StewartG

Yhanks for the reply Roger. I have 45s and the longer trumpets ( sticl out about 60mm from the carb face and the filters are 80mm deep) so I need either shorter trumpets, longer K&Ns or maybe to space the filters out from the carbs somehow. Would I be right in thinking it would be better to keep the lomg trumpets and space the filters rather than fit shorter trumpets which might not be too good for torque. I've got cycle wings so space is not a problem.

I think I remember a pearl of wisdom from Roger King suggesting that standard length trumpets with K&N filters allowed less than ideal clearance between the end of trumpet and the filter cover. What improvement might I expect with a change to shorter trumpets. Anyone tried this?

Franky I can't access the pictures but have you had the weights on the inside of the wheels only, if this is the case you can't get away with it and will have to have them rebalanced with weights on the outside and inside. It obviously looks much better to have no weights showing but sevens are very sensitive to wheel imbalance and mostly need weights on the front and back of the wheels. If you have weihgts on both sides of the wheels then I'm obviously barking up the wrong tree.

Anyone got one suitable for a Vx engine and Caterham branded gauge? Thanks

So to calibrate the gauge you could connect a suitable pot between the green/black sender cable and earth, any idea what value would be needed? Then having checked the oil pressure at say 3000 rpm when hot with a mechanical, accurate external gauge you could adjust the cslibration of the dash gauge to read correctly.

Coughing and spitting from the carbs is usually thought to indicate too lean a mixture. Popping and banging on the overun is normal and is caused by the unburnt fuel (due to carbs not being very efficient hence high fuel consumption) combining with air drawn into the less than airtight exhaust and exploding. Whilst they all do this sir excessive popping maybe indicates less complete than usual combustion which could be a mixture which is too lean (not enough petrol to ignite properly and so the unburnt petrol goes into the exhaust) or too rich (too much petrol to be burnt with the air available). It's worth checking the balance of the carbs as well as this, if miles out, can cause all sorts of nasties. Edited by - StewartG on 6 Feb 2005 15:17:05

Thanks Chris. I've just had a look at the back of the gauge and it seems things are not as simple as I thought. I was expecting the gauge to read the difference between the sender output and earth and so have an input terminal and an earth tag but there are 3 connections, no 3 is almost certainly an earth but I can only guess at this point what the other two are. Maybe the gauge acts as a voltage comparator reading the difference between a known voltage and the one produced by the sender unit. Who knows but my plan of seeing if my gauge indicated 4 bar when fed with 3.1v was scuppered.

That's very interesting Chris, an answer at last rather than the usual it must be a dodgy sender, which it may well be but I'm trying to analyse whether the oil ptessure is indeed low or if the sender is giving a low output or if the gauge is giving a low reading. Just to clarify did you measure the volts at the sender when it was presented with a verified pressure of 4 bar etc or was this the voltage that caused your gauge to display a 4 bar reading. In other words assuming your's is okay, does a genuine 4 bar oil pressure produce 3.1 volts which gives a reading of 4 bar on the gauge or does the sender read 3.1v when the gauge displays 4 bar but being uncalibrated we don't know if this is actually a real 4 bar or not. Sorry to be so pedantic but I'm hoping that my actual oil pressure is ok but the system is inaccurate.

The question was, how does rake affect the handling. The rake could be described as the relative ride height, front relative to back. This slightly changes the centre of gravity, lower front, more weight on front wheels, less understeer. Lower back, less oversteer. More importantly (I suspect) the ride heights affect the geometry of the suspension components. Changes in front ride height, if uncompensated for by rack packing, will add or reduce bump steer. Changes in rear ride height, on a non watts linkage set up, will increase or reduce the rear wheel steer affects of the radius arms. It's much more complicated than this as all adjustments interact, I've only touched the tip of the iceberg. A good starting point seems to be, set the front so that the lower wishbones are parallel to the floor and then set the back to be 15mm higher.

Or a longer lever throw at the pedal end.

Too much pressure- The centre of the tread wears and the grip is low Too little pressure- The edges of the tread wear and the handling is less progressive as the tyre grips and deforms rather than slides until it can grip no more and lets go. Correct pressure- Even wear across the tread and good balance of grip and progression. The correct pressure is specific to each installation so the manufactures recommendation shouldn't be taken as gospel it depends on many things but the most important is the weight of the car. Caterhams may well be lighter than most of the cars Yoko had in mind when they specified the tyre and it's recommended pressure.

Presumably this is nothing more sophisticated than a voltmeter. Does anyone know what voltage should make it read say 4 bar. With this infomation I will be able to determine if my gauge reads low and maybe narrow things down to either the sender unit or perhaps genuine low oil pressure.

Is the oil pressure still high? Can't see how tightening the oil filter would cure this.

I know you won't want me to say I told you so. So I won't, but I did. Regards Stewart

Don't have any pictures I'm afraid but I'll try and describe it. The carb end of the throttle cable was originally secured to a piece of angle iron which was bolted berween the carbs using the 4 bolts nearest the engine holding the bottom carb covers in place. This was replaced with a larger and stiffer piece of alloy U section which is located using all 8 bottom cover bolts. This means the carbs are held parallel to each other but the mountings can still isolate them from engine vibration. The throttle cable is secured to the U section and still pulls the butterflies open from below. With this arramgement the carbs have stayed synchronised to within that which can be repeatably measured using the webcon synchroniser for over 2 years despite having the K&N's off and back on many times and lots of jet changing etc etc.

Yep, I've done the same thing by bolting an alloy u-section to the bottom of the carbs, they can still move so as not to froth the fuel but they can't move relative to each other and therefore they stay synchronized.

As you mention that the engine has just come back from the engine builder I think this sounds like his problem and I'd be sending it straight back to him.

Poley fit for free too.

I would say ACB10's are super grippy when used on a track where you can keep them nice and warm but on the road it's rare to get them hot enough to work properly and they tend to tramline badly making progress on less than smooth roads (all of them) pretty hard work. Yoko 48R's are the obvious choice although we all wish that they had the option of some stickier compounds as currently they're not quite as soft as the 32R's suprersoft compound.

Are you sure Stu, mine are more like 15mm when they are resting on the ball that means that the flat top face of the float is roughly parallel to the top plate. It's difficult to measure at full droop because you need to specify where you are measuring from and to.

Thanks for that it's interesting but it's still talking about the brass floats. Does anyone know about the plastic ones?

This is on DCOE 45's. I want to check the float level but all the info I can find on this refers, I think to the round/cylindrical type floats. I think these maybe made of brass. My floats are black plastic and not cylindrical more like truncated pyramid. Presumably the procedure for checking float height is similar ie with the tops vertical and the float hanging down and lightly resting on the ball measure the distance between the float and the gasket. What should it be 15mm? And what should the gap be when the float is at it's furthest from the top cover. Another question, aparently the one way valve/jet in the bottom of the float chamber spills a certain amount of the accelerator pump's charge back into the float chamber and therefore controls the volume of fuel squirted. These are available, like jets in different sizes. What's a good ballpark size for a 2l Vx? Thanks in advance.

I'm sure it will work fine but it sounds on the smallish side to me. I've always felt that a little more oil to do the lubricating work and dissipate the heat can't be a bad thing.

Made by Protar and incredibly detailed this is a 1:9 model of a 916 race bike. Many metal parts and racing decals. The kit has never been opened. I think it was about £40 new so how does £15 sound?

Does the removal of those internal springs make any noticeable difference to the "weight" of the throttle action? I guess I have four throttle return springs on mine, two internal and two external and the throttle action is so heavy it feels a litle notchy. I was wondering if I removed the internal TRS's the cable might be less stressed and move more smoothly.