Yes, it does sound that there is an air leak. But I'm still thinking very hard where its coming from. Btw, I have changed the tank lid o-ring and exhaust gaskets. Have yet to get it started. But what if the same problem persist?

did u chk front bearing for leak, i had a extech that gavme air leak fits but once i sealed the pinch bolt it was golden.

Already checked the front bearing. No signs of any leak. Does the length of the exhaust tubing affects the idling?

So has anyone tested the shark 9 yet? I seen some people were breaking them in but I'm curious on how they run and fuel mileage.

Ok, another good test is to see how well the fuel flows from the tank to the carb. When you first try to start the car put it on the starter box and turn the engine over without plugging the end of the pipe. If there is a good seal all thru the fuel/exhaust system the fuel should start to flow to the carb without having your finger on the stinger. If this does not work try to put your finger over the stinger for just a second so the fuel gets like half way to the carb, then pull your finger off the stinger. If the fuel flows back toward the tank as soon as you remove your finger there is a leak of some sort.

Another thing to look at would be the header. I have seen tiny cracks in the header cause very erratic idles. generally if the header is cracker you will see some oily dirt buildup on the header it's self close to the crack. The crack it's self will be very hard to see but once the header is up to temp and running that aluminum expands and will cause a loss of pressure which will not push to proper ammount of fuel to the carb.

I ran it some a few weeks ago in Arizona but I didn't race with it as it's still not fully broken in. The engine already feels like it has great power from the bottom all the way to high RPM's. In a few test tanks I ran I was able to get 9:00 and 9:30 on timed runs and that is still running fairly rich (210 degrees) not to mention The Nitro Pit is a huge track where you are on the throttle a lot!! I ran the 192 header and 2045 pipe that it comes with.

I have a b9 from last season before that i had a grp tuned version.The b9 starts but dies not hold a tune idles erattic when it does idle its ok but not right somehow.When you adjust the needles to me it is like they do not do anything where as the grp slight turn and it alters the engine.I have not been very happy with this as they are not cheap?
Any one have any other ideas as i was told that rb were good?
Thanks

When is the last time you ran this engine? Did it run fine last season? have you put a new glow plug in it? What you describe really sounds like an air leak somewhere. Be sure to check the rubber gaskets in your exhaust system. If the one on the engine is torn or even the one between the header and pipe is torn you will have all kinds of tuning issues. Also check the fuel tank it's self and make sure it is sealing real well.

Another good test is to see how well the fuel flows from the tank to the carb. When you first try to start the car put it on the starter box and turn the engine over without plugging the end of the pipe. If there is a good seal all thru the fuel/exhaust system the fuel should start to flow to the carb without having your finger on the stinger. If this does not work try to put your finger over the stinger for just a second so the fuel gets like half way to the carb, then pull your finger off the stinger. If the fuel flows back toward the tank while the engine spins on the box when you remove your finger there is a leak of some sort.

RB s7
 

I have a S7 with a jp-1 pipe it has been running great . I have put about 1/2 a gallon through it. Then today it started back firing ,only when is cold. After i warms up it dont do it anymore. The bottom end is still a little rich. Has a good smoke trail. Running temps are usely 210 . Any help would be helpfull.

Thanks Bigmack

Try a fresh glow plug first. If it's not getting hot enough to completely burn all of the fuel in the chamber that could cause it to backfire some.

Any Idea what kind of times I would have with a D8 with a Kiler9 motor. I run on this track.

http://www.rctech.net/forum/6569245-post1034.html

I am getting about 35sec. a lap but with some practice I should lower that to around 30sec. I am just looking for some times so I can run this at its potential and get the fewest pits in. Thanks.

RB s7
 

Thanks for the help. I did put a new plug in. Its not back fireing today. I tried to lean the lsn alittle. It start hiccuping. A hour or two richer and it wouldnt clean out for 15 or 20 feet at the of 50' strait. I have tried serval diff. pipes
none made any diff. Thanks bigmack

i had a cl7b that would not idle witha 4" pressure line, 6" and it was fine.

What pipes did you try on the engine? I also think you should set the engine back to stock settings. 3.5 turns HSN and 5 turns LSN. Before you turn the LSN all the way in you should have the throttle open. Retune the engine again, the LSN should always end up fairly close to flush.

RB s7
 

I have tried a jp-1 pipe and a 053 with a short header and a long header and a sportworks ht pipe. I reset the needles again and at 5 turns out on the LSN and 3.5 on the HSN it allmost wont move . Thats after leaning the hsn down about two and a half turns so does clear out after a bout 30' to 40' and the temp was at 200 to 215. I then tried to lean the LSN, If i was at 2.5 or 2.25 out it would clear pretty good as long as i didnt not make high speed pass down the strait ( 50' to 60' ). The hotter the engine gets the worse the bottom end gets till will not even idle now.