Melted rings + Problems.

[Capone]

I recently rebuilt my top end after having a head gasket blow and loosing all coolant, which lead to overheating and blown top end, all in one days work. Not a big deal, I bored it to .40 over, bought a cool head & 18cc domes and vito's power pistons. It ran insanely good & super fast, until 2 days ago I was at a track, racing with some other quads when I let off the gas & the ass end drug real hard, almost like brakes where on, I new I had lost power & compression. I pulled off the track to pull in the clutch and it died immediately. After trucking home, and tearing off the head & jugs both bottom piston rings were seized, but the top ones were fine. Slight chipping on the top of the left piston, but no scratches in the cylinder walls. When I upgraded to Vito's Power Pistons I didn't replace the jets, I left them (290's) and the stock needle all the way dropped, on the very top clip, I was also running 104 octane with Golden Spectro oil mixed to around 45:1. I was told it probably leaned out and seized the rings. Just wondering your guys's input on it. Also I order "Vito's Super Stock" Pistons, and Vito's jet kit, and every jet from 340-310. What jetting/needle postition do you guys suggest when I get everything put back together? And since it was bored .40 over two weeks ago should I waste the money on having it bored again, or just have it honed since there are no scars in the wall? I'm located in Central IL about 500ft above sea level/its roughly averaging around 75 degrees. Any info would be appreciated.

 

-JD

 

P.S. Here's a mod list, thought it might help here:

 

'03 Banshee

Open airbox w/ Pro Flo Filter

White Bro's Boost Bottle

Coolhead w/ 18cc domes

Bored .40 over

Vito's Super Stock Pistons

FMF Fatty Pipes w/ Powercore II's

Razr's front & back...

Edited August 21, 2004 by VitoBanshee

[J.J.]

Here's mine:

Vito's SS, original bore

K&N in the box, lid off

Fattys & PC2

Timing at +4

V-Force

PD Coolhead 20cc

Elevation about 1500ft

320 Mains

Stock needles in the middle

27.5 pilots

 

Forged pistons have to be warmed up well, before you hammer it.

 

Edit: If there is no visible damage to the bore, you could just hone it and re-measure just to make sure.

Edited August 21, 2004 by J.J.

[N1q]

In desert racing we need to be careful after crossing a dry lake bed, if you are running wide open and suddenly close the throttle you will be running very lean until the rpms drop and the carbs start delivering the proper mixture. The needles are keeping the fuel from getting through the main jets and your rpm is pulling in a lot of air without enough fuel. It is better to roll the throttle off at the end of a high rpm section.

[J.J.]

The needles are keeping the fuel from getting through the main jets and your rpm is pulling in a lot of air without enough fuel.

Pulling in air from where? If the throttle is closed, the slides are down...

Please elaborate!

[Capone]

if you are running wide open and suddenly close the throttle you will be running very lean until the rpms drop and the carbs start delivering the proper mixture

 

I can see this happening, but I don't think its cause you get too much air. The pistons will still be turning with no air/fuel. This could be very hazardous. I rarely think of this on a wide open run, since most of our riding areas we ride the roads to get to. It'd almost be like hitting nitrous at idle... wouldn't it?...lol. Anyway thanks for the help N1Q, and everyone else thats posted.

 

Also, I have my TORS unit disconnected. Not that it matters. But JJ what kind of power difference did you notice with the degree key? and the v-forces? I need the V-Forces and the Spacers and my engine should be ready to go. I'm running 193psi, which reading about the stock crank not being to handle it... anyway, couple thoughts, thanks for the replies!

Edited August 21, 2004 by VitoBanshee

[N1q]

The air flow is not completely cut off and the air is flowing much faster (high vacuum) than when accelerating. A sudden burst of lean mixture will wipe the alum over the rings of very fast moving pistons. It not like running a lean mixture under power, that will do more damage.

[J.J.]

 

But JJ what kind of power difference did you notice with the degree key? and the v-forces? I need the V-Forces and the Spacers and my engine should be ready to go. I'm running 193psi, which reading about the stock crank not being to handle it... anyway, couple thoughts, thanks for the replies! 

With that level of compression I wouldn't risk advancing the timing at all.

 

To be honest, I've played with the timing from 0 to +4 (adjustable plate, not key) and I can't feel any difference on the ass dyno... Actually, the next time I'm in there, I'll reduce the advance to be at about +2 only, this, after I read something Meat said a while ago..

 

I really like the V-Force reeds, the improvement was noticable on the trusty ol' ass dyno.

[Capone]

I was also told reed spacers will stop my tire blowing power band. I rip tires through 4th gear, 3rd on street when the powerband hits, its an insane pull. So I'm trying to actually have some grip/acceleration in dirt. I constantly get smoked on the track by YFZ 450's and 450R's. Will V-force setup/reed spacers actually help that much? Thanks.

[J.J.]

I'm not sure if the spacers will help much, in theory they're supposed to soften the powerband hit, but I have no experience with them. I can imagine it must be a bitch to get the carbs back into the boots...

 

For serious traction issues, I recommend a shortened swing-arm.

[lincster]

You were definetly lean with those mains.

I would rebuild it, put 350s in there, needle clip at the 4th position from the top, 27.5 pilots and see how it does.

[Capone]

Ok after taking my carbs completely apart, I have some more numbers...

The pilot jets are "30" the needle is "5" and the clip was the third slot from the top.

[lincster]

If it idled ok, I would leave the 30 pilot, that is what I run.

Do you have stock needles? I would move the clip down 1 more position towards the pointing end.

[Capone]

No I just ordered Vito's jet kit, which comes with a -longer- needle I believe... not sure where to start with this new setup, except the reply I got earlier, start at the most fuel and work my way down, but thats an awful lot of work taking the carbs off and on like that... I dunno, thanks for the help.