Web Cams Camshafts?
#11
02-05-2017, 04:10 AM
The carb's biggest impact is throttle response-I suppose that it's possible to get better results from the oe CVK but it was a problem for me when trying to navigate some of the more challenging offroad sections.
I also did some clean up and matching of the ports when I had it apart. My professional background is in hi performance automotive so I've seen quite a few heads. Based on that, my opinion of the port design of the head is a major impediment. The exhaust port is a compromise because of the elbow it has to make to clear the frame downtube. I just don't think that any potential gain is going to warrant anything beyond what you're going to get for the money. I did it because I was already in there and had the equipment to do it. sorta like..You can't make a silk purse out of a sow's ear..
I also did some clean up and matching of the ports when I had it apart. My professional background is in hi performance automotive so I've seen quite a few heads. Based on that, my opinion of the port design of the head is a major impediment. The exhaust port is a compromise because of the elbow it has to make to clear the frame downtube. I just don't think that any potential gain is going to warrant anything beyond what you're going to get for the money. I did it because I was already in there and had the equipment to do it. sorta like..You can't make a silk purse out of a sow's ear..
#12
02-05-2017, 12:27 PM
The carb's biggest impact is throttle response-I suppose that it's possible to get better results from the oe CVK but it was a problem for me when trying to navigate some of the more challenging offroad sections.
I also did some clean up and matching of the ports when I had it apart. My professional background is in hi performance automotive so I've seen quite a few heads. Based on that, my opinion of the port design of the head is a major impediment. The exhaust port is a compromise because of the elbow it has to make to clear the frame downtube. I just don't think that any potential gain is going to warrant anything beyond what you're going to get for the money. I did it because I was already in there and had the equipment to do it. sorta like..You can't make a silk purse out of a sow's ear..
I also did some clean up and matching of the ports when I had it apart. My professional background is in hi performance automotive so I've seen quite a few heads. Based on that, my opinion of the port design of the head is a major impediment. The exhaust port is a compromise because of the elbow it has to make to clear the frame downtube. I just don't think that any potential gain is going to warrant anything beyond what you're going to get for the money. I did it because I was already in there and had the equipment to do it. sorta like..You can't make a silk purse out of a sow's ear..
Reminds me of the Gordon Jennings article on hopping up the SR500 written back in 1979. He found the intake bend to be so tight that it was a waste of time to go to a 38mm carburetor over a 36. One boost was filling the bottom of the intake port a bit, making a D port to help eliminate the slow and turbulent flow on the bottom going in the cylinder. It was interesting. The solution, that some actually would do, was to weld up a bunch of the head to get the port cut with a lesser curve for a straighter shot into the cylinder. Of course those doing that were flat trackers and some others since it could be a competitive engine on the flat track back then. Lots of money though. For my own SR it was just a carb and 33"x1.625 head pipe. The most you could get for the lowest cost.
#13
02-05-2017, 03:03 PM
Join Date: Jul 2013
Location: Toronto, Ontario, Canada
Posts: 43
#14
10-14-2017, 12:13 AM
I was just helping a guy with his KLX300. He's at least the 3rd owner. We were trying to put the cams back in, piston at TDC and slash marks on the cams parallel to of head. But, in that position, the lobes on both cams were horizontal, intake pointed back and exhaust pointed forward. As I recall from a few years ago, they should be pointing slightly up. While handling one of the cams, I noticed that Web and 307 were inscribed on it. OK, Webcams. I don't see a 307 cam on Webcams site. Any body here familiar with them and should the lobes be horizontal at TDC????
Thanks
Ride on
Brewster
Thanks
Ride on
Brewster
#15
10-14-2017, 01:41 AM
Just a visual exercise-TDC @ powerstroke so in ~ 180 deg. of crank rotation the exhaust starts to open. That should be 90 deg of cam rotation-so the nose of the lobe should be at a right angle to the valve centerline.
#17
10-14-2017, 12:48 PM
Looking at my service manual I see exhaust opens at 60 degrees BBDC which means after about 120 degrees of power stroke the exhaust valves start opening. That is 60 degrees of cam rotation. I would say a nearly horizontal exh cam lobe center at TDC is pretty close to correct.
#19
10-16-2017, 03:34 AM
Ride on
Brewster
Thread
Thread Starter
Forum
Replies
Last Post