Alright DTT, be gentle.

[Helve]

So here's my KL 250. I'm hoping to drop the bike ~2" overall while going from a 21" wheel in the front to an 18-19. Going for more of a tracker/brat stance than a cafe. Couple of questions I have.

1: Will dropping the bike and changing the front wheel size dramatically/negatively change the handling of the bike? Would I be better off sticking with the 21 and lowering all around?

2: If I were to lower the front end, would it be better to adapt a set of shocks from another bike or should I simply modify these? I'm trying to stay cost efficient here, and from what I've read it's not an entirely labor intensive process to drop a set of forks with spacers. Also, if I do the spacer route, is it best to trim the springs the same amount or should I keep them stock length for increased preload?

3: For lowering the rear is it as simple as removing the rear shocks, measuring from eye to eye, and then ordering new shocks that are the same amount lower I'd want to go?

4: Is this all a terrible idea?

Sorry if this seems rudimentary, this is my first bike and I'm trying to learn as much as I can before I start modifying it. I'd prefer to have a bike that handles well, sits a bit lower and has more symmetry between the front and rear end but don't want to compromise the stability, handling or suspension in the process. Thanks!

 

[Bozz]

Well first, Welcome!


Second, good for you for asking the question *BEFORE* you start cutting/dismantling.


Third, if this is your first bike, my sincere suggestion is to get it running and safe in stock trim and ride it for a season.
Get to know the bike as a machine under you. Learn it's relative strengths and weaknesses *before* you start to mod/alter/personalize it.


Changing the wheel and lowing the forks *will* affect how it handles, as will shortening the rear shocks.


To best understand what those changes will really mean, you need to really know the current baseline on the roads you travel in your part of the world.


Many folks come to this site because they are excited about a certain "look" be it cafe or brat or tracker or whatever.


What many of the long time members would like to emphasize to those new to the hobby is that a motorcycle is a potentially dangerous machine, and the *function* of that machine is every bit (if not slightly more) as important as the *form* that so pleases the eye.


The above being said, there are rake/trail calculators on the web, several of which have been linked to in threads on this site which I can't bring to my finger tips right this moment.
In addition to the mathematical answer, use the search function here to track down others who have started with a KL250 or similar bike and read of their experiences.

Best of luck, and kudos to you for asking good questions FIRST!

 

[Maritime]

bozz gave good advice there. I will say that if you lower the front only, you change the steering and make it quicker and potentially very twitchy, if you lower the back only you increase the rake and slow the steering down. If you lower the front and rear equally, you keep things pretty much the same. When lowering rear you need to consider swing arm angle for chain clearance etc., travel ie will the tire now hit the frame, when lowering the front to need to consider travel and will the tire now hit the front of frame or exhaust etc. I think with the bike you have you can lower it front and back and stiffen the suspension up for road rinding only without too many problems as it seems to have the clearances, but measure things up first and check that if you take 2" off the front and back that the travel of the new bits full extension and compression is still safe and won't contact anything, bind anything etc. From the looks of that bike, you may be able to just get some KZ200 bits which I think is the street only version and get the results you want in a factory proven solution.

 

[xb33bsa]

welcome good advice so far

that is a PERFECT bike to learn on,AS IT IS,do not waste your time and money modifying it(except for good replacement,oem size tires, shocks and fork oil etc)

riding on dirt trails will teach you very much about bike control
get new brake shoes ! if the original brake shoes are in there, they can kill you, seriously
spend your money on making the bike safe and some decent riding gear,enroll in a certified rider training course

 

[D4N63R]

Understanding the look you are going for I would just swap to an 18" or 19" front wheel and leave it... the bike will act a bit quicker and it will help with the stance, it's win win and you avoid effecting the static geometry of the bike too much.

you start lowring the rear you're going to make the bike handle really slow.

 

[SONICJK]

I say get it running and rideable, and then modify to your hearts content.

Don't lower only front or rear, do both. and dont go crazy with it. But an inch or two front and rear isn't going to destroy the geometry and since its an enduro to start with you likely have plenty of room. Being as its front high currently you can probably afford to lower the front 2" and the rear 1". Do the rake and trail calculations and see.

As far as the shocks, you should be able to comfortably lower the front shocks internally, its fairly simple. As far as preload and cutting the springs you'll have to figure that one out by riding it. Is it stiff now? Or is it bouncy?

Rear shocks, get some quality shocks.

 

[LazloH]

So I started researching and asking questions to some other guys (Junior to be specific). This is all from what I understand on paper and not in practice so I am sure that other people can tell you more.

Rake and Trail is what you are looking at here. Look at the top image.

So by changing out your front wheel and lowering 2 inches.. you will be changing the trail but not the rake of the motorcycle. Junior has told me that 4 -5.5 inches is good... I did read on another chopper site that 3.5 to 6 is acceptable.. but I think I would have to yield to those that have the real world experience.

this seems helpful too.

http://rawge.bravepages.com/minichoppers/trail/Rake_Trail.htm

Hope this helps some.... im still learning this stuff so hopefully I am not leading you the wrong way. Oh.. and I should also mention that all of these measurements are supposed to be taken from a bike that is under its normal load... not up in the air.

 

[xb33bsa]

changing out your front wheel and lowering 2 inches will change rake AND trail
the bikes we deal with here,almost entirely,do not have raked trees that is choppa stuff

 

[oldskool]

I'd find out what the stock rake n trail are, then I'd ride it stock so I'd know how it handles. You can then access How you want the bike to feel. If it feels good to you ,stay within the factory perimeters. If it doesn't handle well, do hours of research about bike geometry and the effects of different set ups. Also keep into consideration how the center of gravity will be effected n weight transfer if you lower one end or the other.

 

[LazloH]

ah.. xb is right.. it will change the rake as well because the whole geometry is lowering in the front.

 

[Helve]

Thanks for all the advice so far! Really appreciate it guys. It's actually in running form right now, just had it apart to fix some electrical issues but they're all buttoned up now. I've already clocked about 200mi in a week and a half (yes I have my permit). So far it feels pretty alright, perhaps a bit bouncy as the front shock is somewhat designed for offroad applications. Turning seems a bit slow, but again, to be expected I guess. I should have mentioned I grew up riding motorcycles, going to the desert, etc etc. I wanted my first on road bike to be a smaller displacement bike so I wouldn't kill myself. I've already pushed this thing about as far as it'll go.

So it seems like the consensus is that lowering the bike just an inch or two in the front and rear isn't going to dramatically change the bike. Good to know. I'll do some serious research before I go chopping into it, I still need to spend time getting hours in on it anyway.

I should have probably stated that this is pretty strictly going to be an around town bike. I'm not too interested in freeway riding right now, just being able to get from my house into the city (roughly 10 miles) and back, and do little cruises with some friends around town. I think 250 will be pretty sufficient for that.

Thanks again for all the replies, really appreciate it you guys! I'm sure I'll have a ton more questions as time goes on.

Rear shocks, get some quality shocks.

Any suggestions as to particular brands/sources? DCC has some cheapy things, which I'm assuming aren't exactly top quality where handling is concerned. Anything in the $100-200 range?

 

[D4N63R]

keep in mind you have a bit more room to play as far as bringing the front down on a trail bike vs a modern street bike, or even a vintage street bike.. Trail bikes and dirt bikes have very conservative geometry in order to keep them stable on loose surfaces. You dont have to be as worried about making the bike overly twitchy.

As far as changing the suspension bits go with progressive springs in the front (about $80 for good ones) and some decent shocks for the rear (about $200 for some good ones) I dont remember the exact amount but front and rear for my bike with all hagon is around $350 Canadian, shipped to Canada from the US. I would bet you could do similar for under $300 then you'll have a fantastic suspension

 

[Helve]

Hagon seems legit. Really liking their progressive stuff. I'll probably end up doing those in the rear to start, lower the front internally and then see if I want progressive springs up front as well. Curious as to how much an 18 or 19 will drop the front end as well. Don't want to be stinkbuggin all over the place either.

From the looks of that bike, you may be able to just get some KZ200 bits which I think is the street only version and get the results you want in a factory proven solution.

I'd love to do that, but unfortunately I can't seem to find and specs for the steer bearings for the KZ200 and it seems like just the fork tubes are smaller. Ideally I'd go with a swap like that, would allow me to upgrade to a disk in the front, go to the wheel size I'm wanting and maybe even widen the forks so I could fit a bit wider of a tire up there as well.

 

[o1marc]

Hagon seems legit. Really liking their progressive stuff. I'll probably end up doing those in the rear to start, lower the front internally and then see if I want progressive springs up front as well. Curious as to how much an 18 or 19 will drop the front end as well. Don't want to be stinkbuggin all over the place either.


I'd love to do that, but unfortunately I can't seem to find and specs for the steer bearings for the KZ200 and it seems like just the fork tubes are smaller. Ideally I'd go with a swap like that, would allow me to upgrade to a disk in the front, go to the wheel size I'm wanting and maybe even widen the forks so I could fit a bit wider of a tire up there as well.

If your existing front wheel is a 21" and you go to a 19" it will drop the front 1"+/- depending on what profile tire you run. An 18" will drop it 1.5" and on a bike that small you might consider a 17" combination that has lots of modern popular tire choices and that would drop the front 2".
Go to Allballsracing.com for front end swap bearing kits. It's easy to navigate their charts to see what front ends will easily swap to your bike frame.

 

[Helve]

Unfortunately they have no information on my bike. Bummer.

 

[o1marc]

They have listings for the 78 KLX250, I wonder if there is a difference in frames between it and a KL? If Kawi's are anything like Honda any of the long list of front ends for a KLX will swap to a KL.

 

[Helve]

So, since I know absolutely nothing about what it takes to swap front ends I figured I'd ask. Let's say I find a front end that has bearing specs that work from another bike. What else is there to it? Stem (I believe that is the right term...) length, is there any possibility for complication there due to different length head tubes? If I could simply buy a full front end from something like a RMZ with nice new shocks, disk brakes, etc I'd be thrilled. Enlighten me, oh gods of DTT.

 

[Floegstad]

You can try marksmanengineering.uk for bearings as well.
Nice bike

 

[Maritime]

That would be te easiest. there is a list of bearing sizes here and I believe All Balls Racing has a complete or at least robust list of front ends with bearing size, stem length etc. As long as the stem isn't too short and has enought threads you can usually use it. But sometimes you can get the stems swapped from your bike to the new front end by a machine shop for reasonable amounts.

 

[D4N63R]

yeah a stem thats too short doesnt work, if its a touch too long you can use it with a spacer though. try to avoid having to have the stem changed, that can get to be a real pain without a press or someone to make up a stem for you etc.