HY Engines

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Scout-1greg said:
I ran two tanks of gas in my 30cc HY and my crank bearings went bad.
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I just recently took my stock HY engine out and found that the bearings have a lot of up and down play so they are definetely shot, maybe that's the weak point of these HY's. Mine has about 2-2.5 gallons on it. Besides a little bit of carbon build up (Klotz?) everything else looks good inside.


Also found out upon opening mine up it is actually a 30cc, not a 26cc like the standard MT's are supposed to come with. I was impressed with the way this stock engine was going, can't wait to see my Darksoul / CY 26 marine top end rip! I prefer the high revving engines.
 
jeffp83 said:
I just recently took my stock HY engine out and found that the bearings have a lot of up and down play so they are definetely shot, maybe that's the weak point of these HY's. Mine has about 2-2.5 gallons on it. Besides a little bit of carbon build up (Klotz?) everything else looks good inside.
Also found out upon opening mine up it is actually a 30cc, not a 26cc like the standard MT's are supposed to come with. I was impressed with the way this stock engine was going, can't wait to see my Darksoul / CY 26 marine top end rip! I prefer the high revving engines.
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Ya klotz does build up alot of carbon. I used to run it but now run some Bel Ray HR1 which is supposed to be alot better on carbon buildup and wear resistance. It's $20 a quart though.


I run a DS 26 also. At least most of the time. I sometimes swap it with my little screamer 23. If you end up getting one let me know. I need to show you a pic of a bracket I made for the shell to mount to a 3rd mounting point to secure the head better. You only need this on the 4 bolt version.
 
DemonRC said:
Ya klotz does build up alot of carbon. I used to run it but now run some Bel Ray HR1 which is supposed to be alot better on carbon buildup and wear resistance. It's $20 a quart though.
I run a DS 26 also. At least most of the time. I sometimes swap it with my little screamer 23. If you end up getting one let me know. I need to show you a pic of a bracket I made for the shell to mount to a 3rd mounting point to secure the head better. You only need this on the 4 bolt version.
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I think I may switch oils after seeing the inside of my engine, I've heard that Bel Ray is good stuff and it looks like it's sold locally. Thanks for the suggestion. I don't mind paying extra if it prevents the carbon buildup.


I've already built up the DS/26 marine engine, but it's the 2-bolt one. Still wouldn't mind seeing a pic of the bracket you made though. Is your's an actual Darksoul/CC racing engine or is it just the Zenoah 26cc marine top end with the DS heat sink?
 
It was a CC Racing Beast engine a few years back. After I wore the cylinder out I replaced it with a Zenoah head and copied all the porting over. Over the last 3 or 4 topends I've changed the porting to the specs I like.


You won't need the bracket I fabbed up if you are using the 2 bolt. The two bolt has the 3rd mounting point which secures the head to the cylinder. The 4 bolt shell is the problem child. It only secures the cylinder with those two iddy bitty bolts on the top. I've stripped those out from normal running and had to retap the threads for 4mm. Then I stripped those out and retapped for a 5mm. I stripped those out and retapped for a 6mm. The main problem with the design is that they only thread in 4-5mm. The cylinder can be tapped 13mm down which is what they should have done in the first place. My 6mm's are holding well but the next topend I buy I'll retap for 4mm and go 13mm deep. That should hold well.


Oh also. The 2 bolt is a better cylinder by far. The exhaust port on the CY 2 bolt is freaking massive compared to the Zenoah 4 bolt exhaust port. I have to grind on my 4 bolt port for 30 minutes just to get the same port.
 
I was definetely surprised when I saw the exhaust port on the marine cylinder, it is massive. The screws that hold the DS head on mine are 4x10mm I think, so they don't go down very far either. Hopefully I don't have any issues with it. Will give an update when I get it installed and running!
 
I have a cy 30.5 mod & ported that i purchased for DDM was running it yesterday and it broke one of the head bolts off at the head and i guest the other bolt loosen up and the whole head was up about a have inch when it stopped running so i took it down and put a new gasket and new head bolts, it is getting fire from the plug gas from the carburetor but now will not start i think maybe it has loss compression it did wind up pretty high when it suck air before it stopped all together anybody got any input on what may have happened other than loss of compression I'M going to call DDM tomorrow to see what they will do about it i just got it less that a month ago and have less than 4 tanks of gas ran through it
 
did you replace the spark plug with the new head kit and did you use a copper gasket and what gasket sealer did you use:eek:
 
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