Need Tips for starting a newly rebuilt 440 Engine

[Hec In Omaha]

Howdy All,

Background info:
Just rebuilt the engine in my 81 Trailfire 440. It got new pistons and rings, crankshaft o-rings, crankshaft bearings and seals, Rod bearings and pins, new fan belt and fan bearings, gaskets, fuel pump, fuel pick up filter, fuel lines, and spark plugs. I found a decent carb on E-bay and rebuilt it with a #25 pilot jet, 230 main jet, new #166-Q2 needle jet, needle and seat, choke plunger kit, bowl drain plug o-ring, and bowl gasket. The E-clip is in the #3 position. The carb was bought from a guy in Washington State so his Trailfire 440 was set up to run lean as he ran it in the mountains. I am in Nebraska at 1,100 feet above sea level. That's why I replaced all the jetting back to factory spec. The only part I am waiting on is a new slide valve. It has a 3.0 slide valve but the inlet edge has been cut down. Should be here tomorrow.

So this afternoon I installed the carb and hooked up the choke, throttle, and fuel line. The air screw was set to 1-1/2 turns open and the idle screw was set 2 turns clockwise from the point the screw contacted the slide, per the manual. The slide is just cracked open about 1/16" with this idle screw setting. It was 11 Deg F out side and starting to snow and getting dark. I decided to try and see if the engine would fire. I put in 5 gallons of non oxygenated 91 octane fuel mixed with Amsoil Snowmobile oil to 40:1. I pulled on the rope and noticed that the engine was really hard to turn over. It has a lot more compression now! The engine has spark,and I could see fuel flowing to the carb. So far so good. So I set the choke and pulled about 10 times then the engine sputtered for about 3 seconds. The headlight turned on while the engine sputtered so that's also a good sign. I pulled about another 10 times and it would do the same thing just sputter for about 3 seconds. My arm gave out so I called it a night.

So any tips for firing up a newly rebuilt engine? I feel like I am breaking it in with my arm! As always any help is greatly appreciated! I'm so close now!

Hec

[harleysportster]

Did you set the choke as per the service manual?
Are you able to flip the choke level up past the center which gives it a little more enrichment which helps in the very cold temps?

[Hec In Omaha]

Harleysportster,

Thanks for response!
Yup the choke is set up per the manual. I took an inspection mirror and can see the plunger lift up over 3/4 of the way in its bore at full choke. It's just over 1/2 of the way up at 1/2 choke and all the way down with the choke off. I have about 1/4" free play at the choke lever on the dash too. On a side note, when it did pop off it was during full choke operation. Couldn't get it to fire at 1/2 or no choke. I was worried that I was going to flood the engine and tried starting with the choke off or at 1/2 choke with no luck.
I can rotate the engine over by grabbing the primary clutch and rotating it. When its not on a compression stroke it the engine crankshaft moves back and forth without too much effort. I also verified that primary clutch was not grabbing the belt. It isn't. I did spray fogging oil in each spark plug hole after engine assembly to pre-lube the cylinders and piston rings vs starting it up dry. Maybe that wasn't a good idea. I wonder if the cold temps have gelled the fogging oil up? The sled is on the trailer outside now. Maybe I should try a squirt of pre-mixed fuel in each cylinder. I will pull the carb bowl off tonight and make sure the starting well is open to the bowl bottom. This carb had a lot of calcium in the bottom and perhaps the crossed drilled hole between the well and carb bowl bottom is restricted. I could of sworn I ensured it was clear by hitting it with compressed air. Maybe I am only getting fuel from the pilot jet?

Hec

[harleysportster]

I would inspect the carb very thoroughly and clean as needed. Sometimes it takes several attempts to get it right. Once you are sure of the carb spotless clean, dump a small cap-full of premix down each spark plug hole and try it.

[Hec In Omaha]

harleysportster,

Tonight I pulled the carb and removed the bowl. The starter well hole was clear. I blew compressed air through every orifice and they were all clear. One thing I noticed when I pulled the carb was that the bowl didn't appear to be as full as it should of been. Maybe I didn't pull the starter rope long enough to make sure it was full? I have a marine outboard squeeze bulb with a long piece of 1/4" line on both ends. I use it to drain fuel tanks on my Jetskis. I will connect it directly to the carb and pre-fill the carb with premix before I reconnect the sleds fuel line. I will also put a little premix down each spark plug hole. I'll try again on Saturday. Hope that was it!

Hec

[flacker36]

Could be timming, did you set the stator to the mark? Are you sure previous owner didnt swap out parts from another sled?

[Hec In Omaha]

flacker36

Timing is set right on the mark. The only parts I know that weren't original JD parts was the old carb. When I bought it the engine had a universal VM34 carb that was jetted way too rich. It didn't have the original air box either. Just a K&N filter. It did run but I wouldn't say it ran great. The engine had two leaking crankshaft seals but had good compression at 145 psi on both cylinders. So I think the PO was trying to compensate for the lean condition caused by the shaft seals by using a rich jetted carb. I now have the correct carb that is jetted correctly and air box for it. Luckily the engine didn't have a melt down!

Hec

[Hec In Omaha]

Update,

Today I reinstalled the carburetor after going through it one more time and making sure all the jets were open and clean. Pulled the starter a few times ans whala! It's alive! Well kinda sorta. I can get the engine to restart in one or two pulls, but it's acting up. At idle the engine will run and eventually die after about a minute or two. I noticed that if I engage the choke just a little it will stay running. It will also stay running if I lightly give it a little bit of throttle. I am barely putting pressure on the choke or throttle lever but that will keep it going. If I snap the throttle it is pretty responsive, but soon will die again. Sometimes if I repeatedly squeeze the throttle I can keep it going but it will die eventually. My thoughts are its either running out of fuel in the carb bowl or it's getting too much gas. Since it helps to apply a little choke maybe the fuel level is not high enough in the bowl or the #25 pilot jet is too small. The float arm is level.
This carb came with a #42.5 pilot jet even though it was on a sled that ran at higher elevations of Washington State. I think I will install the #42.5 and see what happens. Now the universal Mikuni VM34 carb that came with the sled had a #25 pilot jet that was drilled out. Interesting the both of these carbs had a Pilot Jet larger than the #25 pilot jet the manuals say came factory on the TF 440. Maybe these engines need a fatter pilot jet to idle? What are others out there running for pilot jets?

I am running out of ideas. Any thoughts?

Hec

[smitfire]

25 is correct. Factory jetting flat ass works! So keep it stock.

[Hec In Omaha]

Thanks Dustin,

I failed to mention that all my tuning attempts have been with the air box removed. Do you think I should of installed it? Running without the air box will lean things out a bit.

Hec

[smitfire]

Yup

[Hec In Omaha]

Update! I got it running great now! To make it better we received 4" of snow overnight. Here is what I did. I tried readjusting the choke plunger to give 1/8" of free play. Started up the engine and it acted the same way. So then I thought maybe my floats weren't floating. So I removed the carb and pulled the bowl off. I filled it with fuel and measured how much the floats moved up and compared that with the floats on the Mikuni universal VM34 carb. The were very similar. So I made double sure the float arm was level with the carb body and reassembled the carb and reinstalled it. This time I installed the air box too. Same thing. It ran the same again. So off everything went and I installed the #42.5 pilot jet I replaced with a #25 pilot jet. I reinstalled everything and in one pull she came to life! It idled great and had very good throttle response. It never died again! It starts within 1-2 pulls too! So I did about 20 Victory Laps in an empty lot across the street. I gave my 9 year daughter, Piper, rides too as she is my helper. She even helped put the engine in!
By the way the air screw ended up being at 1-3/4 turns open. According to the 1981 tuning manual I don't need to go up or down in pilot jet size. I did pull the plugs and they looked paper bag brown. The PTO side was a little wet but the mag side was dry.

thanks everyone for you suggestions on this. Now its on to the Liquifire track conversion.

Hec