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Loss of power in LC4
Hi all,
I’m in Peru at the moment close to the city of Cusco, touring south America, on my KTM LC4 400, the military version described in anther thread here. I have a problem at the moment where I appear to be losing compression. I can only drive at 10 or 15 km/p/h and I cant get the engine to rev high. Now this problem first appeared yesterday when soon after filling up with petrol the bike started lurch and hesitate on acceleration. There was a village 20 km up the road and I thought i´d change petrol there. There was no petrol there so I decided to return to the previous village. Halfway on the way back my bike lost power and would only drive at 10 km/p/h and wouldn’t rev high. Thinking my carb was dirty or fouled I stopped at a mechanic and we totally cleaned the carb and the jets etc (which were a little dirty). It made no difference whatsoever. Using a finger down the spark plug hole we found out that the compression was bad. Looking at the valve clearances, the injection ones were very very loose. The exhaust clearances were ok. Tightening the admission tappets up made a huge difference and it was almost back to normal. I didnt drive any more that day. So today I got new petrol in a different station and filtered it this time. I drove off and 1 or 2 km up the road the same problem happened, where my power totally went and I could only crawl along. Now whats weird is I had only tightened the valve clearances the day before. I had last adjusted them in Chile around 2,000km previously where both admission and exhaust were pretty good (only a little bit too tight). Whilst driving to Cusco I heard that they sounded loose again but put the noise down to the altitude – for the last 1,000 odd km i´ve been at approx 2,500 to 5,000 meters. I checked them in Cusco and found that the admission valve clearances were really very very loose so tightened them up there (exhaust were fine). I also noticed that there appeared to be a slight hole/tear in the oil pipe going from the frame to the exhaust valve hatch. There wasn’t any oil around the area and so I just patched it up with insulation tape. My oil looks fine through the view window and dipping a magnetic screwdriver in shows no metal flakes. My coolant level is fine and looks fine. Because of the altitude I took off the lid off the airbox to get power (don’t have smaller jet), the air filter is clean and oiled. I´ve been running on 90 octane petrol (cant get 95 here) for the last 1000 odd km and changed the switch on the CDI to 80 octane. The manual says to use 10W50 oil but there is none in this part of the world so i´ve been using 20W50, either motul or bel-ray So i´ve organized a pick up truck to take the bike and me back to Cusco (nearest city) later today. I´ll probably try and take the bike to a mechanic there. Any thoughts on what might be the problem would be gratefully appreciated. - Eamon PS going to post this over on adv rider as well. |
Eamon
Don't know the answer to your problem myself but I have posted your query on the UK KTM forum to see if anyone does. If someone comes up with something useful I will post it here. Martin |
Most likely an intake rocker roller bearing failure.... You've got a few replies on ADV...
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Eamon
Only one reply on the KTM forum so far ..... "Lack of compression would suggest a broken piston ring or worn valve guides." |
Yea I'd agree. Sounds like you're heading towards a catstrophic failure if you're doing them on what seems a daily basis. Best to suggest you take your top end apart to have a good luck and see whats going on.
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Thanks to all for your replies.
I tryed going through a few easy tests today before taking her to a mechanic. It was raining very heavy here today (more so than usual for rainy season) and the bike is outside so i didnt get much done. What i did do is do a compression check. The first reading was 50 PSI (344kPa). Then i put a couple of ml of engine oil down the spark plug hole and re-measured, this time the reading was 55 PSI (379 kPa). Now my manual doesnt say what the compression readings should be so i cant read much into these numbers. Does anyone have a idea what they should be? Bear in mind that its a 400cc LC4 not a 640. The 400 manual says the ratio is 10.3:1, the 640 manual says 11.5:1 I also drained the oil and looked at the sump magnetics. There was a lot of metal on them. Normally i might see a speck but there was a lot and some of them appeared biggish to me. I´ll try and post a pic later. So tomorrow i´m going to track down a good mechanic. Anyone know one in cusco? Thanks, Eamon |
Again thanks to all for your replies.
Well, i lifted the valve cover today and the intake cam follower bearing had broken in pieces. The resulting particles have damaged the cam shaft itself, most of the bearings on the camshaft and the rocker arms. I will post a few pics later. The mechanic and I spent a few hours going around to the bearings shops trying find replacement bearings for the camshaft but could not find any. He reckoned it might be possible to repair the camshaft itself but that a new one would be better. There is a fair chip taken out of the exhaust. Any thoughts there? I got a quote from KTM Lima for a replacement cam shaft and bearings and rockers for around US$600 and 20 days. However the mechanic forgot to say it was the 400cc LC4, so the quotes are for the 625, 640 or the 660. Would anyone have an idea if they would be the same? Is there any chance that there are other problems lurking in the engine that I havent come across yet? I havent looked at the piston yet. What about all the metal that has been floating around (I even found an intact pin from the cam follower bearing in the sump oil). (Havent looked at oil filters or oil in the tube yet). Thanks, Eamon |
Quote:
Peer |
Thanks to all for your replies.
Well i got a little paranoid about the piston and rings and bore being damaged so we looked at that 2 days ago . Thankfully all was ok so the filters and magnetics did do their job. I have decided to try a local repair job. The mechanic here is confident that he can get the camshaft "skimmed" through a lathe and get the chip/chunk that was taken out of the exhaust rocker arm soldered. Most of the bearings can be bought locally. The one bearing that needs machining is the cam follower bearing. Yesterday we found some suitable material for the new bearing. I guess if there is anywhere in the world where they are good at rebuilding engines it is here in Peru. So its a cheap and quick fix. I will have to wait and see how good it holds up. I have around 10,000 or 15,000km left in my trip. As for being stuck in Cusco, well its great spot to be stuck. Plenty to do and see nearby and lots of good people about. Highly recommened as a place to be stranded!! Thanks, Eamon |
Hello Eamon,
If your roller repair does not work and you become desperate to find parts... I have a couple spare intake rocker/roller assemblies on hand that would get you out of a bind....I'm about 10,000 KM up the coast so shipping would take a few days.... David... |
Island Hopper you are a good man!!!!
In Cusco do you know this place Eamo The best bar in Cusco, Peru... Norton Rat's Tavern. Ease the pain. b |
Thanks guys,
Well the new bearings have been made up and are on the rocker arm and i am still waiting for the camshaft to be fixed. Island Hopper, thanks a millon for the offer. Really very much appreciated. Hopefully i wont be taking you up on it!! Bill,i do know Nortans. Its a great spot for a few beers. At least i picked a great town to get stuck in! Thanks, Eamon |
Check carefully for metal all tubes
Eamon,
I had a similar failure, however luckily in Chile where there is the most advanced KTM workshop in the South Americas... Run by a former German mechanic, Roland Spaarwater, today supporting KTM drivers in the Dakar in Africa and since this year in SA. I also know Diego M from the KTM shop Lima, he is more an Importer and can give little to no support on parts. KTM Sommer, now KTMTeamWest, is THE address if you need parts quickly across the world, but Diego can help you to get those parts through Peru customs as his contacts in Lima (Miraflores) are excellent. This speeds up things. I would now recommend that you do very often your servicing of the filters and clean the magnet, although Peruvian mechanics are clever and great (I have a Taxi business in Lima that need tons of maintenance), the KTM needs its own parts. As I guess you are on your way South?!?, it would make sense to stop at Rolands place, either in Santiago or Chillian. They will have the parts, the bits needed to finish your trip as they supported me. His engine still runs today and has since survived to African Rallyes, now I use the KTM only on the street. While you have opened the "heart" now, please clean all parts and oil tubes very carefully (incl clutch area etc). And go to Nortons, drink a Cuscena, greet Chris (?) and put a remark in his book, you might either know or meet in the future some of his visitors. Cheers and Suerte Rasmus |
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