CPI sand pipe vs ProCircuit

[Cholo]

Hey, today I can test the CPI sand pipe in my ´94 CR500. I have rebuilt and tuned the engine recently:

-Rebore the cylinder to 90mm and new Vertex piston.
-190/126 porting, widening the exhaust port, grinding the exhaust port flangle, ...
-V-Force 2 reed cage.
-41mm PWK by Sudco.
-´86 cylinder head cutted to attain 2.5mm squish height.
-HPI 2 curves programmable CDI from www.hpi.be
-Hinson clutch basket with EBC disk.
-`92 CR500 closed ratio trans.

Before rebuild the engine I have a ProCircuit. When I tuned the engine, it lost some low end but the mid-range and top was much better. I can do wheelies in mid range in 5th gear with 15/49 gearing only with the throttle. But I felt the engine wants to pull harder in top-end and the PC don´t allowed it.

Today I put the CPI in my bike and It fits perfect. The sound was very good. The change in power delivery is radical. The bike feel like a 250 with the 500 power.. Again I have lost low end comparing with the PC (and this exhaust isn´t the best in low end ). The midrange is slightly better than the PC with more torque, but the top end was amazing . With the PC I can´t do wheelies in 5th in top end, only in mid range, and now I can´t open full throttle. I can do the backflip in 5th with 15/49 only with the throttle .


If you need low end, please don´t buy this exhaust. If you ride SM, dunes, drag,... and you need amazing power in top end, this exhaust is made for you.

[Roostius_Maximus]

what did you program for a curve?

which model did you use from HPI?

[Cholo]

I bought the CD1509D for the CR500 ignition, with the 2 curves option and the interface to program the cdi. I can program the ignition timing advance for the whole range, but there is other options when you buy the cdi (more expensive) wich allow program power jet carb and differents timings curves at different throttle position.

When I test the CDI in the tuned engine, I felt more mid range hit and less overrev than the stock CDI. Now I have mixed the stock HPI curve and stock CR500 ignition timing in order to have the advantages of each curve. I am waiting to put my bike on dyno for program the "ideal" timing curve, ...

The CDI, selector and interface:




The stock HPI timing curves:

[Roostius_Maximus]

whats that cdi sell for?

[Cholo]

Excuse me but I´m spanish and I don´t understand very well your question.

I bought the cdi directly from hpi.be . It cost me 492 euros (around 670$), CDI+2curves+program interface, cables,... including shipping, VAT.

http://electrexworld.co.uk from england sell this cdi cheaper but they don´t reply my emails and I finally decided bought from hpi.be .

[Kuma]

Thanks for the information, when you put it on the dyno, will you do a comparison with the PC pipe? please be sure to post

[Cholo]

Yes I can do a comparison. I need to move to my friend´s city to make the test on dyno, and he hasn´t time now... Probably in december we can do the test

[100hp honda]

update yet ?

[Cholo]

I can´t carry my bike to the dyno. I have a problem with the cylinder head. I tried to put a decompressor and I ruined my best cylinder head (`86 model). Then I weld the hole for the decompressor but it´s leak some cylinder pressure to the cooling circuit and throw water through the radiator vent... Probably the welding has deformed the head surface ... I´m waiting to put a cool head

[Roostius_Maximus]

I'll sell you a used coolhead, i could also fix your head