Piston / Rings Replacment Discussion

I haven't found much discussion on this subject and thougth I'd start off with a few questions to get the ball rolling since this particular maintenance task will soon be necessary for my bike now that I'm over 6000 miles / 215 hrs.

• can you remove the head and cylinder while the engine is in the frame?
  
• is it necessary to replace the cylinder when replacing the piston?
  
• is the cylinder nikasil plated?
  
• would the 530 piston/cylinder kit require modfications to the fuel injection mapping on a 510 engine for proper fuel metering?
  
• can you replace the small end rod bushing with the crank in the cases by using a portable type press?
  
• the shop manual lists three different thickness head gaskets that can be used. Has anyone installed the thickest gasket to obtain a lower compression ratio that might be more compliant for sketcky fuel situations?

* can you remove the head and cylinder while the engine is in the frame?
Yes
* is it necessary to replace the cylinder when replacing the piston?
Not if it is in tolerance- typically no.
* is the cylinder nikasil plated?
Some sort of plating similar to Nikasil
* can you replace the small end rod bushing with the crank in the cases by using a portable type press?
Sure- you can use a C-clamp and some spacers too.

That's all I got-good questions

Fast1,

Are you experiencing symptoms indicating the cylinder/piston/rings replacement or planning on it as preventive maintenance? Curious to know for the future of my own bike in the next couple of years.

No symptoms of any type of problem but want to ensure that when the time comes for maintenance or a 530 kit I'm able to make it happen without much difficutly or downtime since we have shorter summers here in the upper midwest.

Have been spending some time while not being able to ride reviewing the shop manual and the procedure for piston, rings, and pin replacement. I've done this many times to a 450 Yamaha engine and even split the cases a few times so I plan on doing this type of maintenance myself on the Husky.

One positive I see with the Husky is being able to replace the small end rod bushing without changing out the entire rod which would require splitting the cases. I feel this would be good to do when replacing the piston pin for new mating surfaces.

Another issue is use of the thickest head gasket in an attempt to lower the compression ratio slightly for those times when quality fuel may be an issue.

I've yet to find any information regarding fuel metering with the FI system and the 530 kit. Does it require differnet mapping when running the 530 kit??

Did you complete this job yet? Just curious how it went and if you have any words of wisdom to add post replacement.

I believe Scott Summers shaved a few thousandths of the top of the piston to reduce comp a touch, mellowed it without significant loss of grunt.

I'm riding on 250 a lot and will be 'due' in about 6 months. It may need to become a 300 at that point.

Have not attemped this maintenance task yet. My 510 still runs strong with no oil consumption nor any valve lash adjustment required after 6000 miles and 215 hours of use.

just a quick question..do you not think you should do the big end bearing at the same time? maybe i have missed the term here but i assume you were talking about changing at the piston end only ...

Ya! Spliting the cases is a whole bunch more work. The bottom end is much bigger and gets more oil flow, should last a bunch longer. Maybe George will chime in and lend his extensive experience.

I put 350+/6000 miles on my 06 TE450 without any oil burn or funny noises. Never did anything in the motor. I guess it's all the gamble, replace it before it fails or replace many more expensive parts when it grenades.

I consider oil very cheap and change it often!

along with installing a clean freshly oiled air filter ever ride.. Those two preventative maintenance items will prolong your engine life.

yeah i know its more work but of all the bikes i have ever had when the motor lets go it has always been the big end that did it.
and that includes a te250 from last year when the big end seized (fixed under warranty) i only ever race these bikes, i dont do any trail riding with them so typically they get 100hrs per year at most.

does the manual spec an interval for replacing it?

I'm thinking about pulling the top end off and cutting down the piston, like Summers, but to try and get a little cooler running engine and stop this constant stalling. My plan is to just pull the top end off in the frame, cut the piston and put it back together with a new base and head gaskets.

Should I consider replacing anything else, or any other gaskets at that time?

You could consider a thicker head gasket? I know Athena have that sort of thing for DRZ - they may have for the husky - much more simple.

I haven't been able find any, but I did order the thicker OE head gasket and two base. I might just install two base gaskets.

Can you remove the cam chain gear without removing the cams?

just in the process ofdoing a bigend bearing replacement .what is the benifit of putting a thicker base gasket on or 2 standard base gaskets and being my first european bike i have got a wossner piston to go back in these look a good quality piston what are your views on these pistons

I have a chronic dying problem with my 510 in tight, technical section when riding enduro conditions.

When it dies the starter won't turn the motor over.

That tells me that the engine is just stopping on the compression stroke, due to a lack of crank inertia to carry it through the high compression ratio, or there's some slight detonation or pre-ignition that's stopping the piston.

Regardless, either of these problem can be corrected with a reduction of compression, which can be accomplished with a thicker head gasket, base gasket, or cutting the piston top. The point is to increase the trapped volume of the cylinder head.

Husqvarna rates the 510 at 12.9:1 compression ratio, from what I can find, and I'd like to drop it to about 11:1.

What I plan to gain is a motor that will tractor down very low without stalling, runs cooler, is happier on pump gas and starts easier.

Not sure if 450 & 510 rods are the same, but if it's all apart, this might be a good investment into engine longevity

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