Anybody running a 4.0 pulley with the CBR 8.65 crank pulley? If so what belt length and what position is the idler. Thanks in advance.

If you find out the info, please let me know. Thanks! Bob

Certainly.

That's a good question, because when I'm ready for some more power, that's going to be the route I go. I just need to get my fueling and intercooler sorted out first before I crank up the blower.

I'm just updating this with some new found knowledge. For a 7.65"/4.00" combo, with a Gates, green belt, 52.5" long, you need the idler in the position furthest from the blower. I have mine in the middle position, and I'm losing boost in the upper rpm range, and finally saw the dust on the bracket last night.

As the rpm's rise, and the tensioner takes up the slack, it will bottom out, and no longer be able to take up slack, so that is why the idler needs to be in the further position to allow the tensioner to take up the slack.

In a perfect world, we'd have belts that wouldn't stretch, but till then, we have the Aster bracket setup to take up the slack when they do.

Good info, thanks! Bob

8.65 cank pulley/ 4.0 pulley - 53.7" long 8 rib belt

Thanks, I appreciate it! Bob

I think this belt might have been a bit too tight. I switched to K080545HD with the Idler in the middle hole and that seems to be perfect.

Thanks for the info, I'll get it added. Bob

After blowing through another set of little pulley bearings in three months I decided to try an experiment.

I bypassed the little pulley by routing a shorter belt underneath it, basically doing SDCE style belt routing. Recently made 580 whp on a mustang dyno without meth with this new setup which puts me right at my no meth 650 whp dynojet dyno with the Aster 7.65/3.4 setup years ago. So it doesn't seem to be giving up much not running the little pulley.

Current setup:
52.5" Belt K080525HD. 8.65 CBR, 3.85" Blower, Idler on Far position, little pulley bypassed.

Previous setup:
53.7" Belt K080537HD. 8.65 CBR, 3.85" Blower, Idler on Middle position, with little pulley.

Max RPMS of the pulleys with 7.65 and 8.65 crank pulleys:

Large Idler Pulley 2.75" Diameter, C=8.64"
With 7.65" Crank Pulley: 24.03/8.64=2.78 @ 6500 engine RPM = 18,070 RPM
With 8.65" Crank Pulley: 27.17/8.64=3.15 @ 6500 engine RPM = 20,475 RPM

Small Idler Pulley 1.75" Diameter, C=5.50"
With 7.65" Crank Pulley: 24.03/5.50=4.37 @ 6500 engine RPM = 28,405 RPM
With 8.65" Crank Pulley: 27.17/5.50=4.94 @ 6500 engine RPM = 32,110 RPM

That is good info, thanks for posting it! Bob

Good info.

Is the 8.65" pulley still available?

Yes it is, I even have one sitting on my desk right now.
http://shop.brutespeed.com/CBR-8RIB8...8RIB865PLY.htm
Thanks. Bob

Good deal Bob.

I might pick it up this spring when I decide I need more power ;) :devil:

Belt
 

Did this belt work out for you? Idler position?
Thanks

Yes. Idler was in the middle hole.

Hey guys
I've got a 4.38 pulley and the cbr crank pulley . Wondering what I should go with for belt length? Bases on 95 1LE post I'm guessing I should be near the 55 range?

From the chart on Bob's Aster bracket page it says a 54.125". Closest Gates I found is a 53.9" K080539HD. There's also 54.5" K080545HD which might work with the idler in the far position. The different idler positions make a big difference in belt tightness. Be sure and let us know your results and good luck.

K080505HD
K080510HD
K080514HD
K080525HD
K080530HD
K080537HD
K080539HD
K080545HD
K080550HD
K080553HD

I had seen some of those, I was looking at the gates RPM line of belts and was basing that off 951LE saying the 54.5 worked for his slightly smaller pulley than mine. I think the next RPM belt size up was 55.14 but I'm worried that will be too big!