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I know this has been asked before, but I thought I would just bring it up again as I am probably going to pull the trigger on this before spring.

I am undecided as to whether I should get the 780 Kit, 780 kit & 190 cam, or just the high compression cylinder with 190 cam. The 780 kit with cam will be around $1400 by the time you figure in getting the cylinder bored to accept the new sleeve, and the top end gasket kit. The high compression cylinder and cam kit already includes the the top end gasket kit and the cost is less than half at $630.

Procycle has dyno graphs on their site for the 780 kit, showing it making peak of 54 HP and 50 ft/lb torque. I don't know if this was with the cam installed? If not, how much more power are we talking?

I think I saw some dyno charts from MX Rob with the High compression piston and cam installed, but I can not find them. How much power could be made with the high compression piston and 190 camshaft?

In Procycle's FAQ they mention that the HC piston and cam will make more power everywhere, with biggest gains on top end. This sounds good to me, I only ride street so top end would be nice.

They state that with the big bore (725) kit, most of the power increase is in the low and mid range. This sounds good too but maybe the 780 has more emphasis on top end than the 725 did?

I already have the TM40, open airbox, twinair filter, and an FMF Q4 exhaust. Stock header with weld ground down.

You're leaving one very important factor out of the equation, the clutch and gear box wasn't designed to handle that much HP.

I haven't heard of any problems with the gearbox not handling the extra power... Yes, the 780 kit is pretty new but high compression and 725 kit has been out for a while. I have heard of tired clutches starting to slip when this power is added, so I would probably need to figure on another $200 for the Dunlop heavy duty clutch either way.

Here is the dyno chart for the HC piston and 223 Web cam. 46+ hp. When I fuel injected my bike the HP went up to 48. I have the stock clutch in my machine having 15K miles with lots of hard jetting test miles and dyno test miles. I have had no clutch issues to date.

HC piston, 223 Web cam, 39 FCR, 40F0 GSXR:



HC piston, 223 Web cam, Fuel injection 40F0 GSXR:

So really the HC piston and 223 cam are probably adding only 3 or 4 hp over an open airbox and FMF exhaust




The 780 kit and cam will cost twice as much but gains seem to be a better ratio for the cost. You are adding maybe 12HP over open airbox and FMF exhaust and a 10+ ft/lb torque.

Well if you read my top dyno chart you'll see it's over 6 HP. (39.7 compared to 46.1) You can't compare a dyno chart done on a different dyno to one done on the dyno I used expecting to see accurate numbers. All of my charts listed on my web site are using the same exact equipment right down to the same fuel grade, gearing, rear tire and air pressure.

Your says 39.7 is stock though, and with the FMF Q4 and open airbo you should be up around 42 then. So only added 4 HP with HC piston and cam...

I guess that description is a bit misleading. But you know darn well a stock DR650 does not have almost 40HP right? The "stock" was referring to the engine internals. (stock piston stock cam) All of my dyno testing has been done with the GSXR exhaust system and 39mm FCR or the latest FI system.

I wonder what the HP difference is between the 223 and 190 cams?

Don't really know the answer to that one....

Here is what Procycle says about the two cams:

"The Web Cams #223 grind offers improved performance over the stock cam. We think of this as a 'Stage 1' cam.
Our own #190 cam profile offers more lift than the #223 grind to give better low-end and mid-range punch and more duration to keep the motor pulling hard in the upper RPMs. We think of this as a 'Stage 2' cam."

Just from the description I'd think the 190 might be the better choice for a big bore machine since we have that much more volume to get through the valves.... It would be interesting to see a back to back dyno run of each cam on the same machine. Even that may not tell you everything as the results may vary based on the set-up of the machine. Web states the 223 cam must be used in conjunction with a HC piston: "Performance profile designed to increase overall performance. Stock springs OK. Requires High Compression Piston." All I know is the combination of the Web 223 cam and J&E HC piston is a very nice improvement in the performance of the DR650 as evidenced by my dyno chart above. I can only imagine what a 780 would run like with the proper cam.... I know the 725 that I rode was a bulldozer.