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I'm waiting on some springs (as per Chubs' post) from cmsnl as it starts to float the valves with the springs currently fitted about 12.5k.



I'm also waiting for my dad to return from holiday so I can get some time on the mill, if pressed I'll set my lathe up to do it, but it will be much easier on a mill.



The motor has plenty of torque to be traded off with some retard on the cam, I went out and did some runs and data logging (In my head) and found it really has lots of low end to the point it winds up the rear end at low RPM (3.5K upwards - relatively low end given the engine)



It also seems to hit a wall at 10k in 4th gear, it is running a touch lean up there so that won't be helping.



I run a trailtech vapor and have it setup bang-on so the speedo is pretty accurate, I had it topped out at an indicated 71.4mph in the outside lane of the A14 overtaking a load of traffic, amber shift light flashing away telling me to hook a non existent 5th - It was one of those "You had to be there" moments, but the grin hasn't worn off yet :D
 
Yeah, a bit of work on the head, ports cleaned up, valve guide protrusions taken back and curves in the inlet tweaked to keep swirl/velocity up - Z40 cam and HD springs (cheapies, came with the cam - Honda springs on their way) higher compression piston.



I didn't understand the "CV Carb?" bit, or at least how you asked it, but it's running a 28mm Keihin CV carb from a Honda CBR125, I got fed up with Molkt's etc and wanted something better, one of these CVK28's came up on eBay for next to nothing so I modded the inlet to suit and got it fitted.



I'm liking those sprockets, looks like they may save a little valve train weight too, how much do they go for?
 
That carb likely has a much smaller than desired venturi, and is causing a restriction at high revs. CV's of a bigger nature are on the eBay all the time, too, as are "conventional" 26-28mm carbys.



Cam sprockets are what I run on my GS1100's. CRF sprocket hasn't much weight to start with, and is only spinning half of crank speed. Still a gain, I'd suppose.
 
firepower354 said:
That carb likely has a much smaller than desired venturi, and is causing a restriction at high revs. CV's of a bigger nature are on the eBay all the time, too, as are "conventional" 26-28mm carbys.



Cam sprockets are what I run on my GS1100's. CRF sprocket hasn't much weight to start with, and is only spinning half of crank speed. Still a gain, I'd suppose.


You got me thinking so I went and measured the CV carb. It has an oval venturi of 22x26mm which is 449 sq. mm surface area. A conventional 26mm carb would give 452 sq. mm surface area and a 28mm would give 615 sq. mm, so going to a normal 26mm carb won't give much extra surface area and therefore a negligible gain high up the RPM range but would sacrifice the low speed/demand running.



A 28mm carb has a significant increase in surface area, what are you guys running on yout tuned motors? - I've done some googling and found some 28mm Koso flat slides, anyone got any experience on these?
 
Must be using a different method to calculate, I cheated and used google for the formula.



I'm going to try a PWK copy and see how I get on, I don't want to spend too much on a carb as I plan on running a Microsquirt ECU setup at some point - more for the 'doing of it' than the end result.
 
MonsterMonkey said:
Must be using a different method to calculate, I cheated and used google for the formula.



i plan on running a Microsquirt ECU setup at some point - more for the 'doing of it' than the end result.
good luck with that.i have a 81' gpz550 with 32mm t.bodies and a mini ms.runs great.if you cant find t.bodies that small i have a couple left.
 
1/4 chub said:
good luck with that.i have a 81' gpz550 with 32mm t.bodies and a mini ms.runs great.if you cant find t.bodies that small i have a couple left.


Thanks Chub, I'll bear that in mind - are you a UK member (I'm thinking shipping costs)



tblumer said:
Careful on the PWK knock offs, the one that I had didn't use a seperate emulsion tube and jet. You may have to order genuine keihin parts to be able to swap jets. I ended up with a TB PE28 copy and love it.


The one I've ordered apparently comes with a jet and needle kit, what actually arrives is another matter, although the place I used is usually very good.
 
50rider340 said:
Monstermonkey, How do you like your trailtech vapor??? I'm really thinking about picking one up, but i need a little bit of persuasion lol.


I originally wanted analouge guages and kinda 'plumped' for the trailtech, but after installing it and setting up I can only recomment it.



Nicely engineered, very flexible in every way such as the power supply options - upto 400 volts AC or DC so will work with pretty much anything, wheel sensor installation is good, ignition sensor pick up is very flexible etc etc.



In use it performs well, backlit when powered externally, the screen doesn't seem to fade or blackout when warm (left in Sunshine for 5 hours at around 30 degree's C), it's very responsive and has a clear, uncluttered display, it does some trip computing too, which I haven't messed with - I'm very please with it.



The only downside is the RPM display only hits 12k, but that's liveable with, I certainly won't be replacing it!
 
firepower354 said:
I figure, that once the original subject has been covered, the thread should drift where ever it wants. Kinda like the garbage guys. Ones the cans are all emptied, they spend the rest of the shift at the nudie bar:cool:


That was my take on it also, but as a relatively new poster didn't want to stir anyone up :D
 
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