Author Topic: Pre 75 XL250  (Read 8517 times)

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Offline steve234

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Pre 75 XL250
« on: June 28, 2013, 10:50:32 am »
Looking at setting up an XL250 for pre 75 dirt track and vmx. What are the pitfalls and things to look out for on these babies?

Cheers,
Steve
Bultaco M106 Astro
Wanted: Dirt track bikes / parts / info

Offline Tim754

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Re: Pre 75 XL250
« Reply #1 on: June 28, 2013, 03:45:55 pm »
 What are the pitfalls and things to look out for on these babies?
On the track ,other competitors.............
Seriously find and fit a NOS 305cc kit and ditch the points for an electronic setup. Put your left over hard earned after those two items into the suspension and handling, don't spend it on trying to extract non existent mega power, You will end up with a lot of frustration and dead engines. If you must just bolt an early side port XL350 in, straight fit up   Change the oil very very frequently!!
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Offline Slakewell

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Re: Pre 75 XL250
« Reply #2 on: June 28, 2013, 04:30:31 pm »
1) Dont go for mega power thou methanol adds good torque
2) Weight you can remove like 15kg from these babies get that angle grinder cranking / Fit YZ mag rear wheel 8kg difference
3) Fit later model XL or CR fork legs to give a full 7 ich travel standard is 5. The chrome legs will bolt straight in to original bottoms.
4) Mid 80's Husky seat will bolt on with a little work
5) Fit ignition from postie bike
6) Shave a 1kg from fly wheel if you like to rev
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project. Dont need a pickle just need to ride my motorcickle

Offline steve234

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Re: Pre 75 XL250
« Reply #3 on: June 28, 2013, 04:58:37 pm »
On the track ,other competitors.............

Sounds like one would suit me then  :D

Thanks for the comments.
Bultaco M106 Astro
Wanted: Dirt track bikes / parts / info

Offline huskibul

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Re: Pre 75 XL250
« Reply #4 on: June 28, 2013, 05:49:40 pm »
    Geez steve bit of a change jumping off a pre 75 360 astro onto a xl250 must be looking for a challenge   :)

Offline bazza

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Re: Pre 75 XL250
« Reply #5 on: June 28, 2013, 06:59:23 pm »
305 kit,medium cam,larger valves,large exhaust pie,shave flywheel,electronic ignition,methanol
try to stop smiling
Once you go black  you will never go back - allblacks
Maico - B44 -1976 CR250- 66 Mustang YZF450,RM250
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Offline steve234

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Re: Pre 75 XL250
« Reply #6 on: June 28, 2013, 08:50:05 pm »
    Geez steve bit of a change jumping off a pre 75 360 astro onto a xl250 must be looking for a challenge   :)

Have been considering a small bore modern (either 2T or 4T) then saw this (below), then read that story about the honda sand racer and thought, why not keep it pre 75, keep it simple and keep it cheap (to run). Looking down the barrel of some hard economic times ahead, so that hot rod 450 4T is a long way off for now.



Queried the bloke who posted this pic and he reckons its a stock frame, just looks well set up.
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Wanted: Dirt track bikes / parts / info

Offline MX?

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Re: Pre 75 XL250
« Reply #7 on: July 02, 2013, 07:14:39 am »
Bit of inspiration for ya Steve.
You know you want to.....:P

Offline Andrew L

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Re: Pre 75 XL250
« Reply #8 on: July 02, 2013, 07:39:44 am »
350 swingarm is longer and makes them less nervous
"You have not made any mistakes if you find extra pieces after assembling an object. In fact you have just found a way to make the object more efficient."

Offline steve234

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Re: Pre 75 XL250
« Reply #9 on: July 02, 2013, 04:00:53 pm »
Bit of inspiration for ya Steve.
You know you want to.....:P


Ha ha yeah saw that and it looks great.
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Wanted: Dirt track bikes / parts / info

Offline firko

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Re: Pre 75 XL250
« Reply #10 on: July 02, 2013, 04:59:34 pm »
That beautiful XL reminds me of Steve Greentree's legendary XL250 that dominated the pre 75 4 stroke class nationally for nearly all of the 90's. It was equally as pristine and super fast..........
Nice job.
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Offline Slakewell

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Re: Pre 75 XL250
« Reply #11 on: July 02, 2013, 05:13:20 pm »
If I did another one of these I would add a rib around the swingarm Pivot and find another swingarm from something.
The cushdrive cast iron rear hub on these things is way to heavy I think the rear wheel weighs in at 12 kilo's when you compare to a Yamaha that weighs 4kg. You can shed 8kg just changing wheels. The lack of cushdrive is OK on the 250/305 as long as you dont try for stupid HP the gearbox holds up.The hotted up 350 is a different story.
Current bikes. KTM MC 250 77 Husky CR 360 77, Husky 82 420 Auto Bitsa XR 200 project. Dont need a pickle just need to ride my motorcickle

Offline 80-85 husky

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Re: Pre 75 XL250
« Reply #12 on: July 02, 2013, 06:32:21 pm »
Ol mate had a 305 kitted xl years ago and it regularly sheared flywheel keyways. This was BL (b4 locktite) any ideas on how to sort that issue? I told him to machine 25% off the flywheel so it wasn't rotating to much mass too quick

Offline matcho mick

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Re: Pre 75 XL250
« Reply #13 on: July 02, 2013, 06:54:04 pm »
i run TL flywheel, bit lighter,but i'm binning my 350 motor,(mxer),going back to 250,bloody 350's a lump to jump  ;D,want save $'s stick 350 cam in 250,CR back wheel saves bit of weight,or SL350?,(cheaper than CR),just be kind on gear changes?,think 3rd to 4ths the dodgy one??, :P
work,the curse of the racing class!!
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Offline 80-85 husky

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Re: Pre 75 XL250
« Reply #14 on: July 03, 2013, 11:02:41 am »
The weight balance on the 250 is a lot better than the 350.. if the 350 got out of shape it was generally a trip to the scrub whereas the 250 could be kept in check a lot better.

I had ATF and some air in the forks and koni shox on the back. mikuni carb and a Pascoe peace pipe.....not peacefull.

I repacked it with steel wool one day and then visited some mates and had a few jars..... on the way home, at nite, decided to wring her out in top gear... suddenly lights behind me everywhere .. shit its the cops!! :o

looked around and a 6 foot flame was jetting out the pipe from the oil in the steel wool!!

impressive..frightened the cr*p out of me