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KTM 150 knocking after full engine rebuild!? HELP!

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ive just got my engine back after a full engine rebuild and its making a weird rhymic knocking sound (2 knocks per second, increasing with more rpm) .. it sounds like a mechanical knocking, like the bottom end is on its way out or something..

 

what I had done to my engine is:-
 

Cylinder replated

new piston (wossner)

new conrod kit (genuine)

Bearings (genuine)

gasket set (genuine)

seals (genuine)

DP clutch basket
DP clutch plates + springs

new exhaust packing

new power valve arm (which working correctly)

 

also the mechanic said he put the middle base gasket on in the set of gaskets, he just put the same size from what came off it so don't see how that would change anything.

 

after rebuilding my bike, it started up perfectly, plenty of compression, started up within the first 5 kicks, warmed it up for about 5 mins, then cut it out, waited for it to cool then started it again, and decided to cut it out and wait until I phone the mechanic tomorrow to get his opinion, don't want to damage the engine if something is wrong.. the bike idles perfectly, all carb settings are stock, was ruinning perfect before rebuild. 

 

I tried to take alittle video of the knocking so you can hear, it might take a couple of listens before you hear the knock over the engine, its quite loud and noticeable though.

 

im not the best with engines, but I knock my basics, and what concerns me is that the knock gets faster and alittle louder as the rpms increase.. I daren't take it out for a ride of fear of blowing the thing up! lol..

 

any help or advice would be appreciated before I ring the mechanic tomorrow. thank you .. link below

 

http://www.youtube.com/watch?v=1tnGjI_dLPw

 


 

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I think I heard something when your camera got close to the power valve. The engine sounds great imo, maybe the pv is making noise because it's clean...:) I think it sounds good, KTM engines make a lot of noises imo. I'd ride for a few minutes and see if it continues, gets louder etc. I assume that's what the mechanic would do.

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yeah it almost sounds like a tick tock tick tock tick tock sound.. but the ticks and the tocks get faster when I rev it haha, ive had a lot of bikes in the past, and ive never heard a sound like this on mine or any of my friends bikes.. after spending £920 getting it repaired, the last thing I want to do is dip into my already empty pockets!! lol :)

 

quick edit about the powervalve, I taken the inspection cover off and starteded the bike, the PV is moving about alittle, but nothing major, nothing I havnt seen before when adjusting the power vavle, also, the sound doesn't change when the clutch is engaged or disengaged, and the clutch seems to be working fine, I havnt rode the bike yet, but ive gone through the gears, and tested the bite point and it seemed good

Edited by Xmathewx

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You said "new power valve arm (which working correctly)"

then you say that upon inspection it moves a little ( this PV should open and close fully each way when its working)

 

Ktm 125/150/200's have a variable-height exhaust port and i think your PV is trying to open at the wrong time, did your Mechanic have the assembly apart? this PV it can go together more than one way.

 

might want to look at this,

http://ktmdirtquestions.com/how-to-adjust-ktm-125-150-power-valve/

 

Pay close attention to figure .3 the PV 

it helped me out a ton when my "PV Slipped" and now i know why.

Edited by Escarpment

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Thanks for the

The new power valve arm I had replaced is the horse shoe shaped one, the one with the fork that rolls along the rollers and the gear like things.. And when I said it moves alittle, I mean it just riggles about, not Alot, just what you'd except, it's not trying to open or close on idle, it does open properly when I blip the throttle but obviously the engine has just had a full rebuild so I'm keeping the rpms low for now.. When I adjusted the PV, everything seemed Ok, it moves ok and I set it to the Langston setting.

Just thinking out loud here, but even if the power valve wasn't timed correctly, it works off a centrifugal timer so it doesn't even work until the engine hits a certain rpm so surely it shouldn't cause knocking like that on idle?

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Just thought I'd update this post..

I found a small leak from the center gasket at the front of the engine about 2 inches bellow the exhaust manifold, i have no idea how but it's Spitting fuel out.. Taken it back to the shop that did the rebuild and he's going to sort that out, I'm guessing that has something to do with what's causing the knocking sound. I Will update more once I get the bike back! Cheers!

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Sounds like your mechanic isn't so hot. That 125/144/200 motor is in my opinion, the easiest modern 2 stroke dirt bike motor to service. There are no "got-ya's" and if you have any mechanical know-how, taking them apart and re-assembling them should be like child's play compared to a much more complex and sensitive 4 stroke. So when I hear things like your story, a trusted mechanic making such a grievous error, I'd get my money back and go somewhere else.

Quick story... I bought a used 125 many moons ago and it blew up right after I bought it. The original owner didn't put a gasket on the stator cover, so water got in there from washing and rusted the flywheel, which exploded. Anyway, the store I bought the bike from wasn't going to cover the parts, but they'd do the labor for free. So I went out and found new cases and a new stator assembly and had them do the labor. I got a phone call which said they broke one of the new cases trying to push the bearings in. Funny they said that, because the bearings you don't push in. You actually cook the cases and freeze the bearings and they literally fall in. Once I heard they were using a bearing press, I realized these guys didn't have a clue what they were doing and I grabbed the motor back from them, forced them to replace the case they broke and built the motor my self. To this day, I refuse to use any mechanic's on my own bikes. If I can't fix'em myself, I don't deserve it own them... thats my opinion.

Sorry for the rant, good luck with the service! :)

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That's funny.... a flywheel exploding because it got some surface rust on it......WOW......

Ohh.. the surface is aluminum. There are rivets which hold the aluminum piece to the magnet core. Those rivets are steel. So what happens is, the moisture causes those rivets to rust and boom!

BTW... the flywheel and stator are the only internal motor parts that I know of, which are made in Japan. So its not even KTM's fault!

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Ohh.. the surface is aluminum. There are rivets which hold the aluminum piece to the magnet core. Those rivets are steel. So what happens is, the moisture causes those rivets to rust and boom!

BTW... the flywheel and stator are the only internal motor parts that I know of, which are made in Japan. So its not even KTM's fault!

 

Dude....I've never seen any flywheel that had aluminum riveted to it.  What would be the point, the aluminum is lighter than the iron in the flywheel and it's not magnetic.

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Dude....I've never seen any flywheel that had aluminum riveted to it.  What would be the point, the aluminum is lighter than the iron in the flywheel and it's not magnetic.

Yea, the inside piece which is riveted AND glued in, is actually aluminum. I know because mine fell apart and I noticed it was not magnetic. Since there is no way its titanium or magnesium, then its gotta be aluminum. It was an older unit as well... perhaps over the years they changed the design?

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