do harder compund tyre's give beter top speed? or even higher pressure? since there would be less friction with the ground if inflated highly. and would it not matter one what kind of floor your riding on? and if its wet or dry? or a cold or warm track? do any of you serious racers change tyres depending on the track layout, condition, tempreture or any other reasons?
im only running the tyres that came with my bike but i dont know if there properly round, i dont race because we dont have a track around where i live so i guess my standard tyres will do lol
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cag
49cc 40mm ported
high compression head
ported and lightened piston
full circle stroker crank 52cc
rocket key
stage 3 big bore exhaust (3 peice set up with springs)
exhaust manifold bored to size of manifold outlet
carbon reed
K&N style air filter
alloy velocity stack
metal pull start cog
freewell speedo
high flow fuel filter
boost bottle
lightened and ballanced flywheel
unfitted:
different jetting to try 2nd place is the 1st loser
The track conditions and temperature will heavily influence tyre choice.
On a cold, or smooth track or both you will want to run a softer compound tyre. If you dont have a choice of compound, on a cold or smooth track you will want lower tyre pressures. Lowering tyre pressures (may mot be by mutch) will result in a larger traction patch (the area of the tyre touching the ground). By having a larger contact patch there is increased friction and the tyre is able to build temperature and the result is increased grip.
On a hot or coarse track you can get away with harder compound tyres and higher tyre pressures because you need less tyre on the road for the same level of grip. The heat in the track will also allow the tyres to build temperature without the need to increase the contact patch. IF you ran the soft compounds or low tyre pressures used on a cold day or smooth track the tyre will overheat, resulting in fading grip and a very 'squirmy' feel.
If the track is wet, only groved, soft compound tyres are appropriate. However, "wets" should be run at high pressures so that they are able to force the tred of the tyre through the film of water on the surface. These tyres are of a very, very soft compound and are able to build temperature even in the rain, with high pressures. These tyres cant be run in the dry as they will overheat, deleminate and fly appart.
Ultimately, if we had an unlimited budget you would have a tyre for every condition but most of us dont. You can get away for the most part with adjusting tyre pressures as per my earlier advice. My tip is to get yourself a decent tyre pressure guage such as a HELLA brand one which is very accurate.
Hope that helped
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Trying to get more people to pocket bike events held around Tasmania
ive got some treaded zhongya's and have to say they work pretty well. i think i got them up to temp for the first time on the weekend and they were very sticky. But if i was using them in a race they wouldnt last all that long. Only problem i have had is that i have a leak in both tyres. it may be my rims or maybe a punture but they hold the pressure over a race day but will be completely flat by the next day.
Definitely a great tyre for cags but i wouldnt use them with a W/C unless it was raining.
We have been testing the Sava tyres now for around 3 months and have come up with the following information.
The Sava tyres come in two types and three compounds for a dry track.
The 'R' in the tyre wording means reinforced.
So if you use a MRA tyre this means the tyre is reinforced and suited to riders over 70kg and a tyre MA is suited to a rider under 70kg.
The 'A, B or C' in the wording means the compound of the tyre.
'A' is a very soft tyre.
'B' is a soft tyre.
'C' is a medium tyre.
Now the profile of the Sava tyres are very different to the PMT tyre.
PMT tyres are a very broad or wide looking tyre.
Sava tyres are a very noticeable rounded tyre, much like a Honda race tyre.
With this in mind the lean angle of the Sava tyres is much greater than the PMT tyres.
This allows for a quick change over of turning direction into any cornering.
Now when a tyre has a rounder profile and you have the bike leaned over to the maximum, this rounded profile will give you a greater pull out of the corner.
While a pocket bike does not have a gear box, this more rounded profile allows for a type of gear box on a pocket bike.
If you ever measure the distance from the center of the rim to the center outside of a tyre in the middle it is a larger measurement, than the distance from the center of the rim to the outer edge of the tyre.
Thus giving you a ratio to allow more acceleration out of a corner.
So the Sava tyres WILL give you more power than the PMT tyres out of any corners.
The grip of the tyres is also exceptional with the tyres giving the rider a feeling of almost lying on the track around corners, but never letting go of their excellent grip.
Testing the Sava tyres over the PMT tyres, (which we have run for around 6 months also), we have found the Sava tyres to give the rider an edge over the PMT tyres in all conditions we have tested them.
Of the 5 riders used in the tests, all of which have used both the PMT and Sava tyres, ALL agreed the Sava tyres are the tyres they will use from now on.
So here is the rating given by the riders who have tested the Sava tyres.
To answer the statement regarding tyres going down overnight, it is quite normal foir tubeless racing tyres to go down frequently after being used. Unlike street tyres, racing tyres have very lightly built carcasses with the aim of saving weight.
Secondly racing tyres are designed to be used in very specific conditions within a small range of pressures, unlike a street tyre which must be able to operate safely when neglected, holding pressure over extended periods of time (who checks the pressure of their car tyres every day?). A racing tyre may be checked every hour.
This leeds to a fall in the user friendliness of racing tyres in general, this extends to them going flat when left unattended for periods of time. This is not to say that you dont have a puncture, however with experience in go-karts, mini-moto and full size race bikes i have come to accept that racing tyres go flat even when in pristine condition.
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Trying to get more people to pocket bike events held around Tasmania
ive got some treaded zhongya's and have to say they work pretty well. i think i got them up to temp for the first time on the weekend and they were very sticky. But if i was using them in a race they wouldnt last all that long. Only problem i have had is that i have a leak in both tyres. it may be my rims or maybe a punture but they hold the pressure over a race day but will be completely flat by the next day.
Definitely a great tyre for cags but i wouldnt use them with a W/C unless it was raining.
I put new tyres on standard Cag rims and had leaks everywhere. The casting of the rims leave a lot to be desired as the air was actually coming through it. Solution, either use tubes or as I did, squirt some liquid tyre repair in and slowly turn the rim enabling the liquid to cover all surfaces. Haven't had a leak since
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What is so confidential about cheese that it has to be shredded?
Crash: good topic, but being a gradeA suspension mechanic myself (KONI trained), then i will have to correct you on one thing:
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what's wrong with your bike looking at everything trying to figure out why your bike has the road holding ability of a drunken mountain goat and vibrates like a jack hammer.
Road holding is produced by the shocks (forks are no exception), these keep your tyre planted on terra-firma without them, the contact of the tyre surface would not occur all that well hence the 'jack hammer' effect.
On cars and bikes alike the surface wear of the tyre should be round, flat spotting a tyre (as with bikes and cars) will happen and this is often caused by a 'dead' shock, the bump and rebound forces within the shock work together with the spring to give you a controlled ride (both with cars and bikes), its this unison of forces that gives you both a comfortable ride and a safe ride, it also allows the tyre to wear even over the entire surface, a dead shock will allow the vehicles tyre to bounce giving you flat spot areas over the tyre surface, its these areas that gives you that jack hammer feel.
So while checking tyres, also spend an hour and check the shocks for leaks and if need be, replace any dead shocks (unless the shocks are serviceable, then have the oil replaced), forks work much the same way and we all know how to replace fork oil dont we ?
With pocket bikes, it would be a good time to mention that the axles on most if not all of these bikes are prone to bending, if you have the time, take the axle out and check it, a bent axle will also cause the 'wheel bouncing'.
You'd be suprised at just how good i've built everything from rocket launchers (using shock dampening), to cabin shocks for trucks, kit car suspension, show cars, group A, group C, V8 superlites and the list goes on.
I am currently looking into having some mini koni's built to replace the standard pocket bike shocks, hopefully if the design works, then we can all have a rebound adjustable shock for our bikes would be pretty cool having a slight advantage on the track
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