Jump to content
Sign in to follow this  

400sm Cylinder Wall Scratches-What's causing it?

Recommended Posts

I have a 2005 DRZ400sm and it started getting week in power, sputtering and acting like it wasn't getting fuel. I cleaned the carbs and that didn't help. So i the next time i rode, i started hearing an engine ticking noise that got louder and louder until it was clanging around.....Immediately i killed the engine. We took the head off and found one deep scratch mark in the wall and 2 other faint ones. I am looking to bore it out to a 432 but before i do that i want to know the cause of it. Could it be a bearing? I'm not a mechanic so any information would be helpful...Thanks!

Edited by yzf250dude02

Share this post


Link to post
Share on other sites

dude , I would do a lot of checking on your motor . Look at the free play on the main bearing , grab the conrod and try to move it sideways and up and down without moving the crank . Too much free play means you may have lunched a bigend . It may have been as simple as a auto cam chain tensioner failure as well . Unfortunately many things go clunk , clunk on these motors , whether they fail or not . Make sure you check you cam journals as well , it might be some sort of oil starvation , which could be oil pump related . When they fail they can make that noise . Have you lifted the cam followers and checked the collets on the valves are secure ? I have read on TT , how many people have disassembled there motors , to find scratches like you have , and there motors ran fine without any undue noises . It is very disappointing to reguarly service and look after a bike only to have it fail for no particular reason , it has happened to me many times . Take your time and check all of the bearings and plain surfaces and do the loctite fixes while you have the opportunity , good luck , greg

Share this post


Link to post
Share on other sites

thank you so much for your input. I will certainly look it over carefully. Just curious. What could be the worst case scenario and how much would it cost to fix? We did find a ton of the cylinder wall shavings in the oil filter and throughout.

Share this post


Link to post
Share on other sites

I had the exact same thing happen, died like it was out of fuel and had scuffs on the cylinder wall, turned out one of my rings ****ed off and resulted in rubbage.

replacing with a big bore, hotcams and new valve train.

Share this post


Link to post
Share on other sites

Parts such as piston/rings/valve train do wear and require replacing periodically..

The more frequently done reduces the risk of failure..

It sounds as though your engine will need bottom end disassembly for inspection/cleaning/rebuilding...

Could be better off getting a low mile used engine to add your proposed big bore kit to..

In the past I know Eddie often has both lurking around at his workshop...:busted:

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Reply with:

Sign in to follow this  

×