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Old 12-16-2008, 12:21 AM   #1
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Default This V-spec is driving me insane.

Back when i bought my 8ight kit i also bought a v-spec with one of the new 21J carbs on it.

No matter what i did i could not get the thing to run right, it had good top end but it would not idle and would cut out straight away.

Any how i became fed up and just bought a MRT GRP .21 and it has been nothing but perfect but it now needs its bearing replaced so now i have the V-spec back in my 8ight while i change the bearing in my GRP.

And here we go again:

It still has some metal on metal on pinch, definatly dosent have an air leak, bearings are good, replaced all fuel lines and put a new plug in it just to be safe and has about 1 and a half gals on it.

So the top end tunes ok and it has blistering top end but the LSN is a whole different story, the only way the engine will stay running is if i nearly completely close off the LSN and run it super lean.

A member gave me a good write up on the problem as he was having the exact same problem here's what he wrote:

"I was having the same issues as you were and thought I had an air leak. Yours is doing exactly what mine was. I couldn't get any temp and kept leaning it out. I would have smoke for part of the straight away and then it would go away. I knew it was too lean, I could hear it, but it wouldn't go over 200 degrees. I actually bought another motor thinking it was garbage because of an air leak or carb problem. Mine was too lean on top and too rich down low. That's why it bogs and you have to pump the throttle to keeep it running. Then you probably richend up the top so much now to compensate for the fuel being set so low on the bottom. You say you have the low end closed off. Go back close to the stock settings so it's just way rich and make sure the idle speed screw is set right. Mine would barely move at full throttle like this. Slowly lean out the top until it starts to make more RPM. Let the car sit at idle for 5-7 seconds and then punch it. If it stalls right away, lean out the low speed needle a bit and try again. Start checking temps and lean HSN accordingly. After you have done this, let the car sit for 5-7 seconds again and punch it. If it stalls, it's still too rich down low and lean it out 1 hour. Make small changes. I set my motor so it after 5-7 seconds it has the tiniest bit of rich hesitation, then clears out. If it starts spinning the tires as soon as you punch it, it's too lean. You may have to richen the bottom back up and lean the top. My buddy helped me with mine and it took about 2 tanks to get it right, but it runs perfect again. He took one look at my needles and knew what was wrong, the tune was upside down. I also had to move the screw opposite the low end screw, the one that moves the throttle barrel, in about half a turn. I don't know if this will work for you, but you are having the exact same issues as mine. Try it and see what happens. I was surprsed to. I thought my motor was junk, and now it runs fine and I have good smoke everywhere."

I followed that as best i could but its still wont run right so finally i decided to start playing with the midrange needle, he mentioned that he turned his MSN in half a turn, that helped with mine but still no go, so i kept turning and now i have it about 3 turns in and the engine will at least idle now, 3 TURNS IN. what the hell.

So what the hell is wrong with this engine, its driving me insane im just about ready to donate this thing to the nearest rubbish bin, any ideas?
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Old 12-16-2008, 12:40 AM   #2
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Originally Posted by Jonro View Post
Back when i bought my 8ight kit i also bought a v-spec with one of the new 21J carbs on it.

No matter what i did i could not get the thing to run right, it had good top end but it would not idle and would cut out straight away.

Any how i became fed up and just bought a MRT GRP .21 and it has been nothing but perfect but it now needs its bearing replaced so now i have the V-spec back in my 8ight while i change the bearing in my GRP.

And here we go again:

It still has some metal on metal on pinch, definatly dosent have an air leak, bearings are good, replaced all fuel lines and put a new plug in it just to be safe and has about 1 and a half gals on it.

So the top end tunes ok and it has blistering top end but the LSN is a whole different story, the only way the engine will stay running is if i nearly completely close off the LSN and run it super lean.

A member gave me a good write up on the problem as he was having the exact same problem here's what he wrote:

"I was having the same issues as you were and thought I had an air leak. Yours is doing exactly what mine was. I couldn't get any temp and kept leaning it out. I would have smoke for part of the straight away and then it would go away. I knew it was too lean, I could hear it, but it wouldn't go over 200 degrees. I actually bought another motor thinking it was garbage because of an air leak or carb problem. Mine was too lean on top and too rich down low. That's why it bogs and you have to pump the throttle to keeep it running. Then you probably richend up the top so much now to compensate for the fuel being set so low on the bottom. You say you have the low end closed off. Go back close to the stock settings so it's just way rich and make sure the idle speed screw is set right. Mine would barely move at full throttle like this. Slowly lean out the top until it starts to make more RPM. Let the car sit at idle for 5-7 seconds and then punch it. If it stalls right away, lean out the low speed needle a bit and try again. Start checking temps and lean HSN accordingly. After you have done this, let the car sit for 5-7 seconds again and punch it. If it stalls, it's still too rich down low and lean it out 1 hour. Make small changes. I set my motor so it after 5-7 seconds it has the tiniest bit of rich hesitation, then clears out. If it starts spinning the tires as soon as you punch it, it's too lean. You may have to richen the bottom back up and lean the top. My buddy helped me with mine and it took about 2 tanks to get it right, but it runs perfect again. He took one look at my needles and knew what was wrong, the tune was upside down. I also had to move the screw opposite the low end screw, the one that moves the throttle barrel, in about half a turn. I don't know if this will work for you, but you are having the exact same issues as mine. Try it and see what happens. I was surprsed to. I thought my motor was junk, and now it runs fine and I have good smoke everywhere."

I followed that as best i could but its still wont run right so finally i decided to start playing with the midrange needle, he mentioned that he turned his MSN in half a turn, that helped with mine but still no go, so i kept turning and now i have it about 3 turns in and the engine will at least idle now, 3 TURNS IN. what the hell.

So what the hell is wrong with this engine, its driving me insane im just about ready to donate this thing to the nearest rubbish bin, any ideas?
your mid range needle could very well be the problem.. the mid range needle is designed to work in sync with the LSN. So once you get the correct overall mixture, you can adjust the the two needles in sync with each other to adjust your power-band...example....lean your mid 1 hour,, richen your LSN 1 hour. understand?

try these needle settings as a starting point, and work from there/
you shouldn't have to touch the idle or mid more then an hour if at all..

IDLE: 1 full turn (from just fully closed)
LSN: 4 full turns from closed
MRN: 3-3/4 turns from closed (flush) 10 o'clock
HSN: 3 full turns from closed
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Old 12-16-2008, 12:50 AM   #3
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I had a similar problem with my 28xz with the 21J carb.
The LSN was as screwed all the way in and it was still too rich on the low end. It would bog down on take off, top end was fine.
I ended up putting a new carby on it and it fixed the problems.
I had so many issuses with that engine, I eventually gave up on it.
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Old 12-16-2008, 01:29 AM   #4
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Originally Posted by herb99 View Post
I had a similar problem with my 28xz with the 21J carb.
The LSN was as screwed all the way in and it was still too rich on the low end. It would bog down on take off, top end was fine.
I ended up putting a new carby on it and it fixed the problems.
I had so many issuses with that engine, I eventually gave up on it.
I gave up on mine back in august and bought an MRT GRP .21 and never looked back, the GRP has run perfect for 5-6 gals straight and only needs new bearings because they are becoming a little sloppy and causing quick clutch wear and the O.s is only in there until that happens.

TY very much for the info jpalessi will definitely give that a try tomorrow.

I don't see the reason for 3 needle carbs, my grp tunes perfectly with a two needle...
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Old 12-16-2008, 03:59 AM   #5
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are you sure that you dont have a cracked case? i have seen them crack on the bottom of the case just in front of the rear bearing, it will def make a engine hard to tune
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Old 12-16-2008, 04:17 AM   #6
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Originally Posted by cjm1126 View Post
are you sure that you dont have a cracked case? i have seen them crack on the bottom of the case just in front of the rear bearing, it will def make a engine hard to tune
+1 a well documented V-spec problem. You may not even be able to see the crack unless you take it apart. get a strong flashlight and look it over once you take it apart.
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Old 12-16-2008, 04:28 AM   #7
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it happens from usually from forcing the engine on to the engine mount, you have to make sure there is no stress when you tighten them down, if there is you can crack the case on a hard landing
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Old 12-16-2008, 06:51 AM   #8
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I had major problems with a Vspec that took awhile and a few heartaching losses at important times to figure out...

Motor would run awesome until a fuel stop. As the tank emptied and the engine warmed up good before a fuel stop- then fuel it up and put it on the track and it would spit and sputter, backfire and all kinds of noises. Finally discovered a cracked case.

After some hassle with hobby services they took care of me and gave me a new case. Thing was the old case the crack you could barely see. I could kind of see it but barely had a little ledge which I could scratch with an exacto knife. But when I opened up the backplate and pulled the crank... Oh boy you could see it then, probably 3/4" or so. Check for this good. Good luck
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Old 12-16-2008, 08:14 AM   #9
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I've gone through 3 V-specs this year, won't ever get another until they change their case's and make the quality equal to the price.
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Old 12-16-2008, 08:34 AM   #10
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WOW you guys unload a Vspec for a tuning issue? Send em my way

Thats the easier motor in the world to tune.... OS has the best carbs, the longest needle which makes them cake to tune. I think you've been messing with the jet (Some refer to it as the middle needle) If thats been messed with then your on your own. Set it to stock and silicone over it so you or your novice pit guy dont turn it thinking its the low end

Also 99% of the time run a OS P3 plug only
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Old 12-16-2008, 08:40 AM   #11
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I had so many problems with my V-spec. i would never buy another OS engine again. Mine came from the factory with a cracked case! Somebody must have dropped it along the way. OS refused to do anything about it, so I bought a new case..and refused to ever give a penny of my money to OS again. There are too many awesome engines out there to deal with crappy customer service.
Check my signature, I make sure everyone knows what I think of OS and their crappy V-spec!!
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Old 12-16-2008, 08:40 AM   #12
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yea i have found the vspecs to be really easy to tune, and make really good power
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Old 12-16-2008, 08:50 AM   #13
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Quote:
Originally Posted by jpalessi View Post
your mid range needle could very well be the problem.. the mid range needle is designed to work in sync with the LSN. So once you get the correct overall mixture, you can adjust the the two needles in sync with each other to adjust your power-band...example....lean your mid 1 hour,, richen your LSN 1 hour. understand?

try these needle settings as a starting point, and work from there/
you shouldn't have to touch the idle or mid more then an hour if at all..

IDLE: 1 full turn (from just fully closed)
LSN: 4 full turns from closed
MRN: 3-3/4 turns from closed (flush) 10 o'clock
HSN: 3 full turns from closed
Follow this. he is right. Most people have problems with vspecs because they don't understand the give and take options with the low and mid needles. once you figure it out. get ready to have fun with the vspec
I have owned them all stock,ebmods and speed. only blew up one stocker. I have owned 5 vspecs.
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Old 12-16-2008, 09:22 AM   #14
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Follow this. he is right. Most people have problems with vspecs because they don't understand the give and take options with the low and mid needles. once you figure it out. get ready to have fun with the vspec
I have owned them all stock,ebmods and speed. only blew up one stocker. I have owned 5 vspecs.
Thank you!
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Old 12-16-2008, 11:09 AM   #15
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Originally Posted by Jaz240 View Post
I had so many problems with my V-spec. i would never buy another OS engine again. Mine came from the factory with a cracked case! Somebody must have dropped it along the way. OS refused to do anything about it, so I bought a new case..and refused to ever give a penny of my money to OS again. There are too many awesome engines out there to deal with crappy customer service.
Check my signature, I make sure everyone knows what I think of OS and their crappy V-spec!!
Personally I would have challenged your warrantee claim also... theyre packed practically in an airbag, I cant see it cracking "spontaneously" nothing against you but I just dont see it happening.

Myself I've never cracked a case, I'heard of people breaking cases, carbs, HSNs and of course heads.... those must be some bad ass wrecks
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