Chainsaw masacre

deacon · #1 (**permalink**) 07-18-2008, 05:57 PM

Now I know some of you deal with chainsaws now and then. Some of you surely deal with weed whackers so try to follow along and then HELP ME PLEASE..

I bought this chainsaw that was supposed to be a factory rebuild. I got a really good deal on it because it had parts missing. Didn't matter I wanted it for the motor I worked around everything else but now I screwed the pooch.

I tried to straighten what I thought was a bent throttle lever. I broke the brass rod that made the whole thing work.

Follow this if you can cause I am having a hard time following myself and I'm looking at it.

The engine has two intakes. One is for the fuel air mix from the carb but a second one is for pure air to the cylinder as it throttles up. Since I broke the carb and since the motor is 33cc I decided to try a more or less new carb from a 31cc weedeater.

So I put some tape over the pure air intake thinking it was kind of a ram turbo charger kind of thing for when you ratchet up the throttle to cut with the chain.

I put the weed eater carb on and gave it a try. I got it to start on full choke something it should not have done. I got it to respond to the throttle on 1/2 choke. It wanted to die on no choke.

It was also idling way too fast. Right or wrong I tried to adjust the carb. Those carbs have a high end and low end adjustment. I was working on the low end and the idle screw as well. Then of course the engine died. It wouldn't restart on any choke setting. Still wont

I sat down to think before I went on. I right or wrong decided that air was getting past the tape I put over the direct air vent into the cylinder. So of course I found a cap that more or less fit and I put it on with some blue gasket seal hoping to cut out the air.

Now it wont start at all. So here are the questions Lawn care gurus and chainsaw wielders.

What is the factory setting for the 2 carb adjusting screws. It ran at factory settings last I need to go back there and try again when the motor has rested lol.

Is it possible that there needs to be a small amount of air through the direct vent to get the fuel air mix right. If so I can start drilling holes in the cap by starting small and moving up. I can always take it off and start over I have plenty of the caps. I'm just not sure that it needs that. It seems that the motor should run from the carb alone since it runs a weed whacker of almost the same size and it did run it earlier. Still it might need more air.

It might also be that I have other air leaks or the cap isn't sealing well enough.

I need the factory setting for the carb adjustment screws. The carb is for a ryobi 31cc weed eater. I can't find the factory settings. Thanks guys

stude13 · #2 (**permalink**) 07-18-2008, 07:24 PM

hi dec; it would seem if it ran with some choke it needs more gas to start. start the needles at 3 1/2. try a tool rental mech. good luck mitch

**Bikeguy Joe** · #3 (**permalink**) 07-19-2008, 07:11 AM

The air intake is for the COOLING FAN. Don't run the engine without the COOLING FAN air duct working. You will burn it up.

If I remember right, the screws on those carbs turn IN for richer, OUT for leaner. Get a baseline setting (1 1/2 turns from all the way in) and go from there.

deacon · #4 (**permalink**) 07-19-2008, 09:08 AM

It was the kill switch I forgot I had turned it on. Duh ...

The second intake kills the engine if I open it up. The carb had a swing that only allowed it to open when the engine was running on high. It goes directly into the cylinder that I am sure of. The cooling fan is ducted differently. I can replace the shroud on this one and I will before I run it.

The 31cc carb seems to work fine today since I turned the kill switch off. I will have to make an air filter for it but it seems to be just fine. I'm really surprised. Thanks for all the help and the information.

Three and a half turns seems to be right for the low end adjustment. I had the carb mounted screwy is why the thing was giving me such a fit. I had to cut some of the round choke plate to make the carb's throttle control work right but it didn't seem to hurt anything. Since it's running and takes gas I'm going to leave well enough alone.

Thanks guys as always the help is greatly appreciated.

deacon · #5 (**permalink**) 07-21-2008, 05:59 AM

I must not have explained the air intake thing correctly cause my son in law and I were brainstorming yesterday and it is the choke mechanism. The bike starts with that air vent closed, then after it starts at idle when you open the throttle, it pour pure air into the engine to lean out the mixture of gas/air. It took us a while to figure it out but that's what it does. It just leans out the mixture like turning off the choke automatically. Actually it is the automatic choke mechanism. I have no idea what will happen when I put a load on it without the massive air intake being open. It might just be like running at 1/2 throttle.

I still need to devise some kind of very small air filter for the 'new' carb. I'm thinking bottle cap with a small amount of oil soaked cloth one layer. Lots of holes in the cap,

deacon · #6 (**permalink**) 07-25-2008, 07:31 PM

I need to get back to work on the chainsaw bike. I think after the front end 31cc is running I will try to finish the chainsaw bike. I got the motor to work with the 31cc carb so all is read to ride to be honest. Probably something else I needed to do but I don't remember. The joys of getting old lots of work you don't have to do because you simply forget it needs doing.

Jemma Hawtrey · #7 (**permalink**) 07-25-2008, 07:45 PM

Hi

If I am right then that second port is a stratification system port...

its one of the methods use to make clean burn 2-strokes and it was used on the Zenoah engine as fitted to GEBE's in the past.

Im not exactly sure how the system works but I *think* the idea is to dilute the exhaust gases and also to form an air block so the mixture in the crankcase at that point cant vent to air either way - which maybe something to do with the reason why the little Zenoah kicked so far above its weight.

Its just a suspicion. It would help if you had a manufacturer for the motor so research could be done

Jemma xx

deacon · #8 (**permalink**) 07-25-2008, 07:58 PM

The engine is made for poulan i have no idea who actually manufactured it. My guess would be someone in china.

I think it is the automatic choke mechanism. They call their first step setting the fast idle... At that point the massive air intake is closed. When you throttle up it gradually opens.

A chain saw is under a great deal of stress when it is cutting so it might be just to lean it out and make it more efficient. When I get back to the darn thing I will know more since I haven't ridden it with the 31cc carb yet. When I do I'll know more.

I just have tooo many projects half finished. I am going to finish the mtb front wheel drive 31cc before I do anything else. Then I think the chainsaw bike is next.

It's time to wrap us this building frenzy and move on to something else.

deacon · #9 (**permalink**) 07-29-2008, 04:37 PM

So I put aside the little 25cc and went back to work on the chainsaw bike. The first thing I did was to take the engine off the bike. The mount was not very secure. Probably why I kept putting it off.

The new mount and getting new holes drilled and then getting it assembled took a lot of the day. Once I had it secured to the bike frame I tried to start it. It just would not start. I just knew I had plenty of gas. I had been pouring gas into the tank off and on as I had gas left over from other builds.

I finally took a look and it was all gone. Evaporated or leaded I have no idea which. I put on a different tank and some gas but somehow from an empty tank I managed to flood it. I pulled the plug and let it sit in the sun for an hour while I switched out some tires. I put the tire and wheel from the sissy test bike onto the big ole huffy with the chain saw. I had just bought a new rear tire for the test bike so I might as well use it on the chainsaw bike.

Then I put a clown tire on the test bike. I might try to start it after I finish the chainsaw bike.

The chainsaw bike started fine after I let it dry out. I think it might not need to be choked with that carb on. I'm not sure since I was having all the dregs of the gas trouble with it. I should know tomorrow.

I built a couple of air filters. I wound up using to peanut butter jar lids and some foam rubbler I had laying about. Actually it was one peanut butter jar lid and one dukes mayonnaise jar lid. That is what's on the chain saw.

It's two peanut butter lids on the 25cc bike. I am going to change the construction of the 25cc air filter. I think it might be choking the bike. Use the thin foam and cut more holes in the top. I had one of those donuts with just a few holes. That's tomorrow's project.

deacon · #10 (**permalink**) 07-30-2008, 02:57 PM

This one hour job, (rig the controls and install a new drive wheel) took all day and Im exhausted and not sure it works yet. Im taking a break until tomorrow.