zooma
Scoot Member
Posts: 70
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Post by zooma on May 2, 2021 19:09:56 GMT -5
Hi, I have a Yamaha Zuma 50 2009. It is upgraded to the Polini 70cc top end It has a Yasuni R carb Previously it had a malossi 70cc top end and Giannelli exhaust. It has new rollers(Athena 5.6g), belt, main bearings. Cleaned air filter. Cleaned carb. Here are parts that were installed when I bought it. Haven't changed them. -Mallosi Yellow clutch + Yellow Contra Springs - 85 Dellorato Main Jet installed in stock carb + Adj Needle - Athena Carbon Fiber Reeds - Factory Airbox Snorkel Removed - Throttle Mod The carb is not tuned properly. Bogging at higher rpms and cuts out completely some times. Also the idle screw is completely out and the idle rpm is around 2500 which I know is a bit high. The spark plugs is pretty black . Thinking the mixture is rich? Here is what it looks like after a few km of riding. ibb.co/1n02wLQHaven't played around with mixture screw but just wondering if you guys had any advice on what jet to use, or just any general advice on where to start with tuning. Don't think there are any air leaks. thanks |
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Post by Zino on May 2, 2021 20:59:46 GMT -5
Do you have a larger jets than 85 mikuni and smaller .
With snorkle in
I tried running a 85 or 87.5 to a 90 genuine mikuni
If they are not genuine mikuni they could be a little difrerent mikuni jets are flow rated not rated by size of opening .
With my zuma stock carb malossi paired with the Yasuni R 87.5 and 90 worked best for me the 85 was ok to a little lean .
Do you have a temp gauge goal is to keep wide open temps below 350 degrees .
When going wide open dropping down to 3/4 throttle does it run better.
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Post by Zino on May 2, 2021 21:09:22 GMT -5
Take a picture from top down and from a couple different angles .
A well run Plug color is jut a clue
Hanging idles ,throttle response ,sound ,wide open performance and wide open temps and plug chops are better .
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zooma
Scoot Member
Posts: 70
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Post by zooma on May 3, 2021 0:49:13 GMT -5
Thanks for your reply. I'll look into the wot to 3/4 throttle performance impact + temperature reading and let you know tomorrow. Here is another plug photos, will try to get more tomorrow if needed ibb.co/hVwj7L9I'm looking into finding Mikuni jets online and I'm wondering if this is compatible with the stock Zuma carb www.nichecycle.com/ncs/categories/carburetor/mikuni-parts-by-category/jettting-tuning/genuine-mikuni-main-jets/vm11-22-vm11-22-main-jet-by-mikuni.htmlDo you recommend getting a new airbox with snorkels? I can also order a roller set. Do you think this is necessary? Another thing I thought I'd mention is that the auto choke is currently missing, lost the cylindrical piece that fits into carb. Not sure if this is contributing have to performance issues. Also can't remember if I derestricted the muffler part of the exhaust but I'll check tomorrow.. Finally it's premixed 50:1 with motul oil. Thanks again. |
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Post by Zino on May 3, 2021 7:45:07 GMT -5
Those jets will work vm 11/22 is the right size . I bought mine at www.jetsrus.com/a_jet_kit_scooter/yamaha_50_vino.htm The have 85 87.5 90 92.5 etc I have run with the snorkle out just have to jet accordingly The Auto choke not functioning is a major issue since you have no Auto choke stopping the flow of fuel you have a extra jet always on . The Auto choke is actually a enricher when its cold it is wide open as a piece of wax warms up it pushes the valve shut. The Yasuni R has 2 restriction to take out one by the head pipe and one in the silencer. If you bought it from scootertuning.ca then you only have one in the head pipe . |
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Post by willie678 on May 3, 2021 10:14:37 GMT -5
Check you float height.. Your pilot jet could be off, depends on pilot screw turns. Making it harder to tune your throttle with a smooth transition. I get 90km/hr with snorkel in! Probably about 80km/hr + with stock carb I think its harder to tune with snorkel out.. en.wikipedia.org/wiki/Eddy_(fluid_dynamics) |
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Post by willie678 on May 3, 2021 12:03:47 GMT -5
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Post by ThaiGyro on May 3, 2021 18:48:05 GMT -5
Hi Zooma, I think Zino has you on the right track, but I will give you caution. From an old guy, I/we like to tune evertyhing..especially two strokes by doing one thing at a time. Then check. Seems a pain in the ass? Yes, it is! However, many know, from experience, how to eff-up poop.
My suggestion is to...check ignition settings, (haha, some folks think I am crazy), then think about what you have done to make things different. Record all of that in as much detail as you can.
Then make a change. One change. Run it an write down the results. Like it says on your shower gel...apply, rinse and repeat. The thinking for me? If you do not know what one change did...why do ten? If your friend thinks he/she is smart? How and why? If "everyone does that, so it must be good"? I will show you a loser.
Learn to be "that guy" who checks everything, one step at a time. God-like.
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zooma
Scoot Member
Posts: 70
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Post by zooma on May 3, 2021 20:52:01 GMT -5
Thanks guys.I'll be sure to look into the jet kits posted. And it's great to know that I don't have derestrict anything else on the exhaust since I did order from scootertuning.ca! Here are some more spark plug photos. ibb.co/f09Nnpmibb.co/rcQz5VDibb.co/JjCgwqfibb.co/30tsdBSUnfortunately didn't get the chance to ride it and do the temperature/performance tests as I wasn't able to find the missing piece on the electric choke. The main issue is the missing auto choke part. Problem is OEM replacement is $200 and cheaper knock off versions seem to have a 7mm cylinder and not 6mm for the stock carb. This leads me to think of instead purchasing a whole new carb (17.5mm) that supports the cheaper 7mm electric chokes with the added benefit of improved performance. Few questions. Which would you suggest from scootertuning website. The motoforce is the cheapest but I'm not sure if it's quality. Dellorto is currently out of stock and I'm considering the Polini or Naraku. www.scootertuning.ca/en/search?controller=search&orderby=position&orderway=desc&search_query=17.5mm+carb&submit_search=One issue is that most of these carbs are manual choke compatible and so I'm not too sure if it's a plug and play with electric choke. Additionally I guess I need a larger airbox and intake manifold? Thanks again. |
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Post by Zino on May 3, 2021 21:22:12 GMT -5
the stock intake mainfold work and air box work all the way up to 19mm dellorto .
Plenty of zumas out there that have upgraded the carb you might be able to get a old stock one off someone on here .
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Post by willie678 on May 4, 2021 1:18:36 GMT -5
Thanks guys.I'll be sure to look into the jet kits posted. And it's great to know that I don't have derestrict anything else on the exhaust since I did order from scootertuning.ca! Here are some more spark plug photos. ibb.co/f09Nnpmibb.co/rcQz5VDibb.co/JjCgwqfibb.co/30tsdBSUnfortunately didn't get the chance to ride it and do the temperature/performance tests as I wasn't able to find the missing piece on the electric choke. The main issue is the missing auto choke part. Problem is OEM replacement is $200 and cheaper knock off versions seem to have a 7mm cylinder and not 6mm for the stock carb. This leads me to think of instead purchasing a whole new carb (17.5mm) that supports the cheaper 7mm electric chokes with the added benefit of improved performance. Few questions. Which would you suggest from scootertuning website. The motoforce is the cheapest but I'm not sure if it's quality. Dellorto is currently out of stock and I'm considering the Polini or Naraku. www.scootertuning.ca/en/search?controller=search&orderby=position&orderway=desc&search_query=17.5mm+carb&submit_search=One issue is that most of these carbs are manual choke compatible and so I'm not too sure if it's a plug and play with electric choke. Additionally I guess I need a larger airbox and intake manifold? Thanks again. I stuck one of these on for my tuning. www.scootertuning.ca/en/carburettors-choke/5140-manual-choke-set-dellorto-phbg-19-21mm.htmlI went with a 21mm carb from china for $30 and the rest of my money at scooter tuning for Throttle mod kit Polini 80-89 5mm jets Polini 90-99 5mm Jets PGBG Pilot Jet Set PHBG Needle set See my current notes here. I am waiting on the needles, but i am close... 49ccscoot.proboards.com/thread/28571/power_____________ The Spark plug wont tell you that much right now as you could be lean and rich at different throttle locations. You want to put some tape onto your throttle and use sharpie to see where 1/4 1/2 3/4 and full throttle is. WHen you test it... see where it runs smooth and where it runs rough 1/4 1/2 3/4 and full throttle. You need to learn to tune your pilot screw so you can tell if you need bigger or smaller pilot. Pilot will change you main jet size.. i have somewhere around 90km/hr on 21mm carb now with stock airbox.. I was at about 80- 82km/hr or or with the stock carb right before that. I have had 0 luck tuning the 100cc airbox, once i get needle set not sure i want to try again lol The stock airbox with snorkel has been easiest for my tunining. |
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zooma
Scoot Member
Posts: 70
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Post by zooma on May 5, 2021 13:44:27 GMT -5
Thanks Willie678
I've been looking closely into 21mm and 19mm carbs and think I'll go with a dellorto 19mm which comes with manual choke set and single throttle cable conversion for the Zuma. Looks like they have it in stock at Dynoscooter.com
I really wish I could have used the stock carb but that means I have to spend $200 on the OEM auto choke. Unfortunately I can't find any manual or electric choke sets for stock 15mm. I heard that you can JB weld the choke port shut but then that means I can't richen the engine when needed.
But I'm happy to try out a new carb. Just more tuning it seems haha
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Post by willie678 on May 16, 2021 23:32:45 GMT -5
Ive learned that the knock-off PHBG's' often come with a w16 needle and it doesn't tune well with my setup.
Once i Got a w7 needle its has a very smooth transition now and good to go as is.
21mm PHBG / W7 Leanest-1/ 91M / 38P - 3/4 turns out / AU262
I have the 50 Slide and it seems like 1/8 throttle is still a bit rich so i have ordered a 60 Slide
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Post by willie678 on May 20, 2021 13:40:07 GMT -5
Ive learned that the knock-off PHBG's' often come with a w16 needle and it doesn't tune well with my setup. Once i Got a w7 needle its has a very smooth transition now and good to go as is. 21mm PHBG / W7 Leanest-1/ 91M / 38P - 3/4 turns out / AU262 I have the 50 Slide and it seems like 1/8 throttle is still a bit rich so i have ordered a 60 Slide I just received a PHBG rebuild kit in the mail, I was fiddling with it a bunch and noticed the slide has pretty strong burr's along the bottom edges. Going to mess with some more tuning today and inspect and deburr the slide!! |
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Post by willie678 on May 20, 2021 18:22:32 GMT -5
I stuck in a W11 needle, backed the 38 pilot to 3 turns out and First try I like it better than the W7!! Take off seems fixed and Plugs looks better already after a quick ride. Gunna put the 40 pilot in and then potencially try the w4 and w5 but w11 might be where its at  PS... Fixed the PHBG throttle connector to accept a double nut photos.app.goo.gl/2Qa8Qg4tV1TE4ciG6  |
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