Rebuild...this look OK to everyone??

[Glamis400ex]

Hey gang,

I'm doing a teardown due to a head gasket leak. I'm kind of concerened about a few things.

1) score inside the cylinder?
2)top of the piston...crud?
3) minor scoring on the cam journals..top and bottom
4) valves look OK?
5) how should I clean the crud??

Thanks

Can I email these to someone to host?

Glamis

[Glamis400ex]

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[Glamis400ex]

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[1fst400]

what I would do/ did.

glass bead blast the crud off the cylinder head WITH the valves in place.

replace valve seals. regrind valve seats.

I was told that as far as cylinder scoring goes. if your finger nail doesent catch on it then your good.


I dono about the cam stuf. but the one on my motor looked the same.

[Glamis400ex]

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[enduro400rider]

that looks like alot of crud. if i were you since your taking the time i would replace the piston and bore it out, you dont have to go big bore or anything but go like 406 or somthing just to clean up the cylinder. as for the head. i cleaned one up with brake cleaner and a brush, but your best bet would be clean it up as best as you can and do a 3 angle valve job. you might want to check out your cam too while your in there, the cam chain probably needs replaced if it hasnt been already

[Glamis400ex]

That is a 416 and I've been riding it for 2 years. The one score in the cylinder you see, I can barely feel with my nail.

Hmmmm.....maybe I'll just make it a 426.

Glamis

[Glamis400ex]

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[Bill Fuller]

Cam bed looks fine.As long as your going to use the same cam then the cam followers(rocker arms)look fine.I would rebore that cylinder if it was me.I would also replace valve seals and relap valves.The "crud" on the top of the piston is normal,your rings aren't sealing properly so that could have alot to do with it.

[Glamis400ex]

Thanks BigB,

Re-bore as in make it a 426 or just hone it up and clean the piston up too??

There is one spot where there is a miniscule score on the cam journal. On the above pic of the head, the right side....that "line" I can barely feel. I have a secondary oil cooler (FST style), so I can't image it's starving for oil. Can I take some 600 wet sand paper to smooth it down?

Glamis

[Bill Fuller]

Bore to 426.I would run a Ross or JE piston.If your concerned about the cam,you should be fine aslong as you run the same cam follwers.You could take some 600 and remove any burrs.If your concerned about the cam(you didn't mention what kind)I reccommend the TC 926 XC cam.I ran this very combonation for 2 seasons(XC).I got 4 years out of that TC cam.Stay with a lower compression piston so you can run pump gas.

[Bill Fuller]

Also check those valves carefully.It looks as though that head gasket leak had you running pretty lean.I would definatly relap,if you could afford it then I would look into larger valves and get some head work while your at it.

[Glamis400ex]

I have a Hotcam stg2 and the piston I had in there was a JE 416 11:1 comp. Would you resleeve with the 426 or bore the stock sleeve?

Thanks BigB...youre a great help.

Glamis

[Bill Fuller]

Bore the stock sleeve and resleeve or buy a new cylinder when this one is done.

[Glamis400ex]

Hey BigB,

Do you think I'll notice a difference from 416 to 426?

Glamis

[Bill Fuller]

Not really,I prefered the 416 over the 426 though.I can't say why I think it ran cooler and had power longer during a race.What kind of pipe you running??I loved this combo with the Sparks pipe:muscle:

[Glamis400ex]

Full HMF....I may do a 39FCR too.

[Glamis400ex]

here's the plug...looks good to me. Slight yellow tint, I assume from the leaded gas.

[DieselBoy]

pretty messy....ur valves look burnt

[Glamis400ex]

so, that much build up isn't normal?

[shivvels]

i had the 416 kit in mine and i just had to bore mine out. i went to the 426 and me and my buddies agree it is stronger than the 416 and you can tell quite a bit of a difference.

[DieselBoy]

the 2 look burnt, and there's quite a bit of build up, I guess it's normal considering the wear.

[F-16Guy]

It looks like it was running pretty hot to me. You may consider running a little richer than that after the rebuild. If I were you, I'd probably go to a 426, get heavy duty studs installed, and have the head done (seals, grind valves).

[DieselBoy]

it's totally up to you, but with an older used engine i wouldnt want to put that kind of stress on everything (426), i would gowith something like a 416.... just me, though

[leadfoot_52]

That Engine look pretty good for having 2 years of riding on it. I think your jetting looks good like it is supposed to be. I would recommend getting a valve job and get the seats re-ground. It having that much ride time on and by the way your valves look-it could use a valve job. I would recommend taking the cylinder and just getting it honed It seemed to look pretty good.. you dont need to bore it if it isnt grooved real bad. I would buy a new wiseco or je piston too, but get them valves done for sure.

[prepracing]

Originally posted by Glamis400ex
so, that much build up isn't normal?

that build up was caused from your blown head gasket, where oil got on top of you piston and on your valves and it just didn't burn off. Thats why it has more buildup than normal, take it to a machine shop and get their opinion ( as they would know best ) whether or not honing the cyclinder will clean it up enough. If so let them clean your piston up and valves and get some new rings and headgasket and you will be good to go. I know alot of people clean up their own pistons and valves, you may know how to as well. But thats the heart of your power so I like to leave that to the professionals. If you end up going 426 I would just have it bored on out on that stock sleeve ( I have ran mine for 3 years now on stock sleeve, with one tear down for rings and a slight honing and that was just a preventative maint. tear down ) and never had any problems...knock on wood !

[Glamis400ex]

Thanks everyone for the comments...I'll be taking the pieces to a very reputable machine shop....the same one that initially did my cylinder bore, valves, and porting.

Glamis

Originally posted by Glamis400ex
Hey BigB,

Do you think I'll notice a difference from 416 to 426?

Glamis

Not very much.

Look into the cost of a piston and a sleeve and see which is cheaper. When it came time for me to do the same thing your going thru, it was cheaper to do the new sleeve than the piston.

[LT250RMan]

IT NEEDS A REBUILD!!!!!!! Cylinder is scored(not good)will start to loose compession then get blow by and could wreck the crank by pressuring up to much. I would rebuild it before it blows up dude!!!

[LT250RMan]

THAT PLUG IS WHITE!!!!!!!!!!!!! OH NO running way to hot

[Glamis400ex]

DUDE...IT'S GONNA BE RE-BUILT....SHEESH...LOL

Seriously, I'm waiting for my builder to get back and I'll take his advice on either re-sleeving with the same size piston or going up to 426.

[DieselBoy]

dude those 2 valves are definately burnt..... they dont have any buildup on them, lol

[Glamis400ex]

it's all gonna be handled.

[DieselBoy]

Schweet. When do you plan to have it back together?

[Glamis400ex]

As soon as my builder gets back in town...should be the next few days. In the meantime, I'm going over every inch of my quad and cleaning the crud that's accumulated and checking every bolt and bearing. what a chore. It needs it though.

[Aceman]

Definitely worth going over everything though. There are times I'm way up in the mountains where I would be SCREWED if I broke down. That's a pretty big motivator to do a once over before I ride.

[Glamis400ex]

Well, I took my motor in to my guy. This is the same guy who does alot of the Baja1000 guys bike including Jonny Cambell's and Team Honda.

He looked at it, mic'ed it and determined that the big scratch in the cylinder was not able to be honed out and still keep it a 416. It was just too deep. He told me that ideally, I need to have between .002-.004 clearance between the rings and the cylinder wall to get the tings to properly seal. I currently have .004, and to get that scratch out, it was going to take close to .004 for a total of .008. That's too much and the rings wouln't seal correctly. After that I talked to him about going to an 88mm piston which is a 426 and the need to possibly re-sleeve. He agreed with my concern and he told me as long as I'm not riding WIDE Effing open, in the sand for 6 hours....I should be fine. I also informed him of my efforts to keep things cool by installing a DPR9Z plug, 50/50 gas mix with VPc-12, an aftermarket oil cooler (FST style) and synthetic oil. He agreed I couldn't physically do any more to cool it down and was happy to hear I was aware of the heat issues on built 400ex motors. My motor guy, Bob Schaeffer, also knows the guy that developed the overbore JE pistons for the 400ex's and that guy says that they've sold a ton of them and as long as you follow the couple simple guidlines, he's never heard of a failure, but did agree that I was at the limit of the stock sleeve and to ride smart. Basically, I just can't go out and wring the motor's neck for hours on end in the sand. That isn't something I do anyways.

As for the other parts of the motor, I will be getting new valves and seals and she'll be cleaned up good as new. Total damge should be about $400 or so. Not bad really. I figure if that's what it takes to keep a motor reliable, it's all good. If you don't have you motor in top shape riding the MASSIVE sand dune area out here, it WILL leave you stranded. He told me I could have gotten another "season" out of it no problem, but I did the right thing by tearing it down when it was leaking oil due to a headgagsket failure.

Thanks for reading.

Glamis

[JOEX]

Originally posted by Glamis400ex
Well, I took my motor in to my guy. This is the same guy who does alot of the Baja1000 guys bike including Jonny Cambell's and Team Honda.

He looked at it, mic'ed it and determined that the big scratch in the cylinder was not able to be honed out and still keep it a 416. It was just too deep. He told me that ideally, I need to have between .002-.004 clearance between the rings and the cylinder wall to get the tings to properly seal. I currently have .004, and to get that scratch out, it was going to take close to .004 for a total of .008. That's too much and the rings wouln't seal correctly. After that I talked to him about going to an 88mm piston which is a 426 and the need to possibly re-sleeve. He agreed with my concern and he told me as long as I'm not riding WIDE Effing open, in the sand for 6 hours....I should be fine. I also informed him of my efforts to keep things cool by installing a DPR9Z plug, 50/50 gas mix with VPc-12, an aftermarket oil cooler (FST style) and synthetic oil. He agreed I couldn't physically do any more to cool it down and was happy to hear I was aware of the heat issues on built 400ex motors. My motor guy, Bob Schaeffer, also knows the guy that developed the overbore JE pistons for the 400ex's and that guy says that they've sold a ton of them and as long as you follow the couple simple guidlines, he's never heard of a failure, but did agree that I was at the limit of the stock sleeve and to ride smart. Basically, I just can't go out and wring the motor's neck for hours on end in the sand. That isn't something I do anyways.

As for the other parts of the motor, I will be getting new valves and seals and she'll be cleaned up good as new. Total damge should be about $400 or so. Not bad really. I figure if that's what it takes to keep a motor reliable, it's all good. If you don't have you motor in top shape riding the MASSIVE sand dune area out here, it WILL leave you stranded. He told me I could have gotten another "season" out of it no problem, but I did the right thing by tearing it down when it was leaking oil due to a headgagsket failure.

Thanks for reading.

Glamis
Thanks for the update. The advice of a trusted engine builder is invaluable:)