Bog at engagement RPM

squidbrain · Feb 19, 2019

I Need some help. I am experiencing an intermittent bog at engagement RPM. gone after 4100 RPM. Machine makes power, see 8300 on tach. It only seems to happen after the machine has warmed up and after I ride a few miles. Its a '17 800 assault with an NSP clutch kit. there is about 2000 miles on the kit. 4000 on the sled. New belt about 800 miles ago. I have been more aggressive lately on the throttle playing around in deep and hilly terrain this year. I've done some reading on the subject and talked to SLP (cause I have a silencer), waiting to hear back from NSP. I'm being swayed to either put the sled back to stock and trying or could it be one or both of the clutch springs are getting soft? Its been progressively getting worse over the last couple weekends. Does this sound like it could be a clutching issue?

xpspenziv · Feb 19, 2019

A couple things you can check.
Belt deflection. Loose can make it a little sluggish on the bottom.

Usually if your pri spring is dieing, engagement will happen at a lower rpm. If secondary is dieing, shifts out sooner. Sluggish.

When was the last time your primary was inspected? Bushings, button shims replaced? Is there alot of slop in the weights?

squidbrain · Feb 20, 2019

Haven't looked at it much this since the beginning of the season. Will check tonight. If I don't see anything obvious I'll go back to stock clutching and see what happens. Thanks.

Wheel House Motorsports · Feb 20, 2019

Getting bogs like that are easily casued by worn springs and loose/worn belts. I generally replace springs at the least every 1000 miles. Cheap insurance and that and a super narrow/worn belt and loose deflection can cause poor performance and bogging when pinned out of the hole.

diamonddave · Feb 20, 2019

The 2 times I have seen bogs at tip in throttle both times sleds have had defective aftermarket silencers; baffles flopping around in the cans. I would try stock silencer. With your mileage, your clutches, springs could be worn out as well.

xpspenziv · Feb 20, 2019

I've seen a rats nest up inside a can. It caused the same issues. Springs are $25 each. Bushings are cheaper and easier to knock out and push in. There are lots of guys on here that can and will point you in the right direction.

The weights shouldn't be sloppy side to side. If you have a spring psi gauge, you can check the springs. Installed ht and compressed.

squidbrain · Feb 21, 2019

Pulled everything apart and even went back to stock clutching and stock silencer. still boggy below 4000 RPM. almost like its getting too much or not enough fuel. sounds like crap until 4100 rpm. Dealer had it yesterday and adjusted TPS and throttle cable and relearned valves. checked fuel pressure and it was good. I will add that its been hard to start when cold. Fires up and shuts down. will keep doing this unless I give it and blip the throttle for about 30 seconds. Once warmed up it idles fine. nothing they did made a difference. I wonder about the fuel sock? perhaps its torn or something and sucking too much fuel at low rpm? I've been very cautious when I fill it up. Even use a filter funnel every time.

squidbrain · Feb 24, 2019

I did a compression test and got 100 PSI cold (water temp was 56) on both cylinders. Is this a bit low? Rode yesterday and down low she she bogs but past 5000 rpm seems to clean out and gets up and goes 95-97mph. Its as if its dropping a cylinder or running pig rich. If the top end was on its way out would I still get that really low boggy noise when rpm drops down to around engagement?

ripnit · Feb 28, 2019

Have you pulled and checked Reeds.....4000 miles there's a good chance the tips are chipped

squidbrain · Mar 1, 2019

Sleds at the dealer. Polaris came back after a week and said to change injectors. Now I wait another week to find out if that's the problem. Winter is too short for this ****. At least its under warranty.

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Bog at engagement RPM

squidbrain

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diamonddave

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