Top end

[SICVIC 0]

I've posted some information about this in the past but this time I have a few photos to go along with it.

Please keep in mind that this info is only related to my bike model and is not intended as a tutorial for you to follow. I've left out a lot of steps in effort to keep this short and you should follow your manual closely or take it to your shop.

Why should I change my piston, I don't have any problems and I have 45,000 hours on it. You have problems my friend you're just not seeing them.

This is my 4th and I have 13146 miles and 541 hrs.

Every situation will be different.

Why did I replace it? I started showing oil in the breather (near carb fitting) It originated from the cyl head not the trans so it shows that the rings are starting to blow by and pressurize the case; pushing the oil vapor up and out.

Exhaust is burning with a "oily" smell and you can notice a bit more soot at the end of the pipe.

Of course this means more than normal oil comsuption. Not quarts but just a little here and there.

You can hear the "piston slap" starting to last longer after cooler start ups. (not the normal timing chain sounds)

I was at 150 hrs, well past the recommended life of the rings. (1/3 that time)

I could have extended the piston by replacing rings 100 hours ago but the cost of gaskets and the time does not really make that worth it for me.

I run it to the end and do it all at once.

All this said the bike ran great. The signs are there; do with them what you want.

Example: Tore into the carb awhile back just because. Bike ran great, just thought I'd check it out. The clip on the needle jet had worn the groove so badly that It was "floating" between 2 1/2 settings. Thats an 18% change in fuel between each extreme. The clip could have gone at anytime and then I'm screwed.

Running good does not give maint a hall pass.

Bad photo but the left gray skirt is new, the right sliver skirt is the old

Cyl. This is after cross hatching it. (scratches) It measures properly for reuse. Notice the wear marks from the rings at the top and bottem of the stoke. Replating is in the future. Also notice how the rest looks perfect. This is what you want. The other stuff should be what goes. You got marks, you screwed up!

After cleaning, lapping, measuring, reassy and install of new valve seals. Ready to go back on.

Tech tip for proper ring install

One end in groove other end laying on top then just rotate clockwise

Wrong way would be to start on one side with clip in groove then spread it open slighly at the other end.

Several things here. Install one clip prior. Clip the hard to reach side first. When putting the clip in make sure to put one end in the removal slot. You will be stoked next time. Make sure that the oil scraper ring does not overlap on itself. I have 4 rings so the slots all get spaced 90 degrees from one another. Aids in making a better seal and yes they will move around.

Mounting the head I use new bolts. Torque is quite high and if one fails it will full on suck. Don't forget torque is 3 step in a cross pattern. Final to yield.

Throw all the junk on the inside. Top dead would be a good idea right now. Hope you maked your shims so they can go back to the right spot. I'll check em again after the first short ride.

Rest back together, take one last good look and think about what you did before starting. Fluids back in? Engine lock removed? Am I missing any small tools??? lol

Measure, torque, inspect, loctite and don't rush.

Starts right up and sounds real nice.

Exhaust is clean, rattle gone. Steps in the right direction.

Go rip it up!

I won't bore you will all the measurements but I'll give one example of wear. The measurements of a new scraper ring is 1.93mm. The removed ring was at 1.77mm at one point. Huge in the compression world.

If you're waiting for a huge sign that things are worn you might not like it when it comes.

Please don't hate on any of this. I'm just skimming the surface of how things are done.

THANK YOU WOSSNER PISTONS. GREAT SERVICE, INFO AND 1 DAY SHIPPING. *Well done John*

Vic

[Goofy Footer 539]

Good work Vic! I like that you have one bike and you're not afraid to Run the katoom no matter what the ride! I admit I suffer from MMRS - Motorcycle Maintenance & Repair Syndrome - I often have potential breakdowns/maintenance issues/costs creeping amongst the dark places in my mind. I use regular supplements of clean air filters and synthetic oil changes to help alleviate my symptoms but I still need more invasive diagnostics to ease my mind.

"Running good does not give maint a hall pass."

Regular checkups are needed! Doctors can be overzealous in their billing, major surgery is expensive and I currently don't have the skills needed to accurately self diagnose. What is a spode mechanic like myself to do! Preach Vic - you my friend are performing open heart surgery!

I actually recently took some steps forward with my Syndrome... I have no idea how many miles my DRZe has and I hadn't checked the valves in a year and a half lol. It's been running great but since I had the time, I took it into my local mechanic and had him check/adjust the valves, run a compression test and leakdown test. You never Know til you Know right?

What was your compression reading and leakdown percentage? I should be picking up my bike tonight and I'll go over the results with the mech but I believe he quoted me at 8% leakdown. What is the general consensus of people here on leakdown percentages? From what I've read 5% and below is ideal for a top performance from a racing engine but I've also read that DRZs up to 10% are totally fine. Any insight would help!

Again, good work Vic and great pictures.

I must ask, does anybody else here suffer from MMRS? I think a Maintenance Anonymous Tech Day is in order soon!

[bikeslut 1]

I'm a maintenance and repair nightmare... don't have the time, the tools or the talent. When my DRZ blows up, I'm buying a new one, swapping over all my good parts, and parting out the rest.

When My KLR blows, I'm checking the couch cushions and ash tray for cash, and heading out to Eagle Mike for a 705 kit

see? I have a plan!

Good write up Vic... with excellent spelling and grammar.... hey... wait a second... is this really Vic?

[robertaccio 412]

Vic, even with the second rebuild you still had good piston clearance? No need for replate yet? ring gap?(so just worn rings, right?) and some piston wear? Good post thanks.

at @260 hours my Husky450TXC piston looked like yours, we installed new psiton and rings, bore miked out perfect she was goos to go.(but I did do a toatal rebuild to make her "new" at that time.

PS my next machina will be a 2 stroka, Im tired of all these extra 4t parts.

[Spaugh 1]

2 stroke? Say it aint so!!!

[Guest Crusty]

Nice post, I am at 38 hours of mainly MX. in 2 years, on my CRF 450X

I wont be doing this any time soon.Think I will do this at 100.

What do all your parts cost?

I got a quote from CPR. of 350.00 parts and labor.

Craig.

[SICVIC 0]

The hard part is finding the right information. Plenty of opinions or stuff passed along and it's really hard to sort out.

This is why I always start the post with the "don't do any of this" statement. So many tiny important bits left out that could get someone into major drama.

Example: Ring end gap. Showed how to put the ring on right. That's not the end of it. What you don't see is that it has to measured inside the cyl. then filed to fit, then squared, then cleaned. If the gap is to small then the heat will expand it and it will damage the cylinder. Making it square is no easy task. Of course there is a tool, as always.

Goof, the best advice is to get a proper repair manual for your bike and take baby steps. Opinions are dangerous so think about it before you do it.

Don't worry about every bike out there; just your own. It's the one getting you home.

Guys who are great at spinning wrenches are generally the worst at dealing with people. This is why they're kept back in the fish bowl. You're stuck dealing with the car salesman up front trying to empty your pockets.

Start with easy stuff like measuring chain stretch or bleeding the fliud from something. Another huge plus is keeping a log. Dont just change the brake pads and fly out the door. Measure the thickness of the disc, how much pad was left, how many miles on them/ or hours, what compound were you using and WRITE IT DOWN.

A log is like your own moto crystal ball. You will see the issues before they even arise.

There will always be problems but you're doing something right to be logging these log rides I keep reading about. Baby steps.

Rob: I'm running one over on the piston but yes, the cylinder is still kicking. That coating they use is harder than Woodpecker lips.

Slut: Really????? I'll screw up my streak of 1 with this post I'm sure of it. I hates me-a-spell'n. SEE... there it is!

[SICVIC 0]

Nice post, I am at 38 hours of mainly MX. in 2 years, on my CRF 450X

I wont be doing this any time soon.Think I will do this at 100.

What do all your parts cost?

I got a quote from CPR. of 350.00 parts and labor.

Craig.

Crust,

I'll get back to you on the cost.

Piston

Cylinder head and base gasket

Valve seals 2 intake 2 exhaust

qt of engine oil

Oil Filter

4 bolts for cylinder

New o-ring for cam chain tensioner

I think I'm already over $300 already.

I'll get you hard numbers.

For them to make money they must do it in under 3 minutes????

I do know my piston is grip. You might be saving there????

[HVYWT 3]

Yesterday I went to BMW SD for the same. Talking service they said "they had no recommended hours or miles for that kind of service"? They said "we could do a leak down test And they never had to do a rebuild yet". So that left me kind of feeling good. I have changed oil ever desert run and/or 150 miles. I hope they right. The bike did come with 3 year warranty and additional 3 years option. That is a really good backing.

[tntmo 910]

Nice post, I am at 38 hours of mainly MX. in 2 years, on my CRF 450X

I wont be doing this any time soon.Think I will do this at 100.

What do all your parts cost?

I got a quote from CPR. of 350.00 parts and labor.

Craig.

If the head is fine and the cylinder is fine, you can probably get it done for around that much. Ebay has Honda parts kit for under $150.

http://www.ebay.com/itm/GENUINE-OEM-HONDA-TOP-END-KIT-CRF450X-2005-2009-/190822737305?pt=Motorcycles_Parts_Accessories&hash=item2c6debe599&vxp=mtr#ht_715wt_1161

Cylinder is about another $250 and if your valves are shot then you are looking at another $500.

The CRF engine is easy to work on, single cam makes it simple.

[Guest Crusty]

Nice post, I am at 38 hours of mainly MX. in 2 years, on my CRF 450X

I wont be doing this any time soon.Think I will do this at 100.

What do all your parts cost?

I got a quote from CPR. of 350.00 parts and labor.

Craig.

If the head is fine and the cylinder is fine, you can probably get it done for around that much. Ebay has Honda parts kit for under $150.

http://www.ebay.com/...r#ht_715wt_1161

Cylinder is about another $250 and if your valves are shot then you are looking at another $500.

The CRF engine is easy to work on, single cam makes it simple.

I can handle that.

Sound's GOOD Thank's

Craig.

I had the header wrapped on my XR 680.caused the spark arrestor to FAIL, and my FMF header to rust.

[Goofy Footer 539]

Keep the good info coming!

I'm really intersted in hearing some SDAR members' experiences/opinions on acceptable leakdown percentages. I realize there are other ways to evaluate the performance of one's motor but what are your thoughts on leakdown specifically?

Thanks in advance!

[Bagstr 288]

Thanks Vic,

For the Details. Many of us casual mechanics contemplate tackling the full rebuild but,,,,the un-known details give me pause.

Piston, rings and valve shims I think I can manage. Lapping valve seats, guides and honing the cylinder make me sweat.

So, I wonder how many hours does it take a "qualified" mechanic cost to do the job?

Scared in La Mesa

[bikeslut 1]

Harder than woodpecker lips...bwahahahaha

That is so wrong but still so clear...when in Idaho?

[hobiee 28]

Vic,

What oil do you run ?

[Goofy Footer 539]

These are quality videos. They should help mollify my syndrome but I'm still afraid :axehead:/>

KTM RFS top end rebuild part 1 - Rocky Mountain ATV/MC

KTM RFS top end rebuild part 2 - Rocky Mountain ATV/MC

Wiesco Piston Circlip Install

How to replace the valves on your moto - Rocky Mountain ATV/MC

(yamaha 5 valve dohc motor)

[SICVIC 0]

Vic,

What oil do you run ?

Spectro 4 SAE 20w50

Change every 10 Engine Hrs or less (depending if an event was involved. Oil filter every other time. Air filter is as needed. If riding with others, sometimes twice a week....

[SICVIC 0]

Bags,

Another thought out there is that you should NEVER lap the seat or hatch the cylinder because they are hardened and by doing so it will remove the coating.

So many ways to look at it.

Mt thought is if you don't clean up the valve seat and valve how are you ever going to get a good mate. Another benifit is that you can see where they are sitting. If the lapped surface is way down in the seat then things need to be replaced soon.

I hone because nothing is ever going to seal on a smooth surface. Plus it helps with lubrication.

Either way I'm only doing as little as possible. Just enough to get the job done.

Really, if you take it to a shop you're having it done the way they do it. 5 different places; 5 different ways it will be done.

In the end they call the KTM engine a race engine and that requires short interval tear down, inspection and replacement. That is the one thing that stands across the board.

[tntmo 910]

Titanium intake valves can't/shouldn't be lapped. Sometimes a new head with titanium valves may not even pass the fluid weep test. If I get another Honda CRF, the first thing I'd do is change out the titanium valves to stainless steel. They cause a lot of head issues.

Modern motorcycle cylinders have a Nikasil coating. OEM cylinders have .002 inch plating, aftermarket may be up to .006 inch. That way you can hone it several times before it wears though. The typical life of a stock plated cylinder is about 100 hours or 5 piston changes.

[Bagstr 288]

@ 148hrs and 4185 miles, the 350 is due for a piston and rings soon. Another reason Not to use a Race engine as a dual sport while putting on 2k miles in 2 months.

May as well start the learning process, as it will be a continuing issue.

Thanks for the discussion, Vic.

Race Bike

[Goofy Footer 539]

tntmo, I hadn't thought about ebay for top end kits. Thanks for the idea - Motoworld apparently sells kits on ebay and they seem to be cheaper than if you bought the parts individually in the store! I found an OEM kit for an 06 WR250F for $119 shipped!

Motoworld 03-06 WR250F Top End Kit

Another thought out there is that you should NEVER lap the seat or hatch the cylinder because they are hardened and by doing so it will remove the coating.

So many ways to look at it.

Mt thought is if you don't clean up the valve seat and valve how are you ever going to get a good mate. Another benifit is that you can see where they are sitting. If the lapped surface is way down in the seat then things need to be replaced soon.

Vic are you running stock KTM valves? I believe the RFS stock KTM valves are Steel. The 2014 350 xc-f has titanium valves. I'm not certain about your era motor however.

I read this from an admin on SuzukiCentral

"All Suzuki stock valves (that aren't Ti) are high carbon steel valves, and they're Stellite coated for toughness. You cannot / should not practically lap a Stellite coated stock valve. You'll go right through the Stellite, and the only thing left on the sealing contact area is high carbon steel. They'll start cupping with a quickness once you do that. Intake AND exhausts are Stellite coated from the factory.

You CAN lap stainless steel valves, no matter who makes them or what they coat them with. Safely. Every time.

Big Suzuki hasn't recommended lapping stock valves since 1979. In fact, their official policy on it is: Do not lap stock valves.

The manual give the angles that the valves are ground at, and the thicknesses for each ground area - that's so you can properly inspect the valves to make sure they're still within the factory specified tolerances. That's not for lapping or valve head grinding purposes."

Bagstr, I found this video for you which backs up what Vic said about honing the cylinder :good:/>

I hone because nothing is ever going to seal on a smooth surface. Plus it helps with lubrication.

[HotRod82 2]

Keep the good info coming!

I'm really intersted in hearing some SDAR members' experiences/opinions on acceptable leakdown percentages. I realize there are other ways to evaluate the performance of one's motor but what are your thoughts on leakdown specifically?

Thanks in advance!

In my experience full race engines no more than about 6%, play engines up to 10% or so, although having said that by the time you get to 10% you can usually see excessive oil around the breather and/or you will be using oil.

[Bagstr 288]

Guys and Gals,

Help me with the choices on rebuild parts. Aftermarket Piston/rings vs genuine KTM. Are there choices to be made on rings and stuff?

Consider me an Inquiring Mind.

B

[Spaugh 1]

vertex makes the ktm OEM stuff for the 350 and that is what I would stick with Dave. check out their website for the correct part number for your bike and then search for the cheapest place online for said part. All you should need is a piston kit at 150hrs. You can reuse the head gaskets, they are metal. Replace them if it makes you feel good but its not necessary and they are not cheap.

[Bagstr 288]

Thx