RT carb, with ARROW REED

[Geebt66cc]

Hey there,

Is there anyone that can tell me if this will be a good combination? I've used speed, CNS, but not any change?! I'm hoping that this 15mm RT with the reed valve, will do a bit better?

Glen

 

[obesepolice]

What do you mean as far as better? What seems to be the problem?

 

[JonnyR]

the only timethe reed valves are going to give you any real sort of performance increse is if you do cylinder mods like boost ports cutting piston skirts and opening up your intake exhaust and transfer portsother than that they wont give you much over your stock set the RT carb might on a larger diameter intake so it can flow more into the engine it being a large diameter carb with big jets

 

[Geebt66cc]

Hey,,

That's right Jonny! I drilled 7 holes on intake side of piston. The bike once back together , runs still about the same as it did before reed and opening up piston?

So, wondering maybe if I'll see any change with using the RT carb?

 

[JonnyR]

most people cut a half moon out of the bottom of the piston skirt to have 100% open at TDC yours is lightened with the holes if you diside to take the jug off and do some work to it thats when you should see a real improvement with the reeds
also have you thought about a puch head for it if you are looking for a bit more power?

 

[Geebt66cc]

Yes, but you've got to be very careful doing that or you can kill all of your low to mid torque. It will only help with top end.

 

[JonnyR]

thats where a good expansion chamber would come in

 

[bigbutterbean]

Since he already drilled holes in his piston, it doesnt matter how he ports the cylinder, it will only help with top end now. The best thing to do is port the cylinder and get a new piston and NOT drill holes in it this time. To get the most out of reeds, you need to increase the degrees of port timing. Drilling holes in your piston does NOT do this.

 

[Geebt66cc]

Big, I was directed to drill on other site?! I mean, I was told many times that drilling out the intake side of piston will help reed to complete total circulation by Jaguar? Also, in order to correct all lows and highs, I'll also need to extend exspanion chamber baffle 2-3inches.

 

[bigbutterbean]

Ok here is the down low on piston drilling versus cylinder porting. Drilling holes in the piston does give a slight increase to intake timing, but only when the piston is at or near TDC (top dead center). It basically only adds the same amount of intake timing as trimming the piston skirt does. The real benefit and purpose of reed valves is to give 2 strokes a much wider powerband. The best way to accomplish this is through cylinder porting. If you port the cylinder properly AND drill holes in the piston, you should still see a gain in top end, but it will kill your bottom end, thus your performance increase will be markedly one-sided, and therefore does not really give you a wider powerband, just a peak in performance. Cylinder porting for reed valves involves cutting a groove into the cylinder near the intake port. You can see an example here: http://motorbicycling.com/showthread.php?t=36861&page=2 post #39 shows a picture of how Venice Motor Bikes ported a cylinder for reeds.

 

[Geebt66cc]

Yes, I also did this inside cylinder....... Bike runs smoother now, but close, but not quite as much torque down low........ Uno, I ran up (Drilled groove) inside cylinder from main intake 32.oo mm high.

 

[bigbutterbean]

You dont need baffles on your expansion chamber to correct your highs and lows, you just need a piston without holes in it. I'm guessing you drilled the holes before porting the cylinder? Otherwise you should have noticed increased performance across the board.

 

[Geebt66cc]

True, I just drilled holes in piston, and groove inside cylinder>--- It's a Skyhawk 66 slant, 700 miles,Jaguar CDI,SBP's Chamber,milled cylinder head,n/a head gasket.

Synthetic/castor

 

[bigbutterbean]

Yeah, the first thing I would do is get a new piston. If it still doesnt run smoothly, add a head gasket. I know you ditched the head gasket to increase compression, but the head gasket is made of very soft aluminum that can expand to create a better seal. The cast aluminum of the head and jug doesn't expand, so if the head budges a thousandth (which can happen with vibration and the heat of the engine) you're losing compression. If you put the gasket back on and dont feel you're getting enough compression, get a Puch head from www.treatland.tv. I'm running the 50cc hi-hi head myself.

 

[JonnyR]

if you want to do some mods to the piston read here about piston skirt clipping and piston ramping you might have made holes to high up and arnt getting 100% out of it

 

[Geebt66cc]

Appreciate BBB,

No, after everything was done, I sealed everything up, and the motor is running great now. The only thing that concerns me now is I drilled up my piston? Well, do you know the other site Motoredbikes.com? I've been on there for quite a few years now. There is a fellow there that these bikes are all he hase done for years. He's on the site 24/7 breaking done mathmatically these engines. So, anyway, that's where the idea came from.

BBB, do you think I'm going to hurt anything if I just leave it alone as is? See, like I said, the motor is running as good, if not better than it ever has. It just doesn't have quite as much torque, but pretty close................

 

[bigbutterbean]

its not going to hurt anything, but if you want more torque, you need a piston with no holes. If its only running as good or a little better than before, then you aren't taking full advantage of the reed setup. If you want to run it the way it is, thats up to you. A new piston is only like $11 or something.

 

[bigbutterbean]

2 stroke with reeds and proper cylinder porting should run 10 times better than one without reeds. If its running about the same or only a little better, then it hasn't been properly modified.

 

[Geebt66cc]

Ok, I understand then........Well, I'll run it a while like it is, and get me a piston soon. I was going to ask, what you think once I put in new piston, what I should of done to begin with?...............Note: I was going to get RS reed, but I've got Arrow reed instead.

So, you don't think there is anything that I can do now with the drilled piston? It was drilled right to book specs? I've been told also that the compression on crank with using the Arrow reeds is lower, so might also need to stuff crank. It's really not bad enought to go that far considering my work schedule.

 

[Geebt66cc]

See, reeds are right in the intake with Rock Solid reeds. Also, I tried reeds first without drilling piston, and there wasn't any change as well? So, what you think there?