61X Big Bore; LA Sleeve or Northwest Sleeve

[scottie mac]

I think Erik is using WATCON sleeves made for Randy by NW. NW uses the best sleeve material and you can go thinner before they start to distort. The WATCON sleeve comes preported and it made Eriks life easier plus the price is right.

 

[waxhead]

wonder how well they would do without the tl? leaves me wondering what the 188 lower exh really does for you especially if its a rounded top exh port

I guess the same as most freeride skis without total loss
they would loose throttle response due to the lack of timing down low

 

[masterblaster]

wax,I have a sim cylinder setup to what I was talking about above with the exh port raised a tad from freeride specs. Its round 800 cc and runs enhancer,dual 48s,has sick throttle response. I guess my ? is really what does the low exh duration of 185 do better than a few deg higher if you are going to pull more revs from it as well?

Scottie,I have northwest sleeves in that stroker motor that was at wavedaze,I dont know what is diff about the watcon ver though. Eric did say they were pretty slick,I think both ver have 2 mill lower port durations for stroker setups than 61x sleeves

 

[waxhead]

I would never run my engines at 185, even for a free ride engine
My experience tells me that your engine will not make the power you are after
Some other engine builders will dis agree with me but each to there own
Im not going to give out my actual specs I run but its more than that
There is some great stuff you can do with the transfers to pick up throttle responce as well

 

[masterblaster]

This BB cylinder I run was ported by lamey back in the day,it has some pretty cool stuff done with the transfers and boost as well. Do you know what the other builders case is for having such low exh duration,what is the thinking there?

 

[waxhead]

This is the difference with different engine builders
Some people do some things different than other people
I find lower exhaust takes away from the torque the motor produces

 

[masterblaster]

true but with something like that you would think there would be some continuity among all builders for the same purpose

 

[Matt_E]

Why? There is a bit more to engine performance than exhaust duration.

 

[masterblaster]

Really?

 

[Millertime]

Are most of these motors you guys are talking about flat top or round top motors?

 

[masterblaster]

I have one of each but im referring to flat tops

 

[#ZERO]

The lower exhaust height will increase the corrected compression ratio and give more bottom-end mid-range snap freestyle setups with the smaller displacement engines. The higher exhaust duration is more suited for larger engines and race use. Just because the exhaust duration is a few degrees higher won't make it turn any more rpm, it has a lot to do with the pipe and overall setup. Also the Watcon sleeves are very similar to the NW big bore sleeves with a larger top flange diameter.

 

[davidescu_radu]

Good info!
Keep it commimg!

 

[davidescu_radu]

Where can we buy NW sleeves?

 

[john zigler]

Where can we buy NW sleeves?

NW is out of business.

I still have our Watcon spec big bore sleeves available here;

https://www.watcon.com/engine/cylinder-sleeves/yamaha-big-bore-sleeve

 

[davidescu_radu]

Thank you! can you ship it in Romania?