Might want to read this...
#12
07-20-2011, 03:11 PM
Join Date: Jun 2011
Posts: 592
Marcelino had the dyno run charts for his changes. I remember reading a lot of documentation being done.
His work was done on a stock engine, not a modified one. He was experimenting to gain knowledge and putting forth his results, probably a lot like how Bill got his knowledge. You know, change it up and see what it does. The Marcelino's work was documented for a stock engine and he clearly had a good thought process in doing it. So it seems it isn't a negative on a stock engine.
But as pointed out, when different pistons and other mods come into play the work and documentation from the rider who did the original cam timing modifications is not valid. In other words, what may have worked on the stock 250 may not work on a high comp 250-351. Piston valve pockets may be shallower, although I'd find that hard to believe considering a hotter set of cams would probably have higher lift. But clearly in Jhoffy's case there was a definite problem. It clearly ain't plug and play like the stock set up is.
I've seen this on the KLX650s when things done on the R model are attempted on the C or vice versa. They don't always interchange.
As for Bill vs Marcelino, I've read and seen where hot rodders disagree on things all the time. It's just hard to beat the actual documentation when expressing opinion though. Facts talk... and they seem to tell a different story than the opinion. At least with a stock engine.
His work was done on a stock engine, not a modified one. He was experimenting to gain knowledge and putting forth his results, probably a lot like how Bill got his knowledge. You know, change it up and see what it does. The Marcelino's work was documented for a stock engine and he clearly had a good thought process in doing it. So it seems it isn't a negative on a stock engine.
But as pointed out, when different pistons and other mods come into play the work and documentation from the rider who did the original cam timing modifications is not valid. In other words, what may have worked on the stock 250 may not work on a high comp 250-351. Piston valve pockets may be shallower, although I'd find that hard to believe considering a hotter set of cams would probably have higher lift. But clearly in Jhoffy's case there was a definite problem. It clearly ain't plug and play like the stock set up is.
I've seen this on the KLX650s when things done on the R model are attempted on the C or vice versa. They don't always interchange.
As for Bill vs Marcelino, I've read and seen where hot rodders disagree on things all the time. It's just hard to beat the actual documentation when expressing opinion though. Facts talk... and they seem to tell a different story than the opinion. At least with a stock engine.
#13
07-20-2011, 03:33 PM
I've said all along that I saw on this forum the dyno results where a guy went form a stock hp of 18 to 24 with stage 2 type changes, I didn't see the 18hp pull but he did post the 24 hp pull. This is very close to the claimed results from the cam mod but also with stage 2 type changes being made at the same time. I don't have any dyno results as they won't dyno my bike with the knobbies on but I can tell you with stage two type changes alone I picked up more than 1-2 hp. It's all to each his own and some outside of the box thinking is good but you won't see me re-timing my cams to see what might or might not happen.
#14
07-20-2011, 03:42 PM
I re timed my cams with no valve hitting problems. I have the 351. I took it all the way up to the rev limiter many times.
I also put them back to stock with no problems. Except changing the ACR is a bitch.
To each his own.
David
I also put them back to stock with no problems. Except changing the ACR is a bitch.
To each his own.
David
#15
07-21-2011, 08:26 AM
Jhoffy22 : Let me spell this as clearly as I can :
The cam mod did not cause your valve to bend .
It did not cause any valve bending in any bike that had the mod done .
If it were to cause problems it will do so the fist time you start the engine and get to the ignition cut-off point , 10500 RPM .
There are no differences in so far as the combustion chamber is concerned in between the carb and the EFI model . The only difference from a carb to a EFI model head is the presence of a threaded hole for the ECT sensor in the EFI ones ( ECT = engine coolant temperature ) .
You have said yourself how you have killed your engine , you floated the valve ( s ) . Going at full speed , full on acceleration and pinching the cluch will over-rev the engine past the ignition cut-off point for a fraction of a second . If you insist on doing this you may get to the point where you float the valve just enough for the piston to slap it , and no rev limiter will have enough time to kick in and save the day .
There is a reason why Dyno Shift sold / sells by the hundreds and it has little to do with having yet another cool gadget .
Also please do not put words in someone elses mouth , let the man speak for himself IF he wishes to do so .
I think Bill is far to old and wise to get into this and he has nothing against making 2-3 free horsepower on the 250 . A 350 , what he sells , will make a lot more and especially on lows and mids .
The cam mod did not cause your valve to bend .
It did not cause any valve bending in any bike that had the mod done .
If it were to cause problems it will do so the fist time you start the engine and get to the ignition cut-off point , 10500 RPM .
There are no differences in so far as the combustion chamber is concerned in between the carb and the EFI model . The only difference from a carb to a EFI model head is the presence of a threaded hole for the ECT sensor in the EFI ones ( ECT = engine coolant temperature ) .
You have said yourself how you have killed your engine , you floated the valve ( s ) . Going at full speed , full on acceleration and pinching the cluch will over-rev the engine past the ignition cut-off point for a fraction of a second . If you insist on doing this you may get to the point where you float the valve just enough for the piston to slap it , and no rev limiter will have enough time to kick in and save the day .
There is a reason why Dyno Shift sold / sells by the hundreds and it has little to do with having yet another cool gadget .
Also please do not put words in someone elses mouth , let the man speak for himself IF he wishes to do so .
I think Bill is far to old and wise to get into this and he has nothing against making 2-3 free horsepower on the 250 . A 350 , what he sells , will make a lot more and especially on lows and mids .
#17
07-21-2011, 12:59 PM
It did not work for me.
Here is the thread:
https://www.kawasakiforums.com/forum...s-351-a-36022/ My bike runs like a raped ape. I don't think I could get much more out of it. Right now its averaging about 58 mpg and goes 80 any time I want it to. It will lift the front wheel in first all I want.
Back to on topic,
Bill is a retired machinist. I have all kinds of respect for him and I understand him not recommending the cam mod. I am a mechanic. I tried it and didn't like the way it changed my powerband. I ran a few tanks of fuel through my bike and the valves never hit the pistons. I beat on it pretty good. The rev limiter is a good thing. My valve clearance is within Kawasaki specs.
I have been following jhoffy22 and his bike taking a crap is the result of way too many things to blame it on one thing.
David
KLX351SF
Here is the thread:
https://www.kawasakiforums.com/forum...s-351-a-36022/ My bike runs like a raped ape. I don't think I could get much more out of it. Right now its averaging about 58 mpg and goes 80 any time I want it to. It will lift the front wheel in first all I want.
Back to on topic,
Bill is a retired machinist. I have all kinds of respect for him and I understand him not recommending the cam mod. I am a mechanic. I tried it and didn't like the way it changed my powerband. I ran a few tanks of fuel through my bike and the valves never hit the pistons. I beat on it pretty good. The rev limiter is a good thing. My valve clearance is within Kawasaki specs.
I have been following jhoffy22 and his bike taking a crap is the result of way too many things to blame it on one thing.
David
KLX351SF
Last edited by David R; 07-21-2011 at 01:07 PM.
#18
07-21-2011, 02:01 PM
Join Date: Jun 2011
Posts: 592
Jhoffy22 : Let me spell this as clearly as I can :
The cam mod did not cause your valve to bend .
It did not cause any valve bending in any bike that had the mod done .
If it were to cause problems it will do so the fist time you start the engine and get to the ignition cut-off point , 10500 RPM .
There are no differences in so far as the combustion chamber is concerned in between the carb and the EFI model . The only difference from a carb to a EFI model head is the presence of a threaded hole for the ECT sensor in the EFI ones ( ECT = engine coolant temperature ) .
You have said yourself how you have killed your engine , you floated the valve ( s ) . Going at full speed , full on acceleration and pinching the cluch will over-rev the engine past the ignition cut-off point for a fraction of a second . If you insist on doing this you may get to the point where you float the valve just enough for the piston to slap it , and no rev limiter will have enough time to kick in and save the day .
There is a reason why Dyno Shift sold / sells by the hundreds and it has little to do with having yet another cool gadget .
Also please do not put words in someone elses mouth , let the man speak for himself IF he wishes to do so .
I think Bill is far to old and wise to get into this and he has nothing against making 2-3 free horsepower on the 250 . A 350 , what he sells , will make a lot more and especially on lows and mids .
The cam mod did not cause your valve to bend .
It did not cause any valve bending in any bike that had the mod done .
If it were to cause problems it will do so the fist time you start the engine and get to the ignition cut-off point , 10500 RPM .
There are no differences in so far as the combustion chamber is concerned in between the carb and the EFI model . The only difference from a carb to a EFI model head is the presence of a threaded hole for the ECT sensor in the EFI ones ( ECT = engine coolant temperature ) .
You have said yourself how you have killed your engine , you floated the valve ( s ) . Going at full speed , full on acceleration and pinching the cluch will over-rev the engine past the ignition cut-off point for a fraction of a second . If you insist on doing this you may get to the point where you float the valve just enough for the piston to slap it , and no rev limiter will have enough time to kick in and save the day .
There is a reason why Dyno Shift sold / sells by the hundreds and it has little to do with having yet another cool gadget .
Also please do not put words in someone elses mouth , let the man speak for himself IF he wishes to do so .
I think Bill is far to old and wise to get into this and he has nothing against making 2-3 free horsepower on the 250 . A 350 , what he sells , will make a lot more and especially on lows and mids .
#19
07-21-2011, 05:27 PM
Whatever you do is entirely up to you . Bending a valve was entirely your fault , you never checked anything on the head and you were riding it like you were begging for a valve to float . Insistence pais off and in the end you finally did .
I've been riding bikes since I was 14 , started to fix stuff since about the same age , I'm now 41 and I have this advice for you : Don't overrev the bike , rev matching is the quickest way to shift on any bike that you or I may own in this life . Rev matching on the upshift is really easy , you will learn that in a heartbeat , on the downshift it's a little more tricky but I know you will get there because you are insistent . To help your gearbox reach a venerable age don't forget to blip the clutch when you change .
I've been riding bikes since I was 14 , started to fix stuff since about the same age , I'm now 41 and I have this advice for you : Don't overrev the bike , rev matching is the quickest way to shift on any bike that you or I may own in this life . Rev matching on the upshift is really easy , you will learn that in a heartbeat , on the downshift it's a little more tricky but I know you will get there because you are insistent . To help your gearbox reach a venerable age don't forget to blip the clutch when you change .
#20
07-22-2011, 02:21 AM
anytime you raise compression ratio (ie aftermarket piston), the piston will be closer to the valves, basic engine knowledge. you could have valve relief cut, but its probably not worth the money. i for one wouldnt do that mod, i like to wring the **** out of my bike.
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