2005 Yamaha Zuma (Bws 50) build

[mattyslimz]

I couldn’t help myself but I broke down and bought an ‘05 BWS 50 (Zuma 50) for a mere $600. Mileage is 7600. The RX8 was running great with the new S6 sport cast streetrace bore, but broke down on me on the way home from work Thursday afternoon. The bike starts and runs fine for a minute or so and cuts in and out and finally shutting down. It’s not bogging down when it cuts off, but more of a spark- like issue it seems. My first thought was a fouled plug, changed out, same problem. The petcock seems to be supplying enough gas from the vacuum though I do NOT have clear lines to see if there’s any blockage. Cleaned the el cheapo 19m carb and jets of the minor white flake and still not it. I was tired of trying to track down the issue and I need to get to work. So kinda rushed and skimmed FB marketplace, CL, Offer up and letgo for a decent yet affordable bike.

The Zuma has a aluminum single ring piston and bore (not sure of the quality on Athena, previous owner said it is an O-ring gasket head design.(I know they’re decent for Tomos etc. but not sure of Athena’s reputation with scoots as far as reliability, leaks etc. are concerned) Athena 70 kit with stock crank AND FACTORY OIL INJECTION! (Headshake) PO claims kit was installed 400 miles ago.. I’m thinking of putting on my Stage 6 cast on from the RX8 for reliability reasons, but not sure if it’ll work because pin size. The factory carb has been retained with PO claiming an upjet 88 main. And guess what, the factory airbox is still on there thankfully. After all the talk of keeping the stock airbox in place for keeping cool/lean conditions, I’m glad it’s on her especially with this damn bore that rips and gets hot quick from what I can tell, I think now is REALLY the time to go ahead and order that TrailTech or Koso (if Koso even makes an air-cooled gauge) and slap it on there. With the weather getting warmer and that kit I’am worried about temps. I wonder if my 1e40qmb oversized fan from str8 tuning will work on the Zuma? Thinking of putting Polini CP21 on this. I don’t know what the R&D/testing people were smoking out at Leo Vince when they released this “ZX” pipe, but it’s earshattering loud. Its almost like I’m riding a YZ80 with a Shorty silencer on the street it’s so loud (kinda feels like it (YZ80) with the power-band this thing hits at though.) Mid-range and high out are pretty good with the pipe, down low has a little torque as expected but I’m sure there’s better pipes out there for sure. I’m planning on doing “the ZX quiet mod” by modding the silencer here after this post, but ultimately just getting an S6 or Yasuni variant.

The CVT is in desperate need of some mods. PO said it “may have lighter rollers” but I wont know the status of anything until I pull the cover off. The clutch seems strong as could be so it could be replaced or aftermarket already. The bike is screaming for more at 41-43 mph which feels like the restrictor may still be on the collar (boss) I’m not sure if Zuma 50s from this generation even came with them. You would think if the rollers were in fact changed as the PO claims, that common sense for more speed would to remove it, guess I’ll find that out soon too. I have the NCY secondary pulley in the package still ready to be put on to help with the weird angles for the pins to slide up and down, so coupled with a Malossi Multivar (real) I should have a decent budget overrange set-up. The tires are 100/90-10 front and rear by Kenda. I’m looking into a forged wheel set down the road.

I still plan on keeping the QJ Rx8 and figuring out its issue which I know MUST be minor, so that me and the ol’lady can ride together and to keep it as a spare bike for guests to ride. The Zumas a little clapped out looks-wise but I just ordered a nice seat cover for it off Ebay with white stamped YAMAHA logo for $30 on the “bay”, but it seemed like a decent price for what is and it already has the fender/tail delete and integrated turn indicators which is a plus in my book. Thoughts regarding mods for Zuma or insight on the Rx8 issue is welcome and appreciated. -Matt


Read more: 49ccscoot.proboards.com/thread/24685/2007-qj-rx8-build?page=2#ixzz5oJTJoQ3G

[benji]

I would keep the Athena on there, but do some plug chops. Athena is a good brand. An 88th Main Jet with the OEM carb and airbox is probably fine depending on exhaust. It sounds like you might have a Race Kit, so you might need a pipe and some CVT upgrades to maximize it, or maybe just some up gears if you're just looking for a Dependable bike. With a good Big Bore, The Zuma can take decent up gears. The OEM oil pump isn't bad, but premix is better. You have to remove the bore to get the pump out tho I think, and if it's in there dragging the motor you might as well use it haha

[ryan_ott]

You could gain some speed swapping out or at least inspect to see what gears are in there. The 02-05 Zuma were restricted through CVT, rear TD and the 14.6 final drive. An 2008+ TD would be a cheap upgrade or the Top Performance TD is nice I did the homework on that one for you. I would go through the cvt and get a temp gauge for starters to see what you have. The silencer probably needs to be repacked and it will quiet down. Keep the injection pump or premix, your call, I’d ditch the pump myself.



49ccscoot.proboards.com/thread/24543/top-performance-td-belt-length

[mattyslimz]

Thankyou benji and ryan _ott for your suggetions/input.

benji I subbed your YT channel and checked out your build thread on your 05 Zuma that you started back in 2017. Man thats an awesome looking/running bike. It gives me a little more inspiration to put in some more work on mine. I guess I will just go ahead and switch over to pre-mix especially with this type of bbk on the scoot. if it were an sport cast 70 kit I'm sure the pump would supply an ample amount of oil, but with this kit the revs come quick and power-band hits hard and long. As you mentioned more work is needed to really get the benefits of switching over, apparently its not as easy as the clones with just a loop around cap off. I will search the here and find a thread that fully entails the proper removal of the pump. Less drag would also be great, even removing the electric start plate off the crank would help too, but we all know kickstarting problems could arise at anytime.

ryan _ott I really appreciate the gearing chart. I didnt do enough research on these before I made the purchase I figured the 02-11s were all (mostly identical) I was WRONG. A 21% primary and 33% secondary gain looks good on paper and I bet the gains are remarkable! Id probably prefer to go the Top Performance route. I was hoping to get away with a wider Malossi belt and variator kit with the NCY secondary pulley to see at least good gains (50mph+) but it looks like I'll have to dig deeper and TD. Might as well start looking at some cranks if i'm going to be tearing into it that far.

[benji]

If your not using an overrange kit, use the OEM belt. It is the best and most reliable on the OEM CVT size. The rear td is definitely a good swap. '08s do have slightly taller gears, but aftermarket gears will be taller by far. I suggest 15/52 upgears. 14/42 should put you right around 11:1, and 15/52 is slightly shorter if I remember. I have a bigger version of that chart somewhere...

[benji]

Here it is..


The 02-05 has a shorter secondary, so aftermarket primaries have different ratio outcomes depending on year. Lots of guys consider 11:1 "perfect" for scooters unless you have extremely power. 11:1 maybe too tall for you without more mods like a overrange

[mattyslimz]

I have found this on the Canada rabbit site. I’m trying to avoid splitting the case, buying gears, plus new gasket for everything at the moment. benji you said the gears would be a dependable option, but what about just throwing down on this overrange kit? My goal is 50mph. The acceleration is great right now I’d like to keep it if possible but get into the 50s without the motor screaming getting super hot. I pulled the cover and found everything (contra,clutch,vario) is completely stock including what looks to be the original oem Yamaha belt but maybe not. The fan drive face has chipped off blades. Only the restriction washer on the boss was removed previously.

[benji]

That over range is a good buy, but there is modifications that are needed to install it. It may be Overkill w/o up gears. I would do up gears and tune the OEM CVT before you buy that. You should be able to hit 45-50 on the OEM CVT and gears with tuning. Btw, if you buy the over range you will still have to tune that as well. It is not a bolt on kit. Gears however are much more universal. You will need a press but they're an easy install, not case-splitting. A set of 15/50 upgears are what you need, along with time spent tuning the CVT and maybe a jog90 rear td.

[benji]

May 20, 2019 11:38:18 GMT -5 mattyslimz said:

My goal is 50mph.

this is possible with tuning. Also, a Zuma 125 will do this OEM, no aftermarket parts. Making a scooter faster than stock is almost never "dependable" haha. An OEM Zuma 50 will go thousands of miles with no maintenance (I've seen 42,000miles on one) but mod it and you will need to maintain it more often.

[benji]

Here's a shopping list for ya..




A
I have a jog 90 rear pulley you can use. Or you can buy one, or buy an aftermarket one like the top performance TD.

[ryan_ott]

If you do the jog90 or Top Performance TD you will still need the Polini 248.041 belt. I’ve found that to work best with a stock sized (Polini) variator and the oversized rear pulley.

With the cylinder and pipe you have, stock cvt and up gears you should be able to reach the speeds you want. With tuning.. The gears are a part you can grow with. I would consider them.

[mattyslimz]

Ok great I’ll go ahead and buy the things needed now. Say benji do you mind sharing those discount vouchers with a fellow 49ccscootr’?

:edit:
I was able to decipher one voucher out. I tried a 49ccscoot one and the site said it wasn’t valid. Either way, I’m glad the gears are on the way, plus a few other things that were needed.

I held off on the rollers, contra and clutch springs because I’m probably just going to get Malossi “Multivar” and it has different size weights than the stock vario has and comes with a torque spring. No clutch springs because the adjustable S6 torque control seems pretty trick. I have an NCY rear pulley but it’s just a matching size to the stock TD only with better shift angles. It was cheap ($30) and it’s been collecting dust, I’ll give it a try with the new gears. 

[mattyslimz]

I added a rear shock (not res. adjustable just for looks) and a Stage 6 riser. The riser is for an Aerox so some grinding to the case and riser itself we’re needed. I really like the height now and with the spring tightened up it’s a real smooth ride. I can make deep left hand turns/U-turns with out the Buzzeti side stand scraping. I need to protect that as it’s my only stand, centerstand must’ve been removed by PO due to scraping or fitment of the pipe.





Today I will tackle these gears. Hopefully everything goes smoothly. I have a new nut and washer from Partzilla.com. I gotta buddy up the street that works at the Sunoco inspection station, they have a shop press, said just bring them up when I’m ready and slip him $30.. I will be bringing a 13mm socket to go over the shaft when it’s pressed to be sure it’s not crooked, I’m also going to put some gear oil on the shaft/spline to help with the process.






I’m getting max temps of around 245-250 with a new BPR8HIX iridium as opposed to the hotter plug BPR7HS non-iridium, temps were around  the same.. mind you this is still on factory oil injection with 2 cap fulls upon fill ups. Does anyone see temp changes or performance difference when moving from a hotter plug to cooler? 

[Jwhood]

Yeah I seen a 10-20 degree temp change when I switched from a br9 to a br8 plug

[mattyslimz]

Jwhood did you see any loss in performance with the cooler one? I’ve noticed these iridium plugs are much easier to foul. All the jetting and mixture must be right before putting in one of these $10 plugs.