70+ Hp Xr650l


83 replies to this topic
  • Triple B

Posted December 12, 2007 - 12:55 PM

#41

http://www.race-deze...second&id=22289

They are claming 75hp from a "L"

  • stepho

Posted December 12, 2007 - 02:44 PM

#42

75 at motor, very possible ,at rear wheel/s i dunno. Also pump gas, alkie. Sometimes these answers are vague on purpose. Keeps us guessing. We get around 75 to 80 on a engine dyno on Shell 91octane. Translates to about 57 to 61 rwhp on a chassis dyno.

  • HeadTrauma

Posted December 12, 2007 - 03:04 PM

#43

It's not vague at all.

When they say "approximately 75hp," that means they have no idea how much power it really makes and that their guesstimate is probably 20-30% overrated.

  • HawkGT

Posted December 12, 2007 - 03:33 PM

#44

It's not vague at all.

When they say "approximately 75hp," that means they have no idea how much power it really makes and that their guesstimate is probably 20-30% overrated.


:banghead:

  • stepho

Posted December 12, 2007 - 08:05 PM

#45

It's not vague at all.

When they say "approximately 75hp," that means they have no idea how much power it really makes and that their guesstimate is probably 20-30% overrated.

yeah thats true you can also believe that 75hp also equals a lot lot of money money money. It wasn't cheap for us that for sure.

  • Brtp4

Posted December 12, 2007 - 08:27 PM

#46

yeah thats true you can also believe that 75hp also equals a lot lot of money money money. It wasn't cheap for us that for sure.



Stepho,

I have a question regarding peformance increases for these motors. I am not an engine builder, so it may be a bit simple, but hopefully it makes sense.

It seems that part of the low power output of these motors is a conservative advance curve. The bikes have no "hit" and they build revs really slow. Dyno charts I have seen all have a gentle slope. Intake and exhaust mods help, but the gains do not seem as significant as they could be, and even modified they are well below 100 hp/liter.

I am basing this on a few conversations I have had with a 2-cycle engine builder for karts. He works the ignition mapping a lot to develop faster spin-up and more power.

I knwo some people have done cams, but the rev ceiling as set by the CDI is low, so I don't know what gains are available there.

My questions are, in your opinion is the advance mapping a limit on output, and during any of your development did you work with this?

BP

  • stepho

Posted December 12, 2007 - 09:36 PM

#47

I guess that since we dont use a cdi box on our bikes we have a lot of room to mess with igniton curves. With fuel injection we change the the amount of igniton every 500 rpm and depending where on the map 5 to 10 degrees of tps. We have been doing a lot of tuning with camshafts an timing lately. On a dyno you tune the air fuel ratio first then start adding or subtracting 2 to 3 degrees of timing until you effect the torque. If the torque goes up then adjust the air fuel if needed. Usually you will gain torque and a little hp as well. But air fuel ratio has more effect on hp and timing has more effect on torque. Our bikes are strictly street and using a lower lift longer duration cam has a bigger torque number but the hp hurts a little at the top. But that torque gives you way more seat of the pants feel and quickness on the "butt dyno". I know that people love to see those hp#'s and all but we would alway like to have these motors live rather than fixing them every weekend. For a loss of 1 or 2 hp you feel 2 foot pounds of torque a lot more on the butt dyno. I say butt dyno a lot because we have both chassis dyno and engine dyno but we also have a legendary race car driver, builder, and motorcycle fanatic named Dan Gurney riding these bikes every weekend. We couldn't as for better feedback than that. So setting up the lobe centers with a little leed on the intake seems to work good on a lower lift cam 101 intake 106 exhaust gives more torque and intial hp but you might lose on top but at least you dont have to rev it to 8700 :banghead: to feel like you are going fast. Also changing air horns or intake track messes with inital HP too. I dont know if all of this can translate into result for you guys. But as I start tweaking on my personal xrl I will be trying lots of things. my basic set up will be with a stock cdi box and a fcr bored to a 43 and the rest will be lots of fun. So far i have a stock piston, megacycle cam, a e2 can stock header(yuck), electrex stator,a personaly ported head. 43hp on chassis dyno. 170 main, 52 pilot, lowest clip. 15 front and a 43 rear sprocket and it pull solid first second gear wheelies on the butt dyno.

  • Brtp4

Posted December 12, 2007 - 10:12 PM

#48

Thanks for the info. I am interested in seeing how your personal development goes, your company bike has little similarities with mine. I have the FCR and a slip-on, everything else stock. I may bump the compression in the future, but will probably pass on the cam. If you do any R+D on the map or learn anything that would benefit a near-stock motor, let me know.

BP

  • HeadTrauma

Posted December 12, 2007 - 10:23 PM

#49

Our bikes are strictly street and using a lower lift longer duration cam has a bigger torque number but the hp hurts a little at the top. But that torque gives you way more seat of the pants feel and quickness on the "butt dyno". I know that people love to see those hp#'s and all but we would alway like to have these motors live rather than fixing them every weekend. For a loss of 1 or 2 hp you feel 2 foot pounds of torque a lot more on the butt dyno.


This is very similar to how cars react as well. Lots of people worry about peak power, but engines used off-track usually perform better with lots of area under the torque rather than a peaky power band. Often torque pleases the butt dyno more than power.

  • Fab Shack Racing

Posted December 14, 2007 - 01:04 AM

#50

I got 76.8 h/p at the rear wheels at my last dyno run on my 717cc 650L motor that I run in a 400ex drag quad, All motor run, on methonal, big power is possible on the L motor, just how much do you want to spend, I've run a couple of 717's and am now building some 5 and 7 mil strokers, the power will be in the 80's easy, but of course parts will break now and then, but a whole season can be had on a big h/p motor, in the sand-drag world a year is pretty good yeild for the h/p being produced N/A, but at the same time I can build a good solid 720 that you can dune all day with h/p in the 60's with decent reliability on gas.....

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  • crmc33

Posted December 14, 2007 - 04:49 AM

#51

brtp4,

I have a prgrammabvle CDI that Im fitting to the XRL at the moment. I expect itll give me more midrange and top end drive with the higher RON fuel we can get here at UK pumps.
Ive also removed the starter gear and clutch on my bike - this makes a massive difference to bttom end response and I personally think a lot of the bottom end pickup differences btwn XRL's and XR's is cos of this. Im now running as total loss system (no Gen rotor) and the acceleration is very good.....it needed stiffer clutch springs to cope :banghead:

  • Brtp4

Posted December 14, 2007 - 08:19 AM

#52

brtp4,

I have a prgrammabvle CDI that Im fitting to the XRL at the moment. I expect itll give me more midrange and top end drive with the higher RON fuel we can get here at UK pumps.
Ive also removed the starter gear and clutch on my bike - this makes a massive difference to bttom end response and I personally think a lot of the bottom end pickup differences btwn XRL's and XR's is cos of this. Im now running as total loss system (no Gen rotor) and the acceleration is very good.....it needed stiffer clutch springs to cope :banghead:


Thanks CMRC. I remember you talking about this before, but couldn't find the post. Will you do any dyno veriification or just at the track? Either way, I would like to hear your results.

Regarding the starter stuff, is that a part of the rotating assy? How much weight was it? Either way I doubt I will mess with this as the inertia helps off-road.

BP

  • crmc33

Posted December 14, 2007 - 11:17 AM

#53

Hi,

Yes dyno tuning will be carried out and I will post the curves.

The removal of the starter saves about 5kg off the crank!!

removal of the starter motor another 3 Kg

removal of the gen rotor another 5KG+

So its no surprise the bike flies when you take it all off.

Push starting does get a bit tiresome tho:ride:

  • Brtp4

Posted December 14, 2007 - 12:47 PM

#54

Hi,

Yes dyno tuning will be carried out and I will post the curves.

The removal of the starter saves about 5kg off the crank!!

removal of the starter motor another 3 Kg

removal of the gen rotor another 5KG+

So its no surprise the bike flies when you take it all off.

Push starting does get a bit tiresome tho:ride:



Holy smokes!! 10 kilograms from the rotating mass????? No wonder it revs out like a John Deere!!!

BP

  • XR650L_Dave

Posted December 14, 2007 - 02:34 PM

#55

Holy smokes!! 10 kilograms from the rotating mass????? No wonder it revs out like a John Deere!!!

BP


10 kilograms of rotating mass? No wonder its unstoppable on hillclimbs and rock gardens!!!

That 10kg can be good or bad, depending on your terrain.



Dave

  • crmc33

Posted December 14, 2007 - 03:20 PM

#56

Yes, the starter gear, starter clutch and genny are huge.
Plus the crank web on the XRL are heavier than the XL or XR, and the balancer shaft has more weight.

Great for off road low RPM traction...not great for road race acceleration. The other downside of a very light crank of course is even more engine braking so turning the tickover up is a must until I get the knack of 'backing it in' supermoto style! :banghead:

  • Brtp4

Posted December 14, 2007 - 05:21 PM

#57

10 kilograms of rotating mass? No wonder its unstoppable on hillclimbs and rock gardens!!!

That 10kg can be good or bad, depending on your terrain.



Dave


Dave, with 10kg you could roll up to a hillclimb, shut the key off, and still make it to the top.

BP

  • XR650L_Dave

Posted December 14, 2007 - 06:29 PM

#58

Dave, with 10kg you could roll up to a hillclimb, shut the key off, and still make it to the top.

BP


Well,I do find myself having to chop the throttle before the front wheel clears the top lip, now you mention it...

  • HeadTrauma

Posted January 18, 2008 - 10:46 PM

#59

let me take a picture at work tomorrow and i can explain it better.


Were you ever able to get that photo? :cool:

  • stepho

Posted January 18, 2008 - 10:51 PM

#60

I know I know you got me I forgot. What was I supposed to take pictures of.





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