Starting a scratch build - 125cc or higher

[tpawyant]

Hi Guys!

I am looking to start a scratch build and to start, I am considering what motor would be a good solution for a non-racer type of bike.

To start, I am looking at either a 125CC or higher engine. Would a 150CC be much better? Are there any major performance differences between the difference in CCs?

Next, I am looking for a frame, swing arm and front fork setup.

Any tips would be greatly appreciated......or links would be great!!

 

[MiniFighter]

What are you looking at budget wise? A build from scratch (as a few members here know) can cost quite a bit more than buying a new bike.
A lot of research also needs to be done on parts as a few wrong parts purchased can blow your budget right out not to mention the ill effects it could have on the bike itself.

Building a 125 to me would be a waste of time, yes they are cheap but if you have any more than 5 mins riding experience you will find yourself wanting more only to realize youve wasted a few hundred bucks on an engine you dont want.

My advice would be to have a troll through the china builds section and take a look at what others have done and are doing and make a decision from there.

Good luck!


Wayne.

 

[THUMPINOZ]

There is basically 2 sizes, The real small bikes have 10" or 12" wheels then 12" rear & 14" front wheel

They are based on the CRF50 & the larger style CRF70

If you are fairly tall you will want a midsize bike with 12" & 14" wheels

This thread gives you a full break down of the bikes>
http://www.miniriders.com/minibike-reviews/35025-what-i-want.html

Most here will recommend getting a DHZ frame & going from there>

Heavy Duty Chromolly Twin Tube Cradle Frame CRF50

Heavy Duty Chromolly Twin Tube Cradle Frame CRF70

I went with an slightly cheaper option (Smaller CRF50 style frame)
An Atomik nitrous frame brand new for $55
A new aluminium swingarm for $63
Seat & plastics for $35 etc etc

If you have ridden much you will want a bigger motor, Most frames will take nearly any size thumpstar/pitbike style motor 50cc through to the new 190cc, A 125 will probably plenty enough for you to have fun but a 140 150 & 160 will make it even more fun but a little bit more expensive

Are you planning on doing big jumps or long distance trail riding?

+1 Minifighter, We posted pretty much the same ideas at the same time

 

[THUMPINOZ]

Some people especially young blokes may not be able to get there hands on 600-700 or 800 which is about the starting price for a half decent bike on ebay, It is a good way to build a good bike buying the upgraded parts as you go rather than buying a bike then having to upgrade all the parts after you have spent lots of dollars already, If you are building though make sure you have access to plenty of tools & have a fastener/bolts hardware shop close by to get all the bolts you may need, Being 2k's from the beach I will be buying some stainless steel bolts here & there

A good read, Dont get caught out like mr_plow>
http://www.miniriders.com/ask-tech-masters/35784-dramas-new-build.html

There is usually a fix for everything but good planning can save dollars

 

[MiniFighter]

Some people especially young blokes may not be able to get there hands on 600-700 or 800 which is about the starting price for a half decent bike on ebay

totally agree there mate, but two or three, four months saving to buy one will work out way better than two or three months into a build, having spent the same amount if not more and only being half built..

Check the china builds thread, theres you proof. Multiple build threads on bikes that were never completed. Even i have a build or two in there that never amounted to anything other than lost coin.

 

[THUMPINOZ]

This is where I got my frame, Swingarm, tank, Axles & (BLACK) plastics & seat for a good price, A good way to get started with most of the bike>

hagentools | eBay

He currently does not have the frame & swingarm listed>
hagentools | eBay

hagentools | eBay

I will be buying a set of good forks & shock like GPX DNM or Fastace, Maybe GPX, DNM & fastace seems to be better quality but you pay for it

 

[THUMPINOZ]

totally agree there mate, but two or three, four months saving to buy one will work out way better than two or three months into a build, having spent the same amount if not more and only being half built..

Check the china builds thread, theres you proof. Multiple build threads on bikes that were never completed. Even i have a build or two in there that never amounted to anything other than lost coin.

Yes I do agree with what you are saying too, Without good planning & just buying (expensive) parts here & there willy nilly it will end up costing much more than buying a bike outright

1 of the (only) good points is knowing that it is all assembled properly & the triple clamp bearings etc are greased properly

Im starting out with a cheaper style bike but im going to have some damn nice parts on it & with my build it wont really cost much more than buying outright, I spent some time planning it though looking at different parts & prices

 

[tpawyant]

Hey Guys! Thank you for the great responses. To give you guys some background on me. I currently have a 70CC and 110CC KC Powersports bikes. The 110cc has an upgraded CDI and some cosmetic upgrades. I have a 14" front wheel and tire assembly coming in to make it look a little more aggressive. the rear is fitted with 12". I will post some pics of the bike. The 70 is what my 10 yr old rides, so I can upgrade that one...its all ready fast enough for him.

My goal is to have a project bike and build it up over time, say about 6 months or so. I agree with your points. For example, I am really looking at a 125CC or higher...it really would not make sense to just build a 125.

Regarding the really intricate parts (IE: Front fork setup), I was thinking about just buying a pre assembled setup including triple clamps, bearings, etc. The engine would be all inclusive. Frame components, brakes, rear suspension, plastics, etc would be handled by myself.

Naturally, like building anything, you measure 3 times and assemble 1 time. I am not sure how you would order a 12mm wheel knowing you have a 15mm axle mount. These types of things, plus forums are where you can get advice on your direction.

Now, to the type of riding i plan on doing. First, it would be just bashing around, but maybe some small jumps. I am approx 5'10" and weigh about 155lbs.

 

[THUMPINOZ]

The wheels can be ordered with either 12mm or 15mm axles, Best going with 15mm axles though

 

[tpawyant]

The wheels can be ordered with either 12mm or 15mm axles, Best going with 15mm axles though

Yes, I understand that, but if you forks require a 12mm axle, why would a 15mm wheel be purchased. That's all I am saying.

 

[THUMPINOZ]

Most of the better more expensive forks have 15mm axles

What sort of budget do you have? If your like me with kids you will of course be looking at spending the least amount of money possible?

 

[tpawyant]

Most of the better more expensive forks have 15mm axles

What sort of budget do you have? If your like me with kids you will of course be looking at spending the least amount of money possible?

True thump!! Kids and all. To be honest, there is no necessary budget on the bike. It will make me feel better if I don't know the overall total build cost. I plan on taking the time to build it. I really don't need it, more of a project. I might sell it when done.

I am thinking of per piece budget. For example, I am looking at ordering the following items for phase I:

1. Frame
2. Swing arm
3. Fork set up (pre assembled)

Maybe just the frame and swing arm. Forks look like one the more expensive items and could be part of phase II.

Thoughts??

 

[THUMPINOZ]

My frame & swingarm cost me exactly $166 including delivery

Im going to get some forks soon say cant say yet?

You can spend big money on forks as you mentioned, They can cost more than buying a cheap pitbike, Im thinking maybe a set of GPX black labels but they are not cheap>

GPX Moto Minicross Black Label Fork Kit 730mm Complete Kit

There is not much really in between, Its either buy some cheap ones that may not work real well or pull out the wallet & pay the dollars for the better ones?

I have a set of triple clamps to suit these forks, If someone wanted to do a deal I would be willing to pay $250 for the fork tubes & someone could have the triple clamp set for $150?

 

[THUMPINOZ]

What style of bike are you thinking of? CRF50, CRF70, KLX or TTR
About the cheapest option is the one I mentioned/linked, Atomik Nitrous/CRF50 style frame

The Pitpro 125RR is the same bike so lots of parts cross over for the CRF style bike>
http://www.miniriders.com/chinese-minis/35806-atomik-nitrous-pitpro-125rr-similarities.html

This is an Atomik Nitrous CRF50/Smaller style bike which usually has the 660MM forks standard but this one has the longer 735mm/740mm fork upgrade, I will be getting the longer set of forks for mine>

 

[tpawyant]

What style of bike are you thinking of? CRF50, CRF70, KLX or TTR
About the cheapest option is the one I mentioned/linked, Atomik Nitrous/CRF50 style frame

The Pitpro 125RR is the same bike so lots of parts cross over for the CRF style bike>
http://www.miniriders.com/chinese-minis/35806-atomik-nitrous-pitpro-125rr-similarities.html

This is an Atomik Nitrous CRF50/Smaller style bike which usually has the 660MM forks standard but this one has the longer 735mm/740mm fork upgrade, I will be getting the longer set of forks for mine>

That fork setup looks awesome. I would need to find something like that in the states. but I would not be opposed to spending $300 USD ish on a fork setup.

Regarding the type of bike, I am not sure yet...still looking around. I think I am going to go for the 150cc Lifan motor.....and I am looking for a bigger bike compared to the KC 110CC i have now. I assume the 70 style frames are larger and would be better suited for an adult (5'10") rider? Also the KLX is the kawasaki knock off and the TTR would be??

I also need to source my parts from US.

EDIT: I do want at LEAST a 14" front. do any of the bike support a 14" rear, 16" front? Any advantage?

 

[tpawyant]

Would something like this item be good?

Pit Bike Front Forks & Clamps 730mm Pitster Pro Piranha

 

[THUMPINOZ]

Yeah but note them ebay forks are non adjustable, Spend a little bit more for better forks

There will be plenty of Mini shops over in the US that should have the GPX black label forks?

 

[THUMPINOZ]

Someone like this shop for example>
sgr-usa.com