Messages

91

Project YZ / Re: Parts List

« on: March 05, 2011, 02:20:35 AM »

Go Tubliss! They weigh a lot less and have less chance of flats.

92

Technical / Re: Seized KTM 380exc: How to fix?

« on: February 08, 2011, 02:00:02 PM »

I'll buy it off you or get the cylinder replated for you.Sleeves are bad news.

What is wrong with a sleeve?

My XR250 and YZ125 have steel sleeves and have no problems. High horsepower and high reliability car engines use steel sleeves.

The only downside I know of is a few ounces extra weight and slightly worse cooling. Both unnoticeable.

93

Technical / Re: Seized KTM 380exc: How to fix?

« on: February 08, 2011, 01:55:23 PM »

Running extra oil? how much extra, extra oil could affect your jetting from what I've heard

Normally I run 60:1 fully synthetic. For this break in I was running 40:1. KTM recommends 40:1 to 60:1 for this bike.

94

Technical / Re: Seized KTM 380exc: How to fix?

« on: February 08, 2011, 01:53:41 PM »

check that waterpump, the radiators, everything cooling system related, then check the crank, might be a bent rod..

Still don't see how it can be cooling issues when it was not running hot. It was perfect.

I will check the rod.

95

Technical / Re: Seized KTM 380exc: How to fix?

« on: February 07, 2011, 03:10:13 PM »

If you opt for a steel sleeve - contact these blokes - I think they can provide a few different sizes to bring it up to as much as 434cc. The engine featured in there is based on a 250SX, but the barrel / piston  (and crank) are 380 based. The head spigot, exhaust manifold and exhaust boost chamber are modified because the engines going in a late model SX chassis, so not needed with a std 380 chassis.

          http://rpmmfg.com

I will definitely check them out, thanks. Any word on what reliability and powerband is for the bigger displacement?

96

Technical / Re: Seized KTM 380exc: How to fix?

« on: February 07, 2011, 03:08:51 PM »

Have you checked the jetting? What does the plug look like? You describe a symptom very much like a lean seize, that usually does damage like you identified. I know you say it was running cool, but I would seriously look towards the jetting and the cooling system before you trash yet another cylinder.

It is not jetting. If anything it is running rich. My other 380 has a leaner needle and is still a tad rich in the mid range and I have had no problems with it.
If it isn't running hot I don't see how it could be cooling.
And I was running extra oil for the break in period.

97

Technical / Seized KTM 380exc: How to fix?

« on: February 07, 2011, 08:35:36 AM »

So, here is the story.
I had a 380SX and love the bike. I saw a good deal on a 380exc and decided to jump on it. The guy forgot to mix one ride and it seized. I picked it up for $500.
I asked a couple people what to do and they all said just get it replated(it is all aluminum). Not only was it seized, there was a small crack in a port. Munn racing said no problem about the crack they just weld it up. So I got it fixed, put back together, and took it out riding. I was riding easy, just to break it in. After a few hours it was still working perfect. It was running cool, getting plenty of oil, and then it seized. After taking it apart it looked like it did when I bought it. Completely scraped cylinder and there was a crack in another port.

I don't trust this jug anymore. I think the best thing to do is get a new cylinder or get a steel sleeve.

What are the suggestions? Any places that have good prices?