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2 stroke engine ?

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Old 05-29-2014, 12:59 PM
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iceman0
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Default floods at 1/2 turn on low

It's in a titan if anyone cares. It's a brand new 30.5. Factory settings flood. With the low around 1/2 it starts and idles. As if there is too much fuel pressure. Any input

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Old 05-30-2014, 09:11 PM
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I guess nobody knows anything about topic. I'll try baja forum
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Old 05-31-2014, 03:31 PM
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You could be more specific about the details.What engine? stock or modified? carb? pipe?new or used? age?
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Old 05-31-2014, 04:07 PM
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Originally Posted by iceman0 View Post
It's in a titan if anyone cares. It's a brand new 30.5. Factory settings flood. With the low around 1/2 it starts and idles. As if there is too much fuel pressure. Any input
Titan. Not stock engine . CY 30.5 never used. Jetpro. Don't think info is going to help but thanks.
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Old 05-31-2014, 06:13 PM
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You are right. Not going to help you.
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Old 06-01-2014, 05:04 AM
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I was hoping someone would say. Hey that happened to me. I'm leaning towards some kind of leak affecting vacuum.
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Old 06-01-2014, 06:54 AM
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A vacuum leak won't cause flooding.There is no pressure in the fuel system except from the carbs internal pump.If that is causing flooding then the problem is with the inlet needle or metering diaphragm.If the carb was used at all in the dirt ,there could be dirt inside the metering diaphragm cover pushing the diaphragm or holding it down.

When you say flooding- is fuel dripping from the carb? or what is happening?


*this is assuming the obvious such as clogged air filter or the choke being on have been addressed

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Old 06-01-2014, 04:34 PM
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It's. Brand new 668 and also tried a brand new 990 with new K&N I tried first taking off pre filter. Filter was soaked with fuel. If I take filter off fuel spits out of carb. My thought if there is nothing pulling fuel in. Unless the pipe was somehow made wrong . I just took engine back out.
I don't think there are pumps on these carbs. Am I wrong?
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Old 06-02-2014, 07:16 AM
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The pulse pump is built into the carbs.A little spit back is normal, but if its soaking the filter that could be sign of intake port timing too high.

Even the worst pipe design constructed poorly wouldn't cause excessive spit back.
Is this the engine with the stuffed stroker crank?
if it has a stroker crank does it have the proper shim under the cylinder? If its not set to the correct height the piston could go below the top of the intake port causing cylinder pressure to blow out the intake port. Look in the intake port and see if you can see the top of the ring at BDC.If you can see the top part this is a problem.
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Old 06-02-2014, 06:48 PM
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Yes it does have a stroker. I ripped it apart last night. The base gasket has oil on it. I'm going to gasket seal the case halves and head gasket to eliminate that. I'll look at piston position when I get it back together tomorrow.
Thanks again
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Old 06-03-2014, 06:02 AM
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Ok at BDC the only place where air escapes is out the pulse hole. But it is Damn close. Ill see what I can do. Also the intake bolt was too long once but I caught it right away.


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Old 06-04-2014, 01:30 AM
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Looks like you have first a normal (black) gasket, then a copper and at last another normal gasket...

Is this true??

If yes, then you have found the problem
You should only use 1 gasket, og with a stroker you have to find the right one (not sure which is the right one)
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Old 06-04-2014, 06:04 AM
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The piston is too far down.The ring is no longer sealing the cylinder.

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Old 06-04-2014, 06:57 AM
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I tried with just copper and I hit top then I tried one gasket and I believe I seen bottom of piston on exhaust side at tdc. Didn't seem right so I put it back together.This is a brand new OBR full mod. Ring is out also. Maybe time to change to a 4bolt on that other motor. Something isn't right with it.
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Old 06-04-2014, 07:31 AM
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Something isn't right with it. Indeed.
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Old 06-04-2014, 09:07 AM
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I'll try it with only one gasket. The OBR motor isn't too far off this one. I thinks its fine if I see the bottom of piston at tdc on exhaust side.
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Old 06-04-2014, 09:54 AM
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Given a choice between the ring too far down on the intake side and small amount of free port on the exhaust I would take the free port.
but I was wondering about the piston, isn't there a difference between a CY piston and Zenoah piston?
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Old 06-04-2014, 11:35 AM
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I never had both in hand at same time but they looked like same dimension. Maybe ill just throw the new stock cy260 in for now that I have. Another thing on the list is a engine stand. Im tired of installing the engine to try it.
I'm going to keep the one in question together and try to start when I get a stand together. My buddy has same engine and it runs. I should take his intake off and look.
Thanks for the help.
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Old 06-08-2014, 01:35 PM
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that ring position is normal...that's why the little nub is there, to retain the piston so it doesn't catch the cylinder wall on the upstroke
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Old 06-08-2014, 04:06 PM
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if it goes completely below the port roof you lose the seal and pressure escapes from the cylinder.It way to far down.
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Old 06-14-2014, 07:06 AM
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been doing this for a decade and i've about 10 of these motors laying around and everyone is the same and always has been... trust me it's normal...as isaid that's why the nub is cast in to retain the ring so it doesn't snag the wall on the upstroke...and if you buy a 4 bolt it'll be exactly the same!
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Old 06-14-2014, 12:16 PM
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Yes sir its there for a reason. I haven't tried to start since I used the gasket sealer.
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Old 06-14-2014, 04:51 PM
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Never saw a Zenoah pull the ring completely below the port roof. The nub holds the ring ends for sure,but the ring dropping completely below the port is something I've never seen nor agree with.
trust me I've be doing this longer than you've been alive
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Old 06-16-2014, 10:57 AM
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Originally Posted by Nosedragger View Post
Never saw a Zenoah pull the ring completely below the port roof. The nub holds the ring ends for sure,but the ring dropping completely below the port is something I've never seen nor agree with.
trust me I've be doing this longer than you've been alive
really? i'm 48 so i very much doubt it, you best go check again as i just pulled 2 obr motors off my shelf (a cy 2bolt rp and 4 bolt zen full mod) and both are same as in the picture...oh and zen haven't made these engines for as long as i've been alive...i'll reiterate, the picture shown is normal for obr zens and cys both of my motors ran hard and for many many tanks, all you are doing is confusing a newb with your opinion as to what you think it should be...obr have been doing this a while and know their stuff,if you have an issue with it call Sean for an explanation,he'll be happy to oblige i'm sure
the ring can just be seen on a stock cy26 and doesn't come down that far so for non tuned motors you are correct, however we're not talking about stock motors here
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Old 06-16-2014, 04:09 PM
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Then he should send it back to obr for a refund coz its not gonna run right like it is.
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