Has anyone had to do any work to the cylinder on their 450? I think my bike needs a top end and im concerned cylinder work will be needed. Anybody have any experience or a preference on where to get parts from?
fx 450 top end
- Thread starter jgilbert164
- Start date
How many hours?
Its impossible to tell how your cylinder will look until it is torn down. I recently put a top end in my FX450 at 300 hours because the oil ring had started to go and it was burning a little bit of oil.. Inspected everything, valves looked great. Actually had to re-shim the valves using new oem sized shims. Mine had dimples worn into the shim (soft shims?) and the they loosened up rather than getting tighter.
I went with a Wossner piston kit ordered to fit my cylinder (They sell 3 sizes. you have to measure your cylinder in multiple places up and down the bore to check for wear. It might look good, but be ovaled out or tapered.) The piston kit ran about $180 gaskets another $40-50 and a couple days of work as I pulled my motor out of the frame and spent some time cleaning everything really well and sent the frame off for powdercoat at the same time.
Why do you think you need a top end? Low compression? Smoking?
Its impossible to tell how your cylinder will look until it is torn down. I recently put a top end in my FX450 at 300 hours because the oil ring had started to go and it was burning a little bit of oil.. Inspected everything, valves looked great. Actually had to re-shim the valves using new oem sized shims. Mine had dimples worn into the shim (soft shims?) and the they loosened up rather than getting tighter.
I went with a Wossner piston kit ordered to fit my cylinder (They sell 3 sizes. you have to measure your cylinder in multiple places up and down the bore to check for wear. It might look good, but be ovaled out or tapered.) The piston kit ran about $180 gaskets another $40-50 and a couple days of work as I pulled my motor out of the frame and spent some time cleaning everything really well and sent the frame off for powdercoat at the same time.
Why do you think you need a top end? Low compression? Smoking?
ok, thanks for the info.
I think it needs one because:
1- when running and I rev on it I see a touch of white smoke puff out the pipe
2- it turns over for a long time before it starts unless throttle is applied
I had the tps checked and it is spot on, doesn't matter if the air filter is on or not and the idle screw doesn't effect it.
Once it starts, which w/ throttle applied it turns over for like 3 or 4 seconds then starts, once running it seems fine.
I think its got around 140 hours. not sure tho. So I figured it needs a top end. but if the starting issue is normal for these then im not tearing it down yet.
I think it needs one because:
1- when running and I rev on it I see a touch of white smoke puff out the pipe
2- it turns over for a long time before it starts unless throttle is applied
I had the tps checked and it is spot on, doesn't matter if the air filter is on or not and the idle screw doesn't effect it.
Once it starts, which w/ throttle applied it turns over for like 3 or 4 seconds then starts, once running it seems fine.
I think its got around 140 hours. not sure tho. So I figured it needs a top end. but if the starting issue is normal for these then im not tearing it down yet.
Joined Aug 2009
1K Posts | 346+
Charters Towers, Australia
Mate I would leave the top end alone for now, there are examples of these bikes doing 300-400 hours without a problem. I'd say the smoke is possibly from the sump being a bit to full and oil entering the intake tract via the blow by hose. As for the slow starting you could have a range of issues from a weak battery to a dodgy auto decompressor. What year is your bike mate ?
its a 2010. The prev owner had routed the crank breather away from the airbox.
Not sure if its the batt, i put it on the tender, and it charged full in about 10 min, but doesn't mean the cc amps are not low. I'll try it w/ a boost box. Good idea.
I think I agree w/ you on the top end. I think i'll just run it.
Not sure if its the batt, i put it on the tender, and it charged full in about 10 min, but doesn't mean the cc amps are not low. I'll try it w/ a boost box. Good idea.
I think I agree w/ you on the top end. I think i'll just run it.
Sounds to me like its starving for fuel.. I would start by checking fuel pressure should be around 50PSI. If the pressure is good, maybe dirty injector.
Has the in tank fuel filter ever been replaced?
Has the in tank fuel filter ever been replaced?
yes, not that long ago the pump and filter were replaced w/ the new ktm parts. I finally got to ride it a little bit. once it starts, it runs perfect. Idle, top end to the limiter, no issues. even when hot it wont restart unless a touch of throttle is applied or it will turn over for a good 5 sec or so. Has anybody ever messed w/ the little stop screw that is on the side of the throttle body by the cable cam cover?
I would check your TPS (Throttle Position Sensor) settings first. You shouldnt have to touch the throttle to get the bike to start.
The throttle plate stop that your talking about should be factory set. I have never heard of anyone needed to adjust it, but I suppose it could be closed a hair too much if you need to turn the throttle some. I would still check the TPS first though because the ECU is programmed so that if there is any throttle input it wont start. If you need to give it throttle to start is sounds like your bike is under the low limit for the TPS sensor. I cant remember off the top of my head, but if you apply 5VDC to the sensor and the throttle is closed I am pretty sure you should get .580-.595 vdc out of the signal wire if it is correct (I might be wrong on that spec, it would be best to look it up)
The throttle plate stop that your talking about should be factory set. I have never heard of anyone needed to adjust it, but I suppose it could be closed a hair too much if you need to turn the throttle some. I would still check the TPS first though because the ECU is programmed so that if there is any throttle input it wont start. If you need to give it throttle to start is sounds like your bike is under the low limit for the TPS sensor. I cant remember off the top of my head, but if you apply 5VDC to the sensor and the throttle is closed I am pretty sure you should get .580-.595 vdc out of the signal wire if it is correct (I might be wrong on that spec, it would be best to look it up)
I had that checked. I don't have any dealers near me so I shipped it to action ktm in decatur tx, they tested it and even threw it on a diff bike and it was fine they said.
The tech there said it was likely the top end. Not sure if they were trying to sell me a top end job but it didn't make sence if its in spec.
The tech there said it was likely the top end. Not sure if they were trying to sell me a top end job but it didn't make sence if its in spec.
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