I need more power 650L


47 replies to this topic
  • heavyhitter

Posted September 24, 2007 - 07:47 AM

#1

For the power dept I have a UNI, Q2, rejeted and drilled the slide, removed snorkle, removed smog crap. Geared 14/45 moving to 14/48 soon. I really need to get more power and snap out of this thing but not at the cost of reliability. I am buying a 101 overbore piston with 10.5:1. Who has done this? I can do the work myself for a total cost of @ $200. A port and polish wil cost me @ $350-400. I have been told that a port and polish will give more bang with a hi comp piston than a hi comp piston and hot cam w/o a port and polish. I would rather save the money on a port and polish for a larger tank and custom seat. Anyone here done just a bore and hone with a 101mm kit and what are the results, Im looking for a VERY noticable increase in power, I was not very impressed with the jet, intake exhaust mods. I didnt notice a big increase for the time/money spent. My Brute Force 650 will smoke my XR and its a 630lb utility quad. I am looking for the next logical step in power.

  • martinfan30

Posted September 24, 2007 - 07:50 AM

#2

who told you about the port/polish thing?

  • XR650L_Dave

Posted September 24, 2007 - 08:03 AM

#3

Higher compression and a cam is the ticket. No need to go to an overbore piston just to up the cubes.

No way the "piston/porting" job will get anywhere close to the power of a 'piston/cam' job. The stock XRL cam is very mild, and probably ill suited to making good use of higher compression.

I don't think any combination of mods on this bike will show a decent power increase with a port/polish job- It just isn't built to pull the revs to require mucking with a port/polish job.

Dave

  • martinfan30

Posted September 24, 2007 - 08:10 AM

#4

i thought so.

  • cleonard

Posted September 24, 2007 - 08:17 AM

#5

Another vote for high compression and the cam.

In stock form the compression ratio on a 650L is a very low 8.6 to 1. With that it will run on a tank of regular that has sat for six months. With the hicomp piston it will require a diet of premium. Higher compression also generates more heat so watch the temps.

The port/polish will only give a good increase if your castings have major flaws that need to be removed. Otherwise it is only a modest gain. The hicomp piston will be very noticeable.

Anything that you do to increase power will come at a cost of reduced longevity. More power means more force on the engine components and that makes them wear faster. This is relative though. Even with the hi comp piston it should outlast 3 CRF450's unless it overheats badly. :thumbsup:

You will need to fine tune your jetting. Every bike is different and you need to find the optimum for your bike. Trying different settings is the only way.

  • heavyhitter

Posted September 24, 2007 - 08:20 AM

#6

who told you about the port/polish thing?



Xr's Only mechanic told me.

I do know the value of a port and polish because my RM250 has one.

  • martinfan30

Posted September 24, 2007 - 08:20 AM

#7

i know that cyl. head temp is what is important, so what would you say cleonard, is the highest you would want to see on the dipstick guage?

  • Denn10

Posted September 24, 2007 - 09:18 AM

#8

get your new sprockets first, then see if you still want more power. But i think if you want more then go with a hi comp piston/cam combo and prolly a fcr carb.

  • cleonard

Posted September 24, 2007 - 09:30 AM

#9

i know that cyl. head temp is what is important, so what would you say cleonard, is the highest you would want to see on the dipstick guage?


Currently I don't have one. I'd say you want it under 250. When it gets to 300 it's time lo let it cool some.

For my XR600, it let's me know when it is getting too hot. The way the engine runs changes slightly. Then as it gets hotter it starts pinging under load. Mine just got worse after I put a IMS 4 gallon tank on it. It cut the airflow to the head. I'm currently trying to jet my way around it.

  • heavyhitter

Posted September 24, 2007 - 09:35 AM

#10

I always thought that a cam ususally "moves" the power. Rob Petter to pay Paul type thing. Usually adding more HP means losing low end torque. Moving the power curve from a flatter curve to a peakier curve. Im an missing something? Can a cam give you improvement everywhere? My engine building experience is limited to 2 strokes so I never dealt with cams, but I have a mechanical understanding of how the components work. What is the recommend cam? Hot cams? I had a verndor tell me they dont last as long as OEM or HRC's.

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  • cleonard

Posted September 24, 2007 - 09:36 AM

#11

Xr's Only mechanic told me.

I do know the value of a port and polish because my RM250 has one.


One reason is how many use the engine on these bikes. When I'm trail riding, I'm usually not winding the bike out. Most of the time I'm below 5000 rpm. Porting will mainly show a gain at the higher revs when you need max breathing. At lower speeds it doesn't matter so much. However, the higher comp piston gives more torque at low revs. Now if you are planning on high speed canyon running, that porting job will help more. Another thing, the porting will only help if the rest of the intake and exhaust is also worked on as well.

  • cleonard

Posted September 24, 2007 - 09:40 AM

#12

I always thought that a cam ususally "moves" the power. Rob Petter to pay Paul type thing. Usually adding more HP means losing low end torque. Moving the power curve from a flatter curve to a peakier curve. Im an missing something? Can a cam give you improvement everywhere? My engine building experience is limited to 2 strokes so I never dealt with cams, but I have a mechanical understanding of how the components work. What is the recommend cam? Hot cams? I had a verndor tell me they dont last as long as OEM or HRC's.


As far as I can tell none of the cams available for the 600R or 650L are really that aggressive. Unless there is some flat tracker type of cam that I don't know about.

What kind of riding are you looking to do? High speed desert, canyon carving, or trail riding?

  • martinfan30

Posted September 24, 2007 - 09:48 AM

#13

Currently I don't have one. I'd say you want it under 250. When it gets to 300 it's time lo let it cool some.

For my XR600, it let's me know when it is getting too hot. The way the engine runs changes slightly. Then as it gets hotter it starts pinging under load. Mine just got worse after I put a IMS 4 gallon tank on it. It cut the airflow to the head. I'm currently trying to jet my way around it.


guess its time for an xr400 oil cooler. ive been high as 275 with my wolfman bags loaded and all my camp gear.

  • cleonard

Posted September 24, 2007 - 10:10 AM

#14

guess its time for an xr400 oil cooler. ive been high as 275 with my wolfman bags loaded and all my camp gear.


Unless you are getting other symptoms, 275 might not be that bad. Nothing wrong with a cooler though.

  • Denn10

Posted September 24, 2007 - 10:14 AM

#15

I always thought that a cam ususally "moves" the power. Rob Petter to pay Paul type thing. Usually adding more HP means losing low end torque. Moving the power curve from a flatter curve to a peakier curve. Im an missing something? Can a cam give you improvement everywhere? My engine building experience is limited to 2 strokes so I never dealt with cams, but I have a mechanical understanding of how the components work. What is the recommend cam? Hot cams? I had a verndor tell me they dont last as long as OEM or HRC's.


with cams if your comparing a very mild one to a performance you will gain all across the power range if the stocker is under cammed for the enging. Cams are all about lift and duration, how much is it opening for how long so if the stocker doesnt open for long enough to let max air/fuel in then a performance cam will give you power across the board. What your talking about is prolly from one performance cam to another where you can move the power around in the RPM range.

  • martinfan30

Posted September 24, 2007 - 10:15 AM

#16

Unless you are getting other symptoms, 275 might not be that bad. Nothing wrong with a cooler though.


no other symptoms.

  • martinfan30

Posted September 24, 2007 - 10:16 AM

#17

with cams if your comparing a very mild one to a performance you will gain all across the power range if the stocker is under cammed for the enging. Cams are all about lift and duration, how much is it opening for how long so if the stocker doesnt open for long enough to let max air/fuel in then a performance cam will give you power across the board. What your talking about is prolly from one performance cam to another where you can move the power around in the RPM range.



i'm wth you on this one denn.

holy crap denn, you paying guys to give you gas!LOL!

  • heavyhitter

Posted September 24, 2007 - 11:05 AM

#18

I ride mostly open fields, trails, woods, and street. Im a fat ass so I need more power than you skinny guys. I am looking for that hit when I punch the throttle. I could care less about doing 10000 mph but I love power wheelies and hard accelaration. Since this is my first thumper bike I was guess I was expecting more than what it is. If i could have 1/2 the acceleration of my RM250 I would be very happy. I know its apples to oranges but man, the hit from a 55+ hp 2stroke, gives me wood. Like everytime I hit the throttle it feels like and explosion. ( this is Denny Stevensons old Team Pro-Circuit Suzuki areacross bike). I know the power band is MUCH different on a 4t vs. 2t but my Vtwin cruiser will throw you off the back seat when you hit it and so will my ATV. Hell it hits when you punch it!

  • Denn10

Posted September 24, 2007 - 11:27 AM

#19

I ride mostly open fields, trails, woods, and street. Im a fat ass so I need more power than you skinny guys. I am looking for that hit when I punch the throttle. I could care less about doing 10000 mph but I love power wheelies and hard accelaration. Since this is my first thumper bike I was guess I was expecting more than what it is. If i could have 1/2 the acceleration of my RM250 I would be very happy. I know its apples to oranges but man, the hit from a 55+ hp 2stroke, gives me wood. Like everytime I hit the throttle it feels like and explosion. ( this is Denny Stevensons old Team Pro-Circuit Suzuki areacross bike). I know the power band is MUCH different on a 4t vs. 2t but my Vtwin cruiser will throw you off the back seat when you hit it and so will my ATV. Hell it hits when you punch it!



BRO im 295 rocking stock gearing and having fun I KNOW its no power monster so if you get your piston/cam/carb combo with 14/48 gearing ill bet $100 youll love it.

  • Denn10

Posted September 24, 2007 - 11:28 AM

#20

holy crap denn, you paying guys to give you gas!LOL!



LMAO im a good guy always looking to help why cant everyone see that LOL





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