1978 GS1000E mild performance build (thanks rapidray)

[Ecklund]

When restoring my 1000S I bought a set of Neeway cutters so the seats could be dressed proper like. Not exactly a "5 angle valve job", but it was a fun project. While working on the head the one thing that caught my attention is a sharp machined edge right on the short side radius of the ports. I know better than to get into the ports too much and start grinding away metal, but I found that a file fit perfectly into the port so the sharp edge could be smoothed down. Interestingly, I'm working on a Kawasaki KZ750/4 right now and the ports have an almost identical sharp corner on the short side radius. Going to try the file trick on that head too. Lacking a flow bench, and the knowledge on how to use it, I'll limit my port work to flash removal and smoothing things like these sharp edges. Not sure this is pertinent to this discussion, but you guys might want to check out the ports while the head is off if you get a chance.

Back in the late 70s I tried a similar technique on the two stroke ports. Like you I didn't change the port but just cleaned it up.

Also like you I have no imperial evidence that it improved anything. Just my own accel-o-meter which is anything but scientific.

[philosopheriam]

You don't need the same size exhaust cam as intake cam. If you use a smaller exhaust cam than your intake you will get more bottom end pull without any loss of power. If it were me I would use the .395 lift intake cam and the .365 exhaust cam and set them at 106i/108e with a good set of springs set at 50 lbs. of seat pressure with a set of titanium retainers to lighten the valve train up. No need for under buckets on cams under .400 lift it is the shorter duration higher lift cams you got to watch out for
A 3 angle valve job is a stock valve seat cut where a radius cut valve is just what it implies it is a radius so you end up with a smoother flow over the seat and a nice narrow seat (much better). If you can't get a radius cut most machine shops that do any speed work will do a 5 angle seat cut that will be a little better than the stock 3 angle cut.



.

Honestly, I'll probably just go with the first set of Web cams. Also, I'd love to lighten up my valvetrain, but I don't know of any manufacturers that make titanium or aluminum retainers for use with OEM springs.

[Fjbj40]

Have not done any motorcycle porting but have done car engines. I have ported both Nissan L28 ET and Ford 2.3 Turbo engines. All I ever did was clean up the casting marks and seams and smoothed the radius's so flow had less turbulence. I just looked at it like if I was going to make that turn how could I do it more quickly and travel a shorter distance at the same time. I also did very thorough port matching. Every time I did this work the engine revved more quickly and there was definitely more power there. On the turbo engines I actually saw a slight decrease in EGT's, especially on my Toyota 3B diesel home made turbo system. On the turbo engines the manifolds were also cleaned up.

Regards,
Daryl

[rapidray]

Honestly, I'll probably just go with the first set of Web cams. Also, I'd love to lighten up my valvetrain, but I don't know of any manufacturers that make titanium or aluminum retainers for use with OEM springs.

APE sells Titanium retainers but they are for shim UNDER bucket. Also, do NOT use aluminum retainers! Aluminum is too soft & the keepers will pull through. They used to use them in race engines but changed them OFTEN.
Ray.

[philosopheriam]

Ray,

If it wasn't for the distance, I'd take my engine to you!

[blowerbike]

Ray,

If it wasn't for the distance, I'd take my engine to you!

strap it to a skid and send a blank check

[BadBillyB]

For this build you don't need oversize valves. The stock valves are plenty big. Have the guides, valve job and port work done by a pro. "Star Racing" would be my choice. And I agree with Stetracer, go with the large cam on the intake and the smaller one on the exhaust side. Have the valve job done in a way that you can use shims that are in the "thin" range for reliability and weight saving.....Been there, done that......Billy

[rapidray]

Have the valve job done in a way that you can use shims that are in the "thin" range for reliability and weight saving Billy.

NOT a good idea for a street motor as the valves WILL pound/wear into the seats requiring THINNER shims to get the valve clearance back.
Ray.

[Tarbash 27]

I have a set of web cams in my 1085, .425 lift intake and .395 exhaust, I think I had lobe centers at 106/106. Thing ripped and the wheel came off the ground at around 5,000 rpm, hehe. Currently have the motor all apart for a reseal, and getting a valve job, 4 new guides, new springs, retainers, mill, seals, etc from orient express. Costing me about $800 total for the head work. I am going to hone and new rings for the pistons.

Motor has a GRC crank and robinson unercut trans done a few years ago. Outstanding work by the two of them.

I took the motor apart because my rear timing chain tensioner broke, might of over tightened the manual tensioner, oops.

[philosopheriam]

Head is with Rapidray for porting and other work
Crank is with John Pearson of Pearson racing for disassembly, cleaning, reindexing, and welding
Gears are being sent to John for undercutting

:-)

[blowerbike]

Head is with Rapidray for porting and other work
Crank is with John Pearson of Pearson racing for disassembly, cleaning, reindexing, and welding
Gears are being sent to John for undercutting

:-)

john does nice head work also...he is the 2 valve master