lt250dave

this is the second (blue) head gasket i have blown since installing the 29cc stroker kit on my Baja. when i called DDM about it and told them the problem, i think i spoke to brian, he told me its not that uncommon and he sent me a better head gasket to try which is the one i just put on, it is black in color and made from a different material than the stock style blue ones are.

I guess my next option is to go with a copper gasket.

*has any one else had this problem?

*is copper the best way to go?

*how well does the copper seal?

*should i use any RTV type sealant?

tonyedge540

yes i would use the rtv type copper sealant it works for me

bryan70546

My Feedback: (4)

how she run with the reed kit installed.

tizdaz

...2 blown head gaskets!

bryan70546

My Feedback: (4)

lol

Oneill Brothers Racing

A copper gasket should take care of you problem. We have never had a copper base gasket blow out.

lt250dave

make that three, i still cant figure out why either, the case and head look fine. i installed the Black head gasket from DDM last night and ran it today for about a tank and a half so i'm guessing around 90 minutes before it started revving high at idle. here is some new pix of the black gasket. so i guess i will place the order for a copper .020" gasket and see what that does.

BTW it runs great with the reed kit

tizdaz

ouch

I have no idea, maybe your mixure is wrong? engine running to hot causing the gaskets to weaken? as i said no idea really ?

Timmahh

i would use some high temp gasket sealer from permatex on the next one. thats deffinatly a wierd one. maybe with the reed kit, the crack case pressure is a bit higher, just enough to blow the gaskets?

Timmahh

lt250dave

rctruckz Date 11/11/2006 9:51:32 AM
ouch

I have no idea, maybe your mixure is wrong? engine running to hot causing the gaskets to weaken? as i said no idea really ?

I have been running different types of oil and fuel during all three blow out's, the first was CAM2 110 octane leaded fuel with Klotz oil, second was Sunoco Purple 110 octane leaded fuel with Klotz oil, the third was VP racing C12 108 octane leaded fuel with Royal Purple oil. All mixes are at 25:1, or 5.12 ounces of oil per one gallon of fuel. DDM recommends a fuel with at least 95 octane for use in the 29cc stroker kit i installed, thats why i am running high octane fuel. [link]http://www.davesmotors.com/store/product701.html[/link]



Timmahh Date 11/11/2006 1:06:43 PM
i would use some high temp gasket sealer from permatex on the next one. thats deffinatly a wierd one. maybe with the reed kit, the crack case pressure is a bit higher, just enough to blow the gaskets?

Timmahh


I figure i would try the orange RTV with a copper gasket next. As for the reed kit making the crank case pressure higher i cant say for sure but my buddy that i bash with has the reed kit installed on his Baja with the 28.5cc big bore kit [link]http://www.davesmotors.com/store/product373.html[/link] and he has never blown a head gasket.


I am starting to wonder if the problem is with the flatness of the head since i only started having trouble when i put on the stroker kit. I had the reed kit installed on the 23cc stock motor for about a gallon with no trouble so i really dont think the reed kit has anything to do with the problem. [sm=confused.gif][sm=confused.gif][sm=confused.gif]

Timmahh

thats possible Lt, the mill on the bottom may be slightly off. have all 3 gaskets blown in the same area? if so, then you may have found your issue...

i just picked up the race ported 28.5 kit. prolly gonna install it today.

Timmahh

lt250dave

yeah all three gaskets have blown out nearest the exhaust port and the clutch housing since there is no head bolt there and the gasket is the thinest in that location.


Tim, What color head gasket did DDM send with your Big bore kit?

Earth Surfer

Zen chooses the black, waxy feeling gasket for the two bolt cylinder, but they use the blue ones for the 4 bolt cylinders. The stock Zen black ones are my favorite for the two bolt because I think they seal better. The copper gaskets are great, if you can get them to stop sucking air. I have had good luck with an anerobic sealer, but I am sure there is other stuff out there that people got to work.

I have 2 bolt gaskets blown out like that before, and the blue ones can get saturated, and probably week. Just a shot in the dark though---were you blasting it pretty hard on a brand new top end?

Timmahh

got a blue one LT. just got the motor together, looking for my new set of clutch shoes to toss in with Turtle Racings new steel clutch bell..

hopefully should have it all cleaned and back together in the next few hrs.
Timmahh

ryan@ddm

The Zenoah and Cy 2-bolt designs simply blow gaskets far more often than the 4-bolts, especially when modified. Your best bet is a copper gasket + sealant.

TWsk8r

i find just torque'ing the cylinders down just past snug works great, thatway the cylinder doesnt bend or put to much pressure on a favor'd side of the gasket...

i hardly get gaskets to blow out on my motors turnig 19K+ under a load.

i use both CY and zenoah gaskets, and i dont even machine the cylinder deck or the case deck.

lt250dave

is there a four bolt motor available that will bolt into the Baja?

allanach

Two other guys I run with just installed the 29cc top end less that a week ago, both are on the second blue base gasket.
I noticed there was a lot of compression with this set-up and we even broke the plastic starter ring.
My guess is there is a fair bit of compression and the fact that there is only 2 bolts holding the head down this will always be a problem unless you use a copper gasket with some sort of compound.

lt250dave

i have yet to break my starter ring but i too noticed it was a bit harder to pull from the increase in compression. it seems odd when you think about it, that all the compressing is being done about 50 or 60 mm away from the gasket up in the top of the head but i guess all the added compression basically is trying to push the cylinder off of the case and then on the down stroke pushes the gasket out. but if you look at my pix, it looks like after the gasket was blown out the hole starts drawing air in which continuously gets bigger until it wont idle.

JRexA

You can get Four Bolt engines from several tuners, like http://www.oddified.com and Alro Racing

Oddified produces engines for most of the winners in the 1/5 onroad and 1/4 F1 series in Europe and elsewhere, but they don't come cheap.
I am still hoping to see a decently priced engine with a modded 4 bolt Heli head from DDM or O'Neill Brothers.
A decently priced ESP Heli Tune would be NICE

Earth Surfer

Another thing you can do is lap the case gasket surface on a surface plate using 220 grit sand paper. Zen and CY both think it takes to much time to take a .003" deep finish pass on the gasket surface, the result is, it is not very flat most of the time. I lap the cases, the intake, the exhaust and the spark plug gasket surfaces on all of my engines. Silicone based sealers can disolve with gas. There are better sealers out there. Go see what a dirt bike shop has, they will fix you up. Hondabond4, Yamabond4, Threebond4--they are all the same, but they dry really fast. So fast that you might want to glue one side at a time to make sure it is even. Permatex also makes a expensive anerobic sealer that I hear works awesome (my pro racers dad uses it) on copper gaskets well. It does not dry when in the air (but does when it is squeezed shut by the surfaces), so it does not rush your assembly. I hear it comes apart really well also and leaves less of a mess to clean up. But I would lap the cases first, yours may be pretty bad.

Earth Surfer

The 4 bolt air cooled PUH cylinders I have worked with. There is even a 4 bold TS reed case available and I have one of those engines here. I have not seen the whole PUH engine, but I know the cases and ignition of the PUM is very different from the 2 bolt design. I am guessing that it won't be a problem for a complete PUH engine. The porting is a little less aggressive than on the two bolts, but it is simular. I don't know if stroker cranks are available for the engine, and I am pretty sure you can only get a 34mm piston in there unless boreing and plating are done (want to see some cost?), but to many, a 26cc engine is just fine. It's not something I offer through DDM, because the demand does not seem to be there for me---yet. But if you want one (or anybody) just contact me and I will build you one.

Oh yea--ya have to pay me a decient amount of money --cheap guy (kidding). hehe---and it won't hurt the wallet too much. I have a lot of repeat customers that came to me direct.

JRexA

Oddified, Alro Racing and others use a PUH head on a G230RC/G260RC crank case(or on their own cases), as the mounting holes on the PUH engines are different from the RC ones.

Earth Surfer

Yea, one hole lines up, but the other one is about 1.5mm off. The only time I used the PUH cylinder is on the TS 4 bolt reed cases. The only bummer for the PUH top end is it is not a big enough displacement for the ped racing we do. We have a 30cc limit, and run 29.5cc 36mm bore and 1mm stroker cranks. We just have a hard time making the power of a 29.5cc engine with a 25.4cc engine, so most of us are using the bigger two bolt cylinders for ped racing.

splcrazy

thats what you get when you modify .the same problems as in real life cars keep it all original i say