daytona 125

[roost666]

hey just wondering what people think about the daytona 125cc engine

 

[Dreadful]

Have'nt had one but I reckon the stroke is a bit short leading to overheating problems .At the Brotherhood shootout last year it was running well with little 12 year old Jack Simmo on board ....then Brady threw a leg over it and loaded it up a bit more ....engine temp then tested 140 degrees

I have also HEARD they are requiring a rebuild after 10 hours of racing in the states .

Like I said haven't owned one but hear ya better be good at spinnin spanners if ya do

 

[roost666]

Dam that sucks i just got the new motovert pro which has the daytona 125 in it im only just running it in.....from the few mini bikes ive road they seem to have alot more torque and top end over the lifian ducar and jailin....but ive only done about 4 - 5 hours on it only time will tell i suppose.....anything you can recommend changing if i do come across the problems you have mentioned.

 

[Dreadful]

All good bruz don't stress too much these things are not too complicated to fix ... besides that was last year they will have improoved.... like I said I have'nt been ridin em ....

Cooly has and he'd be ya man he's had no dramas and he revs it ....also corey_58 and his old man have been building motard WEAPONS outta the 4valve daytonas but the price of the kits are off the chain .

 

[Dreadful]

Oh yeah ya suspension n everything else is outstanding....... After all Brady did go 138ft on one .....

so didn't mean to sledge ya bike it's a good thing just passin on stuff I heard about the daychina 125 motor.

 

[roost666]

all good mate thanks heaps for ya info...ya i knew the suspension was good it was just id never heard of the daytona motor till i got the bike.....dam happy wit it killin all me mates hahaha......happy ridin

 

[tldrider]

heyy !
the mv pro is fkn awsum ayee!
their is sooooo much torque compared to all the lifans n all
only downsides so far is the really high heat u get from the engine :|

 

[themountain]

..the only thing I know is that at least 3 bikes with the engine were in the finals in Las vegas...plain stock...and that rips in my book!!

 

[roost666]

heyy !
the mv pro is fkn awsum ayee!
their is sooooo much torque compared to all the lifans n all
only downsides so far is the really high heat u get from the engine :|

Ya mate i know wat ya mean they have serious power for a 125 ay......my mate has a braaap 140 mestro and im kickin his arse he really pissed hahaha

 

[Cactus Jack]

The short stroke isn't why they get hot ... it's the forged piston expanding and creating more friction ...... coupled with the laid down cylinder ..... With forged pistons it's critical that you have the mixture slightly on the richer side of lean in order to keep the denser forged metal cool .... If you run lean and heat the piston up it'll expand and rub hard on the bore .... that's why they need to run more piston to bore clearance than a cast piston .... And no matter what you read ... a forging isn't as dimensionally stable as a casting at high temperatures ..... That's most likely why they need to be rebuilt every 10 hours when raced as Dready says .....

Early XR75's only have a 41.5 mm stroke and CRF150R's only have a 42.7 mm stroke and they don't overheat very easily ..... even when worked off their heads ..... in fact early XR's have stuff all cylinder finning but still don't overheat even when being thrashed all day long ...... that is ...... unless they are fitted with a forged piston in which case you have to watch the engine temp and let the bike cool down regularly .......

A long stroke engine creates far more cylinder friction under normal circumstances purely because the piston has to travel further with each rpm .... so it HAS to go faster and due to the steeper rod angularity there is more piston thrust on the cylinder wall ........ that's precisely why F1 engines run big bore , short stroke , long rod engines ...... if they didn't slow down the piston speed and reduce rod angularity , they would grenade long before they got anywhere NEAR 19,000 rpm ........

 

[Dreadful]

Cheers mate I stand corrected ... thanx for sortin me out .... as for the xr motor you are spot on there too mate ...as usual .

There was a worked xr 75motor in a ktm65 frame at the sx that ran seriously smooth and fast all day ...we ran it in the mag ...really really nice bike.

 

[roost666]

ok im not mechanically minded so you lost me a little.......so all i should do is get the bike running a tad richer which will lower friction therfore lowering heat(but havent had that prob yet)and when it comes time to rebuild shoud i rebuild with a cast piston and back the mixture off or stay with the forged piston.......and are there any dress up kits available for this engine....