Aaahhhhhhhh!!!!!

[Mike4130]

Well, I installed the new 990 carb today with hopes of solving some running issues as well increase the low end power.


I had a hell of a time getting the engine to fire. I finally got it to run for about a 1 minute then I noticed some oil/fuel coming from the lower section of the head. Wouldn't you know it, the head gasket started to flake off & out from the head. That's when I felt the head would sort of wobble on the case.


I tried to tighten the head but after I did that, when I pulled the pull starter there was a lot of resistance and it was very hard to pull.This definitely wasn't normal. That's when I knew there was a bigger problem.


Now the head won't seat flat on the case and caused the piston to rub one side of the cylinder. If I loosened up the head bolts and kind of held the head over to one side the pull cord was normal again.


I guess I'm glad that I found this now rather than after I ran the motor and destroyed the cylinder.


Hopefully after replacing the head gasket I will finally solve this ongoing issue and be able to go out and enjoy my truck.


And of course Dave's is closed until Tuesday, Damn.

 

[TheCount]

It most likely jammed because the magnets contacted to coil pick up. Remove the coil when you tighten the head & re gap it to the flywheel after you tighten the head right up.

I had the same thing happen on my DR. Thought the pull start had jammed, but it was the head loose. & caught on the magnets.

 

[Deluge]

Make sure the sealing surface of cylinder is flat. If you tightened it down too much while it was uneven, you could've warped it a bit.

Good luck with the new gasket!

 

[andyken]

On starting a 990...

I found 3-4 slow pulls, then try to start normal. It's sort of like a choke.

 

[Guest]

Well that's a bummer......

Good to hear you found your issue. Good luck on the rebuild.

 

[Mike4130]

It most likely jammed because the magnets contacted to coil pick up. Remove the coil when you tighten the head & re gap it to the flywheel after you tighten the head right up.I had the same thing happen on my DR. Thought the pull start had jammed, but it was the head loose. & caught on the magnets.

Actually this is what happened. The coil contacts are rubbing against the flywheel. How do I adjust these 2 points of contact? They obviously should make contact but how much?

 

[RampageHopUps]

Loosen the 2 bolts, the use a business card as a spacer and make sure the magnets are holding against the flywheel. Then tighten down.

 

[Mike4130]

Thanks for all the help everybody. After removing the head there was pretty much nothing left of the gasket so that was most likely the cause of the issues I've been having. I also noticed the top of the piston is really blackened, does this look like normal wear. Should I try to clean it off? Here's a pic.

 

[Deluge]

That's just carbon build up. You can clean it off.

 

[Mike4130]

That's just carbon build up. You can clean it off.

What should I use to clean it off?

 

[BertR]

Just put some gas on a rag or WD40 will take it off.. What oil brand are you using and how long have you had this motor prior to the tear down? I ask this because thats a lot of buildup and if it gets too bad it can interfere with the squish and break off causing piston and ring damage in worst case.

 

[Mike4130]

Just put some gas on a rag or WD40 will take it off.. What oil brand are you using and how long have you had this motor prior to the tear down? I ask this because thats a lot of buildup and if it gets too bad it can interfere with the squish and break off causing piston and ring damage in worst case.

I've had the truck since the middle of June. I ran it a couple of times a week and have been running Klotz synthetic @ 32:1 after break in. I ran Yamalube non-synthetic during break in.

I think the truck has been running rich ever since break in. I have had an issue with the idle and engine stalling since day one.

 

[BertR]

Try yamalube 2R ..Klotz is a good oil but known for heavy deposits on the top of the piston.The name engine builders recommend Yamalube 2R and Castor because they leave just a tint on the piston with almost no buildup.I run 2R only and pulled my header off when I saw your buildup and the piston top looks like a clean plate and the last tear down was in April and thats with a tank every other day.

 

[Mike4130]

Try yamalube 2R ..Klotz is a good oil but known for heavy deposits on the top of the piston.The name engine builders recommend Yamalube 2R and Castor because they leave just a tint on the piston with almost no buildup.I run 2R only and pulled my header off when I saw your buildup and the piston top looks like a clean plate and the last tear down was in April and thats with a tank every other day.

Thanks for the info. I'll give it a try!

 

[Mike4130]

Well, I put everything back together (new head gasket & 990) and I cant get the motor to start. I'm going to try a new plug and check for possible air leaks around the manifold. I set the carbs low speed needle 1-1/4 out and nothing. I'm ready to just buy a new motor at this point. Oh yeah, I also found out my crank is bent. Sweet.

 

[TTH]

Klotz does that......I have had the same issue. I prefer Castor 927 it has much less carbon build up over time.

 

[Mike4130]

Finally....

I'm running finally. After breaking down and buying a new motor that is.

I was done dealing with the problems and had a bent crank on it anyways. So, instead of rebuilding it, I found a brand new motor on ebay for $60.00. I think I got a good deal.

I did try to start it with my new 990 carb and no luck, so I'm back to my stocker carb, but I'm running and that's all that matters right now.

Happy to be back up & running!!!

 

[alfred e numan]

Prime it or crank for a while on the pull cord

Good to see you got a deal on a engine. About the 990. There have been lots of methods posted to start a chokeless carb. Here is my angle. Buy a really cheap bottle of nazel saline solution- nose spray. dump the liquid out- dry it well. Put some premix in the bottle- If you run a dt-1 filter, its ez - before the radio is even turned on, remove the filter, move the throttle servo arm by hand till its wide open. Learn how the gas comes outta the bottle- at one angle- liquid comes out- at another its a mist.- put about the vilume of liquid gas- about enough to fill a standard pencil eraser if it was hollow- slowly pull the starter 5-6 times- you will feel the compression increase-Then- its optional- mist a tiny amount of gas in the carb- put the filter back on- fire it up. I had a xb set in the cool basement for 4 months- never drained the race gas- just pumped the bulb- used the method above- started with about 8-10 inches of pull cord - Ever watch racers start a dragster with a blower? same thing. They donot crank and crank either. I have never-ever pulled on the starter more than 3 times- winter or summer- There are other methods- plenty of them. I like lighting off on first pull.

 

[Chief409]

O'Neill Brothers Racing have a caution about Klotz on their web site. Many problems with engines returned having carbon buildup on the piston.

I'm using 990 carbs and found this to be helpful.

http://www.oneillbrothers.com/blog/cat/techinfo/post/breakin/

Remember, on these 2 stroke engines, get the thing started only adjusting the Low needle and idle adjustment, and don't touch the throttle.

Check the plug gap, it should be around .027 - .025. .030 and you'll pull all day. Weak spark at .030, the spark should go across the entire width of the plug gap, not just A SINGLE spark. Mag gap needs to be set with a plain paper business card, not embossed. Embossed cards generally are too thick. I've gotten the blisters to back that up if you don't check. Even with a Power Start, you lose.

 

[alfred e numan]

With the plug-coil gaps picky about there gaps, it leads me to think these engines could use a little hotter ignition. I have no idea if this would even work- J.C Whitney used to sell a kit for lawn mowers. If memory is correct it was a add on to the stock magneto ignition- some sorta capasitive discharge amplifer. I have no paper catalog for this company, and the web site is kinda lacking. Thing is about modding these ignitions- adding anything on could change the timing. I do have a photo in this computer somewhere of a electronic ignition made in europe. It looks really good-- but it has one place thats weak. its how the pick up senseor is bolted up to the engines block- looks as though it could shift in useage and chang the spark timing. I will try to find the photo later. Right now- the Cory cats- tropical fish are acting funny- getting ready to stick eggs on the tanks glass -- gotta get the fry tank ready--- agan!! lol.