This is what happened

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Assi

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Hello,
I bought a 23ccm original HPI Baja 5b. for 500 $. It was clean like a new one!
So my son asked me for a race. He has this Traxx nitro monster and we did a race. I had no chance at all. His speed was way higher than mine. I decided to get a new race pipe to speed a little bit up. Second race.... My noise, speed and acceleration has obviusly increased, but his car was over 60 miles fast...Again NO CHANCE...
Okay, My math said Bigger= more speed!
I decided to get a big bore kit . Yester eveining I disassembled everything and replaced all parts with the new ones from the set. After reasembling I figured out that the motor did not do full turns. From my prospective it looked that the piston was hitting the head of the cylinder at high position. So i decided to reassemble again and placed the original crank shaft (smaller piston arm). So the motor makes full turns now and when I turn it by hand it moves easy and smooth.
I reassembled everything and tried to pull the motor on. Nothing! No picture and no sound (German saying)!
The spark gets electric. Could it be wrong fuel?
Do I have to do a special setup, or was it wrong to use the old crank shaft + piston arm (what is the official word for this part?)?

Thanks!
Assi

By the way: I´m German and I hope you understand my english.
 
first welcome mate

second,,theres not a thing you can fit or do to make your car quicker than your sons nitro its half the size and half the weight if not more

your best bet for more power is a good pipe its the main thing to change when after more go
 
Hi Assi,

Again, WELCOME TO LSF.

If your rig is hitting max revs quickly, and slower than the Traxxas nitro, it simply won't go faster.

The only move, if the power's fine, is to raise the gearing.

There are a combination of ways:
1. Change the gears - hmmm, obvious.
2. Bigger circumference wheels / tyres.
3. Both.

This assumes you're hitting max quickly, thus the power's there.

Al.
 
atom3624 said:
Hi Assi,

Again, WELCOME TO LSF.

If your rig is hitting max revs quickly, and slower than the Traxxas nitro, it simply won't go faster.

The only move, if the power's fine, is to raise the gearing.

There are a combination of ways:
1. Change the gears - hmmm, obvious.
2. Bigger circumference wheels / tyres.
3. Both.

This assumes you're hitting max quickly, thus the power's there.

Al.
Click to expand...
i agree but theres no way a large scale car 2-3 times bigger and heavier is ever going to beat a nitro car that weighs less than our engines,,power to weight in motorsport is everything
 
Hello,

yes, okay I get this!
I saw this nice video at youtube with race in the desert! Amwesome!

What could be the reason why my motor won´t start?
This is a bigger problem right now for me.

Thanks
Assi
 
Does it have fuel? Strange but true - check if the plug's wet.
Does it spark - bad plug?
Does it spark - bad coil / connection?
Is the Kill Switch stuck?
Does it have a remote kill switch? Try disconnecting it.
Is the pull start actually turning over the engine, or is it broken?

A few options to start with!!

Check the carburettor settings - if altered, try resetting to the factory default of 1 1/4 LOW, 1 3/8 HIGH.

Al.
 
Hello,

how could it be that the crank shaft from the Big bore kit is too long?

Could it be that the old crank shaft is too short to build enough compression?

Thanks!
Assi
 
the connecting rod (piston arm as you called it) it the same length on both crankshafts. the pin it rides on in the crank is farther from the center on the bigbore crank. there fore you get the clearance issue at the top with the piston. it is possible that the old crank might not be building enough compression but it should still start even with low compression. the trick to making the big bore crank work is to stack up the gaskets at the base of the head to make the clearance. you want around 4 thousandths of an inch use some soft solder and calipers to measure this.

things to check are
gaskets on the intake and carb there is a small hole that has to be clear for the carb to pump fuel.
check for the key in the end of the crankshaft that locates the flywheel properly
check the plug after starting . is it wet?
i hope this helps you to figure out what is wrong
 
your big bore kit requires gasket spacers i use the copper ones from dave,usually you need 1 mm spacer
your using the big bore kit minus the conrod correct?
i had the same issue sometime back after a build , you have a displacement issue by using a bigger head and piston,and you have a shorter stroke,you messing up the timing a bit so it wont ignite,the term escapes me at the moment either get some head spacers or put the original engine parts back in,
 
Hello,

I think i need to reassemble again and put the big copper spacer and the longer conrod to make this thing back to work.
By the way what kind of big bore do you use? 29 or 30.5 ccm?
Is there a big power difference between the "low budget" I ordered and the race ported 30.5 ccm?

Thanks!
Assi
 
Its a squish issue get the correct head spacer, you should of gotten one with the kit contact the seller
 
I just doublechecked, there is/was a copper spacer delivered and I´m pretty sure i placed it when I assembled the parts. The space was still to short.
I don´t know how thick this spacer is. I will order a new 1mm from dave.
 
grab a couple you never know if you will need additional,just get a couple like 1mm, 0.50 mm,and i think they have a 0.25mm,
the engine kit you got who made it? km requires the shims ,rovan does not,as for the others out there,they should come with the appropriate items needed for install,
when you installed the shim, did you also add the gaskets?
 
Largescalebuilder said:
If you want to go faster then it's all about HP to weight ratio!
Click to expand...

Totally agree.
Point I was making earlier was if the truck's hitting max revs quickly, there's obviously power there, so the gearing can be raised to increase speed - standard racing car stuff.
It will decrease the acceleration, but if there's a long distance, the Traxxas won't romp away.

What is the Traxxas anyway? T-Maxx, Revo, Jato?

Al.
 
assi make sure you have the piston the correct way round:D

also please enter you location in your user CP then it help to direct you ;)

K....
 
top of piston has an arrow,point top exhaust port.could be your carb sttings? low = 1 1/4 turns out and high = 1.5 turns out.as above check gaskets at carb to make sure you haven't blocked pulse hole,did you set the gap properly on flywheel.also check squish with solder to check gap.the spark plug may have spark but might not be enough,change to new one.are the fuel lines on correct? the line into the carb is the underneath pipe,return ontop of carb.

i think you can beat the nitro with a ported engine and pipe with the right gears.but then if your son decides to upgrade, its all over lol. how fast does the nitro hit 60mph?
you should consider the vrc victory for stock engines,its a belter!!
 
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