OzVMX Forum
Marque Remarks => Honda => Topic started by: steve234 on June 28, 2013, 10:50:32 am
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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
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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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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
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On the track ,other competitors.............
Sounds like one would suit me then :D
Thanks for the comments.
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Geez steve bit of a change jumping off a pre 75 360 astro onto a xl250 must be looking for a challenge :)
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305 kit,medium cam,larger valves,large exhaust pie,shave flywheel,electronic ignition,methanol
try to stop smiling
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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.
(http://i948.photobucket.com/albums/ad326/Steve234_album/XL250.png) (http://s948.photobucket.com/user/Steve234_album/media/XL250.png.html)
Queried the bloke who posted this pic and he reckons its a stock frame, just looks well set up.
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Bit of inspiration for ya Steve.
You know you want to.....:P
(http://i32.photobucket.com/albums/d14/photos2u/XL250/Leftside3.jpg) (http://s32.photobucket.com/user/photos2u/media/XL250/Leftside3.jpg.html)
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350 swingarm is longer and makes them less nervous
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Bit of inspiration for ya Steve.
You know you want to.....:P
(http://i32.photobucket.com/albums/d14/photos2u/XL250/Leftside3.jpg) (http://s32.photobucket.com/user/photos2u/media/XL250/Leftside3.jpg.html)
Ha ha yeah saw that and it looks great.
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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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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.
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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
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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
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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
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Back in the 90's I built a very stout XL350 motor using a box full of goodies I bought in the USA. I resisted going big bore and kept it at 350 but used a 12:1 Venolia piston, Megacycle roller cam and springs, ti retainers, Carillo rod, a very nice port job, lightened rockers and CT110 CDI ignition, 36mm Amal MK2. The engine hooted but because I used a non cush drive rear Bultaco wheel I had problems breaking third gear. I was looking into light cush drive hubs and had settled on a small Yamaha hub (can't recall what it was out of) but sold the bike before I bothered.
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That would have been a hummer allright, no wonder third gear went west, they were weak at the best of times.
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Are you guys talking about keeping it in an xl frame? I have a big bore motor as well and an xl roller but keep getting told the frame is a piece of crap.
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090 the XL frame is okay just take to it with a grinder. Remove all unwanted brackets look at losing as much weight as possible. When you finished the race at the front of the field you know you've worked for it. ;D jimson
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Are you guys talking about keeping it in an xl frame? I have a big bore motor as well and an xl roller but keep getting told the frame is a piece of crap.
I've been around this sport since the beginning and during that time I've seen XL Honda motors fitted in everything from Elsinore's to Maicos to CZ's to Bultaco's to Husky's and others including C&J and my own Champion. Despite some of those swaps being successful, the most successful pre 75 4 stroke Honda's have nearly all had the stock frame. Steve Greentree and the Smith Bros from Victoria had the class at ransom throughout the 90's with stock frames XL's, the only the occasional interjection being from a CCM, BSA or Trumpy. Cut all the superfluous shit off the frame, use the longer 350 swingarm, gusset the swingarm pivot area to stop flexing, especially when big horsepower motors are used and use the best forks you can find, find the lightest cush drive rear wheel you can and bung it all together. They handle fine and they're not that heavy. The front brake is pretty handy too, second only to the Yamaha in my opinion.
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Firko and I weighed a bunch of 4 strokes at Amaroo one time and the stock frame bikes were some of the lightest. You can get a stock frame XL 250 based bike under 100kg
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Im with Firko, ive ridden lots of projects from cr based to even a 420 in a Montessa but they never had the balance that original xl frame had so yeah, give it an Enema and suspend it well.
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What's the going price for a sorted stripped bike?
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Couple of cheapies on ebay at the moment with hot pipes and aftermarket shox, two for the price of 1.5. They need work but they look like a good start...