Advice please...?

[The Cosmic Lawnmower]

There I was out having a pleasant run on Domi yesterday, when out of nowhere there was a nasty rattling sound (very tappety), and a reluctance to the motor, I pulled over immediately and made an external inspection around the motor, but couldn't find anything .
So I tried running her again she fired straight up and sounded fine, so off I went thinking it was some kind of blip, but a quarter of a mile up the road it did the same, I noticed then that the motor seemed red hot though.
Being 'out in the boonies' I started pushing, after a couple of miles on an uphill gradient I was feeling rather knackered and stopped for a bit. This little spell had allowed her to cool down quite a bit so I tried her again... she fired straight up but sounded rattly I rode her for a couple of miles and stopped again to let her cool, although this time there wasn't any reluctance to the motor, before it felt like it was tightening up.

Anyway I left it until completely cold and then managed to ride all the way home about 8 miles. When I got back the rattle didn't seem to be there, but a vibration is now present, as though the motor is unbalanced .

The oil by the way should have been ok I probably haven't done 1200 miles since the last change and the level was acceptable.

So any thoughts? I'm a relative newbie to Domi's (bought it in June), but really like it. Any advice gratefully received.

Sorry this post is so long!!

[Simon]

i'm rather new to dommie's too. I would have said the oil level but then you said that its ok so i'm sorry but thats all the help i can give on the subject.

[anton88]

If your a newbie to the dommie - Check AND check again your oil level on a REGULAR basis - this catches people out. These engines do burn a little oil anyway, but if it is using more oil than standard, i fear you may have reduced your oil capacity somewhat and damaged the engine - this has happened to someone else on here before.

If you can, run the engine for 10 - 15 mins and then with the bike level, check the dipstick - it should be no higher than the max mark. If youve no reading then it may be too late.

I hope i'm wrong, but you may have some serious work to be done - let us know what your oil level is after the above checks.


++++++ check the level cold before you start just incase it needs a bit of a top up BEFORE you start it - see if you can get it to the bottom of the dipstick - no higher.

[Rubberchicken]

It sure sounds like an oil problem...

A while ago I read something about air bubbles trapped in the lower oil line, meaning the pump sucks air, meaning the engine doesn't get oil even though the dipstick shows a full tank.

Easy way to test this is to slightly loosen the external oil line going to the cylinder head on the right side of the bike, if you start the bike that should start gushing oil pretty much immediately. (So keep a spanner handy.)

If the engine ran without oil, you're up for some very expensive repairs.

[squirrelciv]

Must agree, it does sound like oil starvation. When was the filter last changed? has anyone got near her with hylomar?? If it was oil shortage I'd expect damage to the head first, so if your feeling brave take a valve cover off and take a peak at the cam and see if you can spot anything nasty
Sorry to hear your news.

[kenny1950]

I would have said it maybe started to seize a piston. Hence the knocking and lack of power.. At a guess I would say you have a scored piston and possible sticking rings. Try to turn it via the wheel or my hand and gauge how well it hold its compression. Not many other things will go away as the motor cools. If you intend to keep running it then change the oil and filter and go steady. Inspect the oil filter and see if any small bits of alloy are showing.

Ken UK

[Rubberchicken]

Good point. I was thinking, it it's really hot and does have oil in it...

Have a look at the inlet manifold, if it's got a crack or a hole in the bottom:



The one on the right was starting to tear but hadn't gone through yet. If it can draw air through there it'll run lean and if the hole gets bigger that will probably cause a seized piston.

Anyway, as you said first order of business is to change the oil and filter, watch for metallic flakes and also check that there was actually about 2 liters in there.

Finally, 1200 miles is already more than halfway through the oil change interval, you really have to check the oil more often because those big thumpers always use a bit of oil and it's not unknown for one to go through over a liter of the stuff within that distance!

[squirrelciv]

I would have said it maybe started to seize a piston. Hence the knocking and lack of power.. At a guess I would say you have a scored piston and possible sticking rings. Try to turn it via the wheel or my hand and gauge how well it hold its compression. Not many other things will go away as the motor cools. If you intend to keep running it then change the oil and filter and go steady. Inspect the oil filter and see if any small bits of alloy are showing.

Ken UK

Good point, could be lean running.

[The Cosmic Lawnmower]

Hey guys thanks for the replies, I do appreciate it.
Oh dear looks like I'm gonna have to raid the piggy bank...!

A possible top end rebuild then, I will check those manifolds though, as I thought it didn't seem quite as pokey last time out (I thought I was just getting used to the power!), or maybe it was already starting to suffer from an oil problem .

I saw on another thread which mentioned if you've got to do a top end job, about doing a big bore conversion/hot cam.
Is this much more expensive than rebuilding as stock? Would it have an adverse effect on reliability? Just wondering whether it'd really be worth doing.

Thanks again guys... seems like I've made a typical newbie error. Doh (admonishs self!).

[Rubberchicken]

There's an article on the OzDom site called Building a better dominator that has quite a lot of information if you want to go that route.

So hotcams aren't all they're cracked up to be apparently, you have to ask yourself what you like in the dommie, as hotcams often give more horses on top but lose torque in the midrange... Which for me just kills the whole idea instantly because all the fun in a dommie is found around the 4500 rpm mark.

Besides, there's reliability to think about. How much are you going to gain, and at what price? The most badass dommie I've found on the net has 56 horsies. Which is a lot compared to the 40ish of the stock NX, but it's had a lot done to it.

Let's face it, there are cheaper ways of getting a KTM.

If the piston seized up, I'd go for a simple overbore and possibly a fancy piston like a forged wiseco with more compression.

I'm not sure what will need replacing when it's been run dry, though.

Ohwell, you'll have to tear it apart first anyway to see what needs doing.

Anyway, if there's anything, don't hesitate to ask!