What should i do??

T

thestu

New Member
Hey guys

atm i have a mountain bike with a 70cc kit on it...

it vibrates like **** (I have read up a little on reducing the vibrations)

I lost my car licence for 2 years so i'm going to be doing a few 100km's on it a week so i want something i can just cruise on comfortably but the 2 stroke kills my wrists!

I was thinking i need something with suspension and maybe a 4 stroke engine?

I would love a cruiser style bike but i have no idea where to buy one in Aus..

What style should i go as i ride a lot and need something comfortable? cruiser or a mountain bike?

And should i keep the 2 stroke and get a jack shaft kit or get a 4 stroke (can you get a multiple speed gearbox for these)?

so many questions i know!!! links to peoples bike are always good too!

Stu
 
I think all the 2-strokes vibrate like nuts, mine does. Some suspension helps reduce that a bit on the body. You can get, springer forks, suspension for you handle bars, and seat post suspension.

If you have fenders on it, you will want to re-enforce them.............there's some good threads here for that.

Outside of these things, you can balance your crank and some guys do that. All in all, for the money (very cheap) a 2-stroke is a great way to go, but there again, you get what you pay for.

A 4-stroke will give you a smoother ride and better reliability, but it will cost much more.

dnut
 
Well i cannot speak for everyone else but i make sure that the rear mount is 100% square and tight with the seat tube this may require filing or grinding the halve moon to re align it so the front is also square. i use a mountain bike with front shocks and i cannot feel much vibration even at full noise.

Forget rubber!
 
While any single cylinder engine will vibrate (yus - even the wonderful 4stroke lol), often times it's not actually just the engine running that's at fault. The number one cause of excessive vibration is the stock "rag joint" style rear sprocket mount and overall chain alignment, while ofc you can get it "pretty close" there's simply no way to get it perfectly aligned.

An aftermarket sprocket adapter that clamps directly to the hub or bolts to a disk brake mount would do wonders, as would a shift kit if it's in the budget, making sure your front and rear drive sprockets are as close to perfectly aligned is a must in any case.

Another source of undue vibration is the "tensioner" - even IF it's actually been bent to be inline with the chain and not the chainstay - it's still a hard plastic wheel that tends to chatter as the chain links travel over it. Doing away with the tensioner if you can or making one with a skate wheel would help - see this thread for some ideas: http://motorbicycling.com/f11/chain-tensioner-suggestions-11815.html

The typically low-quality chain that's included tends to be a touch twisted and with a few binding links - there's another source of much vibration. Replace it with a quality 415 if you can find it, a 41 if ya can't - usually available at any good hardware store. Rule of thumb - quality chain isn't cheap, while you can find 41 and even 415 "heavy duty" chain for anywhere from ten to twenty bucks fer about 10' or so - don't be fooled by the label, it'll prolly be quite significantly better than the stock chain... but it sure as heck isn't "quality" lol True performance chains can run up to a hundred bucks, but that's no doubt overkill heh

Yet another source of the bad shakes is a poorly tuned engine, while many of these 2 strokes will "4 stroke" when not under load and/or still being broken in (misfiring), often it's a simple case of running too rich and/or poor ignition. Replacing the plug with a properly gapped NGK B5HS or B6HS (.025-.030 gap), running it for a while at speed and checking it's color (after cool down ofc), then adjusting your air/fuel mix accordingly (needle clip setting) should help quite a bit.

Here's one that's often misunderstood - attempts to dampen felt vibration by using soft rubber shims, wraps or any other means of isolating the engine mounts from the frame will in actuality INCREASE vibration and can lead to premature fastener failure. Not only will the vibration of the engine wear/cut through the padding in a matter of time (leading to "loose" fasteners as well), these engines simply were not designed with soft mounting in mind. With only two points of contact and both of those quite low - there's just too much leverage to be anything other than hard mounted. There's been some success with hard polyurethane mounts - but that entailed a mount redesign and some welding - the typical "chunk of innertube" method is a recipe for eventual disaster.



When it comes down to it, a properly maintained, tuned & mounted kit really isn't that bad - adding in some quality street tires, gel grips and a soft, sprung seat takes care of the inevitable vibration of a single cylinder - throw in a set of front shocks and yer stylin' ;)
 
This is all great info guys!!! Thanks heaps!!!

Do any of you have a sick bike parts jack shaft kit? Worth getting?

And also where would I find a cruiser style bike? I had a quick look on eBay and didn't find much....
I probably wasn't search the right things!

Stu.shft.
 
EVERYONE that's gotten the HD SBP shiftkit has loved it, usually swearing to never build another bike w/o it... heck - I've even got one, but I've not finished the bike it's on yet :(

Cruisers? Not to sound like a jerk but they're so common and can be so inexpensive new that I'm really surprised you tried ebay o_O Ya got any bike shops around you? Large department stores? Yardsales lol?
 
thestu said:
T
And also where would I find a cruiser style bike? I had a quick look on eBay and didn't find much....Stu.shft.
Click to expand...

Type in "cruiser bicycle" in the search, you'll find lots of them. Also, if you like the greenlines, there's a seller named Greenline_outlet (or something like that) and they will get shipped right to your door free of charge. I bought a single speed off him last year and I have no complaints. If I had the money, I'd buy another one off him.
 
Alright well I guess I'll just hit up a nice mountain bike :)

what sort of speeds can you maintain comfortably with a jack shaft kit?

Stu
dnut
 
BarelyAWake said:
Cruisers? Not to sound like a jerk but they're so common and can be so inexpensive new that I'm really surprised you tried ebay o_O Ya got any bike shops around you? Large department stores? Yardsales lol?
Click to expand...

Nope not over here in Aus they arnt, of all the mbs and bicycles for that matter i have only ever seen 2 cruisers over here.

This is the only distributor that i have found that has edit had, well someone is buyin them cruisershttp://www.mbbimports.com.au/product.php?pid=70
Cost $400 for a bike alone no kit!!!

Its just a different market over here mountain or road bikes thats it, i buy general bike parts from 4 different bike shops none sell a cruiser
 
stv1jzgte said:
Nope not over here in Aus they arnt, of all the mbs and bicycles for that matter i have only ever seen 2 cruisers over here.

This is the only distributor that i have found that has edit had, well someone is buyin them cruisersGT1 BEACH CRUISER
Cost $400 for a bike alone no kit!!!

Its just a different market over here mountain or road bikes thats it, i buy general bike parts from 4 different bike shops none sell a cruiser
Click to expand...

o_O

Crazeh aussies lol, sorry to hear that - but a mountain bike makes for a fine MB anyway *shrug* I'd just keep an eye out for the cruiser of yer dreams while yer riding and perfecting the mountain bike...

oh wait...

That's exactly what I did heh :D
 
BarelyAWake said:
o_O

Crazeh aussies lol, sorry to hear that - but a mountain bike makes for a fine MB anyway *shrug* I'd just keep an eye out for the cruiser of yer dreams while yer riding and perfecting the mountain bike...

oh wait...

That's exactly what I did heh :D
Click to expand...

thats what im doing now. BUT am looking for a GOOD road bicycle, for my next build
 
thestu said:
Alright well I guess I'll just hit up a nice mountain bike :)

what sort of speeds can you maintain comfortably with a jack shaft kit?

Stu
dnut
Click to expand...

"Maintaining" speed depends on whether you ride in a flat or hilly area. If you ride in a flat area, depending on the gear ratio of your rear hub, you can maintain an EASY 40mph. Good wind behind you 50mph is possible. Helmet and disc brakes recommended at those speeds... Just upgraded to disc brakes on mine. Took me 1/2 block to stop from full speed before I did.

redriderdisc.jpg​
 
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Maxvision said:
"Maintaining" speed depends on whether you ride in a flat or hilly area. If you ride in a flat area, depending on the gear ratio of your rear hub, you can maintain an EASY 40mph. Good wind behind you 50mph is possible. Helmet and disc brakes recommended at those speeds... Just upgraded to disc brakes on mine. Took me 1/2 block to stop from full speed before I did.

Click to expand...
Agred pn all the above. Im as broke as a whore in a convent, BUT ive been hitting 40+ with a SLIGHT uphill ( 49.9cc) WITH V BRAKES:eek:(^)(). which is a NO NO. well rear brakes at that speed are ALL but worthless. my fronts are behind/underneath my clutch lever. so am going to relocate my fronts to where the rear controls are, and probably remov the rears. ( not sure exactly yet ), BUT discs are pretty much a necessity. 40+ on a 40+ pund bicycle/engine combo, can be scary at times
 
BarelyAWake said:
o_O

Crazeh aussies lol, sorry to hear that - but a mountain bike makes for a fine MB anyway *shrug* I'd just keep an eye out for the cruiser of yer dreams while yer riding and perfecting the mountain bike...

oh wait...

That's exactly what I did heh :D
Click to expand...

sounds good to me!!

Maxvision said:
"Maintaining" speed depends on whether you ride in a flat or hilly area. If you ride in a flat area, depending on the gear ratio of your rear hub, you can maintain an EASY 40mph. Good wind behind you 50mph is possible. Helmet and disc brakes recommended at those speeds... Just upgraded to disc brakes on mine. Took me 1/2 block to stop from full speed before I did.

Click to expand...

do i need to change the wheels to fir discs or just buy hubs with the disc fitted??

Update on the bike!

I have mounted it all correctly and loctited everything!!!

runs smooth now!! fitted a BP6HS plug and NGK wire...runs like a dream!

just have to get a better exhaust (expansion chamber), fix my kinked back wheel, Jet the carby to 84 (from memory), fit disc brakes and buy a jackshaft kit :D then i will start a 4 stroke 50cc 3 speed semi auto cruiser!!! :D

.shft.

Stu
 
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