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Discussion Starter #1
So I rebuilt these carbs; I'm not an expert at them but I've done my fair share of carbs, new gaskets, new jets, etc. New throttle cable as well.

Sled only has 2600 miles, good compression.

Here is what I am experiencing: It has a high idle (2500ish), so I flap the choke lever and it settles back down, and I've read this is normal.

Off the line: Nothing. Does NOT really do much of a burnout, shoots a little pile sometimes but often times just... starts walking away, a few seconds later the acceleration really kicks in and at higher RPMs she rips pretty good (hits 75mph no problem and still pulls).

But... off the line, it's just embarassing. Pretty sure a well setup 370 would smoke this thing off the line.

What should I check?
 

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Idle should stumble when flipping the choke if the engine has warmed up. Carb slides synced after the cable replacement? Choke cable routed properly? Choke plungers closing all the way/choke cable freeplay? Reeds chipped or broken?

What does the clutch engage at? Broken Primary or Secondary spring? Correct belt? Wore out/glazed belt? Correct belt deflection? Is the secondary sticky and not closing all the way when coming to a stop? Brakes dragging?

That is the easy/free/cheap stuff to check.

Need to figure out if your problem is engine/carb or clutching/belt related.
 

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Discussion Starter #3
- If it's warm and I flip choke it will stumble and eventually die. If I flip it on for a few seconds it makes the idle more like 800rpm instead of 3000.

- Carbs are connected so idk how they'd get out of sync?

- I believe cables are routed properly, do you have a pic of correct routing so I can confirm?

- Not sure what you mean by choke plungers but I set up the choke cable to spec form the factory manual

- I don't think this model has reeds. The carbs go straight into the cylinders.

- Clucth engages around 4k ish maybe 4500?

- No broken springs

- Correct, brand new belt, has 75 miles on it

- I don't know how to check belt deflection?

- I am not sure about the secondary closing when coming to a stop

- Brakes are not dragging and bled a few days ago
 

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Discussion Starter #4
First video that shows my oil injection/carb setup and the work I've done to the sled:

 

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Here is the second video that shows my clutch setup in detail:

What do your spark plugs look like and what brand/ part #? Your sled should have reeds. Maybe you can remove the carbs and try to look at the tips for damage/ excessive wear?
 

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Discussion Starter #7
I can get pics tomorrow, but where are the reeds in this sled? I know where they are on my other sled, right behind the throttle bodies, but this isn't like that at all.





Really don't see where reeds could go at all. Carbs bolt up to head. That's it.
 

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What do your spark plugs look like and what brand/ part #? Your sled should have reeds. Maybe you can remove the carbs and try to look at the tips for damage/ excessive wear?
If you have excessive belt deflection, it will start out in 'second ' gear. Put a straight edge along the top of the belt, on top of both clutches. Using a ruler, push down on the center of the belt. Once all the deflection is taken up, take a reading off your ruler. Should be like 1"-11/2. Check the sheave to belt clearance [primary clutch]. You can use feeler guages or a wire type spark plug gap guage. Should be . around .010-.020". What did you do with the original 9 post clutch?
 

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Discussion Starter #11
Third video, shows the sled up in the air, revving, and clutches working:

 

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If you have to flip the choke to get the idle down, then that would seem to indicate a lean condition, as adding more fuel gets it back in line. I believe the flat slide carbs have a fuel screw for idle tuning, so you may need to adjust that to enrich the idle.

I didn't view any of the videos, but in that clutch video the belt looks low in the secondary. The top cogs on the belt sould be above the clutch sheaves at rest. You may have to remove some shims from the secondary to get the belt deflection into spec.
 

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Discussion Starter #13
Alright, since this is still about clutching, I figured I'd post the update here instead of my overall build thread:

1. Engine movement. I have no snubber at all, which is why my engine is moving so much. I ordered one and that should probably help a lot; you can see in my vids when I try to launch the whole engine moves which INCREASES belt deflection a huge amount.

2. Belt deflection. I noticed I have almost 1.75" of belt deflection. From what I gather, I need to 'tighten' the secondary by bringing the sheaves together. This involves removing the secondary, disassembly, and removal of some shims. I pulled the bolt out, and I swear I got it to move 1/4" by hand outwards, but then it stopped. I've tried:

  • Hammers
  • Picklefork/Prying
  • Soaking in Kroil (both sides)
  • Torch
  • Air hammers
  • I put the belt back on, suspended the sled, revved up the track and hit the brakes a few times
  • Now I have the sled jacked up under 1 a-arm and I'm spraying kroil in the end of the secondary every few hours in hopes of soaking it off.

I might give up on the secondary, but I don't get why my belt is riding so low in it. I am using a brand new belt, factory correct for this sled. Maybe the installation fo the engine snubber will make a huge difference?

Cheers & thanks for the help so far!
 

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Alright, since this is still about clutching, I figured I'd post the update here instead of my overall build thread:

1. Engine movement. I have no snubber at all, which is why my engine is moving so much. I ordered one and that should probably help a lot; you can see in my vids when I try to launch the whole engine moves which INCREASES belt deflection a huge amount.

2. Belt deflection. I noticed I have almost 1.75" of belt deflection. From what I gather, I need to 'tighten' the secondary by bringing the sheaves together. This involves removing the secondary, disassembly, and removal of some shims. I pulled the bolt out, and I swear I got it to move 1/4" by hand outwards, but then it stopped. I've tried:

  • Hammers
  • Picklefork/Prying
  • Soaking in Kroil (both sides)
  • Torch
  • Air hammers
  • I put the belt back on, suspended the sled, revved up the track and hit the brakes a few times
  • Now I have the sled jacked up under 1 a-arm and I'm spraying kroil in the end of the secondary every few hours in hopes of soaking it off.

I might give up on the secondary, but I don't get why my belt is riding so low in it. I am using a brand new belt, factory correct for this sled. Maybe the installation fo the engine snubber will make a huge difference?

Cheers & thanks for the help so far!
Don't be to surprised if the secondary does not come off. I had a 1999 ZL440 that was stored out doors and no amount of heat or force would get it off! You might be able to 'tune' your clutches by selecting a belt that has the dimensions you need. What part # belt are you using [did I see a -020?], and how wide is it now? No sense shimming your clutches for a worn/wrong belt.....

Did your torque stop break off? I have a Pantera, and it requires a lot of disassembly to replace. I made a two piece affair that pops right in.
 

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Don't be to surprised if the secondary does not come off. I had a 1999 ZL440 that was stored out doors and no amount of heat or force would get it off! You might be able to 'tune' your clutches by selecting a belt that has the dimensions you need. What part # belt are you using [did I see a -020?], and how wide is it now? No sense shimming your clutches for a worn/wrong belt.....

Did your torque stop break off? I have a Pantera, and it requires a lot of disassembly to replace. I made a two piece affair that pops right in.
Also, what is your belt to sheave side clearance? [primary clutch].
 

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Discussion Starter #16
I looked into that but not quite sure how to measure it. Pretty confused.
 

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I looked into that but not quite sure how to measure it. Pretty confused.
In order for your clutch to do its job, the belt has to fit properly. Belt deflection and belt side clearance are key. Belt side clearance is the clearance between the belt and the sheave [primary clutch]. If you had no clearance, your sled would not stay put at idle. If you have too much, your engagement may be harsh and it may feel like you are starting in 'second gear". Here's how you measure it: Remove all belt deflection [make sure belt is tightly wrapped around primary at rest] Try to slip feeler guages between the belt and one of the sheaves. Should be around .010-.020" Adjustments can be made by using a different width belt, or shimming your primary clutch [if you can do so].

Your sled has reed valves, if it does not or they are worn /damaged, any tuning efforts on your clutch/carb are a waste of time.
 

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Discussion Starter #18
Okay, I'll check it. I ordered an engine snubber, and I think that is goign to make a HUGE difference. With no snubber, I was getting a ton of movement and when the clutch tried to grab the engine would move towards the secondary, which loosens the belt, makes it worse, etc.

I'm wondering if just adding the snubber will make a significant difference by itself.

Reeds look pretty good, pulled them a couple days ago, one side is perfect, other side 5 petals are perfect and one has one TINY chip. Not worth replacing since they are so easy to get to, for now.
 

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Okay, I'll check it. I ordered an engine snubber, and I think that is goign to make a HUGE difference. With no snubber, I was getting a ton of movement and when the clutch tried to grab the engine would move towards the secondary, which loosens the belt, makes it worse, etc.

I'm wondering if just adding the snubber will make a significant difference by itself.

Reeds look pretty good, pulled them a couple days ago, one side is perfect, other side 5 petals are perfect and one has one TINY chip. Not worth replacing since they are so easy to get to, for now.
Hate to burst your bubble, but my torque stop was broken for a long time, never knew it. Replacing it didn't change a thing [ that I could feel]. But go ahead and put one on, it will help [at least] save your belt from wearing. Have fun putting the OE one on!
 

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What size main jets are in it? It can make those flats slides bog. Have you had the secondary apart? Almost sounds like the secondary cover was not twisted when the cover was re installed. Taking off in second gear. Take the secondary off and be sure the cover was twisted and then pushed down and the nuts put on the cover.
 
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