Under 15's Scunthorpe

[morganbike]

Great thread,

Put one 350 and one 500 out on a 4 lapper and without judging the riders ability, a keen ear will pick up the 350 without any doubt.The sound is completely different.

The expence involved in producing a 350 that looks like a 500 ie engine numbers,barrel,head etc is too great an expence to endure as they are achieving nothing even for those who run on an unlimited budget.

The way to spot a 350 is on the number of fins on the pot.It has one less than a 500 to achieve the stroke and there is no way a 500 can become a 350 without reducing the stroke.You cannot achieve 350cc on a 500 pot just by reducing the bore because the piston's diameter would be rediculous and would lead to a sleeved down carb to make it rev if at all, and would eliminate a sound that eminates a duck with constipation !. So you have to reduce the length of the con rod. Scrutineers need not be afraid.A crankase marked with the traditional 880 signifies a 350 but these cases can be used with a 500 crank,pot,piston and head to make a 500.The 350/500 cases are the same.The same goes for a long stroke jawa 500 marked with 884 which can be turned into a 889 short stroke but they dont change the numbers.

A classic was when on E-Bay a guy had a 500 short stroke for sale.So I rang him for the engine numbers which he gave me and I then rang Bellham to confirm it's originality.It turned out to be a 1998 long stroke 884 but was told on E-Bay that it's a 2003 short stroke !.This was the year it was transformed so be aware.

Glen Taylor (GT Tuning) can graft a 350 jawa top end onto a GM botom end and it will run.How would a scrutineer deal with that ?.Here in the Youth Grasstrack world no-one cares about cheating as the top 5 to 10 riders in each class will achieve their ambitions and the ACU cannot police this each meet.Some say youth grasstrack is the stepping stone to speedway.Some will do one or the other or both when their budget allows.If I went out tommorow and bought a brand new two stroke YAMAHA 125cc engine,I could have it turned into a 164cc for around £500.The rules allow 150cc but would this oversize engine be competative with the new breed of 250 four strokes that are now allowed in the class ? Todays Tuners/Engine Builders have a vast number of areas to play in so don't worry about undersised motors taking advantage as when the pilot gets to 16/17 yrs old the ability will come through.I feel that the under 15's is getting a bit too serious and whilst we hope and wish our kids will one day make it in the speedway world they do deserve the oportunity of a good education and freedom of choice.

Phil

Edited July 14, 2005 by morganbike