Help Please

[zross1]

03 rx-1 Gt2871 9:1 compression, Sunocco 112, updated float bowls,
8-10000 ft eleveation

I have a major problem. The first 3 rides of the year I was riding at about 13-14 psi with 127.5 mains. I was seeing about 12.2 a/f and everything was running great. So yesterday I decided to turn up the boost to 15 psi and changed my mains to 134.5's. It was running great and my buddies and I raced up a good size pull about 6 times in a row. After we raced we parked at sat for about 10 min. When were gettin ready to leave I started my sled, it ran for about 5 seconds and then shut down. I turned the key to turn it over and IT WAS SEIZED. I pulled off the belt and couldn't even come close to making the primary turn with my hands. Pulled the plugs and all plugs looked fine, but two of them had very small traces of detonation in way of a tiny bit of aluminum spekles. Looking into the cylinders with my wash light I can never really tell what the pistons look like because they are so far down, but it seems that the pistons "looked" ok. I put the plugs back in and figured I would try to start it again, and it started again for about 5 seconds then seized again. Towed it home and now it won't turn over for anything.

It really doesn't make sense that I detonated with my low compression, 10K ft elevation, and good fuel. Plus my plugs looked ok. But what else could it be? Earlier that day I blew a belt and I could of overeved the engine (I know there is a rev limiter) but could that have skipped a timing tooth and bent valves? That still doesn't make sense for it seizing.

Anyway any thougths or help would be appreciated and links to help me when I pull off the head. This will be my first head removal on the rx-1.

Thanks

 

[lakercr]

Any bad noises when it would run? You could have tweaked a con rod when the belt blew and over-revved then hurt some valves. Pull your Carbs off and have a look down the intakes.

The head is going to have to come off regardless.

 

[rxrider]

Ouch that hurts. Hope your can fix it soon.

 

[zross1]

Any bad noises when it would run? You could have tweaked a con rod when the belt blew and over-revved then hurt some valves. Pull your Carbs off and have a look down the intakes.

The head is going to have to come off regardless.

That's what is so strange, there were no wierd noises, and the sled ran fine before I shut it off.

 

[BOOST]

Keep us posted how old was the gas?? and how long have you been running it???

 

[lakercr]

Any bad noises when it would run? You could have tweaked a con rod when the belt blew and over-revved then hurt some valves. Pull your Carbs off and have a look down the intakes.

The head is going to have to come off regardless.

That's what is so strange, there were no wierd noises, and the sled ran fine before I shut it off.

You can also pull the valve cover off to start and have a look at the buckets. If there's a problem with the valve train, it will be pretty obvious.

Drain coolant, remove water manifold from top of the head, remove allen head bolts and the valve cover is off.

to remove the head, do a search on my user name, you should have a few posts to choose from.

 

[zross1]

Thanks, I'll post what things look like with the head off in a couple days. Out of town for Christmas. I bought 2 barrels of the Sunoco 112 two months ago, I'm at the bottom of the first barrel.

 

[wheeline]

I run almost the same setup as you but only run sunoco 110. I haven't had any problems running boost as high as 22lbs with 135 mains. My guess is either the 6 long pulls in a row built some serious cylinder heat and caused the problem or you developed a leak in the boost line running to your fuel regulator. Are you running a high flow fuel pump with a 1:1 regulator? What turbo kit? Did you notice what your AFR reading was at on the last of 6 pulls? I can email you the RX-1 service manual if you don't already have it.

Here is a link to my mishap last year. Had to pull the head and replace the timing chain. I was able to do the whole project off of the directions in the service manual. If the link doesn't work search for "bent valves"
[/url]http://www.ty4stroke.com/viewtopic.php?t=36624&highlight=

 

[zross1]

I have the Boondocker set-up with a 1:1 regulator. I dont' know what my a/f ratio was because my wideband went tits up that day. I wish now that it was working. I know "if" everything was working lik it should of I was fine with my a/f's because with 127.5's and 13 psi I was seeing 12.2 or so, then I turned it up to 15 psi and jetted up to 134.5's. I also have the msd fuel pump.

 

[wheeline]

sounds like you better pull the head off and have a look. Let us know what you find.

 

[zross1]

I'll post what I find when I pull the head. I'm out of town for the holidays, so it will be a couple days. It's killing me not being able to tear into it right now. Thanks for the service manuel link, that will be the ticket to have.

 

[Skydog]

I know what you mean!!