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Enduro Engine 4 stroke (including EFI & Exhaust) 4 stroke engine, EFI, and exhaust discussion


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  #1  
Old 08-26-2016, 01:53 AM
Tafka Tafka is offline
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Default FSE 450 2005 idle misfire/stall when hot

Okay...i'm out of ideas.
I have a 2005 FSE450, last year rebuild, new crankshaft,piston,cylinder etc.
At one point, this year, in the middle of the forest, bike started to idle rough(misfire) and then stalls. Starts most of the time easy again and runs a little bit but then again, idle/low revs misfire and stalls if not given throttle.
High revs, everything OK. Some backfire when slowing down. Works fine when cold! but about 20-30min riding, engine getting hot, then the issues start.
Can't ride properly because stalls too often when riding slow forest trails.
Changed and adjusted TPS, new fuel pump, water temp. sensor, checked air temp sensor, fuel injector tested-good spray pattern, no leaks and flow rate ok.
Can't find any air leaks.
My next step would be change:
1) Ignition coil - i think i can find VW analogue (hell no i'm paying $200 GasGas "original" coil if i can get VW coil with $25)
2) Fuel pressure regulator? - PITA to find in Estonia :/
3) Pick-up coil? - does anyone know what should be the gap between pick-up coil and toothed wheel?

Any ideas?
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Old 10-17-2016, 12:43 AM
Tafka Tafka is offline
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Okay progress so far.
Managed to replace original ignition coil with 2013 Honda CBR coil.
Got a brand new fuel pump assembly with fuel regulator for testing.
Put 2007 MAP to ECU, made things little bit better.
But still after all of this, when engine gets hot, at low revs and sometimes when taking off it feels like engine starves and then pulls nicely. Higer revs, everything fine.
I start to suspect maybe leaking valve(seat)?
Out of ideas....
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Old 10-24-2016, 05:39 AM
Tafka Tafka is offline
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One more remark....when bike starts to misbehave and i pull over for couple of minutes, let the bike idle, and then start to ride again, it works okay for sometime and then starts to act up again.....so something over heats but what???
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Old 12-17-2016, 10:38 PM
mikethebike1127 mikethebike1127 is offline
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Have you checked the fuel tank breather??? Might be partially blocked causing a vacuum in the tank!!
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Old 12-31-2016, 09:02 AM
Tafka Tafka is offline
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No issues with the breather
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Old 01-01-2017, 05:25 PM
Nosedive Nosedive is offline
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Hello,

I know these Issues actually from my 03 FSE.
Please check the valve clearance.
Ex is fine, even about 40k Kilometers after repair.
Can't measure both In-valves, cold 0, think they won't close when hot.
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Old 04-17-2017, 06:01 AM
Yngvim Yngvim is offline
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Was looking at the ignition map and at 6000 rpm is the last value, is it running ok between 4 and 6000 rpm

EC 250 2001, FSE 450 2004
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Old 04-17-2017, 06:12 AM
Tafka Tafka is offline
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Bike runs great above idle...if i can hold the throttle up at least 3500-4000 rpm, then everything seems to run great. But riding tight forest trails and considering i don't have balls to ride with open throttle then the problems start. So rev range about 2000-3500.
Slipping the clutch a lot but even then i struggle....get the revs up,slip the clutch, clutch engages, revs drop a little bit too low and it starts to skip beats.
It's not like stalling because of the low revs...that's little bit different.
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Old 04-19-2017, 02:19 AM
Tafka Tafka is offline
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Anyone have any more suggestions?
Let's brainstorm....
What are the chances that ECU is bad? (then it wouldn't work at hig revs also...?!)
Too tight valve clearence? At the moment they are in spec (closer to the min. value) but maybe loosen them a little bit?
Crankshaft/connecting rod bearing f***d again? Symtoms are similar before i replaced the crankshaft/cylinder/piston but started suddenly and appear only when hot.
Decompressor spring too weak, so it starts to open exhaust valves at low revs? What are the chances of that happening? Decopressor looks working when moving it with finger but MAYBE somehow at low revs engages. How to check that?
Anyting else....?
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  #10  
Old 04-19-2017, 03:05 AM
Yngvim Yngvim is offline
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Does it matter what map you run?

EC 250 2001, FSE 450 2004
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