How NOT to build a 450 conversion...

dubious01 · Post by **dubious01** » October 29th, 2010, 5:02 pm

This is a chasis I bought already converted. I knew the cradle would requires some work but never figured I'd find it almost destroyed, once i got the pipe off it, the damage was clearly visible.
It was still a decent deal considering the components it came with.

There is no lateral strength in the direction the motor rotates when it applies torque to the chain.

The motor is able to apply torque across the front and lower motor mounts, which lave less leverage over the top of the engine , the part that rocks the most!

The traditional design like the original oem headstay is much stronger in all the angles required.

The result was this frame that was repaired so many times ther was nothing left to fix. It needed replacement:

worlds longest reed spacer....

Now, the motor was a wore out whore, and i was fed BS about that one...
Mr Woodworth.... heads up dood cause if i see ya.... I have a nice suprise for you in return!

I am deeply disturbed to own such a wreck of junk, but as I said, the bike was a decent deal, and I knew i would be cutting the cradle out of it and replacing it all.

http://www.youtube.com/user/500bigbore · Post by **Roostius_Maximus** » October 29th, 2010, 5:13 pm

wtf is that spacer doing on the wrong side of the reed, and its giant!

Post by **AlisoBob** » October 29th, 2010, 5:16 pm

I think just the weight of it is what cracked the frame!!!

dubious01 · Post by **dubious01** » October 29th, 2010, 11:16 pm

Thats the way it came. I have a a ton of questions...haha

Why are the lower motor mount welds contaminated with iron oxide...
why was the piston 1 size smaller than it was bored for...
why was a prox piston used in a jug with oversize exh ports
why was the headstay not built proper
why the short air boot and long reed spacer
why ceramic coat the head dome, and not the piston dome...
why not use proper bushings, instead of washers for the swingarm / motor spacing...
why was the electrical wiring in such bad shape the plug cap fell off wire
why bubblegum wirefeed weld cracks, instead of fixing the cause of the problems.

I got a pile of questions, and only one answer....

anyway, the frame is getting complete new 1" square by .125" wall cradle tubes bent , fresh engine, clutch, plastics, linkage and swingarm bearings, bars, tripple clamps, cables, etc... a new bike with some nice goodies.

I am environmentally friendly.... I just recycled another of the worlds finest earthmovers!

Tharrell · Post by **Tharrell** » October 30th, 2010, 3:48 am

Just curious, what did you pay for it?

dubious01 · Post by **dubious01** » October 30th, 2010, 9:40 am

I would have to substantiate that with a parts list, local market pricing, or else shipping from US to Canada.

In hindsight I should have payed to have one shipped from the states, but would still need to see, or ride one first hand, so factoring shipping and travel, brokerage... its a wash.

Too much $ due to my location would be my perspective.
If I could have bought one from a guy like Paul Stoffers, RobertG, just to name a few that have been for sale lately.. etc with their reputation would have been a better deal for sure.

I am sure there are other good builds out there for a decent deal, but knowing there is no interference with the kickstarter, pipe, tire and pipe, rad clearance, crossover hose clearance, clutch casting clearance, countershaft alignment etc ....

ususally people are selling stuff cause there is something wrong with it, not because they want to build another, that is unless their in business.

gregrobo · Post by **gregrobo** » October 30th, 2010, 6:20 pm

what is the rest of the bike like

nmdesertrider · Post by **nmdesertrider** » October 31st, 2010, 4:04 pm

Throw the frame in the junk heap and start from scratch... 150$ frames show up on ebay if you are patient.

Mik329 · Post by **Mik329** » October 31st, 2010, 7:40 pm

nmdesertrider wrote:Throw the frame in the junk heap and start from scratch... 150$ frames show up on ebay if you are patient.

Exactly, I have three 250f frames sitting in my basement and not one was over 150 bucks

cryzsurfer · Post by **cryzsurfer** » November 1st, 2010, 4:32 am

That might be some type of dye penetrant leaching out from some of the cracks. Once it gets in the crack it'll keep coming out until it's fixed or in this case possibly scrapped. It's just a possibility. There are tons of cheap four stroke frames on eBay every day.
Craigus

dubious01 · Post by **dubious01** » November 1st, 2010, 7:10 am

its either getting new cradle/ rails formed, or another frame.
will figure it out this week.

Not sure what the implications are for shipping frame to Canada.
New owner will want to register it for offroad....

I am keeping my Gen4 CRF250F roller for my own personal bike and selling the 450 gen 3 chasis, plastics etc,

I like the Gen3 smaller chasis

I posted to display how an improper head stay can allow engine vibes and torque to destroy a frame.

100hp honda · Post by **100hp honda** » November 2nd, 2010, 4:46 pm

i could be wrong but i dont think headstay had anything to do with all your cracks. theres 3 solid motor mounts controlling torque

. dont think vibration cracked anything either. cant recall ive ever seen a head stay on a drag qaud. alot of them have 2x the torque our bikes have. cracks were all in the heat affected zone of the weld, were the temper has been erased

. blame the welder

Post by **AlisoBob** » November 2nd, 2010, 5:01 pm

Clyde, look how much the motor is moving around...

I think a good head stay is a requirement.

I also "match drilled" all the motor mounts to the engine cases. using oversized hardware. Took all the slop out of the connections.

Post by **AlisoBob** » November 2nd, 2010, 5:02 pm

Hey Dub, sent the frame to soliD , for a new cradle and proper head stay.

dubious01 · Post by **dubious01** » November 2nd, 2010, 5:11 pm

I could do that, but I need him to call me back.

I called him today as you told me to do, and left a message.

I found a CR250R frame in California that would be a better donor, better geometry, and easier build, plus I want to get this bike out to its new owner asap, 1 way shipping is alot faster than 2 way, and cheaper too!

If the price was reasonable, I would buy one if has one on hand, maybe a 2nd one before the new year.

I have 3 engines.

edit,.... 2 of those engines, 4 cylinders, 2 carbs, 2 heads, are enroute to Winkler Manitoba. went out yesterday, and should be back around end of the month I am told.

Post by **AlisoBob** » November 2nd, 2010, 5:19 pm

soliD is hammering on his Gen4 A/F, for the Elsinore GP this weekend.

He'll get back to you.....

dubious01 · Post by **dubious01** » November 2nd, 2010, 7:06 pm

Thanks Bob,
all I need is a price, and a mailing address to send him this 05 250R frame I just bought. Its already in California.
they will only hold it for 2 days for his address, then they will ship it to me in Canada

Post by **AlisoBob** » November 4th, 2010, 5:25 pm

AlisoBob wrote:

Clyde, look how much the motor is moving around...

I think a good head stay is a requirement.

I also "match drilled" all the motor mounts to the engine cases. using oversized hardware. Took all the slop out of the connections.

This motor has been sitting in this chassis for 5 years.... ZERO movement.

gregrobo · Post by **gregrobo** » November 4th, 2010, 8:40 pm

100hp honda wrote:i could be wrong but i dont think headstay had anything to do with all your cracks. theres 3 solid motor mounts controlling torque . dont think vibration cracked anything either. cant recall ive ever seen a head stay on a drag qaud. alot of them have 2x the torque our bikes have. cracks were all in the heat affected zone of the weld, were the temper has been erased . blame the welder

blame the welder your the man 100 dont worry about the under engineered head stay that is the obvious cause the welding isnt nice but glad you chipped in

100hp honda · Post by **100hp honda** » November 4th, 2010, 9:34 pm

the welder makes or breaks the job. should of completely wallered out the engine mounts before anything cracked

chachi243 · Post by **chachi243** » November 5th, 2010, 7:18 am

the welder should have used TIG and hand fed the alloy rod in there, those ginormous aluminum MIG welds just stack a cold pile of alloy right on top of a seam with no real penetration..... maybe the welder (machine) and not the welder ( hillbilly fabricator) is to blame..... either way most fabricators know tig is stronger than mig in this particular application.....

good on ya to save them other components from the scrap heap!

dubious01 · Post by **dubious01** » November 5th, 2010, 9:05 am

Thanks,
Ya I noticed the welds were mig, and am going after tig.
Either way it will be fixed right and i recycled a 500!
Roosty has the motor... it needed love too.

I guess some guys have no issue with riding a bike into the ground,

Post by **AlisoBob** » November 5th, 2010, 9:57 am

dubious01 wrote:I guess some guys have no issue with riding a bike into the ground,

nmdesertrider · Post by **nmdesertrider** » November 5th, 2010, 9:15 pm

Another frame breaker is not having the right bolts holding it together- if they are too skinny the motor will move around and shake it apart.

My current frame I used regular width mounts so I could use the original bolts- real happy with that decision I haven't had to tighten them once in the last year.

dannygraves · Post by **dannygraves** » November 6th, 2010, 9:23 am

bearings??? I made a gen-4 250 that had some shitty welds, but was put together properly and it held together great until the rod bearing went, then it was riddled with cracks. All of those cracks look vibe related to me. I am not saying that was a well done conversion, I'm just saying, a messed up motor will vibe cracks into any frame if it vibes bad enough.

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