ADVrider

Go Back   ADVrider > Bikes > Some Assembly Required
User Name
Password
Register Inmates Photos Site Rules Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Search this Thread Display Modes
Old 09-13-2012, 05:57 AM   #76
jwalters
Farkle Proliferator
 
jwalters's Avatar
 
Joined: Jun 2005
Location: Little Marais, MN
Oddometer: 2,186
Cosman,
Being one of the first inmates to suck knowledge off this thread, I thought I would post a few more pictures of the RZ and the progress. Unfortunately, I've been busy getting my XR up to date for a much longer trip lately, as well as build my cabin/workshop, but that's life...

Anyways, here is the RZ in all it's glory. Obviously, it still needs a lot of work, new electrics, body work, etc but it's ridable. And talk about FUN! Thanks again for the advise! I'll probably pick the collective brains on this thread in the future! Thanks again Cos().
__________________
See you at the Minnesota North Shore Shindig 2014 10-13 July (Finland, MN)

Proliferator of Farkles of Mass Percussion
jwalters is online now   Reply With Quote
Old 09-13-2012, 10:02 AM   #77
*GG*
n00b
 
Joined: Jul 2012
Oddometer: 4
Quote:
Originally Posted by jwalters View Post
Cosman,
Being one of the first inmates to suck knowledge off this thread, I thought I would post a few more pictures of the RZ and the progress. Unfortunately, I've been busy getting my XR up to date for a much longer trip lately, as well as build my cabin/workshop, but that's life...

Anyways, here is the RZ in all it's glory. Obviously, it still needs a lot of work, new electrics, body work, etc but it's ridable. And talk about FUN! Thanks again for the advise! I'll probably pick the collective brains on this thread in the future! Thanks again Cos().
Nice bike man!
I've just buy an aprilia rs 250... 2 stroke r a different world!
*GG* is offline   Reply With Quote
Old 09-13-2012, 08:11 PM   #78
Mike_drz
Banned
 
Mike_drz's Avatar
 
Joined: Jul 2012
Location: somewhere near the beach
Oddometer: 402
Quote:
Originally Posted by dentvet View Post
I have one of the many rat bikes described in this forum. Its a ninja 650 dualsport with a dirt front end grafted on. My rake angle is about 33 degrees and my trail is 5 1/4 inches. Do you see anything inherently wrong with those values? The bike seems to perform ok for me offroad but i haven't really pushed it either. Fire and ATV roads are the goal.

I read Foale's article on trail experiments where is was said that 27 degrees rake and 3 1/2 inches trail was the norm but not necessarily written in stone.

I like the 21 inch front tire but i could reduce the rake a bit if i dropped the triple clamps down the fork.

Other possibilities are finding forks with more spindle offset to reduce the trail.

as more angle and more trail, the greater the distance between the front wheel hub to streeting stem. it also gives greater amplitude lower frequency when it virbe, wobble you may call it
Mike_drz is offline   Reply With Quote
Old 09-13-2012, 08:17 PM   #79
Mike_drz
Banned
 
Mike_drz's Avatar
 
Joined: Jul 2012
Location: somewhere near the beach
Oddometer: 402
Quote:
Originally Posted by DaBit View Post
You mean this or this? Worth a study..


http://en.wikipedia.org/wiki/Drag_(physics)

look closer to the formular where the p is,


_______________
it's the tricky part sets what the fun is
Mike_drz is offline   Reply With Quote
Old 02-08-2013, 05:50 AM   #80
Bosshelm
Wishful Thinker
 
Joined: Feb 2013
Location: Round the Bend
Oddometer: 3
Thumb BMW Xmoto to XChallenge conversion

Hello All,

I'm wanting to convert a Beemer Xmoto to an XChallenge and as the bikes share lots of components I think it would be do-able... in theory. But you know that old saying "in theory practice and theory are the same...in practice they seldom are..."

Why, you may ask, do you want to do a conversion? The answer is that, here in the UK, finding a decent un-thrashed XChallenge is like finding hen's teeth!

I'm aiming for something like a low budget version of Walter Colebatch's bike (imitation being the most sincere form of flattery). The biggest problem may be the change of wheels i.e. what hubs to use in the build of 21" & 18" wheels.

Is there anyone out there able to offer any advice.

Thanking you in anticipation.

N.B. Be gentle with me as this is my first ever post despite lurking on various threads for years...
Bosshelm is offline   Reply With Quote
Old 02-08-2013, 08:54 AM   #81
CosentinoEngineering OP
Gnarly Adventurer
 
Joined: Oct 2010
Location: NYC
Oddometer: 183
>>Why, you may ask, do you want to do a conversion

That's the one question that this form cares nothing about. Why? Because you want to!!!!!!

>>The biggest problem may be the change of wheels i.e. what hubs to use in the build of 21" & 18" wheels.

Can you reuse the existing hubs and relace them to the appropriate size rims?
__________________
Chris
moto2-usa.blogspot.com
Check out my products 10% off for ADV rider members
CosentinoEngineering is offline   Reply With Quote
Old 02-08-2013, 10:48 AM   #82
Luke
GPoET&P
 
Luke's Avatar
 
Joined: Aug 2004
Location: Idiotville, OR
Oddometer: 4,074
I'd start by researching all the relevant parts in the microfiche and around the net. Figure out what's the same and what's different. Things like the fork tubes and painted parts are hard because they'll have different part numbers for different colors of the same part. Stuff like bearings and axles will have the same number if they're the same type. That'll tell you what you need to change or adapt.

In addition to the obvious parts, check the rear subframe/fender/whatever in the back to make sure there's room for the new rear wheel.


For the painted parts you might find someone who has the bike(s) you're trying to match and let them drink your beer while you measure parts on their bike.

The companies that sell aftermarket suspension for the X bikes might be able to help too. A lot of people don't like the XC suspension, so going straight to aftermarket might be the way to go. It's probably cheaper than new OEM prices anyway.
Luke is online now   Reply With Quote
Old 02-13-2013, 05:43 AM   #83
Bosshelm
Wishful Thinker
 
Joined: Feb 2013
Location: Round the Bend
Oddometer: 3
Xmoto to XChallenge conversion

Thanks for the feedback gentlemen

Got in touch with the Oracle, the Moto Pornographer: Colebatch. He pointed mr in the direction of the suspension, and all things 'X', uber guru Baz at Hypermoto in Cloggyland. I think all shall be well...

Thanks again.
Bosshelm is offline   Reply With Quote
Old 02-16-2013, 10:52 AM   #84
tdvt
Gnarly Adventurer
 
Joined: Jul 2012
Location: NEK Vermont
Oddometer: 201
Suspension Question

Disappointed I didn't find this thread until now but better late than never. Thanks for offering guidance to those of us who can't leave well enough alone.

I bought a TTR250 last spring to get back into trail riding & at this point am quite happy with its air-cooled, low-maintenance simplicity. Though it's a bit dated & a bit heavy it's certainly enough for me to get into trouble.

Anyway, I am thinking I would like to upgrade the suspension since it is tired & because the TTR was not sold here in great numbers, options are limited. The front end seems fairly straight forward (pun partially intended) & there is a Racetech re-valve available as well as some documented fork swaps out there. Seems the '06+ YZ forks are the most sought after. I am thinking the USD forks might be a little lighter but don't know.

For the rear, there is also a Racetech re-valve available but other than that, not much out there. I am wondering about fitting a WR/YZ shock to the back & this is where my question comes in.

The suspensions seem very similar to me, shocks seem to be about the same length, orientation, etc. BUT the linkages between the frame, shock & swingarm are backwards from each other, ie; the TTR has the double-link connected to the swingarm & the 3-hole boomerang shaped link connected to the frame. The WR/YZ is the opposite with the double-link connected to the frame.

I am not sure how this affects spring rates, damping, etc. & if it is fool-hardy to try an “as-is”swap or if the TTR should be modded to use the WR/YZ linkage. Not sure of the differences in swingarm length but the TTR has around a 3" shorter wheelbase (55.3) than the WR/YZ (58.1)

OR I could always leave it alone but that wouldn't be much fun.


Thanks again, TD


pics of each:


TTR




YZ

tdvt is offline   Reply With Quote
Old 02-24-2013, 04:27 PM   #85
CosentinoEngineering OP
Gnarly Adventurer
 
Joined: Oct 2010
Location: NYC
Oddometer: 183
>>The front end seems fairly straight forward (pun partially intended) & there is a Racetech re-valve available as well as some documented fork swaps out there.

The Racetech stuff is works well but if you do a fork swap you get all the benefits of the more modern design: better stiffness, usually more rigid axle connection, and a well designed fully adjustable damping system. That's what I would do in your place.

>>I am wondering about fitting a WR/YZ shock to the back & this is where my question comes in. The suspensions seem very similar to me, shocks seem to be about the same length, orientation, etc. BUT the linkages between the frame, shock & swingarm are backwards from each other..

You'd be surprised at how similar the actual wheel rates are for link systems that look completely different. The main constraint for a rear suspension is packaging (fitting it in the available space) so there end up being a lot of ways of achieving the same thing.

The first major battle of finding a shock to fit seem to have already been won.

The second item to consider is the overall travel of the shock and wheel. If both measurements for both bikes are similar (+/- 1/4" on the shock, +/-1/2" on the wheel) then you are pretty close so bolt it on and see how the ride is.

If the wheel/shock travel are not that similar than you will most likely have to respring it to get the static and laden sag set properly. You can see how to set sag at http://racetech.com/page/id/30#2

Once you get it sprung properly then you may have moved the damping needs beyond the range of the 'clickers'. Only a test ride will tell you this. To get the damping adjustment back in the middle of the adjustment range someone will have to go in and change the shims and maybe piston. This is not a big deal and any suspension tuner will have the tools and parts to do it.

In general dampers are very stupid devices. They only respond to the speed of the movement of the shock (or fork) shaft. They have no idea if they are connected to a cantilever, linkage or whatever style suspension. The result of this is that if the wheel and damper travels and approx weight of the bike are about the same then the damper will be close enough to try out.

Good luck, let us know how it works out.
__________________
Chris
moto2-usa.blogspot.com
Check out my products 10% off for ADV rider members
CosentinoEngineering is offline   Reply With Quote
Old 02-25-2013, 04:01 AM   #86
tdvt
Gnarly Adventurer
 
Joined: Jul 2012
Location: NEK Vermont
Oddometer: 201
Thanks for the insights. I will probably gather some parts & give it a try though I'm running out of winter down-time. Want to have the bike ready to go as soon as I can get back out in the woods.

I did check the travel, not as close as I would have hoped, 11.0" vs 12.4" & looks as thought the bottom shock mount varies some on the YZ/WR which may require a different 3-hole link.

Anyway, thanks again.

Best, TD
tdvt is offline   Reply With Quote
Old 04-02-2013, 07:55 AM   #87
jar944
Studly Adventurer
 
jar944's Avatar
 
Joined: Aug 2010
Location: Chantilly VA
Oddometer: 551
I'm adding a rekluse core EXP (centrifugal) auto clutch to a cr500. (The company does not [officially] support this application)

Making it fit is the easy part. Making it function may take a bit more thought. What I'm attempting to calculate is the clamping force at various RPM to see how effective additional weight would be (really the only variable easily changed).

what i'm working with


measurements from the exp "ring":

Total wedge weight 159g
wedge spacing diameter (centers) min 124mm, max 131mm
ramp angle 18.5 deg
spring force ? (not yet measured)

engine parameters
primary reduction 2.52:1
idle RPM 1500 rpm


I believe the correct equation to be:
Fc = m v2/r
= m (n 2 ? r / 60)2/r
= 0.01097 m r n2

where
n = revolution per minute - rpm


Or in this case

.01097*m*r*(n*n)
m = .0159kg
r = .062m
rpm = 595

.01097*.0159*.062*(595*595) = 38.3N

which when the 18.5 degree ramp angle is included (3:1) the clamping force would be 114.9N

Can anyone tell me if the basic calculation is correct?
jar944 is offline   Reply With Quote
Old 04-03-2013, 07:49 PM   #88
CosentinoEngineering OP
Gnarly Adventurer
 
Joined: Oct 2010
Location: NYC
Oddometer: 183
You're correct with the calculation.

As you point out mass is the only variable and since mass is included only once then it is a linear relationship. Double the mass, double the force.

One thing to do to get a ballpark mass adjustment figure is to look at the primary reduction ration of the donor part bike and the primary for your bike and see what the difference in gearing is. Even at a 1500rpm engine idle speed the clutch shaft is spinning at a different rpm so the v2term will be different. You already have the force for your bike, now calculate the force for the bike the part is originally intended for and see how big the difference is and how much mass you need to change to get them to be equal.

Even after doing this the easiest thing to get a real world answer will be to throw it on the bike and test it as-is. If it works you're done. If its too weak you won't be able to go at low throttle. If its too strong you won't get the slippage at low speeds. Either way no damage is done and if it needs tweaking its behavior should confirm your calculations for more or less mass.
__________________
Chris
moto2-usa.blogspot.com
Check out my products 10% off for ADV rider members
CosentinoEngineering is offline   Reply With Quote
Old 04-03-2013, 08:25 PM   #89
jar944
Studly Adventurer
 
jar944's Avatar
 
Joined: Aug 2010
Location: Chantilly VA
Oddometer: 551
Quote:
Originally Posted by CosentinoEngineering View Post
You're correct with the calculation.

As you point out mass is the only variable and since mass is included only once then it is a linear relationship. Double the mass, double the force.

One thing to do to get a ballpark mass adjustment figure is to look at the primary reduction ration of the donor part bike and the primary for your bike and see what the difference in gearing is. Even at a 1500rpm engine idle speed the clutch shaft is spinning at a different rpm so the v2term will be different. You already have the force for your bike, now calculate the force for the bike the part is originally intended for and see how big the difference is and how much mass you need to change to get them to be equal.

Even after doing this the easiest thing to get a real world answer will be to throw it on the bike and test it as-is. If it works you're done. If its too weak you won't be able to go at low throttle. If its too strong you won't get the slippage at low speeds. Either way no damage is done and if it needs tweaking its behavior should confirm your calculations for more or less mass.
Thank you.

The wedges are universal across the exp product line, with only the diameter of the ring changing across models.

The two bikes this specific setup is used on both have higher ratios
Cr250 is 3:1
Crf450 is 2.739:1

I was initially wondering how the plain exp held up on the ktm990 until I realized the primary is in the 1.9:1 range.

As for the exp on the 500:
jar944 is offline   Reply With Quote
Old 01-03-2014, 03:38 PM   #90
pennswoodsed
lizards,bugs and me
 
pennswoodsed's Avatar
 
Joined: Jan 2007
Location: Reading,Pa
Oddometer: 675
too many variables , too little patience

Dear Chris and Fellows,
Please correct at will ,"still" intake air is a function of volume/required intake . Could sufficient "still" air be supplied by a smaller air box with positive pressure ?
My starting point sv650 carbed ,has seemingly a very small exhaust cam , -2mm lift ,-24 deg less than intake. Intake cams are routinely installed with nice power increase ,and no obvious torque holes. Is it reasonable to assume that EGR effect is behind exhaust cam strategy ? Raw # like 8.1mm /271deg intake 6.1/247deg exhaust.
I am looking to move power curve down +/- 2000 rpm , peak tq 4500 rpm ,and hp 6500 rpm ish. I intend to advance intake and exhaust cams 6 to 9 degrees and replace 39mm cv mikunis with 35mm flat/oval/round slides .
Should I expect to need accel pumper carbs for sharp off idle response ?

I have in mind 650 thumper lunge with v twin balance .

I have to go rewind my propeller beanie.
Regards,Ed
pennswoodsed is offline   Reply With Quote
Reply

Share

Thread Tools Search this Thread
Search this Thread:

.
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump


Times are GMT -7.   It's 12:55 PM.


Powered by vBulletin® Version 3.8.5
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ADVrider 2011-2014