Guys,
I bought a Techno 250 1997 a month ago used. I was riding last month and towards the end of the ride I heard gurgleing from the coolant system. I topped off the bike and ran it today for about an hour and coolant starting coming out of the threads for the spark plug. I am not sure how these 2 strokes are configured in the head!

Any help would be appreciated.


Fan does work.

Sounds like your inner head o-ring is compromised. Remove head and replace inner o-ring part #12 and outer o-ring part #13 on the engine diagram in the pdf. Heres a link from American Beta: http://www.americanb...02%20stroke.pdf

Drain coolant. Remove head. Make sure the matting surfaces and oring grooves of head to cylinder are clean. Also, make sure the new o-rings are lightly coated with silicon grease and are retained in the grooves when re-mounting head. Torque to spec. Add new coolant. Heat cycle. Re-torque.

This failure could easily be age related. Could also be caused by excessive heat. Keep an eye out for the latter. (I would check WP just for insurance)

laser17, on 30 January 2012 - 05:26 AM, said:

Ya need to, investigate a little... If the o-ring in head was leaking, especially the inner one, I believe it is wierd as hell for water to come out where it is (by the plug), but not have started smoking white sweet smelling smoke, out through exhaust and I'd think it would run badly? Make sure the cylinder isnt getting wet, I mean get it apart asap, last thing you need is rusting up parts inside combustion area or crankcase.

On first read, it Sounds like a craked head? But, that seems extreme, so I look for even other possible reasons... Are you POSITIVE that radiator, or a hose isnt dripping on the head where you "see it"?

Here is my one warning about my comments and suggestions: I have no experience with Beta, only Gasgas. If you get things sealed up right, but the fan not comming on, I dont know how beta is as such, but could have a waterpump problem could have caused or helped contribute this, I would think. might be worth being sure when you get done.

sting32, on 03 February 2012 - 06:48 AM, said:

All very good points... I only have Gas Gas experience too and the first thing I thought about since you didn't mention steam out the exhaust was a horizontal crack at the spark plug threads.. as if the plug had been tightened in a way to separate in the thread area.

happy seal, on 29 January 2012 - 02:06 PM, said:

If it's anything like the single piece head for Gas Gas, it's basically just a hollow cap. Hollow so water can flow through it. If it were air cooled, it would be a solid cap with big fins on it.

If it were leaking enough water at the O-Rings to have water show at the spark plug threads, you should be running low on water very rapidly. Even then, water should NOT be showing at the spark plug threads for an O-Ring leak unless the plug was incredibly loose with a lot of water being leaked into the cylinder.

My money is on a crack in the spark plug thread area... Or as Sting32 said, it's leaking on to the outside of the head at the plug and boiling where the heat from the plug contacts the water... Should be easy to confirm that one.

Good luck.. should be a simple fix with just a new head, maybe not as cheap as you would like but simple.

Yes- I agree, the missing white smoke is a bad sign for a simple oring leak, but a small leak wouldnt be that noticable to the untrained eye. I have seen water look to be getting past the threads. Not sure how. It was on the 2 pc s3 head on a GG though. Didnt appear to be the top oring leaking and the inner one was shot. Im not a big fan of those 2 pc units.

This was what I found on my GG with the 2pc head. Dont know what that silver slime is - but worked its way from the chamber yp the threads with a tight plug!. Silver paste is weird - byproduct of the combustion? Beats me. Piston, rings and Cylinder looked good. Head insert was covered in silver slime, but wiped right off. Went away when Inner oring was replaced. I had several leaks with my HC insert and finally went back to the 1 pc head that came stock.

You know, I was looking at the parts diagram and the cooling jacket is on the outer perimeter of the cylinder head and spark plug dead center. The only way for coolant to travel out the spark plug hole would cause rough running and white smoke from burning coolant. I will need to recheck to see if it was dripping down from the overfull tank after expansion. I hope to have time to look at it tomorrow
Thanks for the ideas guys!

Molybdenum disulphide aka anti-seize. It's a good sign to see it on your spark plug threads. It means somebody cared when they assembled it.

Thats a good guess, but Its not Anti Seize - The same crap was all over the inside of the head! I tore the top end apart expecting to find missing AL on the piston - but it looked pristine, as did the cylinder and ring end gap was correct.

There wasnt alot of white smoke or coolant loss either - Just a faint greenish tint to the white rear mudguard. I have since seen this on a couple of other white fenders and notice a "bit" more smoke than normal. Stu told me he has seen this gray crap on a bike with a leaking inner oring.

I checked the S3 insert and top cap for flatness and wasnt impressed at all. Maybe I got a bad one or maybe I warped it somehow. The stock 1 pc head was dead flat and so it went back on. Dont have much riding time on it yet, but feels much better off the bottom. I have had lousy luck with every S3 "upgrade" ive ever bought... I think they should stick to Ti Pipes.

Well, I had computer problems so surfing TT was a miss. I ran the Beta some more after checking the obvious. I started riding w/ the coolant on the low mark. And it ran great. I ran with the seat plate off so I could see the coolant jug. I was surprised at how much expansion was there. I know I overfilled it before but didn't think it would boil over.
fan works
No leak
no gurgeling.
cross fingers for know.

I did however hve to diagnose a running problem. The bike would start first kick on choke. Run for thirty seconds and I could tell it was ready to come off choke. Take her off choke and rid like a champ for about 5 to 10 minutes. Then it would bog down and seem to starve for fuel. Long story short = gas cap! &%$#@!!

Thanks guys.

!/2 hour before it gets dark a few times a night after work is a good work out! And I signed up for a local training session in April.