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Post by Kenho21 on Oct 2, 2019 20:52:04 GMT -5
Hey all, Going to be tearing down and rebuilding my 1999 Yamaha Jog soon and thought I would start a build thread. This is basically how she sits now...  Not exactly sure how far I’m going to take it, but I know I’ll be doing: - Finally getting that 70cc kit running properly (thanks oldgeek !) - New crank - New gears (taller too) - New carb - New bearings, seals, etc... - Making it look perty - Who knows what else! Just basically want it to run like a “top” come spring time and with more power. My first question... Can anyone tell me or point me in the right direction of where to buy the correct size/spec and good quality innards of the cases (bearings, seals, brackets, special tools, etc., anything I can’t see or measure without opening the cases) before I get going? Here are the specialty tools I already own in addition to all necessary common hand tools: - Compression tester - Crappy blind hole bearing puller - Pressure tester - Degree wheel - Variator removal tool - Magneto puller (or whatever it’s called) I’d like to have as many parts as I can on-hand before I start so that I’m not waiting for a random bolt in the mail once I have the cases split and the scoot out of commission. I do plan on riding at least to and from work throughout winter on it when the weather is permitting. This will be my first time splitting cases and messing with gears and cranks, so be gentle... Thanks much! |
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Post by 190mech on Oct 3, 2019 4:00:50 GMT -5
Bottom end parts are in a wide range of prices and shinyness,like Stage Shiny,or Moshiny.Kidding aside if you are going to run a street cylinder,a quality stock replacement will do wonderful.I'd get one with a 12mm piston pin,,
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Post by Kenho21 on Oct 3, 2019 5:29:30 GMT -5
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Post by 190mech on Oct 3, 2019 5:38:20 GMT -5
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Post by Kenho21 on Oct 3, 2019 6:21:14 GMT -5
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Post by 190mech on Oct 3, 2019 11:52:49 GMT -5
The $100 cheaper price tag caught my eye and its shiny too!
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Post by Kenho21 on Oct 3, 2019 12:34:47 GMT -5
The $100 cheaper price tag caught my eye and its shiny too! Definitely something to consider. I've been leaning toward a lot of Polini and Malossi stuff for everything inside the cases because I'm planning on using this as my daily driver for some time to come, don't want to crack them open again any time soon, and have heard a lot of good things about these brands. Admittedly, this may just be because they have been around longer and are more popular than some of the smaller companies and may not actually be any better quality. I don't mind paying for peace of mind and plan on getting my use of whatever I end up putting in there though. Would love to hear people's opinions/experiences with different performance brands. |
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Post by 'O'Verse on Oct 3, 2019 19:12:57 GMT -5
In my opinion the bigger and more established companies like Polini and Malossi have always been great go to products. To me it seems they just hold higher quality assurance from there factories. Hard to explain over the internet until you hold an actual product in your hand. Ofcoarse some of these companies have certain outsourced products too. But the quality is still present.
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mattyslimz
Scoot Enthusiast
Posts: 222
Location: Northern Virginia
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Post by mattyslimz on Oct 3, 2019 21:12:43 GMT -5
The Malossi “RHQ” crank is doing awesome on my freshly built Zuma even though I haven’t fully tuned the CVT and carb (yet). Was very true and the metal just had that quality look to it if you will. It’s an HPC crank so it’s powerband is quite different than a stocker but boy what difference. I was considering a Stage 6 crank as well (not R/T) they have an LPC variant of their solid looking cranks too. I’m considering one of what Stage 6 has to offer on my next project QJ RX8 1e40qmb.
The “EZBOOST” tools like flywheel puller, bearing separator and seal installer worked very well for my build.
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Post by Kenho21 on Oct 4, 2019 9:19:01 GMT -5
Yeah I was between Malossi and Polini for a crank, but am getting some other Polini parts, so I figured why not Polini for a crank too. Both seem to be highest quality (and prices) out there from what I can see.
I don’t see myself building anything hyper race oriented like that stuff sounds. I’m not even sure what those initialisms you mentioned mean lol. Sounds like you’re making a ton of power though! What size kit are you running?
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Post by Kenho21 on Oct 4, 2019 9:21:36 GMT -5
Also, I’m thinking of switching back to vacuum driven oil injection for this too... with a .9ish gallon tank, I’m tired of having my rides limited by the tank size. Pretty sure it pulls a fairy rich mixture. My girlfriend’s jog is basically stock and the exact same as mine and runs great with it. Even with a 70cc kit, I think it would be fine. From what I understand, a lot of Europeans keep the oil pump, even with kitted bikes.
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mattyslimz
Scoot Enthusiast
Posts: 222
Location: Northern Virginia
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Post by mattyslimz on Oct 4, 2019 11:30:26 GMT -5
I’m not even sure what those initialisms you mentioned mean lol. Sounds like you’re making a ton of power though! What size kit are you running? HPC means high primary compression. An HPC crank will be heavier for less torque, but have more volume leading to more power up top. An LPC primary compression crank (low primary compression) will have less volume leading to a higher charge at low rpm (better for low end torque) HPC Crank  LPC crank (notice the cut-out of the circle)  I have a 70cc Stage 6 MKii race bore but its nothing I could ride to work daily. It works well with the HPC Malossi crank because this bore is high strung and only makes power past 10,000 rpm. |
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Post by Kenho21 on Oct 4, 2019 11:47:16 GMT -5
Ohhhh okay. Wow. I wasn’t familiar with this concept really. Totally makes sense though. Makes a difference in the crank I choose. Is either type of crank more or less favorable as a daily driver crank?
The Polini crank I’m looking at is an HPC crank, which is what I’d prefer. Definitely care more about top end than a wheelie machine.
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Post by Kenho21 on Oct 4, 2019 11:48:38 GMT -5
Now that I’m paying attention to it, there’s definitely a lot of variance between cranks and the cutouts. Wow! Thanks for breaking that down for me.
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Post by pitobread on Oct 4, 2019 14:30:39 GMT -5
A heavier crank doesnt mean less torque. It would increase "torque" as it would give more flywheel effect (storage of energy via mass). But really it's a bad use of term as it doesn't increase or decrease torque. It simply changes how that torque is applied. Light stuff = more zingy. Heavy stuff = more luggy
A heavier crank will help you carry speed a lighter one will get speed faster.
Then there is the whole HPC thing.
HPC is kinda a buzzword that gets thrown around a lot. Shoot, even I thought it was good for a while. But there is a magic ratio of crankcase compression. Everything above and below that is not ideal. And it's not just throw a HPC crank in and boom you got the ratio. Everything from transfer ports to piston to reed valve play into that number. From guys much smarter than I they say the only true way to figure it out is to cc the entire engine as a whole.
What increasing primary compression does do though is much like heavier weight of crank, can change where the powerband comes on. And in some cases on some setups that's desirable. In others, not ideal.
What does all that mean? Pick an affordable quality crank and dont get too caught up in the rest.
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