How To Replace A Cylinder Gasket?

[PrpHed]

Terribly disappointing day!

A nearly new 5B... as in 1 1/4 tanks of fuel and without getting into the crappy details, it has a blown cylinder gasket.

Is there a tutorial or video on how to replace this? It looks obvious enough. I am just wondering if I can get away with removing the head (4 bolts), sliding the cylinder off the piston, putting the new gasket in place, then fitting the head back on the engine?

What are the implications to the engine and it's life? It has had one break in tank of fuel run through it. I then switched to the oil/fuel mixture I was planning on running in the vehicle and a 1/4 tank today and this issue has occurred.

 

[maddmike]

the stock gaskets on cy motors are known for that. You will have to remove your coil and fan cover and undo the head bolts. Pull head off carefully and remove old gasket . Throw new on there and put head back on and reassemble. A business card is what is used to gap the coil. Easy fix and you will be back up in no time

 

[PrpHed]

Thanks for the reply MaddMike.

Watched one of the Team Fast Eddy engine build vids and saw how the head, piston assembly go together.

Already had the engine cover and coil off to install a Super Bee so learned the business card gap process.

It all looks like I figured it would be. Now that I know what to expect, it doesn't look difficult at all and I'm comfortable with dis-assembly/reassembly.

Gasket kit on the way from DDM. Hopefully, will have it running again by the weekend.

It's all part of the learning curve and I'll hopefully be better off in the long run for the knowledge.

Cheers.

the stock gaskets on cy motors are known for that. You will have to remove your coil and fan cover and undo the head bolts. Pull head off carefully and remove old gasket . Throw new on there and put head back on and reassemble. A business card is what is used to gap the coil. Easy fix and you will be back up in no time

 

[tallgoldguy]

My gasket on my CYf270 was leaking as well. I found that when I removed the cylinder, the gasket was not blown out just the cylinder was not tight enough. Re torqued the bolts and it never leaked again! Until I blew the cylinder out from a poor air filter that is....

 

[PrpHed]

The vehicle started to bog and stall recently before blowing a cylinder gasket.

I replaced the cylinder gasket and the exhaust gasket while reassembling the cylinder assembley.

There is plenty of spark but it won't easily start and when it does, it runs really bad, then eventually stalls. At that point, it won't start again. It's like it flooded.

Anyone have any ideas as to what the problem might be?

Video Link;
[ame]http://youtu.be/J3LtiSDkAiQ[/ame]

* Update #1 *
I had the idle mixture screws set to factory spec. So, Low Needle, counterclockwise 1 & 1/4 turns from seated. High Needle, counterclockwise 1 & 1/2 turns from seated. I've tweaked each mixture screw approximately 1/16 of a turn clockwise and the engine seems to have stabilized and now seems to idle properly and has some response.

As well, I've re-torqued the head bolts and exhaust bolts now that they've had some heat and the bolts snugged up a bit more from the cold torque which seems to have helped.

Something I've never noticed before so, now it has me wondering. I could feel air blowing up right above the head/spark plug. I carefully placed my hand by the left rear shock and by the back left roll cage by the carb to see if I felt any air around the fan in those areas. Nothing.

Do the fans (the fan under the pull starter) blow air through the head? Is that what I'm feeling or is it some crazy leak? I don't think it could run if it was leaking that bad could it?

 

[PrpHed]

Mine definitely was a blown gasket.



I've now replaced the exhaust and the cylinder gasket with steel reinforced. Hopefully no more problems.

I only have about an hour of run time. I've been challenged with several issues with my buggy since getting it a month ago even though I took every precaution from checking diff oil levels to completely checking every torque, necessary clearance, brake mod/adjustment, etc., prior to even running. Just a streak of bad luck considering many guys do little or nothing and absolutely abuse their vehicles and they just run and run and run.

I love it when it runs. In the end, hopefully, it'll make be a better capable 1/5th owner.

My gasket on my CYf270 was leaking as well. I found that when I removed the cylinder, the gasket was not blown out just the cylinder was not tight enough. Re torqued the bolts and it never leaked again! Until I blew the cylinder out from a poor air filter that is....

 

[tallgoldguy]

Watched the video and it seems as if it is running with the choke on or partially on? Also, turn your throttle trim up a bit to give the carb opening a little bit more and see if it will idle. Are you sure there was no score marks or plating issues with the cylinder and piston or even the ring? My CY had plating issues after I used what was supposed to be a high performance air filter and ended up being total crap and wasted the plating inside my cylinder. Although, mine would idle but would not hit top end.

 

[tallgoldguy]

Oh yeah, the fan blows air across the head for cooling. You do not have the top plastic shroud on that directs the air flow out the rear but that should not affect it too much as I've seen others run without it too. After a second veiwing of the video, it seems to have good compression. Mid to high reving seems to be off. You may have an issue with fuel delivery like a kinked hose or a hole somewhere sucking air through? Did you take the carb off when replacing the head gasket? Could your fuel lines be backwards?

 

[PrpHed]

Hi,

Thank you for the reply!

Actually, at first I was concerned that maybe some else was wrong or that I had done the ring placement on the piston wrong when replacing the gasket because it was running with a 'gurgle' at first. The engine had 1 and 1/4 tanks of fuel through it and I've used a clean (stock) filter before each time I've run it. The cylinder and piston looked fine. I did use some oil to lubricate the ring and ring channel as well as the cylinder during the gasket procedure.

As it ran, it seemed to clean up. Once it had warmed up, I re-torqued the head and the exhaust. I did that two more times and it improved. I then adjusted the mixture screws and it cleaned up completely.

Since then, I ran it one more time, did another torque check. I've fine tuned the mixtures, replaced the spark plug, which probably had fouled a bit, and put the cylinder cover back on. The carb was not taken off during the gasket procedure. I didn't want to do more than needed and potentially cause another problem. I think most of the mid to high issues it was having were all mixture. When I had the gasket problem, before totally realizing it, I had set the needles back to stock.

Everything is back to normal!! Thank goodness!

Thanks for the eval. I do have Nitro experience and a decent general mechanical background so, fine tuning is not foreign. Nonetheless, it's always great to get feedback, suggestions and response when doing these things to make sure one doesn't miss something or that one is on the right track.

I finally have this thing shaken down I think... I hope! I'm really looking forward to getting some good running with it this weekend, which would be the first real good opportunity since getting it.

Unbeknownst to me, and to my delight and surprise, there is a BMX track in the park about 1 km from my house. There's usually nobody on it in the evening by the looks of it. My LiPo Battery arrived yesterday so my Transmitter will be getting a battery upgrade so I'll have plenty of run time! I think I know where I'll be going.

Thanks so much again.

Watched the video and it seems as if it is running with the choke on or partially on? Also, turn your throttle trim up a bit to give the carb opening a little bit more and see if it will idle. Are you sure there was no score marks or plating issues with the cylinder and piston or even the ring? My CY had plating issues after I used what was supposed to be a high performance air filter and ended up being total crap and wasted the plating inside my cylinder. Although, mine would idle but would not hit top end.

Oh yeah, the fan blows air across the head for cooling. You do not have the top plastic shroud on that directs the air flow out the rear but that should not affect it too much as I've seen others run without it too. After a second veiwing of the video, it seems to have good compression. Mid to high reving seems to be off. You may have an issue with fuel delivery like a kinked hose or a hole somewhere sucking air through? Did you take the carb off when replacing the head gasket? Could your fuel lines be backwards?