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Author Topic: 2150cc Evo Custom Updates  (Read 7600 times)

Offline Bevelheadmhr

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Re: 2150cc Evo Custom Updates
« Reply #20 on: Feb 08, 2018, 17:34:53 »
The alloy swing arm is progressing surprisingly well (touch wood).... 15 hours of machining so far, and this is how its looking.

Harley parts aren't known for being lightweight, and sure enough the original swingarm of my aftermarket chassis weighs a hefty 34lbs.  My target is to halve that with this new alloy copy, so far with all components it weighes 20lbs, but there's still a pound or two to lose, so the target is possible. 17lbs is still a boat anchor in sports bike terms but its better than 34lbs.

Note the 'V' shaped grooves machined into the arm where two pieces are bolted together. This is where its going to be welded, as the groove allows for a neater stronger weld.

Offline crazypj

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Re: 2150cc Evo Custom Updates
« Reply #21 on: Feb 09, 2018, 23:10:59 »
While I admire the work you've done and are still doing, you obviously have more money than sense  8)
 I still have no idea why people fit 10,000rpm exhausts on 'Harley's' though?
With the torque that motor is making I guess next thing will be strengthen left side of frame to make sure it stays in line 'in compression'.
At least your not setting things up 'on the curve' so they get pulled straight during acceleration. They are outrigger bearings on belt cover?


How much did you punch the jugs out and what type of heads are you using ?

You can't bore much further as even with special 'waisted' bolt in th centre of 'V' you run out of crankcase. 1250 is probably as big as you can bore, to get more capacity you need a stroker crank but that needs special rods and pistons (or, about another 3,000)
« Last Edit: Feb 09, 2018, 23:18:25 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Bevelheadmhr

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Re: 2150cc Evo Custom Updates
« Reply #22 on: Feb 10, 2018, 05:35:25 »
The XL is 1250cc, though I see that Hammer Performance now have an updated 1275cc conversion kit. I seem to recall the biggest you can go with a std crank is 1440cc or there abouts?

Not sure what you mean by 10,000rpm exhaust on a Harley?

The Primary belt drive does indeed have outrigger bearings to support the pulleys, though the front one had to be redesigned after it failed at speed.

Since the frame and swing arm is aftermarket and non standard, the only way of having an alloy swing arm would be to commission one from one of the few decent frame builders in the UK. Last time I asked (a few years ago) Spondon wanted 3000, so I didn't bother!

So far the new swing arm has cost 130... 40 for the bearings and 90 for the alloy, so not too bad. Though it may end up in a new project, haven't decided yet.

Offline crazypj

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Re: 2150cc Evo Custom Updates
« Reply #23 on: Feb 10, 2018, 23:21:38 »
If you work out 'tuned length' for exhaust you'll find almost every HD system is way too short.
Some of the worst are 'drag pipes' for Sportsters. I did the math one time, sure enough, just about every after-market set were tuned for 9,000rpm. (in Florida people still believe 'loud pipes save lives'  ::) )
 We dyno tested an 883 with 'drag pipes', even with carb set as good as it could get it lost 8bhp from a stock system (38bhp is pretty pathetic from almost 900cc) 'Sounded fast' though  ;D
With your Merch motor I'm pretty sure it won't self destruct at 6500rpm but even so a longer system will make more power and (gulp) even more torque. That could be an issue as you already have a ton of torque at 'low' rpm. Wheel-spinning 'everywhere' may sound like fun but just gets to be more trouble than it's worth after a while. Personally, I always thought the  1994/98 Ducati 916 under-seat exhaust was to get longer pipe length more than styling, although it is still my favourite Duc.
 130 is damn cheap for 'custom' swing arm, I guess your not paying for CNC time?
« Last Edit: Feb 10, 2018, 23:34:04 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Bevelheadmhr

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Re: 2150cc Evo Custom Updates
« Reply #24 on: Feb 11, 2018, 05:48:25 »
Oh I see ref header length. I don't have the numbers to hand, but in general the shorter the header length the higher peak torque (all other thinks being equal). Minimum length for a Evo Big twin is around 26 inch, any shorter and the engine will never run right. Max length you'll find for HD exhaust headers is around 40 inches (so peak torque low in the rev range). I made mine with 32 inch headers, so slightly shorter than average, to move peak torque in the upper half of the rev range. Sure enough the dyno gives peak torque at 3500 rpm. The ignition is adjustable, and I have it set to cut out at 6,000rpm. I don't think it'll last long at 6,500.
Peak power is at 5200 so no point in revving it much more. A bigger carb may give me a bit more power at the top end, but I'm happy with it as is.

Drag pipes are great ... for drag racing lol... With an OE cam with sod all valve overlap they don't do too much damage to power, but as soon as you add a performance cam, drag bikes can really cause problems.

I don't have access to a CNC miller, its all done by hand on a miller made around 1965.. that's why it takes so long.

Offline crazypj

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Re: 2150cc Evo Custom Updates
« Reply #25 on: Feb 11, 2018, 12:22:44 »
Far more impressed when you 'twiddle the knobs' by hand  ;D
 Doing some nice work.
Just watched the vid and took a look at pictures, should have noticed chain drilling sooner.
I've done a lot of HD cranks over the years, big end is weak spot when you rev them, you can tell by wear pattern if it was oil failure/dirty oil, over revving or ignition problem that caused failure.
Haven't done any of the later 'pressed up' cranks, 50 ton presses scare me  ;)
 The total length of exhaust is also important, megga gives much broader spread of power than 'sharp exits' and will give more power than a parallel pipe in almost all applications. Personally I don't have any faith in US published header length numbers, they are always shorter than optimum but using larger diameter pipe often compensates for incorrect length.
 Of course, that messes up fuel needing much richer than optimum levels to make bike ridable. There is actually very little scientific information on exhaust design, it's mostly trial and error until you find what works
« Last Edit: Feb 11, 2018, 12:31:06 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline Bevelheadmhr

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Re: 2150cc Evo Custom Updates
« Reply #26 on: Feb 11, 2018, 14:03:51 »
There's plenty of research on exhaust design, even for Harleys, ... its just v complex, so most folks follow what everyone else is doing. RB racing have some interesting pages on their site about exhaust design etc...

https://www.rbracing-rsr.com/exhausttech.htm

They were v helpful when I was building the exhaust for my old 120ci drag bike. Both the 131 exhaust and the 120 use 2 inch diam tubing for the headers instead of the OE 1 3/4 inch. Worked out ok..


Offline crazypj

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Re: 2150cc Evo Custom Updates
« Reply #27 on: Feb 12, 2018, 12:31:28 »
Just read through the RBRacing link., well written, gues writer is a good storyteller?
Pretty much mirrors my experiences with some people  ;)
 Most just want 'give us your money and STFU'
Exhaust gas sonic speed can vary a bit more than they say, down as low as 12~1300ft/sec although higher rpm with right F/A mixture is 16~1800ft/sec
Lean mixture can give a much higher speed, until lean miss-fire messes things up  ;D
I doubt it's still in the 'Dynomation' literature but the exhaust designs it comes up with used to be +/- 10% which was fine for majority as it almost always showed a power increase throughout rpm range
I've built stepped exhaust systems, they need to be shorter than the math says they should be, usually about 4" on a <36"pipe but need a longer tail-pipe or velocity slows too much plus collector gets 'complicated'
I did have to look up Manolo Blahnik. though
 One thing that has always amazed me with HD (and clones) why doesn't anyone make a decent downdraft head for them? It would be real simple to machine a pair of head's, weld in tubes with flanges and put some fuel injection or downdraft Dellorto (off  Alfa Romeo, 'racing' air-cooled Beetle or Ferrari) 45~48mm should be good  ;) It would be way more efficient ten the 'updraft' system fitted (they are ALL updraft systems on HD due to the angle of cylinders) I've seen some weird 'air-filter' systems tat need tank cut away but carb is still down in the 'V'  ???
« Last Edit: Feb 12, 2018, 12:39:12 by crazypj »
'you can take my word for it or argue until you find out I'm right'
Best thing I ever overheard
"yep, PJ's my boss, he taught me everything I know, just didn't teach me everything he knows"
Brian Morgan, 1982

CB360's,  http://www.dotheton.com/forum/index.php?topic=11736.0
XS650,  http://www.dotheton.com/forum/index.php?topic=11922.0

Offline canyoncarver

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Re: 2150cc Evo Custom Updates
« Reply #28 on: Feb 12, 2018, 14:02:35 »
When I was in the midst of my 93" shovel build, I looked at and read about the RB Racing pipes.  They make nice LSR 2-1 pipe for the Shovel.  I ended up with a Thunderheader but the RB pipe was a very close second choice.   

Offline Bevelheadmhr

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Re: 2150cc Evo Custom Updates
« Reply #29 on: Feb 12, 2018, 16:25:51 »
Just read through the RBRacing link., well written, gues writer is a good storyteller?
Pretty much mirrors my experiences with some people  ;)
 Most just want 'give us your money and STFU'
Exhaust gas sonic speed can vary a bit more than they say, down as low as 12~1300ft/sec although higher rpm with right F/A mixture is 16~1800ft/sec
Lean mixture can give a much higher speed, until lean miss-fire messes things up  ;D
I doubt it's still in the 'Dynomation' literature but the exhaust designs it comes up with used to be +/- 10% which was fine for majority as it almost always showed a power increase throughout rpm range
I've built stepped exhaust systems, they need to be shorter than the math says they should be, usually about 4" on a <36"pipe but need a longer tail-pipe or velocity slows too much plus collector gets 'complicated'
I did have to look up Manolo Blahnik. though
 One thing that has always amazed me with HD (and clones) why doesn't anyone make a decent downdraft head for them? It would be real simple to machine a pair of head's, weld in tubes with flanges and put some fuel injection or downdraft Dellorto (off  Alfa Romeo, 'racing' air-cooled Beetle or Ferrari) 45~48mm should be good  ;) It would be way more efficient ten the 'updraft' system fitted (they are ALL updraft systems on HD due to the angle of cylinders) I've seen some weird 'air-filter' systems tat need tank cut away but carb is still down in the 'V'  ???


The famous Duckman has a Shovelhead with downdraft Webbers, His site is full of amazing builds... if you haven't seen it before, well worth the time...  http://www.dbbp.com/