858 big bore dropping a cylinder?

[kooter353]

Hey guys. I got a 858 big bore that pulls like a train at 8250-8300 for about 5-8 seconds, then it seems to drops a cylinder and only pulls around 6700. If I let off the the throttle and stab it again it will pull hard again for another 5-8 seconds????
Only maybe 150k on build. 13.5 head, new 100LL, new fuel filter, valves are clean, TPS was set a 1000 k ago? New clutch
Any ideas?
Thanks

 

[pfi572]

What elevation? Sounds like it's sensing detonation ?

 

[kooter353]

Just ditch bangin at 3300 ft.
Come to think of It, may be. I may have grabbed a jug of year old 50/50. I got new 100LL tday an will try.
Thnks

 

[kooter353]

Here's an update. Drained fuel tank and refilled with fresh 100 LL, cleaned & checked exhaust valves, checked value solenoid, cleaned spark plug caps, readjusted TPS and took her for a rip. Pulled real hard to 8250 for 8-10 seconds and then dropped to 6700, held it WFO for 5 seconds, then it pulled back up to 8250. If I let off the throttle when it dies and stab it again it will pull hard again to 8250. Did this at least a half dozen times and it acted the same each time. Same snow conditions, flat land. I'm at a loss! Please help.

 

[andrew3399]

Here's an update. Drained fuel tank and refilled with fresh 100 LL, cleaned & checked exhaust valves, checked value solenoid, cleaned spark plug caps, readjusted TPS and took her for a rip. Pulled real hard to 8250 for 8-10 seconds and then dropped to 6700, held it WFO for 5 seconds, then it pulled back up to 8250. If I let off the throttle when it dies and stab it again it will pull hard again to 8250. Did this at least a half dozen times and it acted the same each time. Same snow conditions, flat land. I'm at a loss! Please help.

What are you running for clutch weights? Thinking you need to throw more weight at it. Thinking it's hitting 8500 rev limit before the gauge is reading it dropping you down in rpms.

 

[dpolacik]

I would Guess a weak injector as My 13 Pro did the exact same thing.
Was over 2000 "events" in the computer when checked but no codes given.

 

[kooter353]

Thanks. Runnin Roosters. 68.78, but i don't think it is an over rev prob. It pulls 8250 for about ten seconds without gainin any r's an the tach should read by then?
I guess ill take er in to the dealer an get checked. Could be an inj. It is not throwin any codes that i can see.

 

[shop quad]

What fuel numbers are you running? I hope to have my 858 together this weekend and do some testing. I read another post that they were up to 74 gram weights and still hitting the rev limiter, also running lower elevation. I'm at 1200-2000 feet.

 

[kooter353]

Runnin fuel numbers from SPS. It is set up for 5000-8000 ft, but it is not fine tuned yet. Now I got this prob. @#$%!!!!!

 

[MarkCos]

Fuel filter ??
maybe cant keep up with demand cuz full of shxt

sorry / u put new one in ??

 

[kooter353]

New fuel filter. Could it be a clutch prob? Rev to fast and tach not reading? It will flash to 8400 the odd time. I need more top end rpm tho. Only pulling 8250 and should be 8450 with the big bore down here on the flats. How do achieve this?

 

[PEAK SEEKER]

I had (keyword had) an 858 last year. Slight cold seize or something along that line combined with possibly poor installation at Cervus in Pincher Creek and it went boom 200 km after I bought it. Wore a cylinder and started with the piston slap and then eventually cracked a cylinder.

I must say, when it did run well it was phenomenal. But to drive 8-12 hours to get to the mountains just to crack a cylinder makes a guy awful sad.

Talk with Trevor Rhodes (goes by Rhodesie on S & M) I'm sure he can help you out. He did all the work on my sled after it blew up and it's been running flawlessly since then. He deals with the 858's a fair amount and has one himself.

I hope you can get it dialed in, they're a ton of fun.

 

[kooter353]

Thanks. I put in Another gram and a half in the centre of my Rooster weights. The heel is loaded to the max. Tip is MT. Total of 69.74 g's on my reload scale. That is just over 1gm more total. Hope t get er out for a rip tomorrow see what that does

 

[Timber_12]

Any update on this? My Carl's cycle 900 is doing the same thing. Although not always. Just when I really need it to make power.

 

[Rhodesie]

just for the hell of it load the weights more and see what it does. my roosters are set at 72g and ride at 5500+. long pull hanging at 8350-8400 rpm. if that doesn't help pick up some new Polaris spark plug caps, give the wires a slight haircut, dieletric grease the wires and screw on the new caps. vibration can break the copper wires where the cap screws in. keep the wires tie wrapped together and tie wrapped to the power valve hoses so they don't shake so crazy.

 

[kooter353]

just for the hell of it load the weights more and see what it does. my roosters are set at 72g and ride at 5500+. long pull hanging at 8350-8400 rpm. if that doesn't help pick up some new Polaris spark plug caps, give the wires a slight haircut, dieletric grease the wires and screw on the new caps. vibration can break the copper wires where the cap screws in. keep the wires tie wrapped together and tie wrapped to the power valve hoses so they don't shake so crazy.

Well if I look back into my long lost memory banks and my ****ty notes, I remember that I actually had it up to 70.48 g's @ 6000-6500 ft and it would not pull over 82-8250, so I pulled the weight back to just over 68. I screwed up my elbow and didn't ride all last year, and am just getting into it again now. So now I think it was an over rev condition and I weighted up to 69..62 g's and hope t my prob goes away.
I was still tuning the last ride when I screwed my elbow, so not sure even on fuel numbers yet.
I'm still waiting for an opportunity to try it again to see if this helps.
What fuel numbers are you running at that altitude? I'm runnin the 858, 13.8 head on 100LL, stock pipe, an reeds with a cold air intake and venting.
Current clutching is a balanced primary with a slp purple/black spring and one shim to eliminate bind. Rooster weights with heel loaded as heavy as possible, 2grn, 2 thick an 2thin washers....centre is loaded w/1 grn, 1 thick, 1 thin washer....tip is mt for a total of 69.62g's on my reload scale.
62-42-40 helix with a 162/340 spring and a delron.
3'' x 163'' with avids and stock gearing. I weigh 190? w/gear.
I'm hoping my cut out goes away with this clutching so I can get back to tuning.
Your help is much appreciated, as I hear that you da man and have this kit rockin.
Thank you.

 

[kooter353]

I have not tried changing the plug caps yet, but they are clean and snap on good. they are tied up well, so shouldn't vibe bad.
Just goin t order an A?F guage to get the tune spot on. What would you suggest for numbers o that? 13.5 WFO?
Thanks.

 

[06 Dragon]

I had gremlins similar to that on my '12 turbo pro. Run and drop a cylinder than light up again on occasion. Frustrating as heck.go back and get the back up sled. I have to agree with the injectors. Changed mine out. Seems better. Have not had it out to elevation yet. Definitely runs better at 3200 - 3300ft now. Make sure to change out the injector harness as well not just the injectors.

 

[shop quad]

I have my 858 together now and definitely needs attention to get bugs worked out. 3/4 throttle it falls on It's face like you hit the kill switch. I'm at 1200 for elevation. If I find why it's doing this I will definitely post it

 

[Rhodesie]

Well if I look back into my long lost memory banks and my ****ty notes, I remember that I actually had it up to 70.48 g's @ 6000-6500 ft and it would not pull over 82-8250, so I pulled the weight back to just over 68. I screwed up my elbow and didn't ride all last year, and am just getting into it again now. So now I think it was an over rev condition and I weighted up to 69..62 g's and hope t my prob goes away.
I was still tuning the last ride when I screwed my elbow, so not sure even on fuel numbers yet.
I'm still waiting for an opportunity to try it again to see if this helps.
What fuel numbers are you running at that altitude? I'm runnin the 858, 13.8 head on 100LL, stock pipe, an reeds with a cold air intake and venting.
Current clutching is a balanced primary with a slp purple/black spring and one shim to eliminate bind. Rooster weights with heel loaded as heavy as possible, 2grn, 2 thick an 2thin washers....centre is loaded w/1 grn, 1 thick, 1 thin washer....tip is mt for a total of 69.62g's on my reload scale.
62-42-40 helix with a 162/340 spring and a delron.
3'' x 163'' with avids and stock gearing. I weigh 190? w/gear.
I'm hoping my cut out goes away with this clutching so I can get back to tuning.
Your help is much appreciated, as I hear that you da man and have this kit rockin.
Thank you.

when i get everything together i will post it on here. mine is a 12 163