Newly developed bog/sled falls on its face

[Vern]

2020 alpha 800, owned since new, always has ran fine out side of the occasional little hiccup these ctecs are known for. Beginning of last season sled was running great, team clutch cracked and the sled sat for a month waiting for adapt parts. Got it back together and that’s when issues appeared. the rest of last season it would randomly fall on its face, like it dropped a cylinder, usually at an inopportune time, but would clear out and run fine again the rest of the day. This was not frequent, wouldn’t even happen on every ride. Finished out the season like that and put it up until fall when I started looking into it. Pulled the hood and put new plugs in, checked the tps which was in spec, towards the low side, but in spec and appeared to be moving smoothly, pulled apart and dielectric greased all the connections I could see. Put fresh gas and some sea foam. We finally got enough snow at the house to take it for a spin and it has now gotten more consistent. Seems to fall on its face for 2-3 seconds every time I mash the throttle from a stop or slow roll. Not just a hiccup, feels like you hit the kill switch and then pull it up again. After that it clears up and runs fine. Occasionally it will do it once I’m already at wot as well. It also back fired once today. Haven’t seen any codes flash. Anyone have any ideas? Have read about injector issues, but I feel that would be more severe. What symptoms do bad reeds cause? I’m trying round up a bore scope to look at those. Could bad spark plug caps cause something like this? The tops of the old plugs were quite worn from vibration.

Sorry for the long post, any suggestions appreciated.

 

[Old & slow]

I would start with bypassing the TSS, then unplug hand warmers, ignition, accessories etc. A broken or chipped reed should be more constant but you never know how its failed until its apart. Injectors are a possibility also, they could be sticking and working intermittently and you wont get a code. When you get a backfire typically if it is from the intake it's a timing issue and from the exhaust it's a fueling issue. To me it sounds like a TSS they act just like you are describing, best of luck and let us know what you find.

 

[Vern]

I forgot to mention the TSS has been disconnected since the sled was basically new. So that rules that out.

The one time I heard it backfire or pop was out the exhaust.

 

[Old & slow]

I would still eliminate all the electrical I could one at a time it costs only time and helps narrow down the problem.

 

[Vern]

I’ll definitely put that on the list of things to check.

 

[Vern]

So messed with it again a bit today. Checked reeds as best I could with a not so clear bore scope, but they appeared fine. Cut a bit off the plug wires and rescrewed the caps on to make sure they had good connection. Cleaned the map sensor with some contact cleaner while I had the hood off. Nothing fixed it so far. I did notice that it seems to get worse as it warms up. When I make the first few laps it’s fine then it will start to cut out once every time I mash it from a stop, then as it got warm it started getting to where it would cut out 2-3 times in a row then it will take off. I’ll try to post a video of it cutting out after it’s good and warm. It doesn’t seem to do it if you roll into the throttle, but it consistently does it if you mash it from a dead stop.

 

[Vern]

I’ve also read a bunch of stuff on faceyspace about to light of clutch weights causing a bog. Is that a real thing?

I don’t think that’s my issue where it seems to be temp related, but I am overreving a bit here at home at 4500ft where I’m clutched for 7-9000k where I usually ride. Is upshifting too quick a possibility?

 

[summ8rmk]

Airplane kinda ruined that video.
When taking off, were u feathering the throttle or, straight full throttle?

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[summ8rmk]

Over rev cut-out is pretty high. 8,600+?
I've hit 8,500 alot on the trails with no issues.
Polaris, on the other hand, will absolutely fall on its face if the engine revs to fast or to high.

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[Vern]

That was straight mashing it no feathering. You can hear it surge 2-3 times right at the beginning then take off. I don’t think it’s overreving and hitting a limiter, it’s only hitting 8300-8350 once it clears out and holds that fine. I was just wondering if maybe it was reving to fast or something right off the bat.

 

[Vern]

Here’s another video my brother took. Pic quality is garbage on my phone, but the sound should be there.

 

[summ8rmk]

Stare directly at the tach and see what its doing while this happens. A needle would be easier to watch... but we don't have those anymore.

If u have adjustable weights, add a bunch of weight or, if u have a lighter spring, toss it in there. Try to eliminate the possible over rev first.

Check fuel pressure at idle and WOT.


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[Vern]

Next time I have it out I’ll try and get a good look at the tach. I also forgot to try messing with electrical connections like old & slow suggested, but where it seems to get worse the hotter it gets I dunno if that would be it.

Unfortunately so far I’ve only got the one set of factory 59g weights and factory spring for the adapt. I’ve been looking to get adjustables but it’s hard finding any sort of info on clutching or what’s working for people on the adapt clutch.

What’s the best way to check fuel pressure? Do you gotta T into a line?

 

[dunatyk]

Vern,
I am in your area. I’m running an adapt on a 2019 with Bikeman Snyper weights. So far I’ve been happy with them. I have 2 other sleds with the team clutch with SLP magnum force weights in them. I’ve been happy with the SLP weights. I may buy a set for the adapt to try just for fun. Can you get ahold of a team clutch? If I was troubleshooting I would put a team back on to see if it helped the problem.

 

[Vern]

The slp weights are actually what I’ve been considering for the ease of adjustment. Might just have to pull the trigger on a set. Even if clutching is not the issue, I had intended on getting adjustables anyway once it’s running right. Unfortunately the only team I have access to at the moment is my cracked one. Might have to do some asking around.

 

[summ8rmk]

Not sure on ur seld , but i assume u will have to put an inline T for the pressure gauge.
Unless the crack is severe,
I would put the cracked primary on for a test in the field near the house. Real easy test. It shouldn't explode in 1/4mi. But i will not make any guarantees on that.


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[Vern]

I’ve been contemplating tossing the cracked team back on for a rip or two. From what I recall the crack is no more than 3/8”. I’ll have to see if I can round up all the team components. I believe I stripped it when I pulled it off, but it’s all around here somewhere.

 

[CB.8]

Vern

What is the side clearance on the belt. I chased ****ty shimming for years on a new cat clutch. When I replace it all my issues went away.

Also have you check the power valves and cables?

 

[Vern]

Vern

What is the side clearance on the belt. I chased ****ty shimming for years on a new cat clutch. When I replace it all my issues went away.

Also have you check the power valves and cables?

No idea on the side clearance, but it engages nice and smooth and low. Haven’t pulled the valves, but checked the cable length which was good, and they pull nice and smooth.

 

[Old & slow]

Vern I know you added some Seafoam not sure how much but maybe a real healthy dose is in order. If you have done that maybe a little 2 stroke oil in the fuel just for a little injector sliptivity. There is no way you got some old/bad fuel is there? Do you have a donor sled to swap parts with?