DASA 1200 burning up orings

[tipafew]

I'm looking for suggestions.
I'm working on my buddies Dasa 1200. He just got the motor last year and someone else installed and tuned it for him. He has burned up three sets of orings on his domes in a VERY little amount of run time. Probably 10 hours at the most. They look like over cooked pancakes.

It seems to get the hottest right between the two cylinders. Between heat and water ingestion I am now rebuilding an almost new motor for him. After the first set of orings burned up I warned him to not do more than a couple of revs out of the water. I thought maybe he was running it out of the water too long.

He has two half inch lines going to a manifold. From there four lines feeding the sides of the cylinders and 4 lines going overboard out of the engine. He has one half inch line feeding the bottom of the RRP pipe. 3/8" line feeding the water box with a T going to the spray bar. He has never had any issues with water flow at all. Pissers always put out nice pressure. He never runs near show and hasn't had any sand blockages or anything like that.

We live in Michigan so usually I am used to having to run restrictors in order to build enough engine heat. These orings burning up has me perplexed.

 

[Big Kahuna]

Too much heat....... How hot are the cylinders? When its cold, my DASA stays really cold!!!! That just looks like there is no water getting to the head at all.

 

[tipafew]

I know!!!! It's crazy. I only rode it one time. I know he never checked any temps. I didn't see all of this nastyness until now and started looking into it. I have a TPE and it runs way too cold. I know billet retain more heat but somethings not right. To me the water lines look correct, but it is totally different than mine since I am TPE and B Pipe.


I guess I will start just hooking up water to everything and see if something is blocked somewhere....... I am pretty sure all the pissers were flowing until the orings would blow and they would obviously start sputtering some air.

 

[Big Kahuna]

Many are running water into the head first now..... Maybe try that. What is the flow order? Where he goes into the cylinders, assuming 2 on the front and 2 on the rear, Where is the water coming out? Head? Seams like there is not enough flow going through the head shell.

 

[tipafew]

Many are running water into the head first now..... Maybe try that. What is the flow order? Where he goes into the cylinders, assuming 2 on the front and 2 on the rear, Where is the water coming out? Head? Seams like there is not enough flow going through the head shell.

Yes, two feeding each side of the cylinders and two out of each side of the head.

 

[tipafew]

He has also blown out two manifold/chamber couplers on his RRP pipe. Makes me wonder how hot his exh. manifold might be running as well. I wish I had seen what they looked like when he removed them.
This would be a whole lot easier if I had ridden it more.

 

[DylanS]

with that much water supposedly coming into and out of that engine it makes me think he has to be running stupid lean. If he’s blowing couplers and eating o-rings like that and flowing water what else could it be. I blew one set of o-rings on my 1200 when my mag pump core rotated 1/8” and only let half the water flow thru my lines and it only took about 30 seconds on a conservative tune to do so.
Engine wasn’t running away out of water? What do the tops of the pistons look like? You have a better view than I do so maybe there is no signs of a lean condition and somehow the water routing is the issue.
I feed my RRP manifold with 2 1/2” lines and have three going right overboard from the shell and one to a t with the spray bar fitting then to FCV.

 

[tipafew]

with that much water supposedly coming into and out of that engine it makes me think he has to be running stupid lean. If he’s blowing couplers and eating o-rings like that and flowing water what else could it be. I blew one set of o-rings on my 1200 when my mag pump core rotated 1/8” and only let half the water flow thru my lines and it only took about 30 seconds on a conservative tune to do so.
Engine wasn’t running away out of water? What do the tops of the pistons look like? You have a better view than I do so maybe there is no signs of a lean condition and somehow the water routing is the issue.
I feed my RRP manifold with 2 1/2” lines and have three going right overboard from the shell and one to a t with the spray bar fitting then to FCV.

Based on piston wash it is super rich, but reading piston wash is probably kind of useless if there was a lot of water being run through it. Plugs are fairly dark.

He did have it run away on him early on after the motor was initially put in. I blamed the first set of burnt Orings on that figuring it got really hot during that. He killed it pretty quick.
I have also noticed that it shakes pretty violently at idle. I was going to double check motor alignmet but also look into jetting. I know it's a big motor but it still shouldn't shake like that.......

I wondered about the water routing to the pipe. It looks to me like it is supposed to have two lines running to it based on RRP instructions.

 

[tipafew]

Are those Viton O-Rings? Viton has a higher/better temperature rating (437F).

Buna-N/Nitrile (250F) or EPDM (300F) probably can't take the Heat...

Also look at Ignition Timing, Compression, Carbs, Fuel Octane and Oil Quality.

Do an Air Leakdown Test to confirm that the Engine is AIr and Water Tight (Cylinder Head).

I will find out on the Orings what kind they are.

I think I may have found the culprit. I started digging in deeper and found that the stator had turned. It was rotated fully counter clockwise.

 

[tipafew]

Dem two Stator Plate Screws need Thread Lock for sure...

That's the thing.......He actually had them come loose once before. I had found it for him and tightened them really good and used red locktite. The guy who originally assembled it had missed a number of bolts and I found a number that weren't tight. I just assumed he didn't get them tight enough or didn't locktite them. Now it happened a second time and I know I got them good. I had checked the hole depth at that time to make sure they weren't bottoming out and they had plenty of depth. The only thing I never checked was to verify if the threads actually ran all the way in.......

 

[DylanS]

Sounds like a job for helicoils or timecerts! Or some of that permanent thread lock stuff ^ jb weld I think it’s called!

 

[tipafew]

I think I'm on the right track now. Thanks guys.

Next I need to get it to idle smoothly. Thinking bigger pilot jet or checking fuel pressure.......Not sure but seem like good places to start.

 

[DylanS]

I think I'm on the right track now. Thanks guys.

Next I need to get it to idle smoothly. Thinking bigger pilot jet or checking fuel pressure.......Not sure but seem like good places to start.

What carbs?
Look down the barrels at idle see if they’re shaking raw fuel out.

 

[tipafew]

What carbs?
Look down the barrels at idle see if they’re shaking raw fuel out.

Carbs are SE Ninja's

 

[Baja 252]

Glad you found the issue.
I have a related question, the billet case on a Dasa 1200 has no timing marks. How do you know where to set the stator?

 

[DylanS]

Glad you found the issue.
I have a related question, the billet case on a Dasa 1200 has no timing marks. How do you know where to set the stator?

Find TDC with a dial indicator, degree wheel bolted to the crank snout, wire arm to see degree, make marks.
I run a TL so I just use the timing light on the brain w/ the degree wheel then verify with a timing light. See attached.

 

[Baja 252]

Thanks for the reply. What advance do people usually run with a 1200 set up on 91 octane?

 

[tipafew]

Reviving an old thread. This dang 1200 is still burning up orings. I guess I might try feeding the head first. I thought when I found the timing issue that I had it figured out. Stator is staying put now, but still burning up orings. This thing has been a nightmare.
It's running plenty rich. Compression is 180psi. Running in pretty cold water temps here up north. Water coming out of pissers is barely even warm. I'm pulling my hair out.

 

[DylanS]

Are the surfaces flat? Are the domes tight in the shell? Have you tried different domes/shell combo? Both domes or just one?

 

[tipafew]

Are the surfaces flat? Are the domes tight in the shell? Have you tried different domes/shell combo? Both domes or just one?

I might double check the head surfaces and cylinder. I could see how that would cause the oring to leak, but not how it would cause the orings to melt.......????