Well my post should have said " I have a YFZ450 that is..." Damn the new laptop on the couch last night.

Congrats Poolgod on the Steelers, my wife was happy about them winning too.

As always good info Randy. Do you think your portwork is lettign you get the benefit out of the 250? Does the stock 250 head, and the stock 230 head flow the same?

 

Good stuff Randy, That 250S cam is noticeably larger than the others. It opens faster and stays open longer than the others from the looks. Do you need to do any modifications to put a 250 cam in a stock 230 motor? All this looks a little intimidating but I was reading through the procedure in the Clymer manual and they seem to explain it pretty well.

How challenging is it in your opinion?

 

<div class="FTQUOTE"><begin quote>Originally posted by: red230

hey randy, you can put a 250s cam into a 230 and acheive better performance?</end quote></div>

Yes, plug n play. I only had to adjust the intake valve .001 between cams!

<div class="FTQUOTE"><begin quote>would you be able to just follow the directions out of my service manual for puttin in the stock 230 cam?</end quote></div>

Yes, just heed my rtv warming. I'm not sure that's in there.

<div class="FTQUOTE"><begin quote>this sound like a quick, easy, and inexpensive way to get some performance out of my 230, if of course I read your post right and am not jumping to conclusions. </end quote></div>

I now consider the 230 cam junk.

I first discovered the 250 cam was different when we rebuilt my friend's. I thought it had a lot of lowend torque for a cam that dyno2003 said should lose lowend torque. Had that feeling for months now.... I just figured it was that he had a small stock carb on it.

The 230 cam does technically have more lowend torque. But its so low down in the rpm curve and the difference is so small, it doesn't mean a hill of beans to me. However, on the topend the difference is measureable and that seems to be where I like to hold the throttle.

I don't know how you ride, but I typically hold the throttle wide open and fan the clutch thru the gears. Sometimes the gear change is almost seemless and you can't really hear much of an rpm change. If you ride like that, you'll notice a decent jump in power with a 250 cam. At least I did. And my friend isn't all that disappointed with his setup. He likes to wheelie (and fall off the back daily, lol) and after a bore job and stock piston, he can wheelie better than anybody else that rides with us.

I'm sure the 250 cam isn't as good as one of the aftermarket cams, but its definitely better than the 230 cam.

Another line of thought is that is suzuki went thru all the changes in 1989 ( bigger valve size, straightened-out exhaust port, bigger wrist pin, longer rod, extra clutch disk, etc ), why would they stick a crappy cam in?

 

<div class="FTQUOTE"><begin quote>Originally posted by: atvman29

Good stuff Randy, That 250S cam is noticeably larger than the others. It opens faster and stays open longer than the others from the looks. Do you need to do any modifications to put a 250 cam in a stock 230 motor? All this looks a little intimidating but I was reading through the procedure in the Clymer manual and they seem to explain it pretty well.



How challenging is it in your opinion?</end quote></div>

It's not too tough of a job... I'm getting pretty good at it! [img]i/expressions/face-icon-small-happy.gif[/img] 3rd or 4th time in a number of months... and I just noticed I'm going to have to do it again because I put the bolt-lock on wrong. It should cover the pin in the cam and sprocket so it doesn't fall out in the engine like it shows in my pic. I put mine in backwards. [img]i/expressions/face-icon-small-blush.gif[/img]

Yeah, I noticed the cam lobe ramped up fast and stayed open at a large lift for a long time. I'm pretty sure most of the difference is on the intake lobe.

The 2 cams are exactly the same, just different grinds on the lobes. I only had to change my lash settings by .001 between cams!

I don't have the plastic on mine, but I suppose if you do that will be about half of the job right there... Just getting the plastic and tank off.

Then next most time consuming part is cleaning the gasket surfaces without contaminating the engine. A piece of dirt in the cam bearing would probably stay in there grinding away for days. So, keeping everything clean is the hardest part for me. Brake cleaner with the little red straw, compressed air, and lots of paper towels help out a lot.

The next thing is knowing how to unbolt and tighten valve covers. When loosening something, you always start on the outsides and work your way to the center. When tightening, start in the center and work out. Just like window tint, taping, or anything else like that.

Take the spring out of the cam tensioner before you tear into the cam, but right after you set the piston at TDC on the compression stroke. After you take the spring out, take the tensioner out carefully. Once out, note how far the plunger sticks out and then pull it out to its max. That's how much cam chain wear/stretch you have left. I'm maxed! I'll either have to weld a nut on the end of the tensioner or buy a new chain and install it, but one day my tensioner will no longer keep the slack out of the chain.

Put the tensioner back in before trying to loosen the cam sprocket bolts. Otherwise the cam chain may skip a tooth and make you have to check everything again and waste a lot of time. Easier to just tension the chain temporarily.

Don't take the chain off the sprocket. Just take the cam off the sprocket and use a screwdriver to hold the sprocket and chain from falling down in the engine. The 250 cam plugs right in and as long as the chain didn't skip, you can start putting everything back together.

I'll rattle off more tips as I think of them. [img]i/expressions/beer.gif[/img]

 

<div class="FTQUOTE"><begin quote>Originally posted by: UGLY88
As always good info Randy. Do you think your portwork is lettign you get the benefit out of the 250?</end quote></div>

I think my porting has shot me in the foot, so to say. I ported it for the 32mm carb. I'm using the 28mm now. A 28mm column of air blasting into a 32mm port can't be good for velocity.... Even if the port tapers to a funnel. I've resigned myself to one day taking it back apart and filling in with jb and re-porting. [img]i/expressions/face-icon-small-sad.gif[/img]

<div class="FTQUOTE"><begin quote>Does the stock 250 head, and the stock 230 head flow the same? </end quote></div>

Shoot No! The 250 has a 1mm bigger valve and more logical port structures. The 250 exhaust port is straight out the head. The 230 exhaust port bends off to the side. That little "boxy area" that Malhombre was talking about a LONG time ago on the 230 head that his mechanic filled in with epoxy is not there on the 250 head. The 250 head would easily outflow a 230 head. No question.

 

I'll be curious as to what you think of the aftermarket cams. Which one are you going to try first? Or are you going to get both at the same time?

 

Both at the same time.

 

Randy, does the 250 head fit the 230 motor?

 

<div class="FTQUOTE"><begin quote>Originally posted by: MalHombre

Randy, does the 250 head fit the 230 motor?</end quote></div>

It should. Never tried though. The 250 jug is taller because of the longer rod, but I don't see why the bolt holes wouldn't line up.

 

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