Mitchell

You got it the wrong way around mate, 5 fine header is more top end

I do not want to disagree with someone, however this is opposite. The 5 fin is for top speed and the 7 fin is for bottom end.

Hope this helps.

DJ Apolaro

DJ

The above is 100% correct.
Thats what happens with these forums, heaps of people dish out the wrong info.

No offence Mitchell

George

woops i must of got it backwards, i gotta get off the turtle weed

I have both the 2602 and the 2630. I have seen my engine faster all-around with the 2602.

Just got my stock 353 in and it has no shims. I guess there are none needed to run 16%. If I wanted to run 20%, 25%, or 30% fuel how many shims would I have to add?

Are you sure there is not any shim in there? Typically there is a .3mm shim for 16%, it is silver. Maybe it is stuck to the button. For 20% add a .1 and for 25% and 30% add .2

16% = .3mm
20% = .4mm
25-30% = .5mm

With 16% I use a 6f plug. with 25 and 30 I use a 7f plug. I am at sea level with high humidity.

Hope this helps.

DJ Apolaro

Thanks I will check again, I didn't know they were silver thought they were brass.

DJ,
Are these shims in addition to the stock shims that came with the engine or total shims?

The .3 should be in the motor already. The .1 and .2 are in addition.

As for the color of the shims. The .3 is silver, the others are brass.

DJ Apolaro

Just checked and there was 1 shim silver and it was .3

Perfect. That motor is ready for 16%.

DJ Apolaro

anybody have any good breakin methods for these engines. I do have a breakin bench.

First I would take the motor apart and clean it. Make sure there is nothing of dirt in the motor. I do this with all new motors. For the break in I would do the first 6 tanks on the break in brench at "WOT" (wide open throttle). Try to get some heat in the motor while doing this. Around 180-190 degrees. You may have to put some aluminum foil around the head of the motor.

Then put it in the car. Use a soft clutch that engages very easy and set the 2speed to shift easy also. Run it in the car for about 5 tanks very rich, it may not even shift at first. Key note; make sure to let the motor sit between tanks at all times and make sure the piston is NOT at the top of the sleeve. This methods helps cycle heat into the motor and helps set the piston and sleeve. After these 5 tanks start leaning the motor a little at a time per tank. Over the next 3 tanks it should get close to a rich race tune.

At this point take the clutch off the motor and rebuild it to normal race conditions and reset the 2speed to normal also. Now the motor is ready to race and should run good and consistent.

Hope this helps,

DJ Apolaro

Just to make sure when you mean 6 tanks, is that 6 of the 150cc tank on the breakin bench or is that 6 75cc tanks like on the car because the tank is 150cc on the bench. And wouldn't WOT put alot of stress on the conrod?