2 Stroke like a 4 Stroke

well,, for what its worth, Id go to a heavier flywheel if its too snappy for
you,

--
Jeff

I never believe anything until I read it on a forwarded email
2004 CRF450R
1995 YZ250 (for sale)
2000 TTR125L
1996 VFC750 Magna
1985 ATC200X

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<wolverinedoc RemoveThis @gmail.com> wrote in message
news:1102387581.276967.248510@f14g2000cwb.googlegroups.com...
 > I just bought my brothers 2001 YZ125 that has been raced and upgraded
 > with all kinds of performance parts. I am not really interested in
 > racing and am used to riding an old 4 stroke. But I do enjoy riding on
 > the track recreationally. This thing is like a rocket compared to my
 > old bike. It is really hard for me to control on trails and just seems
 > a little to snappy for me right now. Can this thing be tuned down a
 > bit. So that it rides more evenly and "easier" for a begineer like
 > myself. Before I make the mistake of having the local shop mess with
 > it, I thought I would ask some of you experts.
 >


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 >> Stay informed about: 2 Stroke like a 4 Stroke 

try a fly wheel weight but basicly thats what you get with a 125cc MX bike
thier all like that.

Mike Simmons
04' KTM 525 MXC
AMA/ Dist.36
http://www.ktm-parts.com
D-H Cycles KTM/Suzuki/ Modesto
Motowrx, Livermore CA
Motowerx, livermore Ca
 >> Stay informed about: 2 Stroke like a 4 Stroke 

<wolverinedoc.RemoveThis@gmail.com> wrote in message
news:1102387581.276967.248510@f14g2000cwb.googlegroups.com...
 >I just bought my brothers 2001 YZ125 that has been raced and upgraded
 > with all kinds of performance parts. I am not really interested in
 > racing and am used to riding an old 4 stroke. But I do enjoy riding on
 > the track recreationally. This thing is like a rocket compared to my
 > old bike. It is really hard for me to control on trails and just seems
 > a little to snappy for me right now. Can this thing be tuned down a
 > bit. So that it rides more evenly and "easier" for a begineer like
 > myself. Before I make the mistake of having the local shop mess with
 > it, I thought I would ask some of you experts.
 >



As far as 125s around that year go, the YZ was probably the best [ yes I am
bias ], it has a nice broad [ stock ] powerband [ for a 125 anyway ] but you
can do other things to make it a little less peaky and make more power at
the same time ..
First off, you probably have a PC or similar pipe on it .. find out what
style of pipe it is , if it is pushing the power up in the rpm , take it
off and run a stock pipe, the stock ones are very good.
Try the V-Force reed cage [ the whole unit, not just the reed pedals , there
is a huge difference ] as well as going up a "tooth or two" [ but no more ]
from the factory spec on the rear sprocket, also like others have said, you
could go to a fly wheel weight but that will make changes to the bike you
may not like if you ride mx tracks ..
The best bang for the buck was the porting on my 00YZ125 as well as the reed
cage and a modified silencer, the bike works great, I have rode pro powered
race gas bikes that are only marginally [ if that ] stronger in the top
end.. but at the cost of race fuel, I am not interested in that extra one hp
...
The bike works great for a 125, maybe you should ride others [ YZ ] 125s to
see if they are going to be what you want in the end, if you are expecting
250 2 stroke grunt or 250 four stroke bottom end power , the only way to get
that is to buy one .
Oh and also , that "snappy" could be your riding style, "old four strokes"
can put the rider in a different mode/position than a two stroke.. try
leaning forward more "before" you get on the throttle.. it will not throw
you back that way .. 125s are a hoot to ride if you ride them the way they
were built to be rode.. higher in the rpm and alot of clutch work to keep it
in the power band.
If you want to get serious.. go out and get the new aluminum frame YZ125...
stock ..it has an awsome power band and turns like its on rails... that and
it is also [ depending on who you believe] 6-10 lbs lighter than last years
125 ..
Dave.<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

You could de activate the power valve in the exhaust port. I have a husky
125 and took four little balls out and it only has a hit now just at the
very top of the rev range. At least on my bike there was some adjustability
in the linkage for the power valve though I am not sure it made a lot of
difference. If you also used a smaller front or/and a larger rear sprocket
you might find you could get out of a tight spot in a trail section without
having to get into the hit area of the power band.


Fran
wolverinedoc.RemoveThis@gmail.com wrote in message
<1102387581.276967.248510.RemoveThis@f14g2000cwb.googlegroups.com>...
 >I just bought my brothers 2001 YZ125 that has been raced and upgraded
 >with all kinds of performance parts. I am not really interested in
 >racing and am used to riding an old 4 stroke. But I do enjoy riding on
 >the track recreationally. This thing is like a rocket compared to my
 >old bike. It is really hard for me to control on trails and just seems
 >a little to snappy for me right now. Can this thing be tuned down a
 >bit. So that it rides more evenly and "easier" for a begineer like
 >myself. Before I make the mistake of having the local shop mess with
 >it, I thought I would ask some of you experts.
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

"BKR" <NoSpam.rchvid7.TakeThisOut@lycos.comNOSPAM> wrote in message
news:10raj2lq8m6vsdb@corp.supernews.com...
 > The ideas with an increased flywheel weight are good. Also consider
 > adding an extra head gasket to slightly decrease compression.

Would the extra gasket not drop the compression enough to lower the bottom
end performance even more than it is ..??


 >
 >
 >
 > wolverinedoc.TakeThisOut@gmail.com wrote:
  >> I just bought my brothers 2001 YZ125 that has been raced and upgraded
  >> with all kinds of performance parts. I am not really interested in
  >> racing and am used to riding an old 4 stroke. But I do enjoy riding on
  >> the track recreationally. This thing is like a rocket compared to my
  >> old bike. It is really hard for me to control on trails and just seems
  >> a little to snappy for me right now. Can this thing be tuned down a
  >> bit. So that it rides more evenly and "easier" for a begineer like
  >> myself. Before I make the mistake of having the local shop mess with
  >> it, I thought I would ask some of you experts.
  >>
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

"dobypinch" <dobypinch RemoveThis @cox.net> wrote in message
news:QQitd.2545$Zo.799@lakeread07...
 > You could de activate the power valve in the exhaust port.

If you are considering doing this to your YZ .. at this point you should be
thinking about another bike.


I have a husky
 > 125 and took four little balls out and it only has a hit now just at the
 > very top of the rev range. At least on my bike there was some
 > adjustability
 > in the linkage for the power valve though I am not sure it made a lot of
 > difference. If you also used a smaller front or/and a larger rear
 > sprocket
 > you might find you could get out of a tight spot in a trail section
 > without
 > having to get into the hit area of the power band.




 >
 >
 > Fran
 > wolverinedoc RemoveThis @gmail.com wrote in message
 > <1102387581.276967.248510 RemoveThis @f14g2000cwb.googlegroups.com>...
  >>I just bought my brothers 2001 YZ125 that has been raced and upgraded
  >>with all kinds of performance parts. I am not really interested in
  >>racing and am used to riding an old 4 stroke. But I do enjoy riding on
  >>the track recreationally. This thing is like a rocket compared to my
  >>old bike. It is really hard for me to control on trails and just seems
  >>a little to snappy for me right now. Can this thing be tuned down a
  >>bit. So that it rides more evenly and "easier" for a begineer like
  >>myself. Before I make the mistake of having the local shop mess with
  >>it, I thought I would ask some of you experts.
  >>
 >
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

Hey, thanks for the suggestions. I am really not afraid of the power,
I just want it to start earlier in the powerband. More uniform power
is I guess the best way to describe it. I thinned out the gas a little
and that helped it run a little more smoothly. I also changed the plug
withich helped a bit too. In terms of the pipe, I dont have the stock
pipe, it is a big aftermarket one. The silencer is the original though
which my brother put back on to quiet it down. I am going to put on
the original rear sprocket. Is replacing the pipe with one closer to
the stock one really going to give me more power earlier?
 >> Stay informed about: 2 Stroke like a 4 Stroke 

<wolverinedoc RemoveThis @gmail.com> wrote in message
news:1102478239.976728.251000@c13g2000cwb.googlegroups.com...
 > Hey, thanks for the suggestions. I am really not afraid of the power,
 > I just want it to start earlier in the powerband. More uniform power
 > is I guess the best way to describe it. I thinned out the gas a little
 > and that helped it run a little more smoothly. I also changed the plug
 > withich helped a bit too. In terms of the pipe, I dont have the stock
 > pipe, it is a big aftermarket one. The silencer is the original though
 > which my brother put back on to quiet it down. I am going to put on
 > the original rear sprocket. Is replacing the pipe with one closer to
 > the stock one really going to give me more power earlier?

Depending on the pipe that is on it .. but most likely yes.. most pipes
push the power up higher in the power band .
The stock on mine works great , and I have talked to others with the same
year bike, they say they like the stock one better . your 01 bike is
basically identical to my 00 ..
The stock silencer is also best for lower end torque , most of the
aftermarket units [ pc etc.. ] will also kill some bottom end power to get
more in the top .
But like I said, get the V-force reed cage, you will notice a huge overall
ridability difference, that and a few teeth up from a stock sproket and you
should be good to go.
What sprocket do you have on it now.. usually race bikes go with bigger
ones..so they rev faster and give more torque multiplication to the rear
wheel, but if you go to drastic [ like 3 or more teeth ] you end up shifting
all the time.. you also lose some top end speed as well, but probably not
enough for you to worry about it.
Jetting is really important on the 125s as they are pretty low on bottom end
torque to start with .
Unless you are familiar with jetting you may want to get someone who "knows"
[ not someone who saw it on tv once ] how to jet your bike.. if you are off
to far [ particularly with the main jet ] you can blow your motor pretty
easily..
I run 38-1 oil. on both my bikes, I have never [ knock on wood] blown up a
motor yet , I also only use the Yamalube "injector oil" .. the "R" is about
twice the price and I have never had a problem with the injector stuff.. and
hey.. if it can run in a sled that makes 150hp and run across a lake wide
open and not blow up... its good enough for me ..
I know others that use outboard motor oil , it is supposed to keep the
piston and power valves cleaner .
Oh and make sure you run the best gas available, I can get sunoco 94oc at
the pump so that is what I use.. any less and my motor would ping .
Although I know of others using Esso 93 with good results...
If you really think it is a dog, you could also take off the pipe to see if
the power valves are moving freely .. this will also make a huge difference
on performance.. that and of course a dirty filter will kill a 125.
Just a tip.. any time you think the bike is down on power.. [ after checking
the filter of course ] change the plug .. then go from there.. mx 125s are
notorious for fouling plugs if the jetting is slightly off and particularly
if they are being trial rode.. when I am on the [ slower ] trails with mine
I usually give it a good rev every few minutes to clean it out.
Dave.



 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

On 7 Dec 2004 19:57:20 -0800, wolverinedoc DeleteThis @gmail.com wrote:

 > Is replacing the pipe with one closer to
 >the stock one really going to give me more power earlier?

Dave can probably comment more specifically on your model, but in
general the expansion chamber (pipe) on a 2-stroke is usually the
single most effective way to alter the power delivery and/or overall
power. (Though a flywheel weight can certainly have enormous value
also).

Generally speaking, most 2-stroke motors make peak power high in
the RPM range. So switching to pipe that takes advantage of that RPM
range you can effectively raise your overall horsepower... at a cost.
The cost is that you usually lose some power on the bottom end.

Now, since motocrossers seldom care about "bottom end" power, the
first aftermarket item they usually add is a new pipe to increase
overall HP (for that drag race to the first turn). Nowhere is HP more
valuable than in the small bore classes. So I think it's pretty safe
to surmise that your brother probably installed such a pipe on the YZ,
particularly if he was racing it.

That said, such a pipe would make the bike overly difficult to
"trail ride." The stock pipe would most likely return some civility to
the machine, and a "Gnarly" pipe by FMF could help even more. I assume
that Dave recommended the stock pipe because it's not only better
(power delivery wise) than the current pipe, but also because the
stocker can probably be found for very little money (try eBay or a
local dealer). Why? Because as I said above most "racers" switch out
the stock pipe immediately. Hope this helps and good luck!


CrashTestDummy (aka Fred)
f.j.bradfordREMOVE DeleteThis @verizon.net<!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

 >On Tue, 7 Dec 2004 09:24:55 -0500, "flymx" <ya DeleteThis @right.ca> wrote:
 >
 >"BKR" <NoSpam.rchvid7 DeleteThis @lycos.comNOSPAM> wrote in message
 >news:10raj2lq8m6vsdb@corp.supernews.com...
  >> The ideas with an increased flywheel weight are good. Also consider
  >> adding an extra head gasket to slightly decrease compression.
 >
 >Would the extra gasket not drop the compression enough to lower the bottom
 >end performance even more than it is ..??

I concur, Dr Dave.
Compression gives torque at low rpms. If anything can help, it's going
to be proper jetting and gearing for his situation.
They have no low torque when jetted too lean on the needle.

Jim Cook
'04 Gas Gas EC300 Woods Pilot
Team LAGNAF
SMACKOVER RACING
BJEC/SERA/TSCEC/AHSCS
<a style='text-decoration: underline;' href="http://www.smackovermotorsports.com" target="_blank">www.smackovermotorsports.com</a><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

two stroke bikes use the suction of the piston to grab some
fresh air/gas to run... then the exhaust shape scavenges the
used up air/gas out making it easier for it to run.... the faster the
engine is running the more efficient the process (to a point).
this efficiency is usually in the upper 1/3 of the RPM of the bike.
engineers shape the exhaust to maximize certain characteristics...
125cc bikes were designed to scream wide open.... but to make
them more tolerable the smartnecks decided to artificially change
the shape & back pressure of the exhaust pipe by putting a
valve in the exhaust that opens & closes in relation to engine
speed/demand... this is an effort to make the bike tune for
both low & high rpm. it works pretty good but the bike is still
focused on being able to scream wide open. you can get a $$
exhaust pipe to work better in the low rpm & put a $$ flywheel
weight in the engine to smooth out the hit of the power band,
but lets face it yz125's don't make really good putt around
the woods bikes. yes you can go very fast on them because
they have a great power to weight ratio, but if you want to
putt around a bike with an engine designed for tame riding will
be eisier on you and the bike.
john
don't bring a seal to a dog fight
<wolverinedoc.DeleteThis@gmail.com> wrote in message
 > Hey, thanks for the suggestions. I am really not afraid of the power,
 > I just want it to start earlier in the powerband. More uniform power
 > is I guess the best way to describe it. I thinned out the gas a little
 > and that helped it run a little more smoothly. I also changed the plug
 > withich helped a bit too. In terms of the pipe, I dont have the stock
 > pipe, it is a big aftermarket one. The silencer is the original though
 > which my brother put back on to quiet it down. I am going to put on
 > the original rear sprocket. Is replacing the pipe with one closer to
 > the stock one really going to give me more power earlier?
 ><!-- ~MESSAGE_AFTER~ -->
 >> Stay informed about: 2 Stroke like a 4 Stroke 

Thanks for all of your suggestions. I do have a v-force reed cage on
the bike. I may try the gnarly fmf pipe or even try to find a stock
pipe. I will have to check out what is currently on there but it is
super fat so I dont think it is a gnarly. The bike is at a friends
house but I will know by tomorrow. Thanks again for all of your
responses.
 >> Stay informed about: 2 Stroke like a 4 Stroke