engine size

[biglegs]

is it possible to use a 250f engine in a sidecar? Will it be strong enough? Will it last with out blowing up? The reason i ask is for our liecence in northern ireland you cannot ride over a 250f until you are 17 ut you can be up graded to a bigger bike at 16 following centre approval but the young team only turn 15 in the next couple of weeks and really wants to get racing , so any advise would be much appreciated
Regards biglegs

[Dave Tye]

Hi There,

In theory you could run a 250f engine, but you are going to be working it very hard. I have poassengered a standard Yamaha 450f with only a slight power disadvantage at some tracks. Any where with major elevation changes etc are going to give more of a disadvantage however.

A lot depends on how small the crew are too... I have to admit Al and I were a little large for the 450 really, both weighing over 14 stone... (Most 15 year olds tend to be a tad slimmer than we were!)

Reliability is another issue... the get the most power out of a 250f you will have to tune it, and it will have to be revved hard to perform, that in turn may increase running costs and detract from reliability. In stock form it would probably be quite reliable, but you would be down on power comparred to the other outfits... However, being honest, how many people ride their (larger) bike to it's maximum potential?

I would think it would be worth giving it a go, another young crew out there would be excellent and the more experience they get before going on to a big engine the faster they will be long term. To be competitive they will have to learn to carry corner speed and jump speed to compete, this in turn will greatly help their riding skills.

Good luck and keep us posted on how it goes.

Dave

[Taffy]

my first thoughts are that you should be using a 250 two-stroke right off the bat. they are plentiful, cheap and likely to take more of a thrashing. spares will abound. defo a 2T.

you can get 45 useful bhp out of one. gear it lower that other outfits as it will run out of breath quicker. as you learn from such a young age you'll decide where you could do with more power, a bit in the middle, more at the top etc.

I think it'll be a blast! consider an enduro engine perhaps for a nice broad spread of power, anything peaky and you'll thrash the motor so badly that it'll be unreliable. a gas-gas 250 has a broad spread of power and the ktm is peakier.

now you didn't hear this from me right but the 250 and 300 katoom/gassers are identical externally...... now you are up to 50+bhp....

regards

Taffy

[biglegs]

sorry but then you would be going to mx1 when they are restricted to mx2 at the young age

[staf]

There are no age restrictions to the engine sizes in sidecars. its not like mx1 or mx2. the only restriction to engine sizes there is, is that the maimum capacity id limited to 700cc or something like that
a perfect engine to start would be a 450/525 or 500 2 stroke.
i dont think a 250f would have enough power to haul around a big frame and 2 people.

[Dave Tye]

Hi Again,

I Think the issue here could be how the rules are structured in Ireland. By the sounds of it they are quite different from the UK, where under the ACU you can ride what you like at 16 (15 with verification from an approved assessor... unfortunately we don't have one at the moment!) and there is no restriction in the sidecar class at all at local meetings. (700 2-Stroke etc being championship and GP rules).

Assuming to be able to race even with the sidecars requires the same engine restrictions as MX2 for 15 year olds then a 250f is the only option (125 2-Stroke would have too little torque and 250 2-Stroke is classed as MX1). I am sure it could do a reasonable job with the right frame etc. Looking at the kids riding in Belgium 150f engines were moving pretty fast with 10 - 12 year olds on. A 250f with two light 15 year olds on a correct gearing could probably be serviceable for a sidecar. VMC make a very light weight frame which would be ideal, Alfie Hyde had one in 2009 that Al and I borrowed for Dunmow with a 450 in it and it was plenty good enough for us...

I get the feeling the tip concerning the appearence of certain 300 GasGas engines may be there in case the you wished to try and sneak one in as a "250" instead, but again, I believe this is only the case with the 2-Stroke engines and therefore not applicable.

Good luck getting it sorted and getting the lads out there...

Dave

[anejit]

All this is brilliant help :) thanks every1 .especially marty (biglegs) btw me and shane both wiegh about 10 stone each and the frame is a vmc (is this good ) wb :D

[biglegs]

sorry but this is not going to happen now as the insurance over here is saying no to anyone under 16 but it looks as if there will be no restriction on engine size, they might say 500 2t and 525 4t , i will just have to play it by ear thanks every one for the advice

[anejit]

thanks for the help every one at the agm of the mra, it was passed that a 15 year old can ride and passenger a 250f with the adults, We have purchased a 2003 KTM 250f exc, which hopefully after abit of tuning will do the job We are now desperately seeking a vmc or eml chassis to suit our engine if any one knows of anything
http://www.mcnews.com.au/newbikecatalog ... Racing.htm
Greatly appreciated Gary Moulds & Shane Taylor