Homelite Model 17 Help Please

[davel]

I have a homelite model 17 I need help with.  I have completely cleaned and rebuilt the carb, cleaned and replaced fuel tank and filter, checked and reset points to factory setting.  Set the carb jets to factory settings.  Started saw with choke on, can only open the choke 1/4 of the way to keep running. Saw would not accelerate, so I took some two stroke gas in a spray bottle and held the throttle wide open with choke 1/4 open and sprayed gas into the carb. Saw had very little change in rpm and still will not accelerate properly. Checked reed valve and appears to be operating properly.  So does this mean the crank seals are probably the culprit of my problem?  If so are engine rebuild kits with seals and gaskets available somewhere?  Thanks for the help.

[Brian VT]

Start with easy things to check before digging in to crank seals.
Muffler screen clean ? (if there is one)
Piston/cylinder not scored ?
Compression check ?

[davel]

Yep, took screen out of exhaust, compression is great, cyclinder looks great.

[Brian VT]

I suppose crank bearings (or some other air leak) are a possibilty.
I would suspect my carb. rebuild/clean 1st though. Are you confident with your "float lever" height?
Maybe you can borrow a known-good carb. to try ?

[davel]

I thought by squirting gas thru carb intake that would rule out the carb, the engine should run even without carb by squirting gas thru intake, it should at least excelerate either way shouldn't it?

[Brian VT]

You said it won't run if choke is on more than 1/4 ? That might suggest that it's too rich or flooding.
Air leaks (lean condition) usually cause a high-reving engine.
If it were lean then more choke should help rather than hinder.

[davel]

I had the choke on full to start, it starts but wont rev, opened choke 1/4 of the way and will still run but wont rev, thats when I squirted gas in the carb and nothing changed. At this point I also opened the throttle wide open and sprayed, also had no change.  If I open the choke farther the engine quits.  If I close the choke it will start to run again but no revs, just like an on off idle type of running.  Does this help.

[davidssmtrs]

Hello Davel. I own and operate a small motor shop, I'm David. It sounds to me more like the diaphragm has got hard or no good. According to y research, you have a Tillotson HP-1B Diaphragm type carb, and the kit is no longer available through regular purchases. If your have to run choke 3/4 that is sucking more gas to cylinder, but diaph. is not pumping to allow acceleration. Try to find a rebuild kit for carb. Good luck, David.

[Brian VT]

I agree that the carb. is suspect. He said he rebuilt it but things don't always go 100% and you end up chasing your tail looking for another problem (which is why many shops just replace the whole carb. rather than rebuild anymore).

[powerking]

If it is not a fuel starvation or over rich problem, then consider that it is an ignition problem; like the coil breaking down/shorting internally at higher revs or possibly the condenser starting to fail. With magneto ignitions, they can sort of work OK a low RPM's, but at higher revs (hence voltages) they can cause behavior like you are seeing. The best way to "catch" this possible problem in action is with one of those in-line spark testers. My brother recently had a model 23 Briggs that acted this way, it would start and idle fine but give it throttle and a few hundred RPM's higher it would flat out die. The coil was bad. We confirmed this by taking a 12v battery and Delco (Kohler K-series type ignition coil) externally wired to the points and it ran like a champ. I keep one of these external coils as a valuable "tester" (go, no-go if you will) in my tool collection.

Tom (PK)

[davel]

Thanks for all the replys, I will see if I can find another carb to try, I did purchase a rebuild kit, cleaned everything, checked all check valves for function and replaced the internal diaphragm and gaskets. Will let you know when I get it narrowed down, but thought all along its a fuel delivery problem. We will see.

[sweepleader]

Thanks Tom for the external coil suggestion, I am going to try that on a balky XL brush cutter I have that has resisted my attempts to cure its similar to davel's troubles. I have been putting off working on it because I did not have a good plan on what to do next. I used to own a auto garage and used several diagnostic aids in similar fashion but this one did not occur to me.

Thanks again,
Dan

[davel]

As it turns out a ohm meter check of the magneto coil says the secondary is open. Ordered a used replacement and it turns out thats no good also. Has anyone had experience with www.magnetoparts.com. I placed an order for a new coil from them a month ago. Cannot get that company to respond to my email, or phone message. Does anyone know if they are still in business or not? Thanks again for all the help.

[ncrile]

Hello all:

I just dug up this thread because I have a similar problem.

So I've been reading as much as I can about the Model 17 (with an HP1A carb) I'm trying to restore. I'm kind of stuck at the moment. When I received the beast, the fuel system was either hardened to a shellac or was gummy. Thus far, I have taken the saw all apart, cleaned out the tank, fuel lines, rebuilt the carb (as best as I know how, replacing the diaphragm, gasket and clearing out all the ports). I'm not entirely sure how to set the lever and needle such that the diaphram can actuate it. I was able to replace the seals (bearings were fine). I replaced the points, and condenser. The spark seems kind of weak But it DOES RUN. Not sure how to figure out how much spark is enough (in line spark tester glows ok but I've seen better from other saws)

Like Davel, it idles but won't rev up. I do notice quite a bit of unburnt fuel in the exhaust ( I have no muffler at this point so it's just spitting out the exhaust port/ manifold ). Seems like a running too rich situation but I'm having trouble figuring out if I have this old carb adjusted correctly? where the High adjustment is? Also having trouble simply finding info on this Carb (Tillotson HP1A) in general.

I'm wide open to all theories and input. I'm kind of new to restoring saws and definitely new to this older style carburetor. I pray to thee saw Gods ( and Godesses)

[dynodave]

I had a problem with my 707 or 7-19 ?
I doubt this is actually your problem...
The crankshaft had worn at the points cam. That will retard the timing. Though the points will open, the firing will not be advanced enough and it will run like a dog. Crank from my spare went into the build. Now I run a 30" with 404 full comp chain.
Just no wood to run it on.

Also I have, I believe a partial carcass from a 17 up for grabs.

[ncrile]

Thanks Dynodave:
How's the coil on that 17 carcass? I doubt the cam on the crank is worn (although it could be). My first guess would be carb (from the preponderance of unburnt fuel). I'm only guessing now.

[dynodave]

Went out to back over ice & snow to tent shelter. dragged out carcass. sprayed acetone/atf mix on screws to soak. Will tear down unit and access coil and report what I find. I'm not actually sure if it is a 17 but it is an early gear drive. What is remaining does look like what is on acres site. It's missing the handle and serial number plate So I can't tell if it is phelon or wico mag until I get it apart. Still has the carb too.

[ncrile]

Hi Dave:

Hope you haven't gone through the tear down. So i think I've figured out a solution to my problem. In my haste to re assemble the carburetor, I forgot to install the Nozzle Channel Plug screw. It had rolled off the bench. I found it a few days later. Without the plug, I think I was just flooding it. After further inspecting, I decided to replace the needle and seat and the main jet as well. I'm waiting on the parts to come in. As soon as they roll around, I'll carefully put it all back together and see if it will make a difference. The Spark issue may or may not have to be addressed.

[dynodave]

AHHHH got refreshed. My 707 and 7-19C are governor controlled, not direct throttle controlled. I see the similar hardware on this 17 that I just pulled the HP1A off of. My 707 and 7-19C were both built from 2 basket cases each, and some of them had cobbled up linkage to bypass the air vane governor. I bought some bits from Parkin to make them work to OEM style. Though I did notice later versions seemed to do away with that feature.
Linkage style and mechanical soundness may enter into these machines ability to run up...17 included

NCRILE
OK...I'll hold off on further teardown