stage 1 or 2 hot cam?


5 replies to this topic
  • steed2

Posted July 09, 2006 - 02:46 PM

#1

I recently bought a brand new 2004 XR650R (sat on showroom floor for 2 years). Any ways i uncorked it and i love the bike awesome power but i want to put a hotcam in it has any one tried either and if so did they like the results. also is a 180 main B53e needle and seat, and 68s too rich for sea level i dont want to be washing my cylinder out inside i think ill try a 175 main but i figured if theres no black smoke it shouldnt be too rich
any help would be greatly appreciated

  • HawkGT

Posted July 09, 2006 - 04:35 PM

#2

Not sure on the cam, but try this for evaluating your main (180 sound pretty big--especially this time of year):

The Roll-Off technique is the quickest and is almost as accurate as the Roll-On method. First, one gets the engine warm on the way to a safe roadway. If there is room, use fourth gear as this allows more time to assess the result.

Now, get the engine rpm high enough that it is on the cam and in its power band. This may need to be as high as 4000 rpm with some cam choices. Apply full throttle. Let the engine accelerate for a couple of seconds until it has settled in and is pulling hard. Quickly roll the throttle off to about the 7/8ths position. When you do this, the mixture richens slightly for a second or so. If the engine gains power as you roll the throttle off, then the main jet is too small and you need to fit a larger one. If the engine staggers slightly or has a hard hesitation, then the main jet is too large and you need to fit a smaller one.



That is from Mikuni and is in specific reference to certain application (notice the rpm and cam comment). But the technique works by exploiting the temporary rich/lean conditions that occur as pressure signals in a carb's venturi change. It works on most any carburetor.

  • Thumpmeister

Posted July 09, 2006 - 11:53 PM

#3

I put the stg 1 in my bike.

I haven't really gotten the chance to take it out and flog it, but since the break-in, and riding it around on the pavement, theres a bit of a difference. I haven't really noticed a HUGE difference, but there is a difference there. For me, it was worth it, because it gave me a little more midrange and low end, and got rid of that stupid auto decomp system that has plagued me for years.

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  • Ramcc4x4

Posted July 10, 2006 - 05:47 AM

#4

With a header, "E" Series pipe, UNI filter and open side panel I was able to run a 185 main with a 70s pilot jet, even in the summer. I ended up going to the Edelbrock with a #21 needle.

  • InternalCombustion

Posted July 10, 2006 - 06:16 AM

#5

With a header, "E" Series pipe, UNI filter and open side panel I was able to run a 185 main with a 70s pilot jet, even in the summer. I ended up going to the Edelbrock with a #21 needle.

When I installed the stage 1 hotcam, I think it was one of the best modifications I did to the bike. I considered the stage 2 cam but was glad I chose the stage 1 for my setup.


Ramcc4x4: I have a very similar setup, full Pro Circuit, Uni with side vents, Quicksilver... You state that the Stage 1 was one of your best mods, can you expand on that statement a bit. I am considering a cam for my R but cannot decide if its worth the hassle.

Thanks.

  • Ramcc4x4

Posted July 10, 2006 - 03:15 PM

#6

Keep in mind this is my own opinion:

After I installed the stage 1 cam I didn't notice any loss of power on the bottom end, the engine revved more quickly, and had noticeably more power in the mid-upper rpms. With the open side panel, header/pipe and hi-rev cdi the power didn't sign off as it did with the stock cam. Everything seemed to work very well as a complete package.

When I installed the stage 1 hotcam, I think it was one of the best modifications I did to the bike. I considered the stage 2 cam but was glad I chose the stage 1 for my setup.

As far as the "hassle", when I opened up the engine I had some initial regrets on starting the project because there was nothing wrong with it. The install was pretty simple, I just paid attention to detail and went above and beyond in keeping everything clean. When the bike started on the first kick I knew it was a good sign. The biggest "hassle" was breaking in the cam and changing the oil before finding out what, if any performance increase i gained.

Overall, it was very much worth it and good performance gains compared to dollars spent. if you do a search you will find my post showing the link where I bought the cam for $129.00 + shipping, by far the best price I've found for XR650R Hotcams.





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