2150cc Evo Custom Updates

Bevelheadmhr

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A quick update on the XL1250, its paintwork was collected from the painter this week, should be on the dyno in the next couple of days.. I like how the hole in the side panel for the ignition barrel have been incorporated into the Hammer and Tongs design .. a v old symbol used by the Army Royal Engineers.
 

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Bevelheadmhr

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Rubbish pic, but the XL1250 was finished (for now) just in time for a local bike show. Goes on the Dyno soon, be interesting to see what it makes.
 

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Bevelheadmhr

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Here's a better photo of the XL1250 taken by the River Mersey today. Its been run on the dyno using ''guestimate'' jetting where it made only 65 bhp. Once the jetting is corrected it should make more, but still not as much as it could, as its still running the original 883 cams and CV carb. Then again the aim is lots of low end torque rather than top end power..
 

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crazypj

Split personality, I fake being smart
Bevelheadmhr said:
Here's a better photo of the XL1250 taken by the River Mersey today. Its been run on the dyno using ''guestimate'' jetting where it made only 65 bhp. Once the jetting is corrected it should make more, but still not as much as it could, as its still running the original 883 cams and CV carb. Then again the aim is lots of low end torque rather than top end power..
Can't you set it up to 1200 Buell 'Lightning' spec?
That makes as much 106 bhp when set up right (friend had one, I liked it ;) )
Modified 883 heads work great as the smaller port can be shaped to work right on a 1200 (better than stock 1200 head) but, if you can't DIY them, after-market works out cheaper
 

Bevelheadmhr

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The heads have been flowed and a bigger inlet (I think) fitted. I'm sure its the standard cams that are holding it back. My mate owns the local bike shop, complete with dyno. They usually work on Jap and Italian superbikes, but I'm sure they can get plenty of power out of this if they wanted.
 

Bevelheadmhr

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My home made alloy swing arm, which has become a mini project in itself, got welded today. It all went ok with no distortion etc. Still to decide if its getting the under bracing of the original steel version its copied from, and what finish it having. Polished, powder coated or maybe anodised?

Its half the weight of the original (17 Vs 34 lbs), still heavy for a sports bike swing arm, but pretty light for a Harley Softail..
 

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crazypj

Split personality, I fake being smart
Although I haven't worked on a softtail for about 10 yrs, the under-brace isn't actually brace but to reduce stress at the connection of arm and upright due to the shocks being underneath tranny and connected to bottom of your 'T'
It acts more like a pull rod
You'll have to remove all the bolts to anodize it, unless you already have titanium ones? (anodizing doesn't like stainless)
 

Bevelheadmhr

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Yep the under braces work in extension not compression, I have a couple of ideas for making them a bit different from just a welded in bar. The countersunk bolts are all stainless, but its no trouble to remove them if needed to get the arm anodised or powder coated, now its been welded together.
 

Bevelheadmhr

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Had an interesting morning, weighing the XL1250 and a near standard XL883 yesterday, using the calibrated scales built into the brake testing machine used for the annual test with have here in the UK.

Wasn't sure how accurate the method would be, as it tests one wheel at a time, but the numbers we got from the near standard bike were close to its official weight (485lbs for a 1991 XL883).

The XL1250 would be lighter of course, but how much? It weighed in at 400 lbs with only a little fuel in the tank. Not bad at all. Still hasn't been set up on the dyno due to lack of time, but it sounds ok being run up and down the road.. here it is if you want to hear it..

https://youtu.be/280lEt7YNe4
 

Bevelheadmhr

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My mates XL1250 finally had its first run on the dyno today. Its running way too rich, and with standard cams and rejetted OE carb, we weren't expecting huge power numbers. Although it was built for low end torque over top end HP in any case.

Despite running rich, it made decent power, with a smooth graph, no sudden dips in HP as the revs climbed. With leaner jetting should make more a bit more HP.

What did it make? You'll have to watch it running on the dyno to find out ..
https://youtu.be/LmodhLHAK7c :)
 

Bevelheadmhr

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Finally got around to working on the alloy swingarm again. It needed two underbraces to replicate those of the original steel arm. But that proved to be difficult as alloy bar cant be so easily bent and manipulated as steel. So after a couple of false starts, I came up with a final design. I bought 1m of 30mm alloy bar, cut it in half, then line drilled them (had to use a friends 1940's Capstan lathe, as ours isn't big enough. I left the last few inches of one end solid. This would be the lower end which was machined down to a 20mm flat, so it could be welded to the lower part of the side plates of the arm. The other hollow end was profiled on the miller to fit the underside of the two arms. That done, just had to take it to Geoff the welder who welded them into place.

Pity I forgot about the need for a bracket on one brace to hold the brake torque arm, but it'll be added when I get time.

Next task is to make a wheel spindle, not sure yet what to use.. EN24 or Stainless steel.. Ti would be light, but I hear its banned from being used in race bikes for good reason, so probably best to stick with steel. Also need to make a battery box for the lithium battery its getting, which should save about 12lbs over a lead acid equivalent... still need to buy a suitable one of those. Then finally have to decide on the finish.. either polish it or polish it and have it ceramically coated.

Total weight of the arm is 17lbs with the temporary thread bar 'spindle'.. about half of the original steel version.
 

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