View Poll Results: Will you do the cam mod
No, I am buying an Aprilia.
0
0%
Yes, but I suck at being a mechanic. Someone else will do it for me.
0
0%
Multiple Choice Poll. Voters: 35. You may not vote on this poll
Another Cam mod POLL
#3
07-02-2011, 11:19 AM
I only wanted to say this once
Yesterday morning I did the mod. I removed the exhaust cam, adjusted the valves, turned the compression release, and timed the cams.
Before starting, I cranked the motor with no spark plug in until it had oil up top. Then I fired it up. sounded a little different. I took it all the way up to the rev limiter before I left my shop for a test drive. I would rather have problems and not push the thing back. No problems.
Off I went for a ride. I lost some of the snap the bike had when I put the slide carb on. I lost some top end. I gained a LITTLE torque in the mid range. It almost wants to lift the tire in second.
Air box is quiet when I am cruising at a constant speed with no lid on it. Open the throttle up and it is still loud. Exhaust sounds different. Neither of these have anything to do with horse power.
I DID NOT GAIN 5 HORSE POWER. I don't think I gained any. I lost it on the top end and I lost the "Pull your arms out of your socket" I used to get when I first cranked the throttle.
SO FAR top speed is 73 mph. It used to be 83 consistently and once I saw 89.
Bike starts great hot and cold. Runs good, but not as good as before. I only went for a couple of short rides then I had other things to do.
More later after a few miles. it takes me a while to digest and get a good feel for the bike.
I have been messing with small engines since I was 10. I worked at a snowmobile dealer when I was 15-20 as a mechanic. I have a 2 year degree in auto mechanics and have been one since. I own a repair shop.
I am now 50.
David
KLX 351SF with TM36-68 carb and my own exhaust mod.
Before starting, I cranked the motor with no spark plug in until it had oil up top. Then I fired it up. sounded a little different. I took it all the way up to the rev limiter before I left my shop for a test drive. I would rather have problems and not push the thing back. No problems.
Off I went for a ride. I lost some of the snap the bike had when I put the slide carb on. I lost some top end. I gained a LITTLE torque in the mid range. It almost wants to lift the tire in second.
Air box is quiet when I am cruising at a constant speed with no lid on it. Open the throttle up and it is still loud. Exhaust sounds different. Neither of these have anything to do with horse power.
I DID NOT GAIN 5 HORSE POWER. I don't think I gained any. I lost it on the top end and I lost the "Pull your arms out of your socket" I used to get when I first cranked the throttle.
SO FAR top speed is 73 mph. It used to be 83 consistently and once I saw 89.
Bike starts great hot and cold. Runs good, but not as good as before. I only went for a couple of short rides then I had other things to do.
More later after a few miles. it takes me a while to digest and get a good feel for the bike.
I have been messing with small engines since I was 10. I worked at a snowmobile dealer when I was 15-20 as a mechanic. I have a 2 year degree in auto mechanics and have been one since. I own a repair shop.
I am now 50.
David
KLX 351SF with TM36-68 carb and my own exhaust mod.
Last edited by David R; 07-02-2011 at 11:23 AM.
#4
07-02-2011, 02:52 PM
Thanks for the report David, that's exactly the sort of info I was looking for. Too bad it's not making more power down low, that would come in handy for lofting the front wheel over trail obstacles, which is something that my bike in it's current state has trouble with unless I time it just right with a big yank up on the bars.
#5
07-02-2011, 03:31 PM
Yesterday morning I did the mod. I removed the exhaust cam, adjusted the valves, turned the compression release, and timed the cams.
Before starting, I cranked the motor with no spark plug in until it had oil up top. Then I fired it up. sounded a little different. I took it all the way up to the rev limiter before I left my shop for a test drive. I would rather have problems and not push the thing back. No problems.
Off I went for a ride. I lost some of the snap the bike had when I put the slide carb on. I lost some top end. I gained a LITTLE torque in the mid range. It almost wants to lift the tire in second.
Air box is quiet when I am cruising at a constant speed with no lid on it. Open the throttle up and it is still loud. Exhaust sounds different. Neither of these have anything to do with horse power.
I DID NOT GAIN 5 HORSE POWER. I don't think I gained any. I lost it on the top end and I lost the "Pull your arms out of your socket" I used to get when I first cranked the throttle.
SO FAR top speed is 73 mph. It used to be 83 consistently and once I saw 89.
Bike starts great hot and cold. Runs good, but not as good as before. I only went for a couple of short rides then I had other things to do.
More later after a few miles. it takes me a while to digest and get a good feel for the bike.
I have been messing with small engines since I was 10. I worked at a snowmobile dealer when I was 15-20 as a mechanic. I have a 2 year degree in auto mechanics and have been one since. I own a repair shop.
I am now 50.
David
KLX 351SF with TM36-68 carb and my own exhaust mod.
Before starting, I cranked the motor with no spark plug in until it had oil up top. Then I fired it up. sounded a little different. I took it all the way up to the rev limiter before I left my shop for a test drive. I would rather have problems and not push the thing back. No problems.
Off I went for a ride. I lost some of the snap the bike had when I put the slide carb on. I lost some top end. I gained a LITTLE torque in the mid range. It almost wants to lift the tire in second.
Air box is quiet when I am cruising at a constant speed with no lid on it. Open the throttle up and it is still loud. Exhaust sounds different. Neither of these have anything to do with horse power.
I DID NOT GAIN 5 HORSE POWER. I don't think I gained any. I lost it on the top end and I lost the "Pull your arms out of your socket" I used to get when I first cranked the throttle.
SO FAR top speed is 73 mph. It used to be 83 consistently and once I saw 89.
Bike starts great hot and cold. Runs good, but not as good as before. I only went for a couple of short rides then I had other things to do.
More later after a few miles. it takes me a while to digest and get a good feel for the bike.
I have been messing with small engines since I was 10. I worked at a snowmobile dealer when I was 15-20 as a mechanic. I have a 2 year degree in auto mechanics and have been one since. I own a repair shop.
I am now 50.
David
KLX 351SF with TM36-68 carb and my own exhaust mod.
#6
07-02-2011, 05:30 PM
David, Thanks for the review. i will wait for your final evaluation. I am still hesitant about installing the pumper carb on MY 351 because of the nice smooth response. My Honda crf250x has a pumper and it's very twitchy, is the 351 snappy and twitchy with the pumper?
#7
07-02-2011, 05:51 PM
very twitchy unless you overjet (rich) the pilot system.. with my jetting, the bike pulls 15% better not twitchy I hate the twitchy feeling when you are cruising at 3-4000 rpm - its jetted lean so that when the pumper kicks in it wont bee tooooo riiiich... you gotta find a happy medium with this carb I have found it and ive had it on the street for a few months and love it.
#8
07-02-2011, 09:42 PM
I donīt think any of you guys have read the original thread , It states :
THE OWNERS OF CARBURATED BIKES WILL NEED TO REJET .
Them carburators are not going to rejet themself . If neither of you know how then go to a bike shop that has a gas analyzer . If you donīt do this SMALL step your bike may run not only the same as before but it could run much WORST .
To the people who have 40 years of experience with engines :
When they teach you the ABCs in mechanic school they teach you that reducing the centerline of a intake cam ( having it open earlier and close earlier ) increases the torque and power in lows and midrange . Why ? Because the engine gets more air and because you increase the dynamic compresion ( the real compresion of an engine , not the advertised/static one ) .
Reducing the centerline of the exhaust cam ( having the exhaust open later and close later ) means an increase in lows and midrange . Why ? because the pressure of the gases stays in contact with the piston longer , pushing down on the piston for a longer time .
This is ABC for ANY KNOLEDGEABLE MECHANIC , and it doesnīt matter if itīs a Kawasaki or Lexus or Ferrari engine .
As far as the theoretical top end that we lose by changing the centerlines from 110* to 100* here is some food for the thought :
The KX250F has 35 HP at 13000 RPM with centerlines of 105* for the intake and 100 * for the exhaust .
My top speed went from 70-something MPH to 80-something MPH , I never lay on the bike , Iīd look ridiculous .
David Iīm glad your top speed went from 80+ to 70+ because you post shXX . My 250 is faster than your 350 !
You should be getting 5 extra HP , you have a 350 !! . I only get 3 coz I have a 250 . Itīs 5-6 in total with the exhaust mod and the lid off the air filter . It is written so in the post , just didnīt put it in bold so you an read it .
THE OWNERS OF CARBURATED BIKES WILL NEED TO REJET .
Them carburators are not going to rejet themself . If neither of you know how then go to a bike shop that has a gas analyzer . If you donīt do this SMALL step your bike may run not only the same as before but it could run much WORST .
To the people who have 40 years of experience with engines :
When they teach you the ABCs in mechanic school they teach you that reducing the centerline of a intake cam ( having it open earlier and close earlier ) increases the torque and power in lows and midrange . Why ? Because the engine gets more air and because you increase the dynamic compresion ( the real compresion of an engine , not the advertised/static one ) .
Reducing the centerline of the exhaust cam ( having the exhaust open later and close later ) means an increase in lows and midrange . Why ? because the pressure of the gases stays in contact with the piston longer , pushing down on the piston for a longer time .
This is ABC for ANY KNOLEDGEABLE MECHANIC , and it doesnīt matter if itīs a Kawasaki or Lexus or Ferrari engine .
As far as the theoretical top end that we lose by changing the centerlines from 110* to 100* here is some food for the thought :
The KX250F has 35 HP at 13000 RPM with centerlines of 105* for the intake and 100 * for the exhaust .
My top speed went from 70-something MPH to 80-something MPH , I never lay on the bike , Iīd look ridiculous .
David Iīm glad your top speed went from 80+ to 70+ because you post shXX . My 250 is faster than your 350 !
You should be getting 5 extra HP , you have a 350 !! . I only get 3 coz I have a 250 . Itīs 5-6 in total with the exhaust mod and the lid off the air filter . It is written so in the post , just didnīt put it in bold so you an read it .
#9
07-02-2011, 10:49 PM
Yes, I will do it myself. It may be this winter but that's what I plan to do.
I hate fooling with jets but I will be doing that as well. If I don't like it I can reverse it. It's FREE, well other than a jet or two and my time or unless I screw something up really bad.
I'm thinking some folks just needed to get a KT ehem, cough, cough!
I hate fooling with jets but I will be doing that as well. If I don't like it I can reverse it. It's FREE, well other than a jet or two and my time or unless I screw something up really bad.
I'm thinking some folks just needed to get a KT ehem, cough, cough!
#10
07-03-2011, 12:44 AM
Done here till some one grows up.
David