Homelite C-series Planetary Gear Drive Wanted

[ol'homey]

Where could I send a chainsaw jug to have it bored? The one automotive machine shop we have around here doesn't have a clue. I'm thinking if I ever find a C9 piston I could send it and my scored C72 jug to have it bored to fit. These saws aren't worth the cost of Nikasil. I have 20 yr old Briggs aluminum bore engines still running on the original bores. I'd never put anywhere near that many hours on these saws.

Have you ever compared the performance of your C9 to a modern saw ? I would guess that the C9 at 85 cc and 10:1 compression would produce about 5.5 HP at around 7000 rpm. If you used 3/8" chain and a 8T rim sprocket (GB makes rim drives for the C series) to get chain speed up and put enough load on the saw to get it to operate around 7000 rpm, I bet it would keep up with a modern saw of around the same HP, chain size and bar length.

 

[GPH85]

Actually, that is the one thing that I have always been facinated about with Homelite... All of the technology they were using in their saws at the time was fairly advanced... I mean look at the planetary gear drive for instance... You may know better than I, but I have honestly never known of any other saw to use this setup... It's so simple, but yet so complicated... It allows the user to switch from direct to gear drive in the matter of minutes, where as any other saw out there, if you had a gear drive, well you just had a gear drive... There was no easy switching of bar covers, you would litterally have had to switch out the whole right side of the engine housing... AND the overrunning clutch setup on the rewinds, lets face it, this is pretty advanced for the time as well even if it may not always have held up to time...

This applys to their power specs too... I have gone through just about every homelite saw with the same bore and stroke in relation to the C-Series saws that I could find and here's what I found to be about the rough guess of power specs of the saws through comparison of other homelite saws with the same specs...

C5 is roughly 5 hp
C7 is roughly 6.8 - 7 hp
C9 don't know couldn't find a saw with the same specs to compare to...

These are all comparison specs granted, from other homelite's that had their hp levels actually written down or actually calculated... You look at other saw company's about the same time era and you will see that you actually did have to have the higher cc's to make any power and some of the saws with 70 or 80 cc's were barely putting down 3 - 4 hp...

Saw comparison to modern day saws --- I don't know with todays tech advances in the small engine industry plus there's the fact that saws today turn at 9,000 or 10,000 + rpms, but I do know that when I completely burry my 36" bar on my C9, that it will keep right on pulling until the tree binds it or the chain hangs on something and these saws originally were only available with a 30" bar at most... AND this is with an old wore out engine, not rebuilt or yet restored...

In reply to your jug boring, you should be able to take it to a fabrication shop, not necessarily an automotive shop... The fab shops will usually have the proper tools to bore out a cylinder... However there still lies the fact that the aluminum cylinder will have to be coated to function properly...

Here's a site you might find interesting... This guy restores chainsaws of all kinds and collects them as well... I'v been in contact with him on and off and as you will be able to see, he does extremely good work... In fact he's the only person, honestly, I would trust to restore my saws, of course he's not what your looking for persay because he is pricy, but I thought you might like his site... --- www.bigdmc.com/Chainsaw.html --- He's got a restored Homelite C9 "first saw he restored" plus many more including a C9 that will include the extremely rare automatic oiler that was available for the C-Series saws at the time, that he is currently finishing up and should be on display in the next month... (For those who know you couldn't get the oiler on the original 3 C-Series saws "C5, C7 and C9, he has put a C91 side engine housing on the saw to make it work) He also will not sale the oiler, I allready asked

 

[ol'homey]

C5= 4.7 cu in
C7= 4.9
C9= 5.2

A reed valve 2 cycle engine operating at 6-7k rpm with a compression ratio designed for pump gas should make roughly 1HP per cu in. So 5 HP for the C5 sounds about right. The C7 is only .2 cu in more so I would give it another 1/4 HP. The C9 is .3 cu in more than the C7 so I would give it another 1/4 HP for a total of 5.5 HP.
5.5 HP is equal to a Stihl MS 440. Now before everybody tells me that an MS440 will smoke an old C9 because the RPM's are so much higher, let me say I don't care what the engine RPM's are, if you have 2 engines and they are both making 5.5 HP they will do the same amount of work in the same amount of time. IOW HP is HP. That said to do a proper comparison the C9 would have to be set up with the same bar length and chain type so that the frictional losses etc. are the same. IOW you can't compare a C9 pulling 1/2 chain around a long solid nose bar to a MS-440 running 3/8 around a short roller tip bar. Once you get equivalent bars and 3/8 chains you would need to choose a rim sprocket size (8 or 9T) to get the chain speed up on the C9 and allow the saw to operate in the rpm range where it's making 5.5 HP say 6.5-7k rpm in the cut. The MS-440 will probably be running a 7T sprocket and running 9-9.5k rpm in the cut. If you call Stihl and ask a tech to look up the rpm at which their max. HP rating is spec'd at in their SERVICE MANUAL they will probably give you a number between 9-10k. Do not accept the 13k+ max. rpm number that's quoted everywhere because it means nothing. The saw is not going to make 13k rpms in the wood and if it does it's not going to be doing much work. A competent tech will tell you that the reason their recommended bar and chain combinations are what they are is that they allow the saw to operate as close as possible to the rpm where max. HP occurs under what they consider to be avg. cutting conditions. So if we took an MS440 with a 3/8" chain, 20" roller nose bar and 7T sprocket and ran it against a C9 with a 3/8" chain, 20" roller nose bar and 8 or 9T sprocket, i bet a good running C9 (not worn out with a scored piston/jug like most of them are) would hang with it. Know anyone that could test my theory?

 

[ol'homey]

My estimate of 5.5 HP for the C9 might be a bit optimistic. Here's a link to the specs on the SXL-925 that everybody loves so much
http://www.acresinternet.com/cscc.n...ac955814c40922b988256c260048fd18?OpenDocument

It's showing 5.2 HP. The SXL-925 is a newer design so it might have a little more HP/cc but the C9 has a couple more cc due to the slightly longer stroke. I bet the C9 is about equal to the SXL-925.
Next question is how does the SXL-925 compare to an 044 or MS440 ?

 

[GPH85]

Good question, but I don't particularly have a XL925 or a Stihl to compare one another to, but perhaps someone on here does

I think the better question is --- would the XL 925 piston work in a C9, because that's the same stroke difference that the C7 had to the C5... Plus the xl925 uses the same bore, so maybe, just maybe there's something there to boost compression on the C9 and you could even take it a little further with using a thinner gasket or shaving the cylinder some

 

[ol'homey]

I don't have either of those saws either. But I bet somebody around this site does and hopefully will chime in.

I think the SXL-925 is based on the XL-12 bottom end which is different than the C series and would bet all the parts are different.

Have you ever tried eliminating the base gasket completely and using a tube of gasket maker? The only problem I see would be the possibility of an air leak if the gasket maker compound wasn't up to snuff. Last time I looked they had about 50 different kinds of gasket maker. Any idea which would work the best for this app ?

BTW boosting compression on these reed valve saws should be a cake walk compared to a piston ported saw where the port timing changes when you move the jug down.

 

[GPH85]

Actually the C-Series saws and the XL series saws aren't that much different... My XL 12 still has the domed piston just like the C-Series saws and is set up pretty much the same internally wise anyway... If I had a XL 923 - the XL 955's piston, I would let you know, but I don't...

2 cycle engines, in my experiance, are the worst engines in the world to use any kind of gasket making compound on, because the air fuel mixed with oil flow is so dependable on gaskets... In other words if you had just the slightest amount of gasket junk get in the crankcase or around the piston, it could and more than likely would hurt the proper operation of the engine... Perhaps even score the piston and cylinder up from mal-lubrication...

Yes boosting compression on a reed valve engine is, as stated, cake walk... You can do the simplest things to boost compression...

 

[Mike mandry]

In case you guys have not seen it, I just saw a new C series planetary conversion on ebay........

 

[ol'homey]

here ya go....
http://cgi.ebay.com/Homelite-C-Seri...ryZ42227QQssPageNameZWDVWQQrdZ1QQcmdZViewItem

 

[bugfart]

The piston pin orientation combined with the domed C-91 piston have it at least an 1/8 of an inch higher than the XL-925 equivilent. Also the XL-925 piston will travel about a 1/16 inch lower into the unit (BDC) so the removed area of material at the base of the newer piston will or will not allow you to play ball. Not that taking it from the base of the piston appears death defying.

XL cylinder mounting footprints are more narrow and do not bolt up. C-91 exhaust port sits much higher than the more modern XL925.

I SUSPECT the newer cylinders are not as forgiving with the squish measurements. Just a guess.

I might be tempted to put the C-91 in a needy xp1020 or 1050 from what you are saying. Might have to bore the mounting holes on the C-91 cylinder.
The piston orientation is right on between these two.

All of these pistons use the same piston pin.

 

[GPH85]

Interesting... I knew the XP's were direct copy's, only larger displacements to the C-Series saws and sorta knew that about the 1050's and their larger versions, but I thought the bore was larger on these saws???

Ok the 1050 and 1130G's Bore = 2.1875 / Stroke = 1.6250

the 2000, 2100 and 3100G's Bore = 2.250 / Stroke = 1.750

The C9's Bore = 2.0625 / Stroke = 1.5625

Since none of the bore's are equal, you couldn't switch out pistons for their higher domes, but if the cylinders were the same size or rather had the same bolt pattern, you could possibly put the bigger bore piston on the smaller stroked crank of the C9, but I really don't think you would gain anything since you are running a smaller stroke crank, you would have to run an extremely thin cylinder gasket and even mill the surface of the seat on the cylinder down to gain back the lost compression... I guess if you just wanted more power from the C9 or C7 and you had the parts laying around, you could do this, but if it meant parting out a larger saw, then I wouldn't do it... Just my $.02 worth... Don't get me wrong now, because if I had the parts, I would atleast try it, but as stated, I wouldn't part out a bigger saw...

BOY I use a lot of comma's don't I... Oh well I guess I need to relearn how to properly write

Thanks for the heads up Mike on the gear drive unit

 

[fubar2]

You guys seem knowledgeable on Homelites. I almost bought one a few yrs ago that had OL BLUE written on it. Know anything about that model?

 

[RaisedByWolves]

It was either an SXL or an XL-12.


They uset to all be blue at one time and this was a more recent markiting campaign.


Good saw either way.

 

[GPH85]

I'm not particularly knowledgeable when it comes to anything other than the C-Series saws, but wasn't the OL BLUE model just a XL that was painted the original blue homelite color and given the OL BLUE title... SEE I thought, while homelite still actually owned the company, that they brought back the original nostalgic appearance of the original high selling homelites to try and bring the company back into a profitable situation... This was before they sold out to John Deere, I believe... This was also to try and win back the general saw public in to buying the original "brutes" that homelite had made for so many years... Homelite was at one time the saw of choice and the XL line up can be contributed for all of the modern day saws that there are...

Now someone please correct me if I'm wrong here, because I don't want to be giving out false info, but this is just what I had always thought

 

[GPH85]

Sorry raisedbywolves... It would seem that you answered before I could

 

[GPH85]

Ol homie, just thought I would let you know incase you hadn't seen it there is a C5 cylinder and piston (No scoring) on ebay for sale from washingtonhotsaws... Just incase you didn't allready have one on the way...

 

[ol'homey]

Thanks, I put it on my watch list. It figures that one shows up right after I bought a whole C5 saw! I'll see what the piston/jug look like when I get the saw. I might put a bid on it anyway if it doesn't go too high to keep as a spare.

Does the C5 piston weigh the same as the C7 ?
I'm planning on doing the piston swap like you did and was just wondering if there was any vibration/balance issues to worry about?

 

[GPH85]

The C5 piston has both more material above the piston pin and a touch more material on the skirt of the piston, so it should be heavier, however I don't believe there will be any vibration issues to worry about here...

You oughta get you some decent gasket material "not as thick as original" and run a thinner gasket as well... Then it would have really been worth it

 

[bugfart]

What gasket seal and where do you get it?

That C-91 jug set is going on this 1020 XP set.
That 1020 jug set's going on this C-91

:hmm3grin2orange:

 

[ol'homey]

I need to do a search and find out what all the guys modding their jugs are using for a gasket maker. I bet there is one that will hold up and not result in an air leak.