advice for YFZ owners
#21
03-08-2004 | 11:54 PM
The Facility
Joined: Nov 2001
Posts: 4,062
Likes: 0
From: Mississippi
advice for YFZ owners
This will make two stupid posts from the illustrious Captain Crunch today.
I don't know what's in the air over at Birmingham, but I feel pretty safe saying that it's laughing gas[img]i/expressions/face-icon-small-tongue.gif[/img]
On any of the hi-po quads, you will need to re-jet with any modification no matter how small. If you do not, you may not burn a piston or have a poorly running quad.....but re-jetting is about making it BETTER than if you left it alone.
I agree with Ridley 100% on the dirtbike issue. The YZ450F isn't very restricted out of the crate......now the WR450F is much more restrited than the YZ model and takes alot of jetting runs to get it right when modifying. The YFZ450 quad is the same way.
I bet your shop is "a fleet of chaos" with all the quads coming in with fried engines[img]i/expressions/face-icon-small-tongue.gif[/img]
I don't know what's in the air over at Birmingham, but I feel pretty safe saying that it's laughing gas[img]i/expressions/face-icon-small-tongue.gif[/img]
On any of the hi-po quads, you will need to re-jet with any modification no matter how small. If you do not, you may not burn a piston or have a poorly running quad.....but re-jetting is about making it BETTER than if you left it alone.
I agree with Ridley 100% on the dirtbike issue. The YZ450F isn't very restricted out of the crate......now the WR450F is much more restrited than the YZ model and takes alot of jetting runs to get it right when modifying. The YFZ450 quad is the same way.
I bet your shop is "a fleet of chaos" with all the quads coming in with fried engines[img]i/expressions/face-icon-small-tongue.gif[/img]
#22
03-09-2004 | 01:10 AM
Range Rover
Joined: Jan 2004
Posts: 110
Likes: 0
advice for YFZ owners
The pipe glowing is usually when you aren't riding, and the header pipe heats up more, turning red/orange. It's not bad, but it does mean its getting hotter. How I understand jet/air/exhaust is.......
IF you put a more free flowing pipe on, the engine is running w/ less backpressure, so it runs hotter/more power because its not working to push the exhaust out. Now if you take off your air box lid, you've got more air in, same amount of fuel, and more exhaust out. The air is going to be more in the ratio of air/fuel and so the motor is lean. You want to match all 3. Usually a pipe comes w/ the recommended jetting and sometimes even suggests what to do w/ the air box.
Now, you can run it w/o a jetkit/air filter if you take your stock arrestor out. The savings in backpressure is there, but not so much that you MUST rejet. But you might as well leave it on because there is no power gain. Its all in your head, its just the sound.
On the other hand, I had a pipe first, then filter..Rode it a week, then rejetted to the pipes recommendations, and it made a world of difference. No lean backfiring into corners, and a big power gain.
With a FMF Q pipe, they suggest a 162 main jet I believe. I did that, and bumped the main up to a 148, and replaced the needle. It runs perfect, the pipe rarely gets red, even at idle, and it got a $hitload of power.
Just my info from what a very knowledgeable friend explained, and my personal experiences.
IF you put a more free flowing pipe on, the engine is running w/ less backpressure, so it runs hotter/more power because its not working to push the exhaust out. Now if you take off your air box lid, you've got more air in, same amount of fuel, and more exhaust out. The air is going to be more in the ratio of air/fuel and so the motor is lean. You want to match all 3. Usually a pipe comes w/ the recommended jetting and sometimes even suggests what to do w/ the air box.
Now, you can run it w/o a jetkit/air filter if you take your stock arrestor out. The savings in backpressure is there, but not so much that you MUST rejet. But you might as well leave it on because there is no power gain. Its all in your head, its just the sound.
On the other hand, I had a pipe first, then filter..Rode it a week, then rejetted to the pipes recommendations, and it made a world of difference. No lean backfiring into corners, and a big power gain.
With a FMF Q pipe, they suggest a 162 main jet I believe. I did that, and bumped the main up to a 148, and replaced the needle. It runs perfect, the pipe rarely gets red, even at idle, and it got a $hitload of power.
Just my info from what a very knowledgeable friend explained, and my personal experiences.
#23
03-09-2004 | 01:26 AM
Pro Rider
Joined: Nov 1999
Posts: 1,526
Likes: 0
From: CT/NJ
advice for YFZ owners
Originally posted by: CaptainCarl
You guys need to pay more attention to offroading in general and not just the quads. Everyone knows about the Yamaha 4 stroke engines being smothered by the exhaust and is the first thing to do for more power. As for the jetting, Ridley, you are way off base. The carbs on the Yamaha 4 strokes require nothing when modified unless you go into the engine. you can change the filter and even to a full exhaust system and not need to touch the carburetor at all. Go to any of the dirtbike sites and they will tell you that the jetkit is a way for them to get more money. There is one guy there who has a pipe, twinairfilter,prolow intake and a thumper racing intake cam on his yz450f bike and still has the stock jetting!
Captain
You guys need to pay more attention to offroading in general and not just the quads. Everyone knows about the Yamaha 4 stroke engines being smothered by the exhaust and is the first thing to do for more power. As for the jetting, Ridley, you are way off base. The carbs on the Yamaha 4 strokes require nothing when modified unless you go into the engine. you can change the filter and even to a full exhaust system and not need to touch the carburetor at all. Go to any of the dirtbike sites and they will tell you that the jetkit is a way for them to get more money. There is one guy there who has a pipe, twinairfilter,prolow intake and a thumper racing intake cam on his yz450f bike and still has the stock jetting!
Captain
#25
03-09-2004 | 05:38 AM
Pro Rider
Joined: Jan 2003
Posts: 335
Likes: 0
advice for YFZ owners
seanDyfz
Will you be racing the OPMC series? http://www.opmc.org/calendar.html
March 28
April 25
May 23
June 20 - Goldstar Series #7 Final click here for more info.
October 17 WA State Championship Series #7 Final
I will be racing the Gold Star Series and the Wa State Chapionship Series.
Also did you know about the Quad Only 4 hour team race at Goldendale Wa. 4/25? that should be a fun race.
A big group of us are going to Goldendale 3/20 for a practice to run before the WORCS race on 3/27 & 3/28.
Will you be racing the OPMC series? http://www.opmc.org/calendar.html
March 28
April 25
May 23
June 20 - Goldstar Series #7 Final click here for more info.
October 17 WA State Championship Series #7 Final
I will be racing the Gold Star Series and the Wa State Chapionship Series.
Also did you know about the Quad Only 4 hour team race at Goldendale Wa. 4/25? that should be a fun race.
A big group of us are going to Goldendale 3/20 for a practice to run before the WORCS race on 3/27 & 3/28.
#26
03-09-2004 | 06:18 AM
Trailblazer
Joined: Mar 2004
Posts: 52
Likes: 0
advice for YFZ owners
if you go to read kory ellis his write up on the yzf he says you can put a factory pipe on ,and that is all you will need to race ,engine wisehe says that will give you all the power you need ,i think if there was any danger of blowing your ouad,s engine he would have said to re jet it as well this advice is from a pro not me.............
#28
03-09-2004 | 12:05 PM
Pro Rider
Joined: Nov 1999
Posts: 1,538
Likes: 0
advice for YFZ owners
OK...too much confusion here on whether to jet or not.
It is a proven fact that when you add an aftermarket pipe...you are doing so to increase airflow and create a more free flowing engine.
In the process of doing this...you are essentially leaning out the carbs, which gives you increased power on your seat of the pants gyro.
With that said.....You "might" be ok with just installing the pipe....or.......You may be - just on the edge - of being too lean.
Most of us recreational riders like to run a tad rich for engine longevity...coupled with the fact that if you add more air...you need more fuel to get the full advantage of that air. That is where we are all coming up with the "Jet with new pipes" attitude.
I do not know how else to put it..other than rejet...it will only help you, and you will thank us later. This is a four stroke engine...Do you really want to risk a costly rebuild. (piston, rings, valves..etc)...just to follow the ill advice of a magazine?
It is a proven fact that when you add an aftermarket pipe...you are doing so to increase airflow and create a more free flowing engine.
In the process of doing this...you are essentially leaning out the carbs, which gives you increased power on your seat of the pants gyro.
With that said.....You "might" be ok with just installing the pipe....or.......You may be - just on the edge - of being too lean.
Most of us recreational riders like to run a tad rich for engine longevity...coupled with the fact that if you add more air...you need more fuel to get the full advantage of that air. That is where we are all coming up with the "Jet with new pipes" attitude.
I do not know how else to put it..other than rejet...it will only help you, and you will thank us later. This is a four stroke engine...Do you really want to risk a costly rebuild. (piston, rings, valves..etc)...just to follow the ill advice of a magazine?
#29
03-09-2004 | 12:36 PM
Pro Rider
Joined: Jul 2002
Posts: 1,618
Likes: 0