Hot Cam and Hi Comp Piston

Have added header/muffler, desmog, de-snorkel, dynojet..

to my 2005 650l...more power is required!:applause:

Anyone have experience with:

HotCam stage 1; JE Piston 101mm (657cc) Big Bore Kit combo?

Low end torque loss?

Proper Jetting?

Any input appreciated.:applause:

Good questions. I am interested in this same setup. I do have the edelbrock carb as well. Would also like to know the performance difference between the Hotcams cam and the Hrc cam. Hrc is more, is it worth it?

Ive used both Hotcam and HRC cam but not on the same engine.

The Hotcam I used on my 675 with a bored VM40 roundlisde Mikuni (bored to 42.5mm). This went well, had quite linear power delivery. Ideal for off road (I use mine on road based track days).

The HRC cam Im now using (with XBR500 head and HSR48 pumper carb) has gained about 5HP but it now has a kick at 4K rpm. By the way, the HSR48 works great, I removed the pumper off it as it doesnt need it. THis engine also runs a longer inlet tract to gain high RPM power.

I would say for off roading stick with the hotcam. The HRC will give btter top end power, but this is limited by the std CDI.

Ive spoken with a lot of top class tuners in the UK about the XRL based engine. The heads breath very well as std so dont need much porting (mine has opened up inlets to the valve seats to make use of the big carb). They also said anything over about 9.5mm lift is wasted on a std engine unless you fit much bigger inlet valves. (optimum valve lift is usually relative to valve dia).Bigger valves = bigger seats which then cause the head to crack.

A lot of high mileage heads are cracked. Mines been welded for 1/3 inch into each exhaust port!

Im now concentrating on improving the CDI. In fact Im seeing a specilaist this evening to discuss a CDI transpalnt. Sounds painful! With a CDI that allows the engine to rev to 8K, 60HP should be readily achievable (currently at 55HP)

Anyway, HTH.


Whats about the stock rev limiter for a 650L anyways? Im thinking about something like this for when i need a top end refresh, good info CMRC THX

On the CDI, it seems its not so much the rev limit, as its the advance curve.

Word on the street is the XRL CDI has a much softer curve than the XR600R.


Dont mean to hijack this thread, But Dave any luck on the 650r cdi swap to the 650l?


Cam and piston is fine, as long as you keep the compression no more than 10:1 if you go higher then you will start to have cooling, and high dollar fuel requirements. Remember this is a dual sport/ commuter bike not a race bike. Sure you can mod it a little but dont push it too far it will become a lot harder to ride especially in the slow stuff and not as much fun as you thought it would be. Its a lot like alcohol moderation is the key. Good luck!

Is there a noticeable loss of low end with the hotcams? Is this loss overcome by the piston/ comp upgrade? I cant imagine doing the upgrades and saying crap stock was better! Is durability compromised with the small upgrade in piston/ comp and HOTCAM cam? A little worried about the durability of the HOTCAM. What about white bros cam? Any better or worse?

Hotcam durability is fine. I wrecked mine cos my oil pump got clogged by a sliver of rubber from my goodridge oil lines!! Crazy but true!

Now using a stellite welded HRC cam and followers.

I never used the hotcam on a std 650 but there was never a lack of low down power with it. It should be better than std if the carburation is good.

Th problem with the CDI on my engine is that it doesnt suit my engines ability to rev higher. The std XRL CDI kills the advance at 7500rpm so the engine wheezes at this point. I want something that allows the engine to spin to 8000-8200RPM as in theory my engine should be ok at those speeds. If the dyno curve is extrapolated then I should be upto just under 60HP. Which is good for a bike running pump fuel (99 ron V-power) and std valves.

The CDI discussed is based on a Suzuki GS125. Its battery driven and is simple to wire up. It also has no known rev limit. So in theory is ideal for what I need. Cost is about £60UKP ie $120 for the CDI and coil. It also works off the std trigger coil off the RHS crank end.

I'll update next week if anyone is interested.

Also plan to dyno the std XRL and GS125 CDI back to back.

crmc33, yes absolutely! keepus posted. interested in the advance curve of this suzuk cdi compared to the xrl's.

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