Author Topic: NOS Big Backfires (Read 18799 times) Tweet

altiki · « **on:** May 30, 2009, 08:58:23 PM »

I know this one has been done but I can not keep dropping valves on these big NOS shots. I am open to all comments on how to interupt the NOS during the shift!!!!!
The back fires are so large they are exploding my air box and spiting shims on the valves.
Help

Stocker64 · « **Reply #1 on:** May 30, 2009, 09:47:13 PM »

Quote from: altiki on May 30, 2009, 08:58:23 PM

I know this one has been done but I can not keep dropping valves on these big NOS shots. I am open to all comments on how to interupt the NOS during the shift!!!!!
The back fires are so large they are exploding my air box and spiting shims on the valves.
Help

al call me tomorrow,i can help,sorry about your bad luck last night,but before the mis-hap,i heard of your backhalf on the pass before

.....

altiki · « **Reply #2 on:** May 30, 2009, 10:20:52 PM »

Ya, I am not quite sure what happened but the bike was on great pass 132 in the 1/8th and it was 6 mph faster than my first run at 8.85 @165mph .

I think I dropped a valve and apears to be connected to the backfires and this the third time.

I will give you a call tomorrow.

gnd111 · « **Reply #3 on:** May 31, 2009, 01:54:02 PM »

A window switch that cuts the NOS off at a set RPM is how you avoid that issue.

Gixx1525R · « **Reply #4 on:** May 31, 2009, 08:18:58 PM »

What kind of system are you running? (wet or dry) how much are you spraying? How much are you retarding the timing?

altiki · « **Reply #5 on:** May 31, 2009, 08:38:25 PM »

I am shotting 80 shot dry and a second at 120. w/ 8d degrees of timing and the fuel is 112

Gixx1525R · « **Reply #6 on:** May 31, 2009, 08:41:55 PM »

You may have to go with C16 and retard the timing 12 degrees are you running colder plugs?

Stocker64 · « **Reply #7 on:** May 31, 2009, 08:55:21 PM »

al,are you running stock valvesprings in that head you just put on?

Gixx1525R · « **Reply #8 on:** May 31, 2009, 09:21:07 PM »

Quote from: Stocker64 on May 31, 2009, 08:55:21 PM

al,are you running stock valvesprings in that head you just put on?

I hope he is running 65 or 70lbs springs with stock retainers.

Stocker64 · « **Reply #9 on:** May 31, 2009, 10:12:30 PM »

Quote from: Gixx1525R on May 31, 2009, 09:21:07 PM

Quote from: Stocker64 on May 31, 2009, 08:55:21 PM
al,are you running stock valvesprings in that head you just put on?

I hope he is running 65 or 70lbs springs with stock retainers.

well nick,that is a thought i had,i know it will cause problems with the backfire opening the valves/and or causing them to slam on the seats/pistons.I know of a 1000 with that had problems with that too,and still keeps destroying motors,this time the 1000 broke from another problem,but in the past he has split shims and bent valves when he used both stages of nitrous.lets see what al is running?

altiki · « **Reply #10 on:** June 01, 2009, 06:56:31 PM »

Sorry for the delay
I am running the Carpenter 60lb springs but stock everything else in the head. I am still working on getting the motor out to investigate further. This just happens to be the same cylinder as before. Maybe there was piston damage and I didn't catch it but one thing for sure it was lean because I lost two spark plugs. I am running 46 psi on the fuel pump and I went by NX website for the spread which was a 31nos and 26gas and that was obviously way too lean.

altiki · « **Reply #11 on:** June 01, 2009, 07:07:11 PM »

I forgot this one, I am also running colder plugs 10's with a 22 thous gap.

gnd111 · « **Reply #12 on:** June 01, 2009, 08:16:05 PM »

You need something to shut off the NOS before you shift .... a window swith works. A Schnitz controller works as well...

speedninja · « **Reply #13 on:** June 01, 2009, 08:26:40 PM »

Quote from: gnd111 on June 01, 2009, 08:16:05 PM

You need something to shut off the NOS before you shift .... a window swith works. A Schnitz controller works as well...

+1

SPARKY1397R · « **Reply #14 on:** June 01, 2009, 10:51:32 PM »

i have a msd rpm window switch i'll make you a deal on

http://www.mpsracing.com/products/MSD/ig02i.asp $147 from MPS, i'll take $85 shipped.

badass1000 · « **Reply #15 on:** June 02, 2009, 01:34:58 AM »

hmm.. I am runing a 100hp wet shot with schnitz two dial for a year on my 05 supercharged 1000 runing 8.5bs of boost.

I am runing 12lbs of boost now and retuning it. I havn't hit the nitrous now that I am runing 12lbs of boost. Hopefully get it on the dyno this week to tune it for 12lbs.
I don't run the nitrous all the time though. less then half the time.
I did hit it once and it came up to fast and choped throttle right away as it hit the rev limiter. back fire blew the plenum apart. It was loud...

No problems droping valves though. runing carpenter valve springs and yosh stage r cams. cr9e's at 20 thou gap. c12 on supercharger only and c16 on the nitrous. 10.5-1 compresion.

Gixx1525R · « **Reply #16 on:** June 02, 2009, 07:57:36 AM »

if you drilled the head to install the nozzles make sure air is not leaking in that area allowing that cylinder to be lean. Check your injectors and coil for that cylinder also.

altiki · « **Reply #17 on:** June 02, 2009, 07:53:13 PM »

Quote from: Gixx1525R on June 02, 2009, 07:57:36 AM

if you drilled the head to install the nozzles make sure air is not leaking in that area allowing that cylinder to be lean. Check your injectors and coil for that cylinder also.

I did drill the head but all are Tefloned and tight and the injectors were just flowed. I can switch the coils out if you think that will help. I will have the motor apart tomorrow. I think it might be the NX jet spead is anyone else running the four jet size spread as called for on the site?

How does the window switch work? I am using the mps auto shift, will it kill exactly on the shift?

Gixx1525R · « **Reply #18 on:** June 02, 2009, 08:20:27 PM »

You can also have a bad nozzle you may want to check that. I use a old school MPS kill for carburated bikes for my Nitrous kill and it is tied into my engine kill. ( one button for both). Here is a pic of a bad NOS nozzle. The NX nozzles are thin in the threaded area.

altiki · « **Reply #19 on:** June 02, 2009, 08:27:17 PM »

So you think the spread is ok and it may be something else. When i test the nozzles just disconnect the fuel and hit the nitrous and look for it to come out the fuel side?

sportbikeryder · « **Reply #20 on:** June 02, 2009, 08:33:07 PM »

Quote from: altiki on May 31, 2009, 08:38:25 PM

I am shotting 80 shot dry and a second at 120. w/ 8d degrees of timing and the fuel is 112

You are spraying two stages, 80 first, then up to 120 and you are only running 8.85@165?
Don;t take this the wrong way, but it seems you may be having more issues than just the backfiring.
What are your motor specs?
Are you spraying 80 HP dry and hen adding 120 HP wet on top of that?

altiki · « **Reply #21 on:** June 02, 2009, 08:42:07 PM »

No harm no foul that was the first attempt and I did not spray the second shot untill I was 3/4 track with 3 sec delay. The next pass was the one I had the problem with and it went 8.80 at 149 slowing due to the break again a late hit but closer to half track. I have had a few 12 oclocks w/ broken ribs so I was moving a little slow.

Gixx1525R · « **Reply #22 on:** June 02, 2009, 08:52:06 PM »

If it was your jet spread then all cylinders would be effected. Check that one cylinder that you are having problems with first and then go from there.

badass1000 · « **Reply #23 on:** June 02, 2009, 08:52:35 PM »

4 jet spread seams pretty big. what fuel pump are you runing for the wet kit? what psi fuel pressure? Most imporant of all put a wide band on it so you KNOW what the a/f is.

Gixx1525R · « **Reply #24 on:** June 03, 2009, 07:48:01 AM »

I agree,a 4 jet spread is pretty big

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Author Topic: NOS Big Backfires (Read 18799 times) Tweet