<span class="Apple-style-span" style="font-family: verdana, geneva, lucida, 'lucida grande', arial, helvetica, sans-serif; font-size: 13px; ">The pull start on my OS CV-X .15 has always acted up. When the engine is cold (even at 70 degree room temp), the one-way bearing catches for one revolution at the beginning and end of the 12" stroke. It just slips in between. Once it starts and warms up just for a minute, the one-way bearing works perfect through-out the pull-starters stroke. I have replaced the bearing but not the shaft (the shaft looks perfect and the engine does not have much time on it), it worked fine for a very short time and then the same problem. I have cleaned and lightly lubed the bearing and when I have the pull start off and try the bearing by hand, it grabs perfect with no slipping. I'm ready to give up and buy a starter box. Anyone have experience with the same problem??</span>

Here some thoughts:

First....could the coil spring inside the pull-start mechanism be slipping? The ends can slip for a variety of reasons dependant on the design.

Second......every slipping OWB I had seemed to work perfect when I tried to turn it with my fingers. In fact, it usually wouldn't slip if I used the pull-start slowly...but so slowly, the engine wouldn't start.

Third...despite the fact you changed the OWB, my only experience with OS OWBings wasn't good. Brand new OS 30VG and the OWB lasted one bash session. I switched to a HPI "Made in Germany" OWB and it's been fine since.

I will check the spring. I also searched HPI website and Google for the OWB. I found them fortheir engines but not for OS. Do they make one for OS or did you find one with the same dimensions? Do you have part number? Mine is a OS #5.


Thanks

Oh boy. I'm looking for you, but in the meantime, I'll fil you in on what I know so far.

My OS 30VG has a 6mm dia starting shaft, and uses this OWB:

http://www3.towerhobbies.com/cgi-bin...?&I=LXJPZ8&P=Z

I was able to replace it with one from teh HPI Savage, and that's this one:

http://www3.towerhobbies.com/cgi-bin...?&I=LXDLN7&P=7

Unfortunately for you, your bearing appears to work with an 8mm diameter starting shaft. The #5 is the P/N for the whole recoil unit, but the actual OWB that you need is this one:

http://www3.towerhobbies.com/cgi-bin...?&I=LXSS33&P=Z

Knowing that the OS 6mm OWB fails prematurely, one might think that the 8mm unit might also fail prematurely, so I'm looking for a better 8mm unit that will fit in your starter. No luck so far, but I'll look some more because I suspect that a better quality OWB will also be surprisingly cheaper.

Oh....your whole starter can be bought here:

http://www3.towerhobbies.com/cgi-bin...&I=LXSS31&P=PU

EDIT: I looked up the Tiger Drives, but not only does the OWB not appear to be available seperately, a TigerDrive isn't available for your engine due to the short shaft.

Do you know anyone with a Duratrax Nitro evader? I'm thinking the whole pull-start from it might fit you engine. You'd have to use the whole thing as the OWB is not hex shaped and won't fit your current pull-start. Would be cool if it fits, as it's a lot cheaper than the OS stuff. It's here:

http://www3.towerhobbies.com/cgi-bin...&I=LXCLX0&P=PU

There are 8mm diameter OWBs available that are better than the OS unit, but not all advertisements list the dimensions. Sorry I couldnt' be of more help. Maybe someone else has been through this before and can add more info.

the OWB shaft needs to be changed with the OWB...they need to be toleranced correctly to function correctly .....usually a slipping OWB damages the shaft when it slips..

No doubt you're correct, but I havn't had that happen yet. I'd say it depends on how long it's left in a slipping condition as well as the type of OWB failure.

I checked my spring, it's looks fine and when the PS does slip, I still have spring tension on the rope. I also measured, you are correct, it's 8mm diameter. The PS assembly was replaced with a new OWB and it started slipping after just a few runs. I did not replace the shaft but will try that next. Should I replace the OWB agian even though it has like no time on it? I agree with you on the Duratrax, it's cheaper in price and also made in Japan, so most likely same quauity - or lack there of. I was looking at the electric starter drives, they use a different housing but still use a OWB and the shaft so Iwould still help the same problem, correct? Thank you for the quick help too!!!

One other thing and do realize this isn't the correct place to post it but... I have mis-placed the charger for my Hobbico glow plug ignitior. I know the entire unit is $15 but being cheap, does anyone have the charger and willing to donate? I'll pick-up the shipping if it's $5-6, Scranton, PA

I'm not sure "exactly" what Supertib was referring to, but I took it as he was talking about the OWB ruining the shaft. In your case, he may be right about that.

The other place you might want to check is where the shaft comes through the inner backplate. Often there is a bronze bushing there. If either the bushing or shaft wears at that point, excess fuel can leak out and cause the OWB to slip, even if it's good.

It's possible the backplate is an issue, so I'd check carefully, or you could wind up with quite a bit of $$$ spent on this engine, and possibly some of it needlessly.

every time a OWB slips it wears on the OWB shaft, which is why often times just replacing the bearing doesn't help much........ when a Owb starts slipping you need to stop immediately and clean it...people who insist on trying over and over will just do more harm then good....... myself as soon a OWb starts to slip I flush the engine with WD-40, let dry for 5 minutes, the usually the bearing grabs right away........ As soon as you feel slip you need to stop, hammering the rotostart over and over just wears the OWB shaft.......

Let me ask you this, I did clean it with solvent and then greased it. Should I not grease it?

No....no grease at all.

Many engines are designed so the starting shaft does not rotate once the engine starts. For those, OWBs work best dry. I clean mine with alcohol.

Your engine has the shaft spinning all the time, so a tiny bit of lube might help. You can try WD40 as Supertib suggests, but I use a single small drop of ATF (automatic transmission fluid.....the red stuff)

Well here's what i did. I looked up the part number for the shaft, # 21421200. No one carries it, Tower Hobbies or anyone else, just a few ocscure entries on Google, I call OS and ask if the part number has changed. Mark Looks it up and said yes to 21812200, the same as the .18 CV-RX. I check Tower Hobbies and there it is. I check the Tech Notes and it said fits the .18 but no mention of the .15 (mine). So being the kind of untrusting person I am, I disassembly mine to measure. The length of the new shaft is 19MM, mine is 22. The other dimensions are the same. I then notice the plastic PS wheel has a groove worn into it, not deep but it's there. Imeasure the amount of the shaft that protrudes from the OWB and it's 3mm!! So I carefully insert it into my lathe and removed the 3mm. Cleaned and reassembled using Magnalube Grease (Google it, best stuff made -I sell it in my shop) and I pulled and pulled (without the GP ignitor), it will not slip. Only time will tell if it really is fixed but it works as it should. So OS must have had problems with this and determiined the shaft was causing the problem and the new ones are a different part number. Remember, when I say new, my engine was purchased new in 2000 but had not been used since 2001 so whatI considers the "new" design most likely has been out for years.

Thank you for your help and sorry for the long post - like to be thorough.

So you're gonna keep the grease there?

I converted some of my engines from pull-start to Tiger-Drive. The instructions for the Tiger-Drive say to put a little grease on the starter gears, which I did. Worked great until the first time I ran the engine. The engine heat caused the grease to liquify and run into the OWB. Took a lot of cleaning of that OWB before it would work again.

Oh well, maybe that was just me.

Magnalube's upper temp is 550F

www.magnalube.com/magnalubeg.html<br type="_moz" />

I'm sure someone will have choice words for what I'm about to say, but it does work and havent had to replace a OWB or starter shaft ever. If cleaning the OWB still results in slippage, I've used 400 or 600 grit wet/dry sandpaper (I call it abrasive) with a little ARO or light oil and just "rough up" the shaft just a teeny bit and have had good results. The key in doing this is to remove the backplate and starter shaft and sand/clean the shaft outside of the engine so there is no chance of the metal particles to get into the bushing on the rear of the engine. Just my 7½ cents.

Before reassembling I thoroughly clean with denatured alcohol.

Not at all. I didn't go to the point of dissassembling the engine, but I've used fine emery cloth on the shaft. I never was sure if I was roughing up the metal, or removing a sort of baked on glaze. Many people do the same thing, so you're not alone.