The Jag has always been a bit more difficult to start vs. the Puma...despite the same general engine; (Puma being about 100cc smaller).
I feel like it's starting a bit rich. Back in the early winter, I noticed the plugs were wet when I started the machine...even with the choke off. I adjusted the choke (enricher) to spec and it seemed to solve the problem. However, it's still an issue. I fired the machines up for a mid summer warmup a few weeks ago. The Puma started pretty easily despite not running for months. The Jag took a lot of pulls. It was getting fuel to the carb; no issues there.
The fuel systems is new in both sleds: all lines, pumps rebuilt with kits and new impulse lines. Carbs are rebuilt once a season.
Can the enrichment plunger go bad? Do they wear out? Maybe try dropping it down further as an adjustment? Are there any hidden o-rings in there?
No O rings, but there is a neoprene gasket on the bottom that can go bad. They can get a wear groove in them and not seal properly. You can also get some debris in there from time to time, which prevents the plunger from sealing.
It's very possible that your jetted too rich. Rich jetting will really make starting in the summer iffy.
I would adjust the enrichment plunger so that it has no slack, and then go down one size on the main jets to see if that helps.
When it's winter and you can run it, do a plug chop by finding a nice long straight stretch. Pin the throttle for about 1/4-1/2 mile, then without removing your hand from the throttle, kill the engine and coast to a stop. Pull the plugs. If the plugs are black, you can safely jet smaller. Appropriate jetting will give a cardboard brown color to the insulators. Too lean will give light or white plugs. It's always better to be a bit rich than too lean!!
Dan,
I'm rich on both sleds. I went up one size on the main in each. On the sticker on the belt guard, it says to go one size up if using fuel with ethanol in it.
I'll pull the plunger and inspect the carb body and plunger for wear. Who knows...maybe something is causing the issue there.
Bear,
I was at 120psi in each cylinder a year ago. I put maybe 12 miles on the sled this winter. But still, can't hurt to test again.
I adjusted the plunger so it's dropping as far down as it possibly can. Still difficult to start. Took a lot of pulls. Plugs are black too. So it's rich. Any thoughts from here? Compression is good. Just a tick under 120 in each cylinder.
Pull the plugs, turn off the fuel, pull the cord about 8 times. Do you notice a mist coming out of the spark plug holes?
Maybe your fuel pump pulse line is leaking? Pull the pulse hose off and see if there is any fuel in it at all. If so, rebuild/replace fuel pump.
It should be dry.
Other than that, I'd pull the carb apart and check the float level again, and also make sure the needle is sealing up by blowing into the input fuel line with the carb upside down. You can even do this with the float bowl off.
Great tips Bear. I'll pull the plugs and check for a mist. I'll also take a look at the impulse line. I put a rebuild kit in the fuel pump least season, but you never know.
I didn't even think of the float! I'll pull the carb and measure. I'm pretty sure the specs are in the manual...which are up north with the machines.
I'm still guessing it's jetted rich. Factory jetting is normally pretty rich to begin with, and with you adding a size for the alcohol-infested fuel we have to buy, plus the warm temps... I've had sleds that were so rich in the summer they wouldn't move if/when you could get them started. Jetting down solved the issue, just remember to jet larger when winter comes!
Gotta like EFI.... jetting changes are a thing of the past for me!
Yeah!
And on the float, with the bowl off and the carb upside down, use a piece of hose and blow into the inlet.
Move the float up and down by hand til you cant blow any and the float arm should be just level with the carb body, that's 'float level'!
I would drain the gas, clean the carbs, syc them, then wait till the first frost and then see what you got!
If you are still itching to do something, go through the skid!
Yep! Skid is on the list! I may bring that down south where my air tools are and I have a garage.
I'll probably adjust the carb this weekend. There's only one and it's pretty easy to remove. Getting it back on is a chore. It's tight between the airbox and the carb. Oh well.
4-5 pulls just now and no starting. Pulled the plugs. As you can see, they are wet.
Where can I get a new float needle and seat? Carb is a Mikuni VM-34. Pretty sure the needle or seat is the culprit unless there's something I'm overlooking.
So, now you have fouled plugs.
Leave them out and let it dry up the gas in the cylinder and when you try to start it again, do not use the choke and you may have to hold the throttle open a bit [or more] to get it started.
Before you go and try to replace the needle and seat ( you will still have to do this with the new one!)
Adjust your float to level!
Hose on inlet hold upside down.
Blow into the hose and lower the float until no air passes, this is your float level.
Now bend the tab until the float arm becomes 'level' with the carb body!
If it wont stop air flow, then replace the needle and seat!
That needle in the picture doesn't look very healthy on the edges. Might be just shadows. All 4 of the edges must be even and slide evenly into the seat.
The seat should also be perfectly round, so no matter which direction the needle is sitting, it won't rattle side to side.
The attached is a picture of a really bad one. Notice the hole is almost square.
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