Author Topic: Broken Power Valve Actuator (Read 1083 times)

Sdunlimited · « **on:** September 04, 2013, 04:17:28 am »

So as I'm trying to replace the plastic bushings that hold the arm that controls the Power Valve, I broke the tip off the lower cam shaped lobe where the arm connects to. I've got another one kicking around but it's super loose. The one in the motor was really tight until I started screwing with it to try and take it out. Since one of the screws that hold it in place is hidden by that upper lobe I had to force it out of the way. In doing so, it seems as though I may have pushed it too far...I'm not sure if I broke the thing I broke or what.

After searching around online a bit, I'm finding that people are saying they've seen no difference with the Power Valve connected or not. I'd rather not leave it in there while broken, but, with my luck, I'm problem gonna break something else trying to replace it!

Few Questions:

- Is it needed and does it make a difference?
- Is there a trick to moving that lobe to access the upper screw?
- How would you suggest backing out those screws when they won't budge? Heat? How much heat?
- Is there a trick to tightening that mechanism back up? The spare I have is super loose too and is flopping around on the two ball bearings it rides on. Not sure if the snap ring in the back can be readjusted or not...

Thanks for any info you can provide!

LT250RWV · « **Reply #1 on:** September 04, 2013, 06:26:51 am »

Most of them are loose anyways never was a tight unit. But their are 3 ball bearings in the back of it. Plastic clips are not expensive.I like the function of mine with my pipe. The screw on the side were you adjust the spring I had to drill the screws carefully and use a easy out. Then I replaced them 6mm bolt with a 1.0 thread. But when you get them out take to to your local store and check the bolt and thread.

Sdunlimited · « **Reply #2 on:** September 04, 2013, 07:41:50 am »

When you say that most of them are loose to begin with, how loose should they be? The two on the complete, previously running motors I have were really quite tight - I couldn't move them with my fingers. The one on the parts motor is wobbly loose and flops all around. After being a little aggressive with the one I broke last night, that one too is now wobbly loose but still attached to the case due to those super tight Phillips head screws.

I hit them w/PB Blaster and was going to try them again today. If they don't want to come out I was going to hit them with a little heat.

LT250RWV · « **Reply #3 on:** September 04, 2013, 09:37:08 am »

Drill them heat could warp the cases they are pretty loose just rebuild the actuator if your worried. Mine was wobble and itcworks nust fine ps pic help us a bunch to help you

Sdunlimited · « **Reply #4 on:** September 04, 2013, 09:44:43 am »

Sure thing - I'll snap some pics or grab a quick video of it wobbling around tonight when I get home (EST) and post them up. I appreciate the guidance.

Sdunlimited · « **Reply #5 on:** September 04, 2013, 03:14:06 pm »

I grabbed a pic and put a video together - hopefully this will help a bit. I'll post the pic here first and work on getting the video uploaded:

Sdunlimited · « **Reply #6 on:** September 04, 2013, 04:27:50 pm »

Here's the video. I hope it works. It's uploaded to Photobucket straight from the phone so I'm not sure how it will play or how good the quality is. If you click on the image, it should bring you to Photobucket to play. It's just under 2mins long:

Chuckie25 · « **Reply #7 on:** September 04, 2013, 05:22:42 pm »

Here's the one in my spare bottom end. I think you may have yanked them too far up and got them stuck. I believe that drilling these screws out is the only option once they start to strip

Sdunlimited · « **Reply #8 on:** September 04, 2013, 05:26:30 pm »

Thanks Chuckie - that's super helpful. My screws aren't stripped yet so I'm hoping I still have a chance. The two I pulled out with the spare actuator are in perfect condition so if I have to drill these out I'll still be OK. Any tips for trying to get them out while I can still get a bite on them? Impact drill?

Thanks again for that vid - very helpful.

Chuckie25 · « **Reply #9 on:** September 04, 2013, 05:33:49 pm »

If you've got one of those Ryobi impact drill's I bet it would walk them right out. The old fashioned hammer-impact-driver might work too but that's beating on your cases with a hammer and THAT is sketchy lmao

I'm glad it helped!! About time I have back to the community lmao

Sdunlimited · « **Reply #10 on:** September 04, 2013, 07:40:52 pm »

Chuckie - you have no idea how precise your advice was for this. I have exactly one of those Ryobi cordless hammer drills that I haven't used in years. Had to charge the battery for about 1-1.5hrs then went to work on both motors. Got the broken actuator removed and working, non-stuck actuators installed with new bushings in both motors in no time at all. All it took was a quick 1/2 second bump of the drill to pop em loose. Easy as could be.
On the motor that didn't have the broken actuator, when I removed it I found a nice 1/8 inch piece of broken metal hiding out back there. I can't quite tell if it's a piece of former thrust washer or a small chunk of case. It's rounded but looks to be a little too tight of a circle to be a thrust washer. Couldn't find any obvious breaks anywhere so who knows where it came from.

Thanks again for the advice. Here are a couple new pics showing the spare re-installed with a full range of motion:

Chuckie25 · « **Reply #11 on:** September 04, 2013, 08:26:51 pm »

Heeeeelllll to the yea!!! I freaking LOVE those Ryobi's!! The only thing is the batteries are EXPENSIVE!! But man do they make life a pleasure. Glad you got it all fixed up!!!! Did you triple check the spare actuator real good to make sure that piece of metal wasnt a piece of the internal bearings? There's no way for a thrust washer to get to that unless it blew through the case. And there's no way for a piece of case to get through there to behind it either really..

Sdunlimited · « **Reply #12 on:** September 05, 2013, 05:38:28 am »

So I couldn't sleep last night and decided I had to pull the actuator off the spare to take a look at where that chunk of metal may have come from. There was nothing obvious in there at all. It's been back there for a while because the bottom half of the boss the bearing is in (actually, much closer to the back side of the actuator) was all worn down from that chunk spinning in there for a while. The structure of the curve of the piece of metal looks like it could be part of the inner bearing race but the type of metal makes it look far more like a chunk of the actuator piece. Who knows...At least there's nothing left in there for the time being..

Planning on putting the head on this thing tonight, clean the carb tomorrow and hopefully fire it up this weekend. It'll be the first time I've ever gotten one of these guys up and running. Time and finances have kept them in pieces for the past two years (I got everything I have in not-running condition).

We'll see how it goes. I'm sure I'll be in the forums for advice all along the way

Chuckie25 · « **Reply #13 on:** September 05, 2013, 06:33:01 am »

Make sure to get a video of it firing off!! Glad you got it all square away,, these forums help a LOT, thats for sure. Theres things the clymer manual leave out, like the 3 timing marks on the gears,, lol. You're gunna love it dude!! It's such a fun bike and has a plethora of power.

James Dandy · « **Reply #14 on:** September 10, 2013, 08:53:24 pm »

To answer your question on is it worth it.. Yes it is. It won't really affect your maximum power in the powerband, but it will drastically increase bottom and mid range pull. Take off the PV adjuster on the left side of your motor. Clean it up with 1000grit sandpaper. Wash it off with WD40. Line up the grooves with the spring that's under the cap. Put the plate and the two screws back in. Should say 250 at the top. Leave screws loose. Turn counterclockwise 360' to wind the spring. I had mine wound the wrong way before I got my manual. Wow what a difference that made!!

Sdunlimited · « **Reply #15 on:** September 10, 2013, 09:00:01 pm »

Ironically, I was just reading that section of the manual about 30mins ago. I pulled it up to look at the wiring diagram and checked that out because the PV isn't moving on a motor I have on the bench downstairs.

This other one that I was hoping to have up and running last weekend is a little delayed at the moment. I'm missing a few pieces and am trying to button it up correctly. The wiring was pretty hacked but it's 90% there now. I needed to grab the light/run switch off another frame I had. Need to decide which stinger I'm gonna run. It had an FMF Powercore from something else on ti originally but I've got either a stock or DG I can put on for now. I'll throw one of those on tomorrow if I have time, make sure the wiring is good, fill with oil/coolant and give it a few kicks.

Any suggestions on priming this thing for the initial kick over?

Chuckie25 · « **Reply #16 on:** September 10, 2013, 09:31:31 pm »

I had mine on choke, rolled it over twice slowly, then kicked the crap out of it. If I had **** the throttle it would have started on the first kick but I didn't. Six kicks later I blipped the throttle and she barked to life. I always do two slow priming kicks, then lock it in the middle of the 'clicks' (around tdc) and then lay into it. Fires on the first kick every time.

Sdunlimited · « **Reply #17 on:** September 11, 2013, 05:39:24 pm »

Hi Guys - I know I'm taking this thread a bit off topic but I've got another quick question. I put a 'lightly used' topend on this motor and I'm thinking the compression may be low. Honestly, I can't tell if the upper piston ring is on the correct way since it was not marked at all. The lower ring was fine.

I lightly coated the piston and cylinder with Mystery Oil while assembling. No fuel tank is connected yet. I want to do a compression test but am curious what you'd recommend I use for a lubricant in the cylinder - more Mystery Oil? WD40? 2-stroke oil? In any case, how much would you recommend I put in?

Thanks again for the guidance~

PCS · « **Reply #18 on:** September 11, 2013, 07:05:49 pm »

ive used engine assembly grease on the piston pin and premix on the rings. ive read of people using ATF and conventional engine oil as well. mystery oil and wd40 is too light for initial break in but im sure plenty of people have used it and say it works great.

Chuckie25 · « **Reply #19 on:** September 11, 2013, 07:55:44 pm »

Not sure about your top ring,,, mine were marked and I just followed their instructions lol. I used the oil that I run in my motor (Golden Spectro) as assembly lube and for doing the 'unrun' compression test. I didn't even think to pour more into my cylinder after assembling it so I probably messed up there but I still kicked it to 175 lbs (8 kicks WOT, completely dry carb). Not sure what its at now after a year of running but it's close to the same for sure.

James Dandy · « **Reply #20 on:** September 11, 2013, 08:37:03 pm »

There Should be pins inthe piston. The ring gaps should be over the pins. The ring will be angled on the top side, square cut on the bottom. Ring gap should be .22 to .39" there should be an arrow on the top of the piston that points toward the exhaust. Get it backwards and she'll seize up before u hit 5th gear. Well at least that's what my YZ125 did. I got it right the second time. Luckily that was the first year for the nikasil coated cylinder!

Sdunlimited · « **Reply #21 on:** September 12, 2013, 04:11:15 am »

@Chuckie - sounds like I'll be good w/a little 2-stroke oil in the cylinder. On my 4-strokes, I recall it was suggested to use a 'capful' (of the oil quart container?) in the cylinder then give it a few kicks or push of the start button. Carb is totally dry at the moment so conditions should be very similar to yours.

@James - the ring gaps are over the pins and the arrow is pointing to the exhaust port so I should be good there. I could not for the life of me see any indication on that top ring at all of which end should be 'Up'. There was no writing, indentation or anything. I tried getting a good edge on look at it as well to see the angle but it looked almost entirely square to me. This top end came from a machine that recently had the top re-done with very few hours on it. You could still see most hone markings on the cylinder wall and the piston look essentially new.

Worst case scenario, if this one is shot, I'll finally spring for a new oversized piston and have a spare jug bored to match. THEN I'll get it back together and running!

James Dandy · « **Reply #22 on:** September 12, 2013, 07:15:02 pm »

Sounds like a plan. Check out this link man. I been reading on this for days!! This info is freaking priceless. This book is out of print and VERY expensive to buy, so copy it and keep it forever!! It's almost like the Sports almanac that old biff gave to young biff in back to the future!! http://www.datafan.com/Horsepower_Blog/gordon-jennings-two-stroke-tuners-handbook/

Sdunlimited · « **Reply #23 on:** September 12, 2013, 07:47:25 pm »

Thanks for the link - that looks like some good reading. A quick search turned up this too (it's save-able FYI): http://www.amrca.com/tech/tuners.pdf

Similarly, I've got binders w/lots of printed pages for some of my manuals. It can take a while to print out a few hundred pages but it sure is nice to hold it and flip through while sitting at the bike in the garage

James Dandy · « **Reply #24 on:** September 12, 2013, 08:08:09 pm »

Man I can weld and turn wrenches, but I'm not too computer savvy. My laptop is junk so I just use my iPhone for all my interwebbing. Is there any way for me to upload pictures from my phone? I know I'm way off topic here, but I wanna show off my ol quadracer.

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Author Topic: Broken Power Valve Actuator (Read 1083 times)

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