Rocket42

AZTman you nailed a lot of things.

I would check the length of the pressure line. I have heard that you want the pressure line to be half the length of the fuel line. If you pressure line is too long it won't provide good pressure and you will see air bubbles in the line.

How did you test your tank. You should dunk it under water as well to check for bubbles its also a good idea to run a bead of CA around the tank seam.

The 5 port tunes a little different then the 7port and likes the bottom end to be a little on the rich said compared with the 7port.

I would be sure and seal the carb anyways, when the engine is cold it may not be leaking but when it gets up to temps the expansion could cause a small leak. I would also check the throttle boot. People don't realize that the boot is an air tight seal and a pinhole in it would cause an air leak.

Dotan the head shims will help with this, the majority of piston breaks are user error and not a defect (I am not saying yours was user error just crunching the numbers I have seen) . It occurs almost always in the 7port and is the result of overreving the engine too soon in the break in proceess or not making sure the engine is placed at BDC as soon a it is shut off.

Adding a head shim at the factory will soften the compression during break in and help with this, also trying to inform the customers to not rush the break in is very important also. Trust me when I say the actual failure rates are very low but in this day and age. When 1 engine breaks on the wrong person and that person goes and blames the factory online you will have thousands of people questioning the quality of the product (people who are anxious for the sightest flaw to reasure themselves that there $300+ engine was worth the money) It is better to also have the engine over shimmed for race conditions then to expect a customer to have to go out and buy a shim with there brand new engine. You can always remove the shim but I would wait until the engine is fully broken in around the 1 - 1 1/2 gallon mark.

AZTman

OK, backplate sealed.
1. Remove backplate.
http://i198.photobucket.com/albums/a...engineback.jpg
2. Wipe off around the top side near screws.
http://i198.photobucket.com/albums/a...-backplate.jpg
3. Apply SMALL amount of sealant as evenly as possible around the top side.
http://i198.photobucket.com/albums/a...ithsealant.jpg
http://i198.photobucket.com/albums/a...thsealant2.jpg
4. Insert backplate into engine WITH THE DIMPLE AT THE TOP. Tighten screws.
http://i198.photobucket.com/albums/a...withexcess.jpg
http://i198.photobucket.com/albums/a...ithexcess2.jpg
5. Wipe off excess.
If anyone sees anything wrong, PLEASE let me know. OK, except for photo quality. Crummy camera...

MassiveMods

Sounds like you are lean on HSN not LSN ... Richen HSN 2/8 ... If i can try to guess you tuned the motor on the box maybe ? at full tank ? Try running the engine to half tank before tuning .. that way its at operating temp and you have an average tank pressure..

hope this helps

all the other suggestions from AZT and Rocket are very important to check too but my guess is the HSN was lean

AZTman

Where are you suggesting a bead of CA? On the outside of the cap where the screw on top tightens the plastic-to-plastic? Or on the underneath of the tank where it closes onto the tank body? Wouldn't that keep it from opening? Maybe I just need to dunk mine to see where/if it leaks.

MassiveMods

I suggest .6 because thats what we found worked for our racing team .. it lowers comp and helps combustion at high speed.. Its very hard to tell why your piston shattered . Anything could contribute to that ... if the piston was faulty it would break in the first couple of tanks normally .. having said that the Go Tech engine has to be one of the best quality checked engines on the market bar none.. so faulty parts is very very un likely .

What you have to consider is when a piston is fin full flight anything gets in its way and it can break no matter what the brand of engine.. So i would check for any foregn matter inside the engine .. possibly taken in from your air filter or in your fuel tank .. This can also happen when you change plugs .. Some people dont realise that there is dirt around the plug after running ... if you do not clean this off before changing it you risk dirt getting in through the re...

Hope this helps

Paradoxmaker

NO, i think he meant the seam of the tank where the 2 halves of the mold come together....not the lid.

AZTman

*looks over at tank*
......
Oh.

Jerseyboy

Thanks for the advice. I'll report my findings when I get the problem.

fastbanshee

iTrader: (1)

Are these new versions in the states yet? If I buy a Go 5 port turbo head will it have the new carb on it? Who has the new versions in stock?

Rocket42

The engines in the U.S. have the revised LSN but do not have the extra sealed carb. I would not worry about it too much since it is a very easy and permanent fix.

vr6

iTrader: (22)

getting ready to start breaking in my new go 7p turbo. my carb throttle seems to have alot of play, is this normal? my os carb doesn't have any slop on the throttle slide of the carb

Rocket42

Should be fine, I haven't noticed any excess carb play. just make sure that the carb pull is straight and you should be fine. I have also noticed that if the idle is backed out and you slide the throttle body out and put after run oil in the groove on the throttle and reassemble that the carb movement will be much smoother.

Jerseyboy

OK (egg on my face) Problem was only tuning. For some or other reason the conditions inside the engine changed. It was the firt time racing with the 5 port. Also these engines has to be retuned once run in.
I found that I had to richen the bootm end needle almost 2 full turns. Its a rocket again. I'll take to the track over the weekend and test on the track.

kamlooper

iTrader: (7)

2 turns? That seems like a lot...?

MassiveMods

All the carbs made from about a week ago have the problem sorted.