MassiveMods

I would check to see if the piston is scored on the side .

Check to see if you are getting tank slop , add a fuel filter in line with the pressure hose from the pipe.. if you are getting the flame out on the corner at the end of the straight ...

Check to see if your brake shoes are not binding onto your fly wheel..

Check the chassis braces , if they have come loose the chassis will cause the clutch bell and C Diff to bind ...

Crank Case cracks are common on the OS

Rear bearing faliure is common on the OS

Rod faliure is common on the OS

Check these faults ..

any debris in the HSN or fuel line can cause this ..

Hope these help..

Don Duct

P3 Plugs only
JP-3 Pipe
Running in Arizona at the Nitro Pit
Stock Carb Stack.. the bigger opening


Well... I just checked the clutch and the clutch looks really good. All springs working fine, very little ware.

I looked in the exhaust hole at the top of the piston and it's shiney looking as new, so no build up.

I looked close at the exterior of the case with a bright flashlight and didn't see cracks... I'll have to look inside if cleaning the needles and replaces the exhaust seals don't work.

I'm going to order new pipe seals first. When you put the pipe on there is enough slop you can wiggle it side to side, so I hope thats the problem. However not many here seems to think that is the cause of my symtoms and that has me worried.

How do you check the con rod for slop?

I'm timid about doing surgery on my engine as I am new, but I have to start somewhere and I do want to learn all there is to know.


Suggestions??
On what steps I should take to begin my troubleshooting... ideally from easy solutions to the more difficult I assume?



Thanks everyone I really think the people on this forum awsome.

jpalessi

iTrader: (55)

you prob need to lean out the bottom end about a 1/4 turn. I always ran my v specs about 230 -255.. it sounds to me like your loading up on the infield and even more at idle. Leave the idle at 1-1/2 turns from fully closed and then lean the bottom end to stabilize the idle. Out in AZ you should prob run a OS P4 plug, it's colder then the P3. so running the P4 you'll also require a leaner setting. Good luck.

desertbird

iTrader: (7)

Rich LSN sounds like something to dig into.

jamminnay

iTrader: (11)

dont box tune!!!

Don Duct

Yup, not good. Best to tune on the track.

It was running rich at the bottom end. Leaned that out quite a bit. After full throttle it kicks down to a nice idle after 6 seconds. Before when the bottom end was rich it took 15 seconds to kick down to a level idle.

I just ordered new gaskets. Should be here in a week or so. I'll let everyone know what I find out.

-Don

nta01

iTrader: (19)

Don,

Seal the carb and the back plate, reset your needle to stock settings and start the tune over. Sometimes that's all it takes.

Did you check the front bearing to see if there is any leaks?

I'll be at the pit on Saturday and we can tune it then.

Tom

Gliptal

Check to make sure there's not any debris floating around in your pipe like a piece of the gasket your going to replace. I've seen that happen, it will cause random flamouts like you described.

MonkeyWrench

Well make sure your idle set screw is isn't turning and moving on you. Slamming the slide shut killing the motor. I had an OS I used a small amount of thread lock on cause the screw would rotate on its own. Then I second the idea too that,
the clutch shoes are dragging too and intermittently killing your motor. Change the bearings maybe they are oblong and you cant tell and the bell is wobbling ??
Oh and Off topic here but something I do, keep a roll of plumbers Teflon tape in your box, has been a life saver for me when the seals get loose and you don't have another set of manifold and pipe seals around. Just wrap the existing seal to a nice snug fit.

cheesecake

iTrader: (27)

dont bother with anything else just replace the rod and i bet your problems will be solved. when the vspec rod gets slop it causes the engine to flame out. replace the rod seal the backplate and you should be good to go

COBRARACING

shim your engine to 0.9mm and use a p3 plug and your problems will be fixed.there is no way you have alot of slop on the conrod after a simple gallon.

ngo8

it might not be the motor at all did you check the tank for any cracks on it ormaybe youre fuelline is ripped somewhere my friends motor was doing the same thing and it turned out his tank was broken .

Don Duct

Well everyone, I wanted to give you an update on the actual cause...

A few of you said hairline crack... and if you did you would be correct.

CWalters described it DEAD ON. I just didn't have the trained eye to see it before.

I want to thank everyone here, and a special thanks to the crew at the Nitro Pit who are such a great bunch of people willing to spend time and help out. www.nitropit.com

The guys at the Nitro pit was able to find the crack and show me what it looked like. It was exactly where CWalters said it was...


I also did find out that there is a chance OS will replace my case. A few guys at the Nitro Pit had cracked cases with little as a gallon though them and OS did replace their case. I'm going to give it a try and I will let you know if they did replace the case for me.

-Don

nta01

iTrader: (19)

Sorry to hear that Don. You should have a new case, so this shouldn't been a problem.

Anyway, if you need a motor until you get a new one, you can run one of mine.

Tom

Bigedmond

iTrader: (20)

That is the reason i stopped running OS motors. I had 3, 2 vspec and 1 speed get the crack in 1 piece motor mounts.

I am surprised now one mentioned an obvious possibility. FUEL. you live in AZ, as i live in NV. the heat were we live kills fuel.