Re: KTM RC 390 Ownership Experience

VJ and team,

I have already dropped my bike off at the SVC just to ensure I don't take any risks. I'll be present when they are opening up the head and probably the cylinder.

So some help:
1. What are the tell tale signs of valves/valve seals being out of spec?
2. How do I identify leaks across piston rings?
3. How do I check the condition of the piston and bore?

I understand these are a lot of questions, but your help is greatly appreciated.

Thanks
Avinash

Re: KTM RC 390 Ownership Experience

How many kms have you done on this bike?

Re: KTM RC 390 Ownership Experience

White smoke during cold start is normal for 390. There shouldn't be any white smoke after 20-30seconds.Thanks s1d, will try this.

Re: KTM RC 390 Ownership Experience

Update on the fuel bar issue:
Went to the service centre to get it checked. The guy opened the tank and inserted a strip of metal with a hook at the end, which would raise the float to the top. The float went all the way to the top, but the top bar was not glowing even after waiting for some time. They suggested to change the fuel pump as you correctly said that it comes as a composite unit and no repair can be done on the part as there is some pcb attached to it.
I had gone to a valley trip 1.5 years back and the petrol pump attendant bent the metal strips that prevent the nozzle from entering the tank. Nothing happened then and I was careless enough to ignore fixing it. The subsequent petrol fills were such that the entire nozzle entered the tank as it normally happens in bikes.[emoji17]
Now my question is, did the repeated entry of the nozzle screw up the float? If so, then why is the top bar not showing? Neither could I feel any resistance from the float while pulling it up with the metal rod/strip. Is there any sensor at the top?
The svc has quoted 4900 for the part and 375 as labour but the part is not available currently, hence I could not take a snap of it. What are the probable workarounds for this?

Re: KTM RC 390 Ownership Experience

Update on the low oil pressure issue.

The engine was disassembled today.

1. Valve seals need replacement.
2. No scoring of the cylinder walls.
3. No scoring on the piston.
4. Piston rings need replacement.
5. Valves for some reason have to be replaced. I don't know why. It was caked with carbon on the stem side.
6. Timing chain and chain tensioner needs replacement.
7. Asked them to replace the coolant pump seal while they were at it.

Anything else worth replacing now that the engine is wide open?

The bike has been maintained really well. Coolant and Oil levels, always checked and corrected. No highrevs while cold. Oil changes every 2-3 track days. (Total of 5 track days and 2 oil changes). Never turned off on a hot engine.

The question is if this engine head work is routine at 25k for a rc?

Thanks
Avinash

@faysal, 25k on the odo.

Re: KTM RC 390 Ownership Experience

Yeah, KTM is comparatively unreliable than other brands.

Re: KTM RC 390 Ownership Experience

The pressure from the fuel nozzle can sometimes ruin the sensitive sensor if inserted deep, not happens all the time, but they happen. On the other hand, it's due to the fuel itself gumming up -- call it bad fuel, all these reduce the life of the electronics. One last revival method is to remove the pump, clean the sensor board, or the printed circuit board by applying contact cleaners and see if it helps. If it's still the same, I'd recommend you to get a new pump, or if you can, a used one. A used one can be sourced at half the price.

The float is on the side of the tank. Though it's well concealed, age, vibrations, bad fuel, constant nozzle pressure, and finally bad luck everything comes into play here. Try the above method and keep your observations posted.

Sweet! Exactly as I predicted earlier. Now that you have the major part ticked off, the piston and the cylinder. It's a good idea to replace your valves when the valve stem oil seals are replaced, as they can cause a new seal to go bust again due to roughened surface, so it's best to replace both the valves along with the seal replacement. Secondly, rings replacement is common. It could have been lot worse, replacing rings is normal. It's also advised to get the timing chain, tensioner replaced.

Things to be looked at this stage/replaced

Make sure your shims are replaced.
A decarbonization procedure of your head and piston can be done now. Basically removing excess carbon the top of the piston and the head i.e where the valves are.
Good that you've insisted on them to replace the water pump seals. Removes the guess work later.
Clean your throttle body and injectors.

Check your clutch bearing for any play, if it has play, it's recommended to replace the bearing.
Also make sure you check your clutch plates, can be considered for a replacement depending on the condition.

Keep your observations posted,

Didn't see your earlier post, sorry about that.

Cheers!
VJ

Re: KTM RC 390 Ownership Experience

Please correct me if I am wrong, why exactly should the Piston rings be replaced?

There is no scoring issue on piston/cylinder, there is no oil burning inside the cylinder as mentioned or any oil deposits accumulation on the head/spark plugs/valve base. If compression check passes then current rings should be fine with whatever is running.

Any other specific reason for only the piston rings being replaced?

Re: KTM RC 390 Ownership Experience

Piston rings can sometimes expand not having enough tension in them, leading to engine oil consumption and compression loss. Remember it's the rings that hold the compression in place. Those little rings have to take in 3x the load, size for size.

Cheers!
VJ

Re: KTM RC 390 Ownership Experience

Its customary, if you take the head off you'll have to replace Ring's as well as other gaskets and seals, saves you a lot of moolah and trouble in the future.

We did just the same when rebuilding a fellow xBhpians CBZ that's under my care.

Re: KTM RC 390 Ownership Experience

Thanks for the info will dig some more info on this, I'll keep in mind to check on the rings separately next time, I've always stayed away from doing things in parts when it comes to piston/cylinder.

Always went for a full kit replacement for piston set and/or cylinder and crank rod instead of only replacing in parts only the piston, sleves, rings, crank rod separately. My mechanics have also suggested to stay away in replacing only one parts a time in a way it gives me more peace of mind because of the reason a factory machine inserted and sealed piston rings are far more reliable than a manually done one.

You cannot entirely say they are completely unreliable, in a way I see it the kind of usage these KTMs go through for the performance it offers, I'm actually impressed how durable their parts are actually built.

KTMs get hooned like crazy for majority of what I've seen, be it the abrupt outright acceleration, running at high rev range for majority of the engine running duration, running at 7K+ rpm at constant 100-120kmph for 200-300kms non-stop on highways, aggressive rev matching and engine braking from high rpm's, all of this while the engine is operating at very high temperature of 120+ degree Celsius. All parts having to through such sustained wear and tear is very demanding task!

Even with these kind of abuse the engine goes through they do a good job perform at top notch condition with giving average life of 25-30K kms per valve/head/engine job! Which in my view is a tremendous feet! Had it been any other bike I doubt it'd perform the same way at this price to performance ratio, at the end of the you get what you pay for, the kind of price we are getting this pocket rocket bike or cheap parts, we shouldn't be complaining much!

Re: KTM RC 390 Ownership Experience

already told you the workaround.. remove the fuel pump out and try to clean the contacts where the float makes contact.

atleast you weren't taken for a ride with replacing the entire block piston blah blah..
seems a reasonable choice of components for a top end rebuild.
again, remember.. without seeing the condition and measuring the clearances, take advice given here in online forums with a pinch of salt.
when they put it back together, hopefully they measure the various clearances (e.g. ring end gaps, valve clearnances) and rebuild it properly.

if you want to take the guess work out and have it easy then going ahead with all new block/piston/valves/seals is the way to go. the cost vs benefit is worth it on a small 100cc bike, the price difference between a rebore or a new block piston isn't that much on these small blocks. and most of our mechanics don't want to measure accurately but rather replace parts to avoid a risk in failure.
i've seen plenty of these small bikes (splendors, activa's) run fine on a rebore with new oversize pistons.. it all comes down to workmanship. and in some cases even a rebore isn't required.. just new std size rings.
on the other hand the new gen higher cc/performance bikes.. their block/piston kits aren't exactly pocket friendly for most ppl, and oversize pistons aren't easily available. if a good mechanic can identify that the block is in good shape and just new rings will do, then that shud suffice if installed correctly.
risk is relative..

25k is a bit early for a rebuild, but again it all depends on how the bike was ridden and maintained. the 390's shud be able to do around 50k km before requiring a top end rebuild.
most folks have the mentality that the bike should last 2 lakh km since we paid Rs.2 lakh for it everything else like performance, maintenance, servicing doesn't matter.. it shud be fill it shut it for 2 lakh km.

Re: KTM RC 390 Ownership Experience

Indeed. Factory fit and finish cannot be replicated by local mechanics. The catch here is, it isn't rocket science to replicate the same finish. It does need the right tools, right torque values, loctites, the right sealants wherever recommended. As they say, the devil is, was, and will always be in the details.

Going for full kit replacement is always, always recommended especially when opening up an engine that's run quite a chunk of KM. But, is it always necessary? Not really! And the answer to that in the second quote...


Not customary, Ashwin. Once a head is removed from a the bike, it isn't always recommended to replace the piston or rings for that matter. Unless and until it's a "cylinder replacement job" then yes, what you've mentioned would suffice. Yesteryears most didn't have the manual nor the numbers to play with or to get an idea as to when a part should be replaced. These days, piston slap gap, ring gap, everything is mentioned in the service manual. It's easy to check them before splurging unnecessarily or for that matter, ruining a good engine in the name of doubt, which have happens, one too a many.

Basic checks like, ring gap, compression check, et al can save money, at the same time, it helps reduce the guess work.

Cheers!
VJ

Re: KTM RC 390 Ownership Experience

True to the Dot.

But when it comes to practical application it would be best to simply get the rings replaced without a second thought when you have the head off, as gaskets come in a kit, meaning you've already got the base gasket, and since the gasket and the piston rings are consumables it makes sense to invest another 250/- and replace the rings as well along with the base gasket.

Same case when it comes to pro-actively replacing cone-set when rebuilding forks or vice-versa.

Takes the hassle off having to go in for another rebuild within a shorter span of time after investing time and money in the rebuild at hand.

Plus in the case of changing rings with the head off, the only parameter for concern is the base gasket, which is already part of the gasket kit. So you see why the argument of 'Why Fix Something that ain't broken' doesn't apply here.

Again, that's just me being lazy or stingy or both.

@KTM People,

Would anyone be able to share the distance between your motorcycles swing-arm at the point where the axle bolt goes through, also would need the distance between the wheel hubs outer edges, measurement to be taken with the help of the axle bolt, and finally the size of the metal wheel spacer.

Wanted to know if the KTM's rear alloy can be accommodated for the Pulsar 220, also can NS<>KTM alloys be interchanged?

Thanks in advance.

Cheers,
A.P.

Re: KTM RC 390 Ownership Experience

That's one tall order for us KTM-ians to process and digest, but I'd love to hear more on this one. The measurement from the swing arm pivot to the wheel can be taken, the hub and finer details would need to be measured correctly. I'd suggest paint the rim orange as most Kulsar fan boys do to make their rides look royal. Well, it's cheap, cost effective and well in the end both are kinda Bajaj, that gives one a satiated feel doesn't it.

Cheers!
VJ