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HB .15


David Hazell 1
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I made the grave error of perusing eBay whilst under the influence of one too many intoxicating beverages. In said state I ended up making an offer on an "OS 15" engine on eBay, and the offer was accepted. I paid up and then looked more closely at the pictures... Not an OS .15. It's an old german manufacturer. HB. It's a lapped pistoned crossflow jobby.

 

I did some searching on t'internet and found the usual "you have to run it on Castor" from circa 2006 era. I wondered if that really is the case?!

 

Also, without knowing ANY history about this particular engine, is there any way to tell if it's been properly run in? 

 

I'm tempted to just run it on the test bed with some Laser 5. Any advice on best practices for this kind of thing? @Jon - Laser Engines, yeah I'm kinda asking you for a bit of sensible advice here! Oh and it's got a crazy fat nut on it which will completely prevent me from being able to stick a spinner on it - any idea what kind of thread it might use? The shaft behind the threaded bit is EXACTLY 5mm, the thread a bit less, kinda about 4.9mm.

 

Link to the eBay ad which will still show piccies if you're interested (scroll down and down a bit more to see the listing) https://www.ebay.co.uk/itm/rc-plane-engine-Os15-/203992353160?nma=true&si=obnAY23PkiBM5zIaU7S%2BCbamgcs%3D&orig_cvip=true&nordt=true&rt=nc&_trksid=p2047675.l2557

 

Thanks kindly!

Edited by David Hazell 1
added shaft info
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I don't have direct experience of the HB 15 but am familiar with the HB 20 / Veco 19 series, which is much the same design save for a ballraced crank. My experience is that the piston seal on these engines is not very tight and does benefit from some castor content. Years back, I always had very poor results trying to use low oil synthetic fuels in the HB 20 / Veco 19. Basically poor starting and idling as a consequence of leaking compression. The presence of gooey castor helped improve the piston seal. I don't think you would need full fat castor based fuel, but a percentage of it in there would likely be of benefit. E.g if your fuel has 15% synthetic oil, add an extra 5% castor.

 

Be aware that the Perry carb requires clean filtered fuel. The internal metering slots may already be blocked with old gummed up oil and/or debris, in which case it will be hard to find a stable running setting. Also, there are o-rings inside the carb which can deteriorate and then cause running problems. That said, the Perry carb is very effective if in good condition and fed with clean fuel.

 

The cylinder head is designed for a long reach plug, ideally. Most plugs these days are short or medium reach, but you can still find long reach if you look around.

 

I'm sure others will disagree and probably shoot me down in flames, but I can only give you my personal experience of the iron piston HB and Veco engines. Anyway, if you don't like the engine, I am happy to take it off your hands and you can seek out an OS. If you want a basic 15 size engine, I would personally recommend the Enya.

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awww its so dinky. 

 

Anyway i think you will probably be fine with the laser 5 fuel. I do not think anything JW said above is wrong and is well reasoned, but I ran my OS15fp on it and it loved it. A club mate also ran his Enya 25 (with similar construction/materials) from new on the laser 5 and it too lapped it up and screamed for more. If i dig around in my dad's old engine box i can probably turn up a few other old nails and try them out, but i do not expect it to be a problem. i have loads of older engines that stipulate 20% castor in their original documentation and yet all perform brilliantly on 15% synthetic. My 15fp, saito 45, OS240 and i think even my enya 53? 

 

If however they do protest due to the piston fit being sloppy a little castor might help plug the gaps. It is a bandage on a broken leg as the piston fit should be tight and often the reason they arent is because mistakes were made when running the engine in. Ferrous piston liner setups needed longer running in and if this was not done correctly the fit would go out of the window. 

 

The only caveat to all of this is that closer examination of the beast reveals the conrod has no bronze bushes in it. Now plenty of saito engines have no bushes either and run fine on laser 5, but they are 4 stroke, this is 2 stroke. Do i think this is a show stopper? no. Does it give me pause for thought? yes. 

 

Ultimately i do not think running it on laser 5 will cause any problem. However, if you are concerned then add the additional oil as described. Alternatively sell it to JW and if you need a little motor like this i will sell you my 15fp (or 20? i have a 20 as well somewhere) as it is currently not needed and will run on laser 5 for sure. I just have to find where it put them all. 

 

 

Edited by Jon - Laser Engines
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Thank you so much gentlemen! I feel some gooey bonding going on here! Is that the 5% castor? So the little engine has a very nice amount of compression, it's really quite clean on the outside, and looks like it has been liberally "after oiled". It's almost certainly been kept in nice condition. I've sent a message to the eBay seller informing him he really hasn't sold me an OS, but that I'm more interested in finding out its running history. I await his reply.

 

I will fire it up on the test bed with some laser 5, and the OS number 8 plug (because it's all I have!). I quite like the radial mount and I am curious to see how it runs. 

 

I still need to figure out what the thread is on the engine, I'm hopeful it's just M5 and I can swap it out for something with a little less bulk to allow a spinner plate to fit...

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Not sure if you found this on your travels but its a review of the engine from when it was new http://sceptreflight.com/Model Engine Tests/HB 15 RC.html

 

One other thing. If the engine is castor gummed i recommend you remove the front housing and make sure the oil hole in the conrod big end is not blocked. If it is the conrod will seize no matter which lubricant you end up using. 

 

Given the construction of the engine its better to remove the front housing and poke the rod oil hole with a bent piece of wire than to remove the head and disturb the piston/liner 

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1 minute ago, Jon - Laser Engines said:

Not sure if you found this on your travels but its a review of the engine from when it was new http://sceptreflight.com/Model Engine Tests/HB 15 RC.html

 

One other thing. If the engine is castor gummed i recommend you remove the front housing and make sure the oil hole in the conrod big end is not blocked. If it is the conrod will seize no matter which lubricant you end up using. 

 

Given the construction of the engine its better to remove the front housing and poke the rod oil hole with a bent piece of wire than to remove the head and disturb the piston/liner 

 

Yes I saw that review and read it, but not super closely. I also found this: http://www.hbengines.com/guide.htm

 

I took the carb off and the hole looked fine. Then I went ahead and pull the prop driver and took the front casing off. Pics here: https://photos.app.goo.gl/MWeZuEwnfyjC7YEd6

 

Looks pretty clean? Although I can see some signs of wear on the back face of the cam? Oh and  prop shaft wise, M5 seems to wind on fine, so I imagine that the fine German engineering is using nice standard thread.

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Well that was difficult. I don't really know what I'm doing, have no reference for main needle starting point and I don't know what's going wrong where!

 

I got it started with a few flicks, and then started trying to tweak things. I'd gone for the default 2 turns out of the main needle and left the idle disc in the middle position. After a while it stopped, seemed to get bogged down and perhaps flooded. I fiddled about for ages, and gradually leaned it off and off, and eventually the main needle was only about a quarter turn open! I thought that must be wrong, but maybe it wasn't as I opened it up to 1.5 turns again and then struggled to get it firing.

 

After much messing about, I have the main needle at about 3/4 of a turn. Idle disc just pointing slightly +. I have no idea whether the idle disc is on a thread or not.

 

I have it now so that it will rev well when opening up, but seems to then drop off when kept on high revs. I can't get the idle to maintain for long though.

 

Mucho oily fuel getting spat out all over the place. On lowish revs fuel spits up out of the carb. If I blip it, it keeps running. At idle it dies after about 10 seconds. 

 

I dunno what to do to be honest. Wrong plug? (OSnumber 8, meant to be a long reach plug). Still way off on the mixture? Dirty carb? 

 

ahh well thanks to this thread: https://www.modelflying.co.uk/forums/index.php?/topic/43577-perry-carbs/ I now have access to some details. I will pull the carb apart and clean it to see if that fixes things. Wooohooo!

 

 

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If fuel is spitting from the carb that suggests the seal of the crankshaft is poor and crankcase pressure is leaking out. 

 

Following this little foray into old 2 strokes i dug out asuper tigre 20 that was kicking around and work and fired it up. I have a similar problem and fuel pours out round the front bearing as well. While it was a fun little diversion, the engine is dead. 

 

When it comes to tuning the number of needle turns is totally meaningless. If its running well, its tuned correctly and how ever many turns the needle has on it is not important so do not be worried if you are only a half turn open. The 300v in my P39 is only about a half turn open if memory serves. 

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1 hour ago, Jon - Laser Engines said:

If fuel is spitting from the carb that suggests the seal of the crankshaft is poor and crankcase pressure is leaking out. 

 

Following this little foray into old 2 strokes i dug out asuper tigre 20 that was kicking around and work and fired it up. I have a similar problem and fuel pours out round the front bearing as well. While it was a fun little diversion, the engine is dead. 

 

When it comes to tuning the number of needle turns is totally meaningless. If its running well, its tuned correctly and how ever many turns the needle has on it is not important so do not be worried if you are only a half turn open. The 300v in my P39 is only about a half turn open if memory serves. 

Oh no, that might mean my engine is knackered too. There's quite a bit of play in/out but none side to side. I have disassembled the carb and there was quite some detritus came out, but maybe the spitting is indicative of a worn out engine.

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the ST i was playing with is ball raced and they are toast, but i also have a PAW 249 in a box somewhere and this has a ruined plain bearing. there is loads of end float, but little in the way of rocking movement and yet when it runs fuel leaks around the prop driver before accumulating into a big drip that gets splattered everywhere by the prop. Its the same with my ST and i was plastered by the end of the run. Also where its been sat the ferrous liner and piston acquired a coating of surface rust and now its rubbed that off by running all the compression is gone as soon as it warms up. 

 

I had been toying with the idea of taking the PAW to work and modifying the crankcase to accept some ball bearings but had forgotten all about it until just now. 

 

 

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The Perry carb is highly intolerant of detritus, so needs to be cleaned out and spotless. Then you might achieve a more predictable and stable response to adjustments. Where the o-rings in good condition, or breaking up?

I would not worrytoo much about a bit of end float on the crank. It's radial play that makes problems.

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https://photos.app.goo.gl/1CGUa9MbUcKpK5V46

 

Detritus. You can zooooooom in on that. This was just the carb barrel, needle and the idle disc. Prior to putting the carb body in...

 

I'll have another play with it tomorrow with my clean carb. I'm realising how amazingly lucky I was with the Flair Kite trainer I bought for £100 including all servos and a super tigre 45. It's got impeccable table manners by comparison - no spitting or puking gunk of any kind!

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Well, at least you've got most of the right bits! Although, there should be a small circlip to retain the carb barrel at the main needle end. The serrated washer would not normally be present. Maybe somebody lost the circlip and substituted the washer?

 

It's important that the metering slots are completely clean. As I recall, there is a very fine slot in the "reservoir" which is the part with the knurled mixture adjustment disc. Also, the two O-rings on the reservoir must be in good condition and make a good seal within the bore of the carb body.

 

If, after all your fiddling, it still runs erratically then might be worth adding a bit of castor to your fuel to get a better compression seal. The problem with the HB and Veco lapped piston engines was that the liner material was fairly soft steel, compared to the hardened steel used by Enya, for example. The wear rate is consequently quite high and that's where the castor goo can help out.

Edited by Jonathan W
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Just a thought on the crankshaft threads... The larger HB engines all used imperial UNF threads, e.g. 1/4" UNF on the HB 20. The HB engines, although made in Germany, were actually derivatives of the K&B/Veco engines from USA. Although you say an M5 nut fits on your crankshaft, it is possible that the thread is actually No. 10 UNF. An M5 nut will fit onto a No 10 thread, but will probably be a little loose and prone to stripping. I do not know for sure which thread was used on the HB 15, but best just to make sure your M5 nut is not sloppy and at risk of coming loose.

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Ha, i had the circlip in the little bag I stuck the carb in - in case it pinged off - it's back in place! I couldn't work out where the star washer came from, so stuck it behind the spring of the needle valve. The two rubber seals of the idle disc are still absolutely perfect.

 

I wouldn't be surprised if this little engine is a dud, but I'll give it some more attention!

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Good luck. From the ebay pictures, It does not look to have had a hard life. The screw heads normally get chewed up when people have been messing about inside and yours still look like new.

The washer might or might not be advisable. When the carb is all back together, make sure that the main needle rotates with the carb barrel. If the main needle remains stationary while your work the throttle open/closed, then this is actually changing the mixture. The presence of the washer might interfere with this, depending on its precise dimensions.

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