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Gs500

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Cool, extra lift... what does that achieve exactly? I get extra duration keeps the valves open a little longer to let more air/fuel in and more exhaust gases out, but lift... well I can only think it pushes the valve open more, but that's not really lifting as much as it's pushing down with the lobe... unless of course I'm way off track!
 
GR cams give a very insignificant increase in lift and less duration.What the GR cam provides in lift,it looses with short valve open time.Also,the GR cam is only good to 7000rpm and the GS engine is good to 11,500rpm,it can spin to 13,500 with valve spring upgrade.Above 9000rpm a GS engine starts loosing torque.IIRC,Dgyver on GST tried the GR cams in his track bike and the out come was less than bad.All this was discussed over on GST.
 
The cam part.
I did some searching and I didn't find anything on it and I guess that's why :p

I'm not sure why anyone would want to rev this engine to 13 500. It must be out of steam by then. Plus the added drag of stiffer springs for street riding doesn't seem like its worth going for if you rarely see that high rpm's.

I'll have to measure the difference between th gr and gs. I'm curious now.
 
Mekanix said:
The cam part.
I did some searching and I didn't find anything on it and I guess that's why :p

I'm not sure why anyone would want to rev this engine to 13 500. It must be out of steam by then. Plus the added drag of stiffer springs for street riding doesn't seem like its worth going for if you rarely see that high rpm's.

I'll have to measure the difference between th gr and gs. I'm curious now.
Click to expand...

The cam thread was lost years ago when the forum was hacked and they updated everything.Surprised it wasn't mentioned in another thread.I did a google advanced search on the forum and nothing came up for me either.

Some of the racers that build track bikes want the extra rpm.I've never felt the need to rev past 9000rpm when I'm out blasting mountain roads.I've been to red line on my GS a few times,there's just not enough umph past 9000rpm to go there.May with head,cam,and different carbs may make it possible to utilize the rpm range above 9000rpm.For what I do,I got plenty of power to hurt my fat @$$.
 
I'm about the same there Ben, with my Acewell I have no redline and I don't look at the gauges too much when I'm hooking through some nice twisties. I know I hit 10K at one point because the Acewell tells me my max but I know I shift a lot earlier than that normally...
 
pete said:
I'm about the same there Ben, with my Acewell I have no redline and I don't look at the gauges too much when I'm hooking through some nice twisties. I know I hit 10K at one point because the Acewell tells me my max but I know I shift a lot earlier than that normally...
Click to expand...

Yeah,no point in needless wear on parts for very little gain.
 
One Thing I used to like to do with my 400 is rev it up to near 7K in 3rd with very little throttle and drop it to 2nd with full throttle. Then shift at 10500 and carry on drag bike style. That engine came alive between those rev's but below that it wasn't that fun to ride.
 
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ben2go said:
GR cams give a very insignificant increase in lift and less duration.What the GR cam provides in lift,it looses with short valve open time.Also,the GR cam is only good to 7000rpm and the GS engine is good to 11,500rpm,it can spin to 13,500 with valve spring upgrade.Above 9000rpm a GS engine starts loosing torque.IIRC,Dgyver on GST tried the GR cams in his track bike and the out come was less than bad.All this was discussed over on GST.
Click to expand...
Are you quoting a specific test or just what what you read on the Budahnet?
I don't understand what you mean by "the GR cams are only good to 7000 rpm" . The GR's are a mid-range cam and they're designed and degreed for a motor that has lot longer stroke. The whole idea of twin cams is having the luxury being able dial the power to where you want it.
If your going to TRY to ride the GS at 11,500 and 13,500 you'll at least need to re-degree the cams. And if that's where your going to ride it you'll also need a big pile of cranks. 'Cause it's going to break on the right rod journal closest to the clutch side.
Tachs have a red line for a reason. My 612 motor(83mm pistons)will for sure rev past red line but if I did, I wouldn't have 3 racing seasons on the crank.
 
That's why I have a DRL200 rev limiter for this one and a 2 stage DRL-400 for the Frankintwin :)

What I want is a nice smooth powerband for cruising but to also have lots of reserve for having fun. Something lower than the 7-11 that I'm used to would be great.

Here is the difference between the cams for lift.
the GR intake is 0.589"
The GS intake is 0.582"
Difference of + 0.007"

The GR center is at 98 IN and 99 EX
The GS center is at IN and EX
 
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wera90ex said:
Are you quoting a specific test or just what what you read on the Budahnet?
I don't understand what you mean by "the GR cams are only good to 7000 rpm" . The GR's are a mid-range cam and they're designed and degreed for a motor that has lot longer stroke. The whole idea of twin cams is having the luxury being able dial the power to where you want it.
If your going to TRY to ride the GS at 11,500 and 13,500 you'll at least need to re-degree the cams. And if that's where your going to ride it you'll also need a big pile of cranks. 'Cause it's going to break on the right rod journal closest to the clutch side.
Tachs have a red line for a reason. My 612 motor(83mm pistons)will for sure rev past red line but if I did, I wouldn't have 3 racing seasons on the crank.
Click to expand...

The cam deal was covered a few years back on GST forum.Then the forum under went changes and the thread was lost.The deal there was the GR cams were designed for an engine with a lower redline and lower operating rpm range.The racers were discussing running a certain aftermarket valve spring to be able to reach the 13,500 redline.I don't remember all the specs quoted in the forum post because I am not a racer.I'm going off what I can recall.It was interesting read.I don't take my bikes to redline.It's pointless for my type of riding.I just wanna stay in the torque range to pull the mountain curves around here.
 
Mekanix said:
One Thing I used to like to do with my 400 is rev it up to near 7K in 3rd with very little throttle and drop it to 2nd with full throttle. Then shift at 10500 and carry on drag bike style. That engine came alive between those rev's but below that it wasn't that fun to ride.
Click to expand...

But was that the 8 valve motor? I find the 4 valve 450 is strongest from around 5K to probably 8K or maybe a bit higher... especially now that I have my needles in a better position.
 
pete said:
But was that the 8 valve motor? I find the 4 valve 450 is strongest from around 5K to probably 8K or maybe a bit higher... especially now that I have my needles in a better position.
Click to expand...

Yeah it was pete, The powerband only started at 7k. Below that it was enough just to get around. At 5-6 was when it vibrated the most, so I was always above or below it.
 
Ok cool, I figured the 8 valves would have their power higher up in the range...
 
Its actually a "motor-cycle" again :P


8578917292_f76758d1a5_z.jpg


8577814085_c59a02ea15_z.jpg


I had to use the rear guide from an 8 valve engine because the original one was cracked and worn sideways.
 
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wera90ex said:
My 612 motor(83mm pistons)will for sure rev past red line but if I did, I wouldn't have 3 racing seasons on the crank.
Click to expand...


What did you use for parts ?
Piston's
Sleeves
Block...
 
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Just bought a DynoJet kit and K&N RU2970 filter. Apparently this is a worthwhile upgrade and I don't have to use the clunky airbox :)

Only thing I have to find now is a good pipe.

The one that came on it was an aftermarket pipe of some kind. Not sure what make it was because It was painted an beat up. Id like to find a nice V&H whole system.
 
Mate she's lookin' good! Nice to get it where it looks like a real bike again :D
 
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