CT engine failure on 350 big bore

[adamson350r]

I took off my top end to look at my top end I had a four corner piston seizure and my piston had a dent on the top. Seven hours total after ct bored it and sent it back with a new piston. I will give more details later.

[derby]

Originally posted by adamson350r
I took off my top end to look at my top end I had a four corner piston seizure and my piston had a dent on the top. Seven hours total after ct bored it and sent it back with a new piston. I will give more details later.

Did you do what allen recommends and crank it on wd-40?

[redred55]

sounds like a cold seizure

[morse250r]

wiseco or a wossner piston ? did ya do some real good heat cycles?

[adamson350r]

I have always been a big CT fan and this put a big crimp into it. Bought a 330 from them and it runs just fine.

Bought a 350 Power valve and broke it in and ran it for about 6 hours and sent the top end to have some more porting done. Ct said the cylinder was out of round and that they needed to bore it out and put in a new piston. It had looked great to me.

So I put it back on around July of 2009 and broke it in again following the same procedures CT sent when breaking in a new cylinder, and I only had about seven hours on it including the dyno I posted.

I had a gut feeling to check my top end before the season started. When I removed the top end the cylinder walls where scored and the piston too. Crap. The piston was sized to big for the bore that CT did.

[adamson350r]

So I called Dave Moore who has been reputable with two strokes and asked if I could drive up to his shop by Salem, Oregon. Sat and talked to him for two hours over things he could do with the top end. He always explain why and give reasons which was awesome.

Right now I am not happy with Ct. I feel I have been screwed.

Jetting was fine though. Dave even let me know because the color on the piston was great. He conclusion was the same as mine. The piston was sized wrong.

I didn't catch the dent in the top of the piston though, he did. He said I wouldn't of lasted too much longer. Before something broke.

[MOVIN32]

YOU ARE TELLING US THAT YOU TOOK SOME ONES WORD THAT EVERY THING WAS ORK YOU DID NOT CK RING END GAP OR CK PISTON TO CYL LIKE ALL INFO IN THE BOX TELLS YOU . DID YOU CK PISTON TO HEAD ,MAKING SURE 0 DECK WAS WHEIR OS PISTON DID NOT HIT HEAD. NOT SAYING ITS WRIGHT BUT YOU ARE DOING THE WORK YOUR SELF FIRST THINGS FIRST COVER YOUR A.. . THE DYNO IS NO HELP ON ANY 2 STK

[adamson350r]

The dent in the top of the piston is due to the friction heating up the piston and then the compression from firing dented the softened metal. CT matched the piston to the bore job they did. I am not a professional mechanic, but CT said put it in and go.

The deck height was fine. I checked that out.

Wossner pistons are flat on top. Different design.

Dynos are a base line.

Nice Caps lock. Don't be personally offended.

[mdickerson319]

I had similar prob from CT310 and Wossner piston. Allen bored cylinder and said everything was fine, but turned out it wasnt. Two bores jobs later, I bought a Duncan!

[86 Quad R]

are they setting their cylinders up tooooo tight or what? this isnt the first i've heard of this. i actually have a ct310 cylinder setting on the shelf thats suffered the same damage(seizeco piston). :huh

[morse250r]

ct gives you the option for a flat top or not
ive only bought pistons from them, but i agree they are selling the product doing the machining you are a customer once you recive it you should beable to throw it in... why i belive they started going with wossner is that wesico didnt have enough material on top of the top ring to the top of the piston wossner is much thinker making it last ( my engine guy discovered this) ive has a few problems with ct and they never admit to anything they sit on the phone and act like this is the first they have ever heard of such a problem thumbs up to dave moore i have called him more than once and had nothing but time to talk ..

[adamson350r]

I was chatting with my padre last night and he thinks CT is sizing the piston to big for the bore so the motors don't last very long. That would suck if true, but I probably wont buy anything from them to find out.

[need4speed]

First off, piston to cylinder clearance for any type forged piston used, should be set at 0.0030 clearance.

The Wossonrs are forged just like the Wisecos, except the Wossnor has a coating on the outside.

Reason CT offers the Wossnor pistons & not Wiseco, is because they get pistons from LA Sleeve & LA dont carry the Wiseco pistons any more.
Price, was the reason LA dopped the Wisecos & then CT just followed.

Ok, this dent your talking about, I think we need to go over this dent deal in the top of that piston, because in all my years, I've never seen a dent in the top of a piston from it running hot enough to seize.

Dent in the top, if its close to the middle, normaly will be from to high an ignition timming, wrong head dome shape & more or less all the gas burning right in that one spot.
It could come from to low of an octain if you only rode short burst like drag racing, make a run & park.
Low octain can do it as well, but longer you ride, more it eats away at the edge of the piston on the exhaust side because thats where the most heat is consentrated.

Anything to do with building up heat, like low coolant & the cylinder running hot, jetting to lean pilot or main or air leaks, that will cause the bore to get tight & take away piston to cylinder clearance & then you end up with a seize.

There is such a thing as a bad bore job though, I know for a fact because it cost us two championships in two classes.
Two of my cylinders bored at the same time & place, a 330 & 350, seized both in their heat races so nothing running for the main.
Afterwards, measured bore & had 0.0040 at the top, 0.0040 at the skirt & 0.0020 just under the ports where they both seized at.
Who ever it was did the finish hone, let to much slop in the honer & those stones were walking it the holder & didnt cut the area in the middle of the bore.
So I know that can happen.

Did you check compression after the rebuild.
Did you do a presure test.
Did you change jets & go to larger jets for break in & then jetted down accordingly.
What octain race gas you using & was it fresh & not been sitting in a plastic jug for any lenght of time.

This is just some of the things I know can bite you, after a bore job because I've gone through just about any type can be over the years.

That dent in top of that piston is what I'm thinking most about & I dought it came from a bad bore job.
Neil

I just seen the screen name is need4speed, but this is C-Leigh Racing, Neil in the reply.
It seems some people like to use my computer when I'm not home & cant remember to log out, not a big problem & I CAN fix it.
Neil

[MOVIN32]

I think your wright on the money. NEED 4 SPEED

[adamson350r]

After I read you post I was a little worried about my ignition so I called Dave Moore.

He had asked me the same questions when I met up with him.

I Run half half fuel.
89 Ignition
Broke it in very carefully and rich
Always run a little rich.
Run Yamalube oil.

Dave said the piston looked like it had been shaved to make it lighter. Said it wasn't convex at the top. The piston was flat with a small section the protruded out in the center that was flat. Dave explained because it was thin at the top and the heat of the piston it dented.

The dent is a very slight dime length area.

[adamson350r]

I did do a compression test and pressure test.

I have stock timing and sea level dome.

I will have to show some pics of the other piston I have the Ct put in it the first time.

First ordered the kit broken it in and took it out twice and had about 7 hours on it and didn't like the porting. Sent it in and they said the bore was out of round. I paid for the piston and this happened.

Neil can you pm me you number. If I did something wrong I like to find out what it is and avoid it next time.

[adamson350r]

This is not the piston. This is the first piston before that I had a few hours on when I didn't like the porting and they said the cylinder was out of round.

This is what the piston looks like. It is a wossner piston.

[adamson350r]

This is not the dented piston. This is the first piston before that I had a few hours on when I didn't like the porting and they said the cylinder was out of round.

This is what the piston looks like though. It is a wossner piston.

[2-330s]

doesn't look like the 4 wossners that have taken a **** on me. they look like a normal wiseco. those are made or turned down like that for allen's motors.

[adamson350r]

Why does Allen have the pistons shaved. Seems like a way to make a piston short lived. What are the pros and cons?

[2-330s]

i would guess that it has something with his head design.

[LT80]

When I use a forged piston (and I don't like to), I have them make it .0035-.004 clearance.
They swell like my belly on a big beer night.
There is a reason that you don't see many CT motors in GNC racing.
I've had to work on a cpl of CT's LT80 motors.

[adamson350r]

I have a question on puma top ends going to start a new thread

[2-330s]

i was referring to the design on the crown of the piston and not the clearance of the bore. it might be less rotating mass or that the pro-x heads come with a huge dish in the dome and he is trying to get a better burn?

[adamson350r]

Pulled apart the CT 330 and it looked great. You are probably are right about the dome. I can't wait to get it fixed for the warm season.

[adamson350r]

Found out I was running way too rich with my pilot jet hard to read the numbers.