT -5
Thanks for the advice guys, so I have one dilemma. The bbk should be getting delivered tomorrow I ordered the jets for the carb but I don’t known when they’ll be here. Do you think it’ll be safe to run it without changing the jets? I plan to lower the needle clip and I’m pretty sure you’re not supposed to run it over 3/4 throttle for a while to break it in anyways.
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Post by Zino on Apr 11, 2022 22:36:18 GMT -5
If it is just the polini contessa kit with stock exhaust you may not even have to upjet ever. You just have to be prepared to up jet for long term safety and best performance . Dropping the needle with the stock carb one notch richens the mid throttle range 1/4 -3/4 . It takes a full day to swap in a cylinder to let all the sealants cure. So the jets may not be far behind .
Pipes and Open filters drive the biggest jetting changes .
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Post by Zino on Apr 11, 2022 22:56:20 GMT -5
Dont stress the jetting yet focus on a good install. Start early in the morning . Go slow take alot of pictures . As you take off the shrouds So you get the oil hose snapped back in the right way. Brett has a very good install guide to follow 49ccscoot.proboards.com/thread/556
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Post by chris7420 on Apr 14, 2022 14:57:55 GMT -5
Dont stress the jetting yet focus on a good install. Start early in the morning . Go slow take alot of pictures . As you take off the shrouds So you get the oil hose snapped back in the right way. Brett has a very good install guide to follow 49ccscoot.proboards.com/thread/556I’ve replaced many top ends before on dirt bikes/motorcycles so pretty confident I can install it no problem. I just got the kit today, the instructions say to use a #88 main jet and a #46 pilot jet. Should I get those and install them along with the bbk kit or do you really think it will be okay with stock jetting? I have to go to a Yamaha dealer to get a new wrist pin bearing cause the kit didn’t come with one so I could probably get the jets there.
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