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Old 09-04-2011, 05:22 AM   #856
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Grey XL 250

I have an old XL250 with the grey tank and was wondering if an XL500 motor of the same vintage would fit in the frame?

Any help would be greatly appreciated.

Regards Phil.
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Old 09-04-2011, 06:12 AM   #857
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Quote:
Originally Posted by PIC View Post
I have an old XL250 with the grey tank and was wondering if an XL500 motor of the same vintage would fit in the frame?
Any help would be greatly appreciated.
Regards Phil.
Grey tank?.... 1972-73 like mine?
http://i255.photobucket.com/albums/h...0/P4090097.jpg
I don't think a 500 would fit, but you might be able to squeeze in a 350.
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Old 09-04-2011, 06:29 AM   #858
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Quote:
Originally Posted by jitterymonkey View Post
Grey tank?.... 1972-73 like mine?
http://i255.photobucket.com/albums/h...0/P4090097.jpg
I don't think a 500 would fit, but you might be able to squeeze in a 350.
I think he's talking late 1978-80 Aussie gray tank 250. They were red in the states. A 500 motor may fit but not sure.

As for the 1972-73 250, my understanding is that a 74-75 350 motor fit just fine and can be bored and stroked to nearly 500.
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Old 09-04-2011, 07:19 PM   #859
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1st gen ('72-'75) 250's and 350s interchange, 2nd gen ('76-'78) 250's and 350's interchange with the exception of the '78 250- it was the first "S" model, 3rd gen ('78-'82) "S" models 250 and 500 should all interchange as well. after that, not sure if the 4th gen / RFVC engines are interchangable or not.

Interchanging engines between generations is definitely NOT an easy drop in project...
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Old 09-06-2011, 04:43 AM   #860
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XR75 Parts

I have two complete 78 XR75s that I've been fiddling with for a while now and just don't have the patience for any more... Anyone looking for specific parts PM me and let me know. I'm getting photos and the whole list together for the classifieds, but thought I'd give a shout out here first.
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Old 09-06-2011, 07:30 AM   #861
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Quote:
Originally Posted by dorkpunch View Post
1st gen ('72-'75) 250's and 350s interchange, 2nd gen ('76-'78) 250's and 350's interchange with the exception of the '78 250- it was the first "S" model, 3rd gen ('78-'82) "S" models 250 and 500 should all interchange as well. after that, not sure if the 4th gen / RFVC engines are interchangable or not.
Interchanging engines between generations is definitely NOT an easy drop in project...
So what would be the best bang for the buck....
The powroll stroker kit for my 250 or just throwing in a stock 350?
(with the option of stroking the 350 later.)
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Old 09-06-2011, 11:13 AM   #862
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Quote:
Originally Posted by jitterymonkey View Post
So what would be the best bang for the buck....
The powroll stroker kit for my 250 or just throwing in a stock 350?
(with the option of stroking the 350 later.)
All depends on what you want in the end. A 350 in a 250 frame will give you the wider ratio transmission, and a base engine that will have more potential, can go up to 400 or so with just a bore, 440+ stroked, 460+ sleeved and 480ish with an external oil feed to the head. Stock pipe and air filter have to go, they won't line up to the 350 engine so there is some fabrication. Engine should be a drop in everything under the seat, the pipe, battery box, airbox, etc are different and the mounts are not on the 250 frame.

A 350 engine can probably be gotten cheaper than a Powroll stroker kit and piston, if you look at it just at that level. A 350 in a 250 frame however is pretty much a commitment to a pretty modded bike and nothing resembling stock. If you use an other than stock airbox and pipe then you are probably rejetting or changing over to another carb entirely.

The 250 stroker kit will have a shorter rod/stroke ratio than a 350 engine so will have more of a tendency to try and push the piston through the side of the cylinder or snap the wrist pin. It's the nature of stroking an engine and retaining deck heights.

I'm contemplating option 3, dropping a 350 crank into a 250 case, having a friend mill me base a riser then resleeving the new "taller" jug to take a 350 piston or maybe a bit bigger. Deck height would only be a few millimeters difference, between 6-7mm maybe and would need to add a link or 2 to the timing chain. I think when I figured it out, to get the same bore stroke ratio as a 250 with a 350 crank, it worked out to be right around a 400. The real issue I think would be the bearings on the crank so I might need to try and put 250 bearings on the 350 crank to make it easier. It's been done, but details are pretty sketchy. Minor tweak to the pipe and a little ovaling of holes on the airbox and it looks like a stock 250 but is really closer to a 400.

I'd drop in the 350 gears to get the wider ratios, rejet the carb, and maybe get a Musket Mufflers pipe, cut it open and shorten the baffles a little to make it breath a bit better on the exhaust side (made to accept the stock heat shield and so looks like a stock pipe for the most part...so they say). The 250 head has always been able to out breath the engine so a mild megacyle cam should be fine. A lot of effort to pull off a masquerade I know, but I personally really like the look of the stock 250, the 350 looks a bit too much like a bigger version of an XR75 to me. The 250 ('72) just has that clean simplicity, that makes it hard to pin a year to it, in some senses it's very retro but in other aspects it's very timeless. The wingless logoed tank and mock pin striping make it very unique in the XL/SL lineup.
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Old 09-06-2011, 04:12 PM   #863
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I wouldnt call a 350 motor in a 250 frame a pretty modded bike... Just about the only difference in a 250 and 350 in the 1st and 2nd gens is the size of the top end. There are a few other differences. Externally the engines are a direct bolt in- no cutting / serious modding required. If you wanted to put a 250 motor in a 350 frame of the 1st gen, its a little harder because the pipes are different, but the 350 pipes I believe will fit on the 250 frame without any issues.

Most bang for your buck would definitely be a 350 motor- you can still find XL350's every now and then on craigslist for under $100. Sure, they need work, but what doesnt!?

Also have to remember, any time you increase performance, maintenance goes up and reliability is likely to go down- chances of catastrophic failure also increase.

Thats my .02, dont know that its worth even that much!
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Old 09-07-2011, 04:27 AM   #864
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Quote:
Originally Posted by dorkpunch View Post
I wouldnt call a 350 motor in a 250 frame a pretty modded bike... Just about the only difference in a 250 and 350 in the 1st and 2nd gens is the size of the top end. There are a few other differences. Externally the engines are a direct bolt in- no cutting / serious modding required. If you wanted to put a 250 motor in a 350 frame of the 1st gen, its a little harder because the pipes are different, but the 350 pipes I believe will fit on the 250 frame without any issues.

Most bang for your buck would definitely be a 350 motor- you can still find XL350's every now and then on craigslist for under $100. Sure, they need work, but what doesnt!?
Is it like trying to squeeze a motor from one manufacture into the frame of another? no, far simpler than that.Does it matter that a stock pipe will hang on a 250 frame? well probably not, since 350 pipes are far rarer than the 250 pipes being a low pipe as they are they don't survive often and rarely come along with an ala carte craigslist motor. You can't use your original pipe, there is no bosses for the 350 air/battery box. is it a big deal to bolt on an after market pipe, a K&N, swap the front sprocket, and probably put on a Mikuni VM and a new throttle cable? no, as mods go that is relatively tame, but if you are trying to source all this new, you have a motor in an unknown state, then the 350 motor is starting to not be all so cheap and you are getting into the area where you could have just bought a 350 as a runner, put on the 250 tank and fenders (if that's the part you really like) and parts out the 250. It won't really look like a 250, but it kinda does I guess. So if the cheapest and most reliable way to make a 250 into a 350 is to change all but 3 parts, I'd say that's pretty modded.
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Old 09-07-2011, 06:06 PM   #865
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Heres a pic of my 84 xl250 out on the trails. Absolutely love the bike, light and fast for the narrow trails. Only thing I would like is a set of rear racks for it... anyone know where something is available????
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Old 09-07-2011, 06:18 PM   #866
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Top racks or side racks?

Top rack on my '76 XL250


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Old 09-23-2011, 04:39 PM   #867
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XL350r Spocket Recommendations

I'm new to chain driven bikes, having ridden beeemers for the last 25years. I recently picked up an '84 XL350R that needs a chain and sprocket replacement. I'll be doing little or no single track or anything gnarly & would like to gear it more for the road.
Any recommendations on sprocket size and/or good vendors?

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Old 09-23-2011, 06:08 PM   #868
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XLint Engineering is a good place. Got my steel sprockets for my '76 there. Converted from the stock 15/48 to a 14/42 with a 102 link chain IIRC. It's geared more for off road with that configuration.
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Old 10-16-2011, 11:56 PM   #869
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(This is for a 1981 XL250S)

Does anyone know if this mark is for alignment? I've looked in the manual and at the engine but can't find a corresponding mark (except for the journal oil holes in the shaft and guide.)

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Old 10-17-2011, 08:06 PM   #870
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I cant for the life of me think of why you would need to align your clutch basket, I guess its possible. My guess is there is a special washer that goes right there- the washer would have a tab that is bent to fit into that hole, then the nut goes on and the washer gets bend around the edges of the nut to keep it from coming loose. Just a guess though.
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