REAL STRANGE PROBLEM

m8magicandmystery · Apr 21, 2018

OK folks...hope someone can help me. My engine turns over extremely tough and if im lucky enough to get it started it runs fine all day and starts warm but thats only if im lucky enough to get it started and even in plus 50F she is a monster to turn over...and this problem started a year ago and this unit has very few miles.

I take the belt off...no difference...i take the starter recoil off and wrap a rope around hub and still the same.
I have removed power valves and pipe and still the same.
If i remove one plug at a time still the same but with a plug removed from each cylinder then she rolls easy.
The pistons and cylinders are in awesome shape from what i see through the plugs\powervalves and exhaust.
I have never blown a belt on this machine but is it possible still my crank ended up out of phase..?? any help appreciatted..

summ8rmk · Apr 21, 2018

Stock primary clutch or P-85?
Lighter clutch makes it harder to pull over.

m8magicandmystery · Apr 22, 2018

its a stock clutch with the thunder cover upgrades and adjustable weights...all seems fine...its not just hard to turn over...its a real tug and its a chore to get over center...but i have done nothing to change my compression...and she rolls easy with the plugs out...and when it is lucky enough to start it runs fine for hours and my egts and air/fuel and temps are in the zone. I am possibly going to put back the stock recoil hub that bolts onto the mag as i had put on a bdx titanium a couple years back and maybe out of round or something...don;t think its a bent connecting rod as all looks good. Its real strange...pulls hard like pulling up a deep well pump with a 3/4hp pump 100 feet down..

MountainCat1 · Apr 22, 2018

I'd pull the recoil starter housing to see if something is binding or loose. My 2 cts.

mbcat · Apr 23, 2018

Tough to turn over

You have a bdx oil delete eh? Could the shaft be seizing?i have an old f7/800 rktek with bdx oil delete & out of the blue it almost stops when trying to pull it over. It runs killer though.

tjcatman · Apr 23, 2018

oil

What oil are you using? I used to use Amsoil in my sled and it was hard as hell to pull over when first starting. Of course that was a 990 kk and not a 800 but the oil when cold was really gummy. Good luck

m8magicandmystery · Apr 23, 2018

the oil is fine...and outside temps above 50...i have the recoil off as i thought under load the rope was "wedging" in the pulley..but no such luck..and if the oil delete shaft was an issue i would expect it to turn over tight even with the plugs out but it rolls easy with the plugs out....but with one plug in she rolls hard...both plugs in its a friggen tug of war...oh well i will tinker this weekend some more ...lol..what a mystery though..

summ8rmk · Apr 23, 2018

Easiest way to solve that ........

Trade it in on an Alpha.... lol

89sandman · Apr 23, 2018

Any sign of excessive fuel coming out of the spark plug holes when you pull it over with the plugs out? Seems like you are getting too much compression and if the float or needle and seat in one or both of the carbs is leaking fuel into the engine when it sits this could raise the compression. I'd do a compression test first thing.

Betterview · Apr 24, 2018

You need a new recoil, had a similar problem in the past on a 600 that began to pull over stiffer than an 800. As an aside it started poorly because of the slow labored pull.

01ZRTCAT · Apr 24, 2018

Is this a stock motor, or the Big Bore in your sig?
Is this a new problem?

m8magicandmystery · Apr 24, 2018

this is the bigbore...but its been in for years...and its efi and no fuel hydraulic issue...i am thinking possibly the recoil hub that is mounted on the mag could possibly be out of round and when the dogs catch it may be oscillating and tightening against the recoil housing on the dogs etc...i am going to inspect very closely this weekend and given that the hub is the BDX lightweight hub it may have finally had an issue...i still have my old one i can put on..

m8magicandmystery · Apr 24, 2018

01ZRTCAT said:
Is this a stock motor, or the Big Bore in your sig?
Is this a new problem?

started slowly over the last two seasons..

snowmobiler · Apr 25, 2018

maybe its just older and weaker.LOL

m8magicandmystery · Apr 25, 2018

it would be me older and weaker...haha

KMMAC · Apr 29, 2018

Oil build up?

I've wondered about this,, is it possible that there is oil residue built up in the ring lands forcing the rings to be expanded causing the rings to be tighter in the cylinders?

mbcat · Apr 30, 2018

I could definitely see that with stock oil pump & horrible apv/glue! But he's got pump deleted premixed

m8magicandmystery · May 3, 2018

it turns over easy with the plugs out so i don;t think its oil behind the rings.I see some weird wear marks on the hub that fastens to the Mag but i can;t find my stock one yet to put on so i may put this titanium one in a lathe and remove some materiel.What i think is possibly happening is with the plugs in and with compression that when i pull the cord there may be enough play in the recoil that it walks forward and i am actually pulling the recoil in and against the hub much like energizing a brake shoe. I think my stock hub will have more clearance when i find it to try but my recoil does not be appear to be worn out enough to be a problem unless this titanium hub was in fact less less tolerance then the stock. But for certain marks indicate an issue but spring chores are interfering...lol..

sledbasher M7 · Jul 3, 2018

Hard pull

Is your recoil housing cracked. My Cutler crackes them all the time. If its cracked when you pull over might deflect and cause super hard pull. Check under heat tape. My center cracked as well as the mounting bolts tabs.
Just a thought

m8magicandmystery · Nov 12, 2018

well i finally found the problem....removed power valves...still same problem...removed dome heads and put stock head on and still same issue..removed clutch and still same issue..But what i did find strange that when i was doing head exchange even though cylinders in excellent shape was that the pistons seemed to be sitting a few thou off center at tdc..tight against exhaust side and more gap opposite...

I removed the cylinders and pistons and all in excellent shape EXCEPT the top ring on each piston would not float in the groove and was expanded out on one side and totally tight one exhaust side.

What i found in both pistons at the exact same spots was that the top ring land was just so slightly pinched so that the ring could not escape being flush with the land and extra protruded on the opposite side of the piston which given the connecting rod angle was actually making it extremely hard getting to roll over this section of the stroke even though it would with significant force.

The ring land damage was so so small it was almost not even noticeable..just a super small bow down of the ring land pinching the ring not even doing damage that can be seen to the piston or ring..

The pinching was done on two spots on each piston and was just in about 1/4 inch from each of the power valves outer ears.

The power valves showed at disassembly no signs of striking but as indicated the signs of damage anywhere was so microscopic.

I am possibly thinking that when the bigbore originally was done the clearance was on the edge for the power valve and that maybe my STMs which are bellow style maybe i had set to open a tad latter the should have been...but anyway i think the new style STMs are the answer and i am thinking of now possibly just throwing h/o cylinders/pistons and head on .

Anyway just like i said though...the existing parts are steller with just almost visible only microscopic pinches.

REAL STRANGE PROBLEM

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