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Has anyone ever worked on a dek motor ? . I have a 11 hp dek motor on a brush master chipper shredder model ch3 . The owner said he used it twice and after that when trying to start it you can only pull the cord out till it builds up so much compression you cant pull it anymore. When you remove yhe spark plug it pulls fine . Ive checked the flywheel key , valve clearance ect . Im stumped , could it be the cam binding?
Thanks

What was the result of the compression test you performed?

Well it only will pull about half way and just from that it was hitting near 70-75 lbs of pressure .

If I understand you correctly, you are not able to complete a full crankshaft revolution when pulling on the starter cord, is that correct?

Recently I have had two generator engines, one a Briggs and the other a chinese honda clone that both had the same symptom and the same cause. The symptom was that the engine would turn about 350 degrees one way and the same amount the other way. The cause turned out to be a brown, powdery substance on top of the piston coming in contact with the combustion chamber in the cylinder head. The technical term is CCDI or combustion chamber deposit interference. This substance was not the familiar black carbon but rather a brown powdery substance. I cleaned out the deposit and both engines operated as designed. Perhaps this is the problem you are experiencing?

Wrong spark plug? Too long?

The thing is brand new so i dont think its the wrong plug but i will check to confirm . Its a ohv engine and yes you are right you cant pull it through a full cycle . It tightens up right about half way . I marked on the starter cord where it tightens up or builds up so much compression and i pulled it again and let it recoil back to where i marked and it was tight right at that spot . Ive tried different starter tops ect so it has me puzzled .

Also could this thing have ccdi after only been ran two times?

jetrail said:

Also could this thing have ccdi after only been ran two times?

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If some foreign matter got in the cylinder it could.

jetrail said:

The thing is brand new so i dont think its the wrong plug but i will check to confirm . Its a ohv engine and yes you are right you cant pull it through a full cycle . It tightens up right about half way . I marked on the starter cord where it tightens up or builds up so much compression and i pulled it again and let it recoil back to where i marked and it was tight right at that spot . Ive tried different starter tops ect so it has me puzzled .

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The next step I would take is to remove the recoil starter and turn the engine over by hand to determine if the problem is with the starter mechanism or the engine itself.

I had it off when i pulled the flywheel . You can turn it by hand but turning it that way is so slow compaired to pulling the rope . It seemed like it turned a little easier . But when i put a different dek top on it it still binds up . Maybe its the cup because when o took the top off i pulled the top and it pulls fine . It also pulls fine without the spark plug so i def think its compression related

jetrail said:

I had it off when i pulled the flywheel . You can turn it by hand but turning it that way is so slow compaired to pulling the rope . It seemed like it turned a little easier . But when i put a different dek top on it it still binds up . Maybe its the cup because when o took the top off i pulled the top and it pulls fine . It also pulls fine without the spark plug so i def think its compression related

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I thought you said the crankshaft would not make a complete cycle. I must have misunderstood. If you can pull the starter rope to full extension with the spark plug removed then maybe something in the starter assembly is binding up under the stress of compression?

If you pull it like trying to start it. It will tighten up or build up so much compression but it you slowly pull it takes pretty much most of your strength it will pull through but its so bad the handle bends . That has been the case with both starter tops on it . I didnt try a different starter cup yet

Does the engine have a compression release? You will have to search online using your engine numbers for an illustrated parts list to see if there is an automatic compression release on the camshaft similar to what Briggs & Stratton uses. Could be just the valves out of adjustment if it is an OHV engine. Sorry, I'm not familiar with dek engines. Is this engine a chinese knock off of honda?

There a couple of Kawasaki engines with high compression/hard to pull even with the release. I instruct my clients to pull the rope slowly until the compression stroke. Then pull HARD. The flywheel effect will give it the momentum to sustain rotation

Lawnranger, i tried a different spark plug and got the same result . It is a chinese motor . They use these on stanley generators and brush master chippers . Im not sure if it has a compression release. Ive looked and havent seen anything . The owner said it pulled great the two times he used it and then it started doing this . Either way he doesnt want to replace the motor and said i can have it . Its a 900.00 chipper with a crap motor lol . The thing has the ruixxing carb on it but its 11 hp and replacing it wont be cheap

You can try removing the valve cover and watch the valve/rocker movement as you slowly rotate the flywheel by hand (spark plug removed). The intake should open as the piston goes down and then close. Next the piston comes up (compression stroke) and both valves should be closed. Then the piston goes down (power stroke) and followed by the piston coming up and the exhaust valve opening. This completes the four strokes of a four stroke engine. Now, if you watch very closely at the valve movement on the compression stroke, you will see one of the valves open just slightly and close again. This movement is very slight and you have to pay attention while the piston is coming up on the compression stroke. If the valve moves slightly you have a compression release but if the valve doesn't move you still may have a CR but the valves could be out of adjustment so find the proper procedure for setting valve clearance and follow it exactly.

Good luck.

I got the correct clearance and set the valves sat and that didnt help . I thought it would

I've gone through and reread all the posts from the beginning. If this engine had an automatic compression release and it broke, you would have the symptom you are experiencing. Do you have an illustrated parts list for this engine? If so, will you post it so I can have a look? Again, I'm not familiar with Dek specifically but if it is a clone of Honda's it will be similar.

Another thought just came to me - did you check for a bent/broken push rod? I had a Briggs engine that had a completely severed push rod but the engine still ran, just with reduced power. I know it's a long shot but worth checking.

Post the IPL if you can.

Ok ill see what they have . I signed up to do service repairs for dek( stupid move on my part lol ) and every motor that has came through has left me wondering if they are worth a dime . They are just a chinese engine with a name . Ill check on that parts list.

Lawnranger said:

did you check for a bent/broken push rod? I had a Briggs engine that had a completely severed push rod but the engine still ran, just with reduced power. .

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HUH? I must be missing something here. A broken pushrod would not allow either the intake or the exhaust valve to function making it impossible to run.

chance123 said:

HUH? I must be missing something here. A broken pushrod would not allow either the intake or the exhaust valve to function making it impossible to run.

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You would think until you see it right in front of your own eyes, like I did. The engine ran, cut grass, but was low on power as the valve was only opening a small amount.

Lawnranger said:

as the valve was only opening a small amount.

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What stumps me is if the push rod was severed/broken "what exactly" was pushing/opening that valve even a small amount?

chance123 said:

What stumps me is if the push rod was severed/broken "what exactly" was pushing/opening that valve even a small amount?

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The particular way the push rod broke and the fact that it was held in place limited the amount of sideways travel and the two broken pieces managed to still connect. Wish I took pictures.

Sorry to get back to this so late ( i was out of town ect). Havent had much time to mess with the motor but im gonna contact gxi to see if the motor has a compression release . If not i will pull the push rods and inspect them