splcrazy

i have a baja 5b that i had recently bought a bigger head kit for it, the dealer told me it was a 29.5cc kit . today i spent nearly $300 bux on parts , i got a spare piston a new hpi baja tuned pipe and 8000rpm clutch spring . i installed the pipe and spring and then started it up did a few donuts then the engine turns off . i checked it out and found that the magneto coil had moved from position i fixed that up then tried to start and still no go i then take off the head to inspect the piston and found that one end of the ring had fused in the ring groove ? why would it do that ? . So i get the spare piston go to put it on and it doesnt fit lol i then realised that the head kit wasnt 29.5cc but infact a 29cc so the hobby shop guy made a mistake and told me it was a 29.5cc head kit , so now i have a bigger piston thats no use to me . it just makes me angry, well at least i got to hear what the pipe sounds like for less than a minute .

Osirisf16

LOL And what are you going to do now?

sheograth

Do headkits EVER end well?


Also, I've never heard of a 29.5cc in this sector of the hobby :/ had you asked us we might have warned you

Still, real sorry about that - we all know the feeling it invokes.

splcrazy

go back tommorow morning and throw it in his face . ill have to now order the correct piston that is 29cc and ill get two of them since i paying fast friegt next day delivery so i should get them tuesday, so monday he puts in the order and tuesday its there and not only that he made me pay for a 29.5cc head kit when it was a 29cc and if it wasnt for my piston failing today i would have always thought it was 29.5cc

yeah i measured the spare piston and its 1mm bigger than the piston that failed so the spare is obviously a 29.5cc and mine is a 29cc

mikeinoz

Who was this dodgy dealer?

jasrx

yeah id like to know too

Osirisf16

Two things happening:
1) or the dealer DIDN'T have a clue about the engine
2) or his measures were wrong

Actually, both are symptoms of NOT good dealer.[:@]

Mudgy

Mate I have just done this for a bloke I know....
He bought : 2mm stroker crank & conn. rod
new piston & pin & needle brg.
new head/sleeve
new plug
copper head gasket
header + Pipe

I saw before I even started the copper gasket was water cut, or something - it had to have material removed(was covering transfer ports)and edges smoothed
the header was port matched and rounded internally
pipe and header (brand new) had metal dust right through them
carb gasket partially blocked pulse port
the join in the ring has to be inserted to the sleeve in its final position - not slide in and turn... this could cause the ring to over ride the locator
pin in the piston crown NOT GOOD

Guys, I'm no expert
this is the first Baja ive mucked around with, mind
but it went well![8D]

gotta say, these cars aren't real neighbour friendly
If I had to describe a Baja in one word -- LOUD
BTW, I bonded the case gasket with loc tite 518 master gasket (blue Hylomar would be just as good)

I also saw the air gap on the magneto to the flywheel....in its fully down position, the gap must be 2.0 mm or more
Is this normal????
The fattest spark comes from flywheel magnets CLOSE to the laminations from the coil
this is only possible if the flywheel is balanced and trued.(no eccentric motion at hi RPM)
I wouldn't mind experimenting with the coil as close to the flywheel with, say a business card as a shim.
this would have to make for a better spark?


Kettering ignition is a collapsing magnetic field inducing a voltage in the secondary (reflecting)coil
Magneto ignition is the reversing of a magnetic field, inducing a voltage in a primary coil
the only other ways I remember are glow plugs, or light a match!!!

jasrx

badz

My Feedback: (1)

29cc piston is 35mm, there isn't a 29.5cc engine it's 28.5cc which uses a 36mm piston, the 29cc is 35mm, as far as I know there are only a few pistons available, 32mm(23cc), 34mm(26cc or 27.5cc with 2mm stroker crank), 35mm(27cc or 29cc with 2mm stroker crank), 36mm(28.5cc or 30.5cc with 2mm stroker crank)

flywheel gap, yeah alot use a business card to set it, i have and it's always worked for me.

carpy100

you shouldnt have been doing donuts on a new head and piston!! it takes at least an hour of carefull running in and slow heat build up on new engine parts. you cold seized it i'd say

jasrx

yeah id t bet thats what happend , that and if he didnt reset the carbie to give it more fuel.

splcrazy

lol mate you didnt read properly, i said i did a donut on the first old piston , then it cut out . i then opened her up to put in the new piston and it wouldnt fit .. and as now as BADZ is saying , my piston that came with the head kit is 35mm making it 29cc. the new piston that he gave me measured 36mm making it a 28.5cc.. hmmmm thanks for that info badz ill ring him tommorw and tell him this ...

but thats strange why would a 28.5cc piston measure bigger than a 29cc

badz

My Feedback: (1)

The piston for the 29cc is smaller because the cc's are increased with the use of a 2mm stroker crank, the 35mm piston used without a 2mm stroker crank is 27cc's, assuming you already have a 2mm stroker crank you could always just purchase a 36mm top end thats cut for the 2mm stroker crank and you'll be at 30.5cc's. You could always refer to these sites if cc's confuse you http://www.aircooled.net/gnrlsite/re...info/calcs.htm
http://www.sjvwc.net/EngineSizeCalculator.htm