2002 Quadrunner 250- Knackered cam and journal/"bearings", difference between 2001-2002 part and 2000 and earlier

[kiriyaaoi]

Hello everyone, I just picked up an 02 LT-F250F the other day and have been in the process of tearing it down to fix some stuff- one of which was the cylinder base gasket leaking like a sieve. Well, I know why that is now, and I also discovered that someone had been in there before. I didn't take pictures, but it looks like it was probably run low on oil at some point, the cam journals and the "bearings" (for lack of a better term) in the head and the valve cover are totally wiped out, very deep grooves.  From what I know it's very difficult to repair aluminum in this way, so I'm trying to figure out where to go next.

 

1. Have someone grind down the head and valve cover and fit actual bearings in since the aluminum is screwed, and have the cam ground down to match.  I have no idea what this would cost.

2. Buy a replacement head+cam+valve cover.

 

#1 I was hoping someone might have some advice on, but #2 seems like it'll (probably) be the more cost effective option.  However I'm running into some difficulty, it seems like the 2001 and 2002 models specifically use a different head part number,  11100-19B10, instead of  11100-19B01 like for all earlier models.  What exactly is the difference between them? There are obviously far more of the earlier heads because it ran for over 10 years.  Are they actually interchangeable? I've also noticed there are heads from the LT250EF that has 4 valve heads but also otherwise look identical.  Would those work as well possibly?  I'd like to not have to drop $500 on machine work or new heads on a $1300 quad that I'm already putting a bunch of new parts on.  Oh, and it has a new piston and the cylinder itself looks pretty good too, as I said someone was in here before me.

 

Any help or advice would be greatly appreciated. I'll post pics of the carnage tomorrow.

 

 

 

[kiriyaaoi]

Here's some pictures, they look pretty chewed up. I know that it might be possible to grind down the "bearings" and insert real automotive bearings but I'm not sure if that would be worth the cost versus a replacement. The cam also looks pretty rough and I'm not sure if that's salvageable at all.

 

[Gwbarm]

I think you are on the right track replacing the head, thats what i would do, machine work is not as cheap as it used to be and could exceed the price of a used head in good condition. I would look on Ebay and im not a big Ebay fan but when it comes to good quality used parts i have had good luck, there are somw quality seelers of good parts there you just have to look.

[Mech]

The inner most bearing would be easy and cheap to machine out and fit a caged needle roller bearing, which I've done several times before on honda engines, but that sprocket flange is a problem at the other end. On a honda you can fit a common ball bearing race on that end, but not on the suzuki.. It does look like a repair or replace of the head is going to be the way to go. I'd clean it all up and go pick the brains of a competent engineer, he may be able to build the bearing surfaces up and machine them easier than you think.

Other than that, I see that both versions (different years) of head listed for your model,  use the same cam.

Each of the two head designs get used in several other years, but it's far from clear just quite all the small differences are. In these links you'll see they say which other model bikes each head fit, and you'll notice that they aren't just earlier or later consecutive years, they jump around a lot.

https://www.partzilla.com/product/suzuki/11100-19B01?ref=64703b8d4d387f224d0394c7c7e590909bddd469

https://www.partzilla.com/product/suzuki/11100-19B10?ref=64703b8d4d387f224d0394c7c7e590909bddd469

[kiriyaaoi]

Thanks, I decided to just order some from ebay after asking the seller (it's a large ebay seller) if it should fit. If it doesn't, well I tried.  Actually the bore isn't quite as good as I thought, there's a bit of light damage- maybe corrosion, hard to say, not normal scoring at least- at the bottom of the bore (where moisture would be sitting when not running). I was thinking about seeing if it would clean up with a hone- do we know if these bores are nikasil plated or straight cast iron?

[kiriyaaoi]

Ended up getting the cylinder bored and honed by G&H Discount ATV on ebay, $200 and included a new Namura piston and rings, a Hi-Caliber top end gasket set.  Picked up a used cam and head on ebay, they were both in pretty good shape to start, I cleaned up the journals and the cam, with some 1500 and 3000 grit with WD40, they came out beautifully.  Had the fight with one of the rockers, the PO broke off one of the valve cover bolts that holds the rocker shaft in place... Had to drill it out and absolutely wreck the shaft and even further wreck the valve cover, but at least I was able to save the follower/rocker itself, those aren't cheap.  Cleaned up the contact patch on those with the same 3000 grit and they polished up nicely.  Other than fighting ongoing chinese carb issues it runs great and has excellent compression now as you'd expect.

[Gwbarm]

You have been busy, good you got the cylinder bored, and everything working. Good work!