Time for another dirt bike - which one to get for a short rider?

[sixstringsteve]

Here's a pic of my carb:

oh, and you are the man. YOu're like wikipedia for all things diesel and dirt bikes... and more I"m sure.

 

[Rot Box]

Here's a pic of my carb:

oh, and you are the man. YOu're like wikipedia for all things diesel and dirt bikes... and more I"m sure.

Haha thanks It is the Mikuni TM flat slide. The philips screw directly above your vent tube is the idle screw. It has a a tapered end and the more you thread it in the higher it raises the slide. If you have to thread that in all the way and you still can't get an idle or you only get a really high idle you'll need to tune the pilot jet.

That small brass screw (flathead between your hose clamp and air boot) towards the rear is your fuel screw. That works with the pilot jet to meter your Idle-1/4 throttle jetting. Clockwise/in is leaner out is richer. It is only efficient between ~1-2.5 turns out and never more than 3 in fear that it will come out while your out riding If you get the bike to idle decent at a low RPM and you can turn that screw all the way in an NOT have it die you need to lean out the pilot jet (numerically lower). Ideally the bike should run great at 1.5 turns and die if its threaded in past .5 turns. If you need more than 2.5 turns (richer) out to get a decent idle you'll need a step richer (numerically higher) pilot jet. It takes time, but once you get it you'll be able to start the bike in less than 3 kicks every time along with a smooth idle. Does that make sense?

Make sure you have a clean air filter and check the gap on your plug both of these really factor into jetting.


EDIT: If you clean the pilot circuit take out that brass fuel screw (careful not to loose the spring) and clean that out as well. Make sure there's no gunk on it

 

[rholbrook]

Flat slide. This may be too obvious but have you tried to adjust the idle at the handle bars?

 

[rholbrook]

I went for a night ride Saturday and as always was very dissappointed in my light. I had bought another and finally put it in after my ride Saturday night and adjusted the light down some. Yesterday I changed my fluids and filters and decided I had been hearing something weird coming from the case on the clutch side so I opened it up and pulled my RevLok out. Lucky I did because there was a screw that had sheared off of it. I had a couple of bearing fall out when pulled it out.

I know that RevLok has gone away in the US but they are alive and well in Austrailia so I sent them an email to see what they will do about it. That could have been disasterous. I pulled the rest of the clutch out to inspect and then put it all back together with the original plates and now I am back running again. I forget how hard it pulls when there is no slipping action going on. The front end is really light now and I have never ridden it without the Revlok since I put the YZF Exhaust cam in it. Rekluse may now be in my future but I have to get a Z Start Pro for my WR since they dont make the ring for a 2006 and older.

 

[sixstringsteve]

Flat slide. This may be too obvious but have you tried to adjust the idle at the handle bars?

by giving it throttle? If I keep giving it throttle, it'll stay running, but when I let off the throttle it dies.

Where can I get jets for this? RMATV doesn't list anything for this bike.

 

[sixstringsteve]

I cleaned out my pilot circuit today, along with the fuel mix screw. I won't have time to test it 'till Thursday.

I'm thinking that even if I did lower it enough, I'd still feel like the bike is super bulky. I'm too spoiled with my trials bike. I can finally do 180 wheelie/turn things, I could never do that on any other bike, and I doubt I'll ever be able to do it on another bike.

 

[pELYgroso]

Hey Steve, do you know Levi Ellis in Alpine?

 

[sixstringsteve]

I've talked to him a few times. I doubt he'd remember me, but I know who he is. His brother and my brother used to be friends. Is he looking for a bike?

 

[sixstringsteve]

Ok, I'm trying my best to make my YZ250WR work for me. I like the power, I like the gearing, it's easy to reach everything and work on it, and I like that I got it so cheap. I don't like the weight, how overbuilt it is, the bulk, and the height. I guess I'm spoiled with my trials bike, but it feels pretty bulky. I can't do much about the weight, and there's very little I can do about the bulk, but I have some ideas with the hegith. I need input (paging mr rot box).

Here's what I've gathered in my research. There are several ways to shorten a bike.

1) lowering link (not an option, I hate 'em)
2) cut the seat foam (I plan on doing this)
3) cut the rear subframe to lower the seat another inch
4) have the shocks/forks professionally lowered so their travel is reduced


It looks like I can slide the forks up about an inch, which will help a lot. It also looks like i can slide the rear shock mount up an inch. That would be a GREAT cheap way to get a lower seat height for me, without having to send my suspension out to get reworked. What are the thoughts on this? I'd have to cut the old mount off and weld up a new one, but that's a piece of cake.

the subframe doesn't unbolt, so I"d have to cut and weld it. Again, not a problem, but the pipe would start to get in the way. I don't know how to cut and weld the pipe, I'd have to have someone do that for me.


a couple more questions.

1) are there any disadvantages to swapping to a smaller airbox and filter? My trials bike has a tiny airbox and filter, and I really like the design. I'm wondering if my carb would get enough air with a smaller filter. Also, is there a way to add some sort of "bump stop" to the bike so I don't max out on my rear fender?

 

[Caleb]

FWIW, adjusting the front forks up will drastically affect how it handles. Usually front fork adjustments are measured in millimeters not inches Just something to be aware of.

 

[Cascadia]

Is 2 inches plus trimming the foam really even going to be enough? That bike fit me ok, but I'm probably 6-7 inches taller than you. I feel like it would probably still be too tall even with all that work. That's what happened with your last bike and you sold it. But I guess that's to be expected.

 

[sixstringsteve]

FWIW, adjusting the front forks up will drastically affect how it handles. Usually front fork adjustments are measured in millimeters not inches Just something to be aware of.

what if you lower the rear the same amount? I can see lowering just the front affecting the rake and trail, but if the rear is lowered at the same time, it shouldn't affect it too much, or should it? I'm new to this entire geometry discussion, and I'm trying to understand it.

 

[sixstringsteve]

Is 2 inches plus trimming the foam really even going to be enough? That bike fit me ok, but I'm probably 6-7 inches taller than you. I feel like it would probably still be too tall even with all that work.

I think you're right. The only other option is to make a smaller bike bigger.

 

[Caleb]

You'd still be affecting the behavior of the bike because you are pulling your front tire in closer. I know this is an extreme example but there is a reason you don't see pros riding shortened bikes (and some of the pros are pretty damn short). No matter how you do it, it will affect handling. Doing the internal modifications is probably the least impacting way to do it. All they do is add a spacer, you could probably do it yourself or Ibet it wouldn't cost more than $100-$200 to have it done by a shop. (I know, still more than free )

 

[sixstringsteve]

doesn't shortening the shocks also bring the front tire in closer? in other words, how is a 1" spacer going to be different than raising the forks 1" in the clamps? I'm not trying to argue, I'm trying to understand. Are there any good suspension guys in Utah, or do I have to mail them all off to So Cal?

 

[Caleb]

Yes it does, that's why I said the least impacting way to do it is by using the spacers. Not using the spacers will make it so (as you already showed concern about) you'll end up rubbing on your fenders. Using the spacers, you won't get any closer to your fenders than when it's stock. You can read a little more about this from Race Tech http://racetech.com/html_files/LOWER_PHOTO.html (it's still more of a sales page, but they have some info on it).

EDIT: As for Local shops, yes, there is a guy in Riverton that does a lot of the Desert guys' bikes. He's a little spendy but cheaper than the big shops (Race Tech, Factory Connection, etc). There are also a couple other shops around, even some that are certified by Race Tech I believe but all their names slip my brain at the moment, I bet if you checked MU you could find the names.

 

[sixstringsteve]

That makes sense at full bump (or whatever you call it). But the handling should be the same until it gets to that point, right? I definitely agree with you that having the suspension modified is the right way to do it, I'm just trying to understand the principles. I could get by with rubbing the rear tire on the rear fender, but the front is downright dangerous and unacceptable.


Thanks for the link Caleb, that's very helpful. Yikes, $225 for the front, $225 for the rear. But that's still cheaper than modifying a kx100 to fit me...

 

[Rot Box]

Steve, I agree with Caleb leave the shock mount where it's at along with the forks or your handling will go out the window. I can walk you trough modifying your suspension as I had to remove a 2" lowering kit from my Husqvarna. They are very simple as in I'd make it myself if I wanted one. much safer than a lowering link as well. Once I get home I can explain it a lot better

 

[rholbrook]

I ride with a guy that moved his forks up in the triple clamp and he cant figure out why his WR handles goofy. I pointed out his problem, fixed it on the trail and now he is happy. He figured he could lower it an inch.

 

[sixstringsteve]

did he lower the back as well, or just lower the front?