All Things CR250

Thomas Davis · Posted: Tue Apr 22, 2008 8:54 am Post subject: Acorn Nuts

Ian Harrison · Posted: Tue Apr 22, 2008 10:08 am Post subject:

Hi Larry

Usual coating (Vertex are big on coated pistons) is Bi-Sulphide.

It supposed to aid break in and help to avoid seizure during the running-in period.

Andy, thanks for the tip. I have been polishing my nuts none-stop all day. Wow, that's hard work Embarassed

Dan, the RTS site looks good for you guys - I hope they are giving you commission and yes those are shiny nuts alright!!

Regards

Ian Very Happy

_________________
Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012

Ian Harrison · Posted: Sun Apr 27, 2008 3:31 am Post subject:

Hi Guys

With a 4 week lull in our UK and European racing programme work has been going on a-pace with the interim "Super CR250" and we hope to be carrying out initial running in about 4-6 weeks time.

I hope you don't mind if I keep things a bit sketchy for the moment but some detail is as follows:

Swept Volume 249.2cc
Revised bore and stroke.
Revised port time areas and port timing
Bespoke Manufactured Piston
Bespoke Manufactured Crankshaft
Revised Stroke/Rod length ratio
6-speed close ratio box
Revised primary gear ratio
Digital Programmable ignition (best of 3 choices at present).
New design of carburettor (if it works!!)
New Reed Block/intake system to go with it.
Experimental Clutch System (I especially like this one, if it works!!).
We will also probably install a quick shift system.

I will post an external picture of the motor when it is ready, some internal pictures as we go along and more just before we leave for Laguna.

We plan to do as much dyno running as possible and track testing at Kirkistown, in Northern Ireland, to ensure we are reliable.

The race motor we bring to Laguna will be brand new and just run-in on the dyno. "The Donkey" will be our spare (if it survives).

The whole package will be installed in an Anderson Maverick chassis.

Regards

Ian Very Happy

_________________
Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012

Bernie Adamson · Joined: 20 Jun 2003 Posts: 3001

Larry Dobbs · Posted: Mon Apr 28, 2008 9:26 pm Post subject: vforce2 vs vforce3

Help! I sucked a reed pedal screw through my motor and lost the head barrel top end and I am in the process of checking the bottom end for damage. So now I have a vforce3 and it is smaller at the intake than the vforce2. When I bolt the two blocks together for comparison there is vforce3 block showing all the way around. Should I open up the vforce3 so that they have the same opening? I would really appreciate some help so I don't ruin the vforce3. Should I leave it alone and run it as is? Can any one tell me what their experience has been? Thanks.

Andy Kiker · Posted: Tue Apr 29, 2008 5:44 am Post subject:

Larry, the V3 opening is offset to one side for the angled intake. if you are using a straight intake you will have to open up the other side to match up with the straight intake. That is what I did with mine anyway. You do not have to make it as big as the V2 opening. I also found that the V3 would run leaner on top end so watch you jetting.
_________________
Andy Kiker #24

Anderson Karts
WiWa GasGas
Powrpad

Dan Davis · Posted: Tue Apr 29, 2008 6:31 am Post subject:

Hi Larry,
Andy is right, you simply need to match the probably already modified boot to your new reed valve stuffer. (Nice to be able to remove the stuffer and work on it separate from the rest of the assy.) Mark the VF3 stuffer from the boot side with the boot and valve in assembled position and the mounting holes aligned. Then grind/sand the stuffer to your line. Ive found that the Dremel type sanding drums (both smaller and larger diameters) work very nicely on the VF3 material.....best part for me is, the VF3 can't discharge loose ferrous hardware into the engine at speed.....a real plus I'm sure you'll agree.

Jon Anderson · Posted: Tue Apr 29, 2008 2:51 pm Post subject:

So it is time to give up on the stock CR250 idea and move on. Who are my options for a mild build?

I already have a Paul Leary modified V-force block and intend to keep the stock box for now. I use a Kehin with a pump-around and an RCE pipe. I guess I'd like a quick and dirty jug spacer / o-ring head program to get things rolling.

later, Jon

Riley Will · Posted: Tue Apr 29, 2008 3:47 pm Post subject:

Jon,

Viper racing is who I would use. Ian is pationate about what he does and it shows!!!!
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Riley Will
BRC Engineering
rwill@brceng.com
(403) 216-0630 wk.
www.brceng.com

John Stafford · Joined: 23 Jul 2001 Posts: 252 Location: Danville, Ca

Jon, I would think twice about leaving the stock box in. I presume you're talking about the ignition??? They seem to work okay with a stock, or near stock motor, but when you throw some HP at them, they tend to develop detonation problems.

One option to deal with det is to use a Speed box. They sell one with a curve for the 250 (NOT the 125). It's made to be used with an '01 stator.
If you get one it will bolt right into your case.

I'm fairly certain that your stator will work too, with some mods. Just visually, the coils and the pick-up look the same. And the plug to the box is the same...except for the wiring orientation. The rest is for the servo motor on the power valve that I don't think you're using, so it can be removed. So just re-arrange the wiring to match the '01 and plug the Speed box in and go.

Ian Harrison · Posted: Tue Apr 29, 2008 7:42 pm Post subject:

Hi John (and Jon), and all

HELP!!

Yes, John you are absolutely right about the standard Honda CDI, a real "piston melter" once you up the rpms.

I am at the start of a development programme with ignitions that will use the 2002 onwards generator, but one of the programmable CDI boxes I am trying has the '01 style plug only (I am not using the power-valve motor, rectifier, etc).

I am in the embarrasing position that right now I don't have an '01 generator pack (for about 2-3 weeks), but need to know the '01 pin wiring for the socket, so that I can wire the '02 generator to the '01 type socket that is already used on the '02 harness but with different wiring. (if that makes sense).

The 02 onwards CDI is twin plug as opposed to the '01 single plug.

I probably have 60 brand new '02 gerators, harnesses, CDI, rectifier and stepper motor sets that are lying idle, so it makes sense to get at least the generators into use!!

John from your post I think perhaps you (or anyone else, please) can help.

As I say it will save me waiting for my new '01 stock to copy.

Best Regards

Ian Very Happy

_________________
Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012

John Stafford · Joined: 23 Jul 2001 Posts: 252 Location: Danville, Ca

Ian,

I PM'ed you the info you need to convert your generators to the '01 configuration.

If anybody else needs it I'll post it here.

Ian Harrison · Posted: Wed Apr 30, 2008 5:41 pm Post subject:

Hi John

Many thanks for the info, PM received ok. That has saved me some time.

I know there is an issue with the actual timing positions between the 2 systems (raised segment position) and I will post pictures and info in the next few days.

Many thanks

Ian Very Happy

_________________
Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012

Roger Lockey · Posted: Thu May 01, 2008 4:42 am Post subject:

Hi Ian,
Any chance of you posting the timing curve for you SS CR250?
Thanks,
Roger

Ian Harrison · Posted: Thu May 01, 2008 9:47 am Post subject:

Hi Roger

By SS I assume you mean our "Superstock motor"

Thats easy!!

Our Superstock uses a PVL flat analogue ignition (i.e. no curve).

We strobe the ignition and mark the stator adjacent to the manufacturers rotor mark on the rig at 10,000rpm, then it is fitted to the kart with the rotor and stator marks aligned at 0.8mm BTDC. It is then drilled pegged and lock/sealed so it can't be tampered with.

Obviously it's not the highest performance option, but it's safe and reliable and they're all the same.

I have never seen any det on a Superstock piston and we recomend changing every 6 meetings!!

Horses for courses.

Our F250 National motors and the Super Single is a totally different kettle of fish.

Regards

Ian Very Happy

_________________
Ian Harrison
Viper Racing UK
www.viper-racinguk.co.uk
sales@viper-racinguk.co.uk
+44 7984 225 564
+44 161 343 2009
Championship winning Superkart race team 1997-2012