[Ian Harrison]

Hi Matthias

As your going with the single, I would probably go with the PVP.

If a used Anderson was to be your choice then, by preference, I would be looking for a Maverick not a Mirage.

Do you know how much the Anderson/Rotax 258 package is? and can you put me in touch with the vendor?

Best Regards

Ian :-)

[Ian Harrison]

Hi Guys

 

Here are Matthias’ pictures of the Rotax 258 motor. I still would like to buy the motor!!

 

[Ian Harrison]

Hi Matthias

 

If you e-mail the pictures to me, I’ll post them up for you: sales@viper-racinguk.co.uk

[Ian Harrison]

Hi Gerry

Was a bit of a fad for a short while. Cable and fulcrums. Just pointless to be honest.

Best Regards

Ian :-)

[Ian Harrison]

Hi Matthias

You should e-mail the CIK and ask if it is possible, what paperwork you would have to complete and the cost. There are some regulations regarding having the manufacturers signature which if applicable would probably be impossible to get.

Like with the 256 tandem twin although that too was a grand prix engine from before 2001, the CIK withdrew it’s homologation last year, so that it can no longer be raced in CIK/FIA events like the European Superkart Championship. But in the UK we still allow the Rotax 256 in our National events.

As I said, I would be interested in the engine for use in a motorcycle.

No, the revised EKN forum is not so easy as the old version.

Best Regards

Ian :-)

[Ian Harrison]

Hi Matthias

If you buy and decide to sell your 258 drop me a pm or e-mail on: sales@viper-racinguk.co.uk

I could trade for a Honda CR250 single if required. I’m in the UK.

I wouldn’t have thought a 258 V-twin would sit very well on a Superkart. Be interested to see some pictures.

If your regulations require that an engine is CIK homologated then you wouldn’t be able to race the 258. For instance in the UK it wouldn’t be allowed. You should confirm this with your karting association.

I’m guessing that your 2008 chassis will be an Anderson Mirage (2-bearing axle). You can use this with a single, but it’s a little soft. Also there may be an issue with the curved tube coming back from the side rail being too close to the clutch case (CR250), although a Rotax 257 single will fit no problem. The Anderson Maverick (3-bearing axle) is better suited to a single. If this leaves you with doubts about your chassis, I can give you more detail. There is nothing particular to look out for but you should check that the chassis is flat and square and check around all the tube joints for cracking.

Here’s for an image of a bare Mirage Chassis

Apart from the 3-bearing axle, the Maverick is easily identified by the chassis extensions that carry the bottom ball joint, on the Mirage they are tubular but on the Maverick they are a solid construction see image below of a Maverick.

Best Regards

 

Ian :-)

 

[Ian Harrison]

Stupid forum!!

Click on this link

http://i186.photobucket.com/albums/x225/Speedbateau/image_zps107ad77f.jpg

At that price, I’m guessing pre-2010 cylinders and wedge cranks. Also Tec Sav don’t build the fastest FPE’s if you get my drift. You probably have to spend $6K plus to get the motor anywhere near, if my guess is correct. Still if you accept all that it’s not a bad price at €8,490.00

Ian

[Ian Harrison]

Hi Nigel

I’ve see the Ken O’Connor videos and he certainly knows what he’s at.

The best way to measure a crank is between centres (make sure the centering cone on the ignition side is in good order), but V-blocks or knife edge rollers are OK

Good luck

 

Ian :-)

[Ian Harrison]

Hi Nigel,

The ’05 Honda crankshaft will fit in the Honda ’01 cases. It has a slightly larger O/D than the ’01 crank and sometimes (most times!) it is necessary to relieve the cases a little at around the 10 and 2 O’clock positions. The way to check this is to install the crank into each crankcase half in turn, fit the piston and cylinder and rotate the crank with the case laid horiziontally on the bench. You will see any positions where the big-end eye comes close or contacts the case and you can mark these areas for relief before final assembly.

Generally the ’05 crank will be closer to the casings anyway, so if a big-end fails it is 99.5% going to damage/crack the casings.

Another way to do this is to machine the flywheel circles and linish the big end eye O/D, but this really requires disassembly and reassembly, so would add to your cost.

The reduction in crankcase volume will generally help low end power and into the midrange, but will restrict the over-rev. The advantages of the ’05 crankshaft are:

1. You get rid of the tin shrouds

2. A stronger big end (25mm pin)

3. They are easier to rebuild/true/adjust the balance factor

My experience with the Wiseco/Hot Rods Taiwanese manufactured replacement ’01 crankshaft, is that it can be supplied outside of tolerance and is harder to correct (due to the tin shrouds). Also that the tin shrouds can crack and peel off in less than a seasons use in a Superkart application.

It is possible for the ’01 crankshaft to be rebuilt by a competent engineer with the correct equipment. When doing this I would recommend the Pro-X rod kits. But make sure the guy knows what he is doing and is used to working with the Honda tin-shrouded cranks. Get him to guarantee what tolerance he will work to and if possible check it before assembly. In Superkart use, our recommendation is, Season 1 new crank, season 2 rebuild, season 3 new crank, etc.

$400 CDN isn’t so much for peace of mind.

Best Regards

Ian :-)

 

[Ian Harrison]

Hi Gerry

We have found them more prone to the classic 4-corner seize.

If the cylinder is new or just replated and the clearance is on the tight side, you can cross-hatch the corners with 120 grit emery paper. Shame to remove some of that coating, but otherwise you may pay the price!

You can’t go wrong with Genuine Honda

Best Regards

Ian :-)

[Ian Harrison]

Well done Andy . . . . . . life in the (not so) old dog yet!!

Best Regards

Ian :-)

[Ian Harrison]

Hi All

Here are Stephen’s dyno plotting points. That’s a very generous dyno. No 250 single 2-stroke race engine ever made 37 FtLb of torque at 9,000 rpm. . . . . I’d guess about 15-20% over the top.  Most likely be around 55 Hp at peak and around 29Ft Lb of torque. Anyway, as long as you always use the same dyno you can at least make valid comparisons as you make any improvements:

Best Regards

Ian :-)

[Ian Harrison]

OK Stephen,

I’ll pick your e-mail up at work tomorrow.

I’ll try one of mine to see if it works. Could do with preview on here!!

OK, if your on photobucket you have to click on the “insert image” icon in the EKN message box and copy and paste (only requires a left click to copy) the “direct” link from photobucket.

Shame the window is now so narrow. Much prefer the old version EKN forum!!

[Ian Harrison]

Hi Stephen

Sounds like you engine can pull all the air it can swallow through a 38mm venturi

On our fully race tuned CR250’s we find the optimum size to be 41.5mm. However, a 38mm will give exactly the same power up to about 9,500 rpm. It’s only really the last 1,000rpm from 10,500 to 11,500 were you begin to see an appreciable difference of about 2 Hp at say 11,200 rpm. Of course if your engine is in a lesser state of tune and doesn’t pull those kind of revs or the power drops off after 9,500 rpm, then your wasting you time, effort and money. Can you post up a dyno graph for us to see?

Best Regards

Ian :-)

[Ian Harrison]

Hi Dillon

Click on the link below for the info you need regarding US Distributors for Big Head Fasteners

http://www.bighead.co.uk/english/contact/distributorlist.asp?country=USA

Click on the link below to browse the product range:

http://www.bighead.co.uk/english/products/standardbigheads.html

Best Regards

Ian

[Ian Harrison]

Hi Bob

Thanks for your kind words.

The SKE chassis is the brainchild of Carlo Chermaz from Australia. Carlo along with Jason Smith and Russell Jamieson, came over from Aus to race at the last European round at Assen and Carlo and Jason have also taken in the German Championship round at The Red Bull Ring.

The chassis has many innovations including the unique style of bodywork. Is it the future . . . .perhaps not entirely, but very welcome to see a bit of original thinking and variation.

Best Regards

Ian :-)

[Ian Harrison]

Hi Dillon

I can send them to you from the UK if required. They are £22.05 each and shipping would be about £30.00 for 4 That would make an axle set £118.20 (currently about $184 USD)

I’m sure you must be able to get them in the US, perhaps others will post up.

Best Regards

Ian :-)

[Ian Harrison]

Hi Dillon

Yes the TRS 1225 and the short series plugs are best quality kit. Sounds like Robert gave you the answer for the lead.

 

Best Regards

 

Ian :-)

[Ian Harrison]

Hi Dillon

I would recommend a 7mm O/D high performance double insulated racing HT lead with copper core.

The core should be made up of 40 strands of 0.25mm copper (or similar).

Plug cap should have a 5K ohm resistance (NGK LB05EMH or similar) and you should always run an Iridium resistor racing plug with a fine wire ground-strap (NGK R7376-10 or similar).

The resistor plug and cap cut down electro-magnetic interference that can affect the CDI box

Best Regards

Ian :-)

[Ian Harrison]

Hi Gerry

We always powder coat. OK it can hide very small cracks, but very small cracks don’t stay very small for long ;-)

I think a shot blasted bare frame looks great, especially a fully brazed one. Just keep it clean and rust free (saves weight too!!

 

Best Regards

 

Ian :-)

[Ian Harrison]

Hi John

You can forget running an HPI box with an ’02-’07 stator.

We have developed a fantastic basic programmable ignition with Zeeltronic that works with the ’02-’07 generator (ignition only, no powerjet, powervalve or quickshift). This is designed around our UK regs.

Prices are:

New ’02-’07 Generator (if required) – £200.00

New Rectifier Regulator (if required) – £40.00

New Coil (uses standard Honda CR250) – £39.00

Programmable box programmed with 2 Viper Curves – £245.00

Bespoke Wiring Harness – £40.00

Best Regards

Ian

[Ian Harrison]

Hi Nigel,

We sometimes slip fit the left-hand main, particularly on test engines that might be split frequently. We have a simple jig that locks the inner bearing track whilst we mount the bearing in the lathe and then we seal the bearing with grease. We then spin the bearing counter clockwise, whilst we run a close fitting 120 grit flap-wheel clockwise in the bore at about 15,000 rpm in an air die-grinder. 15 seconds does the trick. Just keep the die-grinder nice and square and move it in and out quickly from one extreme of the flap wheel to the other and it will be very accurate. Then just a quick clean out and it’s ready to go.

The only advantage for normal race use is that it makes gearbox ratio changes a bit quicker, when you don’t have to remove anything on the right-hand side. Otherwise we just use a crankshaft puller and installation tool.

Even if you have slip-fitted the bearing or crank, sometimes the dowels take hold, so if your only splitting it once a year you may have to use the puller anyway, then it’s not really of any benefit.

Best Regards

Ian :-)

[Ian Harrison]

Hi Nigel

This is usually done by spinning the head (or head insert) in a lathe and turning out some material.

Now I’m not saying that you can’t do it with a Dremel, but it will certainly be tedious and difficult to get a consistent geometry

There is a lot of experimentation to be done with combustion shapes, volumes and squish band design. These designs are verified by dyno/track testing and then chambers are produced on a CNC machine to those designs for sale to give specific power characteristics.

In terms of just adding 1.5cc of volume, and keeping it as simple as possible, then it’s probably easiest to just follow the existing profile.

The procedure I would follow is to first weigh the head (or inset) on a set of precision 1kg digital scales (cheap off Ebay – sometimes known as drug dealers scales!!) and measure the volume with a burette. So lets say you do this on the engine with the piston grease sealed to the bore at TDC and measure a volume of 21.5cc including the plug hole.  The target volume is to be 23cc. Now we want to remove 1.5cc of aluminium from the combustion chamber. The density of aluminium is 2.7 grams/cc, so we want to remove 1.5 x 2.7 = 4.05 grams of aluminium.

In the case of an insert, it might have a starting weight of 108 grams, so our target weight is 103.95 grams.

It’s much easier to just keep putting the head/insert on the scales rather than having to keep bringing the burette into play and installing/removing the head from the engine.

In terms of estimating how much to remove, it is really just guesswork until you gain experience, so at first just go at it slowly with frequent weighing.

Lots of different views on the best liquid to use in a burette, anything from very light machine oil or a 50/50 oil/paraffin mix to the degreasing fluid out of a workshop parts washer. Certainly not a heavy oil as half of it will be left sticking to the wall of the burette!

Yes the same would apply to a 125, but the target increase would be say 0.75cc. The increase in volume, just gives a free revving motor with better over-rev.

I hope that helps, and good luck.

Ian :-)

[Ian Harrison]

Hi Chris

The 450 guys have decided that they want to be classed separately from the 250 singles, so although they compete in the same race as the 250 Nationals, they do not compete against them with regard to race or British Championship positions.

This will allow them to evolve some rules that may more suit the 450 4-stroke (like airbox, for instance) and perhaps lead to a greater interest, who knows?

The lap record for F250 National on the Snetterton 300 circuit is 1:52.836 set by Paul Platt on our last visit on his PVP/CR250. In this years GP Stephen did a 1:52.959, so getting very close to the F250 National lap record.

The KTM appears to be the only engine of choice for this class and very soon there may be a couple of 2013 versions (fuel injection, single cam, die-cast cases) competing. The new engine is a little lighter than the twin-cam version, which also has ultra strong sand cast crankcases, but we’ll have to see if the new motor is strong enough to withstand the continuous high rpm’s.

Best Regards

Ian :-)

[Ian Harrison]

Hi Nigel

We don’t notice any difference with the holes drilled or not. The idea is that you get some extra cool mixture lubricating the port bridge.

In my view your just as likely to get pulse-returned hot contaninated exhaust gas passing the other way when the piston is on the upstroke and crankcase pressure is negative.

Best Regards

Ian

[Author]

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