99 rm125 bottom end he;p

darringer

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Dec 2, 2001
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I'm looking to pick up a little more bottom end and midrange on my 99 rm125. I already have boyesen dual stage reeds and 2 teeth larger rear sprocket. Was wondering if a reed spacer or different pipe will help. I'm running the stock pipe now. Any help is greatly appreciated
 

lilcr80

Member
Dec 26, 1999
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I have the same bike and run afmf fatty pipe with fmf silencer 2. Pulls very strong in the low to mid but lacks a little on the top.
 

darringer

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Dec 2, 2001
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Thanks for the tip! A new pipe was the next thing to replace. Wasn't sure which pipe to go with. Maybe ther will be a "Fatty" undeer the tree this year!:p
 

RM_Dude

Member
Jul 16, 2001
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How well do carbon and other reeds help low end of this bike?
I installed a VForce Delta2 on my 99 RM125 and am not all that impressed with the low end gain. Low end stayed about the same, I don't notice a difference. Mid comes on sooner and stronger. Top end is like a different engine compared to the stock reeds, very strong ! This is on the low tension setting by the way.

Only other mods are PC pipe/silencer
Before installing the VForce the bike had a very smooth power range but now has a stronger mid and top hit thus not quite as easy to ride as before but I got used to it. I would trade some of that top end for more bottom.
 

Malden

Member
Feb 28, 2000
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RM Dude your analysis is very similar to what i experienced with that bike when i owned one. V Force only enhanced the mid to top end. I found the stock pipe to be the best pipe for low end. PC was all mid and Bills was all top. The 133 overbore kit helped the most, and spending time on the low throttle jetting was crutial on thet bike. I swapped needles constantly and a leaner slide crispened it up too.
 

marcusgunby

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Jan 9, 2000
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IMO with 125s the only real way to increase low end power is to have the head modified to run more compression which then requires race fuel, or to have the cylinder decked(lowered) and maybe the transfers stuffed with epoxy like eric gorr does,He made a KTM 125 screamer into a tree stump puller still using a 39mm carb.However you do give up top end to get it.
 

MoToMaNYz125

Member
Apr 2, 2001
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i think the bills pipe set-up and the pro-circuit set up are the best ones for a suzuki, what gearing do you run right now 1-2 teeth+ on the rear should make a big difference in low-end, on my yz i run a pro circuit pipe and 304 silencer with a 13/49 gearing 1 tooth up from stock and i have notice a big gain in low end im thinking about going back down to stock (13/48) to get moe mid-top end out of it im not sure i might like where its at
 

Jeff Allen

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Sep 23, 1999
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Darringer,
How much of a change did you get when going up 2 teeth on the rear sprocket? I have thought about going up at least 1 tooth to gain a little more low end also. But while talking to Rich at the DW01 I think I might go with an overbore kit from Eric.
The other things that I did to help the bottom end were adding Boyesen dual stage reeds and FMF SST pipe and silencer. These helped immensely, but I need a little more.
 

darringer

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Dec 2, 2001
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Re: upping 2 teeth on rm125 rear sprocket

You will be pleasantly surprised going up 2 teeth in the rear. If you don't have to worry about top speed it is a great trade-off. Not only do I have more low end now, but my gearing is a little tighter which also helps it pull that much harder out of corners or on hillclimbs.
Darringer:D
 

Jeff Allen

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Sep 23, 1999
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pulling out of corners is my weak spot as I am to lazy to down shift :)
I'll give it a try,thanks
 
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