Jump to content
Sign in to follow this  

New SM owner question - speedo accuracy

Recommended Posts

This weekend I was able to snatch me up a sick '09 DRZ400SM with 8k miles. I've been riding MX (CRF450R) for the past ten years with my son, and I'm just tired of getting hurt anymore. 

 

But I had a quick question..

 

I took it for a quick spin on Saturday night around the area I live, despite not having a tag yet, and I noticed that the speedo displays what I feel is much faster than I'm really going. I did notice that the new front tire the dealer installed was a 120/60-17 vs I think stock was 120/70-17. Would a tire size from a 60 to a 70 really cause that much of a difference in speed? Or was I just having so much fun I didn't realize how fast I was going? 

 

What a freak'in blast this thing is! 

 

 

http://s17.photobucket.com/user/450xDaD/library/DRZ

Edited by MotoJunkii
  • Like 1

Share this post


Link to post
Share on other sites

welcome aboard!  Looks like your bike has some nice goodies on it.  MRD exhaust, zeta top clamp, does it have an FCR carb on it?

 

as far as your question about the speedo.  the stock speedos can be off at 25mph by a few off the showroom.  There is some sort of function(ive heard) in the speedo that allows you to compensate your odometer for tire wear, but not the speedo reading, odd right.  Anyways the difference between a 60 and 70 profile tires equates to about 3" more traveled per rev of the front tire.  So with the 60 profile tire you are going 3" less per rev. Break it down to a mile, your new tire has to go almost 900 revolutions for 1 mile where the 70 profile was about 850.  Now these seems like they are adding up to be big numbers....  In reality i think its just under 10% so at 25 you would be about 2mph off.  at 60 you would be closer to 6mph off.

  • Like 1

Share this post


Link to post
Share on other sites

Yes sir it does have the FCR. I spent some time inspecting it this weekend (since I couldn't legally ride it) and found that the previous owner spared no expense as it  appears anything that could have been upgraded, actually was. It appears to have been garage kept and in good order. I even took the tank off and it was clean as a whistle under there. Thats when I realized it was an FCR conversion. So I'm pretty stoked to say the least! 

 

The throttle seems a bit heavy for my taste. Im used to the snappy-ness of the throttle on my mx bike. Not sure if that is normal trait of the FCR-DRZ conversion or not yet. But I plan to dig into it.

Edited by MotoJunkii
  • Like 1

Share this post


Link to post
Share on other sites

figure out what cams it has.  Also there is a single cable R6 throttle mod that makes it a quicker turn.

 

What you are probably feeling is just the slower revs.  The rotating assembly is a lot heavier than an MX bike.  The kick only model of the drz had a different left side of the crank, different stator and flywheel and it revved faster.  of course the DRZ doesnt get hollow ti cams, super light rotating assembly etc like MX bikes do and the pistons have a good bit more meat on them to withstand long term use without rebuilds.  The stock cams in the S/SM models are pretty limited.  Just using E cams or hotcams stage1 really opens the breathing.  Chances are with all the mods your bike has that it got cams too.  if you can rev up to the rev limited without feeling like you are waiting then it has cams.  Stock it checks out about 2k rpm before redline and just feels flat.

 

Also when you are checking it out pay close attention to the FCR throttle cable routing.  I, along with most, ran it with just a pull cable because the FCR MX carb cable routing doesnt really work on the drz.  there isnt much frame clearance.  You could have a cable binding up causing a heavy feel.

  • Like 1

Share this post


Link to post
Share on other sites

awesome thank for the tips. Yea- it's definitely in the action of the throttle. It doesn't SNAP back like I'm used to. Kinda whiskey-throttle type scary. I will check that cable routing as you mentioned. It does almost feel like it is kinked somewhere. However, I noticed that it doesn't have the two cables on the throttle like my CRF450R has or the stock DRZ. It almost appears to be an aftermarket throttle assembly now that I think of it.

 

Also will be looking into that R6 mod you mentioned

Edited by MotoJunkii

Share this post


Link to post
Share on other sites

awesome thank for the tips. Yea- it's definitely in the action of the throttle. It doesn't SNAP back like I'm used to. Kinda whiskey-throttle type scary. I will check that cable routing as you mentioned. It does almost feel like it is kinked somewhere. However, I noticed that it doesn't have the two cables on the throttle like my CRF450R has or the stock DRZ. It almost appears to be an aftermarket throttle assembly now that I think of it.

 

Also will be looking into that R6 mod you mentioned

 

this is probably what you have

 

http://www.sisnerosspeedworks.com/ssw-single-pull-quick-turn-throttle

 

the return spring on the FCR is pretty stout so chances are good that your cable is just bound up somewhere.  I think i ran mine through the frame near the coil and on the left side of the neck of the frame because the 'pull' cable had a 30degree metal guide at the carb end.  It did take awhile to work it out on my bike.  Also pay close attention to the actually wheel on the carb, it can hit and bind up on the frame.  That could also be what you are seeing.  Some guys would take a hammer to the frame for clearance.  I ended up just tilting the carb a little more counter clockwise and running a single cable.  I got many trouble free miles that way on and off road.

Share this post


Link to post
Share on other sites

figure out what cams it has.  Also there is a single cable R6 throttle mod that makes it a quicker turn.

 

What you are probably feeling is just the slower revs.  The rotating assembly is a lot heavier than an MX bike.  The kick only model of the drz had a different left side of the crank, different stator and flywheel and it revved faster.  of course the DRZ doesnt get hollow ti cams, super light rotating assembly etc like MX bikes do and the pistons have a good bit more meat on them to withstand long term use without rebuilds.  The stock cams in the S/SM models are pretty limited.  Just using E cams or hotcams stage1 really opens the breathing.  Chances are with all the mods your bike has that it got cams too.  if you can rev up to the rev limited without feeling like you are waiting then it has cams.  Stock it checks out about 2k rpm before redline and just feels flat.

 

Also when you are checking it out pay close attention to the FCR throttle cable routing.  I, along with most, ran it with just a pull cable because the FCR MX carb cable routing doesnt really work on the drz.  there isnt much frame clearance.  You could have a cable binding up causing a heavy feel.

 

So I'm thinking this is definitely has performance cams. I got my tag today and took it out for a spin. It PULLS all they way through to redline. WOW. Also played with the throttle cable and got the action to feel better. Ended up pulling the throttle forward about 2" to change the tension on it, and it seems to have done the trick. Feels better.

 

Also found that the left side fork leg seems to be leaking a bit- not too bad. Ordered a set of replacement seals and dust covers tonight. Seems to be relatively same Showa as my Honda- so should be an easy fix.

 

Thanks again for the tips. I'm going to love this SM thing.

  • Like 1

Share this post


Link to post
Share on other sites

So I'm thinking this is definitely has performance cams. I got my tag today and took it out for a spin. It PULLS all they way through to redline. WOW. Also played with the throttle cable and got the action to feel better. Ended up pulling the throttle forward about 2" to change the tension on it, and it seems to have done the trick. Feels better.

 

Also found that the left side fork leg seems to be leaking a bit- not too bad. Ordered a set of replacement seals and dust covers tonight. Seems to be relatively same Showa as my Honda- so should be an easy fix.

 

Thanks again for the tips. I'm going to love this SM thing.

 

 

thats good to hear!  if it pulls to redline its not stock cams for sure.  Also glad you got the throttle feel sorted!  Just remember it is a pumper carb so everytime you twist the throttle you are shooting gas into the cylinder(if your valves are open) as long as there is fuel in the float.

 

The forks are straight forward but of course being USD you have to have some tools to do them.  They are very similar to the RM forks.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×