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HLA's. I know everyone knows this, but I didn't


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I recently installed rebuilt head's on my EA82 in a Trike.  Used new lifters.  Started engine, ran perfect, but after reving engine @ about 2,500 RPM for 10 seconds,  returning to idle, it run rough and I could hear hissing out of the exhaust (short dual glasspacks). driving it for a couple miles and it would idle fine, hissing gone. this would happen every time after engine cooled down.  I pulled towers back off,   installed old HLA's that worked fine befor headjob,  put on timing belts and no compression.(I know you knew that).  Pulled tower's again,  bled down lifters and compression was good again,  but still it start's and idles fine,  just leak's out exhaust valves for a couple minutes after reving it up for a while.  The head's had new seat's and guides and resurfaced,  but the valves were reground.  At first I thought the HLA's were pumping up or something, that's the reason I changed them out. I checked bypass valves in the towers and they were fine. Only thing I can guess, a couple of the valves were warped,  grinding straightened them out,  and they go back warped after a while, then straighten up.  Yes,  I poured solvent in the exhaust ports and not a drop of it leaked past the valves. A compression test was fine, I'm thinking about replacing the exhaust valves next.  lucky  the motor is very easy to work on out in the open on a trike.  If this had been in a car,  I would ov had a door kicked in by now.

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It's not the HLA's, nor do you have a warped valve stem. No machine shop with half a brain would grind even a slightly bent valve. I've ran into this before on other heads. I'm guessing your valve guides with either knurled to the wrong size or came out of the box the wrong size. You need to have the stem to guide clearance checked. I'm betting you'll find it'd out of spec.

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Been there, done that. I did everything trying to resolve very similar issues. Thanks to a mob of smart are head reconditioners in Melbourne Australia I went on a further goose chase. Shoot, is it US based things that won't accept the word smart arse or my tablet? The smart arses claimed my valve springs were within spec, funny the factory manuals don't use a high and low parameter....I did all the tune stuff, injector swap and service, new hvla and when they went in got worse. Even worse when I went propane. Propane, turbo and a miss not good when overtaking with auto tranny. Then some guy on a forum said he knew what it was ...weak lazy valve springs getting bullied by hvla, more so with new hvla. I got new genuine spring sets and as I installed them could see the ones the head place said were within spec - soft as flipping marshmallows! Gotta be worth you trying same ?

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Dee2, I put a vacuum gauge to my motor.  It runs around 17 cold, after reving it up for 10 seconds, engine misses and it reads about 13 vacuum,  then after a minute of idling ,  vacuum goes back to 17 and the engine runs smooth.  also engine runs smooth at idle after a 2 mile drive. Compression is 120 on 2 cyls, and 135 on two others.  Topend overhaul scheduled this winter.

  Going by what jono suggested,  I ordered new oil bypass springs in the cam tower as I have stretched them trying to get rid of a TOD (which 3 different times resealing oil pump didn't cure,  but new HLAs did).  I'm hoping the HLAs are pumping up is the cause, and I am going to 10-30W oil instead of the 15-40 I am now running.

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Dee2, I put a vacuum gauge to my motor.  It runs around 17 cold, after reving it up for 10 seconds, engine misses and it reads about 13 vacuum,  then after a minute of idling ,  vacuum goes back to 17 and the engine runs smooth.  also engine runs smooth at idle after a 2 mile drive.

this guide will help you analyze the vacuum readings

 

http://www.secondchancegarage.com/public/186.cfm

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Dee2, I put a vacuum gauge to my motor.  It runs around 17 cold, after reving it up for 10 seconds, engine misses and it reads about 13 vacuum,  then after a minute of idling ,  vacuum goes back to 17 and the engine runs smooth.  also engine runs smooth at idle after a 2 mile drive. Compression is 120 on 2 cyls, and 135 on two others.  Topend overhaul scheduled this winter.

  Going by what jono suggested,  I ordered new oil bypass springs in the cam tower as I have stretched them trying to get rid of a TOD (which 3 different times resealing oil pump didn't cure,  but new HLAs did).  I'm hoping the HLAs are pumping up is the cause, and I am going to 10-30W oil instead of the 15-40 I am now running.

Hydraulics don't just pump up as such in all the motors I've dealt with, if they DO pump up it's normally during high revs with weak valve-springs.

 

They only 'pump up' enough to take up any clearance so I doubt 'thinner' oil will make a difference.

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I'm with you on that KiwiBrumby.  I'm just grasping at straws here hoping for an easy fix.  I am pretty much resolved to doing a top overhaul this winter with new spring's and valves.  If it was in a car with a single muffler,  I probably wouldn't give it much thought,  but on a trike with dual shorty glass packs, the sound is fairly obvious. It surly acts like a lifter pumping up or a valve warping for a few minutes.

 

post-48420-0-87479100-1503586541_thumb.jpg

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I would highly recommend looking for an EA81 engine in good shape and compare that to the cost of just your materials in an EA82 top end job. You may have to look for a while, or take a road trip to find one, but it will be a much more fitting mill for your trike. Much less maintenance and headaches, and more parts availability.

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check your tensioners on the timing belt.  maybe a stripped bolt or something is letting them move the belt out of alignment.   also check that oil pump cog wheel.  if you had the TOD and resealing the oil pump didnt fix it then maybe the pump is actually bad and you just made it less noticeable with the new lifters.  maybe wobbly shaft on the oil pump?

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  • 3 weeks later...

A follow up.   I done a complete overhaul,  fun little engine to work on.  But a new set of valves fixed the problem.  I won't bash the people I purchased the rebuilt heads from (EBay),  but I would recommend to them to put in new valves the next time,  also I wasn't impressed they knurled the guides instead of putting in new ones.  I sort ov got took.  At least they resurfaced the heads. Vacuum is pulling steady 18 inches now.  MM

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