Frame swaps?

[mga]

I have a Yamaha Big Bear 400 4x4 2000.  I've posted on here about the frame being bent. Does anyone know what year frames are interchangeable? Also, would the frame from a 350 be the same as a 400? Would it matter if it was a 4x4 or 2x4?

thanks for any help with this

[Gwbarm]

Thats a big job, never could get it right. Im not sure about frame swap, i know the 350 was different the battery holder was down next to the rear tire. The 2000 big bear 400 was the first year and i think it changed fairly rapidly on the early models, im thinking maybe 2000-01 were the same and then there were some changes but maybe not in the frame. I havent been able to find any information on that yet, but im looking.

[Mech]

Look the frame up in partzilla and it should tell you what other models it fits..  which are also the other models that will fit your bike.

[Mech]

Partzilla have changed their layout.. here's what they say are directly interchangeable.

2001

YFM400 Big Bear 2x4 YFM400 Big Bear 4x4

2000

YFM400 Big Bear 2x4 YFM400 Big Bear 4x4

[Gwbarm]

Good info Mech! I keep forgetting you can do that on Partzilla. Suprizingly my memory was good. 

I saw a couple of 2000 frames on Ebay for way too much money. I think if i wanted to go that route i would be looking for a parts bike locally, sometimes they go cheap and you have a lot of extra parts

 

[Mech]

Can the frame be straightened Mga ? I've straightened frames before. If they are bad we cut and then bend the tubes then weld them again. If it's just the entire frame a bit twisted they can be chained to a tree and tweaked using a long length of lumber and/or a come-along. The wheel alignment is nothing near as important as in a road going vehicle.

[Gwbarm]

I remember this thread from a while back, didnt you buy something new, and try to straighten the frame, im assuming it didnt work.

[mga]

On 7/19/2024 at 7:47 PM, Gwbarm said:

I remember this thread from a while back, didnt you buy something new, and try to straighten the frame, im assuming it didnt work.

only bought a new A arm...didn't help. I see a few big bears for parts...i was just wondering about the frames. i guess i could try to straighten it.

thanks for all the feed back.

[Gwbarm]

I think i would try that first, its a big job swapping frames.

[mga]

On 8/9/2024 at 1:16 PM, Gwbarm said:

I think i would try that first, its a big job swapping frames.

i guess you're right. I'll try that this winter when i have the time. I just thought swapping frames would be an easy way out, but, after getting the feed back, it would be difficult to get everything back to normal.

I think i'll have to just bend the front end to the right. the left wheel is about an inch back from the right wheel. At this point i have nothing to lose trying to bend it back

thanks again!!

[Gwbarm]

Another thought, you might find another quad that needs work cheaper than a frame, when i was looking on ebay they wanted more for a frame than i paid for my whole Big Bear, but i did have to rewire it and do a few other things. Straitening it would be the cheapest option. My philosophy is if it can be bent it can be bent back. 

[Mech]

Yup. If you are in the country then find a good tree and gets some big blocks of wood. Chain the bike to the tree carefully, on blocks so it's real solid if you are going to twist it, then use something to bend the whole frame or just the tube you want bent., a big lever/beam of wood, chain-block, fence strainer even would probably move it.

The slow pull of a chainblock or fence strainer is best. Use lengths of timber as straight edges and to measure from to check things.. Once you'd figured how you are going to chain and block it and apply the force where you want it, then it's  only a couple of hours work. You might need to put a short length of plank inside  the frame somewhere to pull on or for the chain, so the pressure is spread out. Wherever you apply pressure it needs to be spread over at least the length of the pipe/tube you are bending, but in this case with a twist or bend that's not obvious try to apply pressure so it's pressing on the frame top and bottom, or perhaps left and right, rather than pulling on one point. It will move easily with a small chain-block.

I'd take the wheels off on a flat floor and make measurements off the floor and straight-edges to work out what direction and where the bend needed to be, then i'd figure out how I was going to chain and bend it, then put the wheels on and drive it to the tree. I'd spend a couple of days figuring how and what I was going to do till I had it all clear in my mind, and was confident it would bend as I needed. At the tree and as it gets bent you'll have to use straight-edges and looking across tubes that are supposed to be parallel, checking that when viewed so they appear with a small gap between them, they do look parallel.