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rush66

A couple top end job questions

19 posts in this topic

Hey, doing a top end job on my bike for the first time and I have a couple questions. My bike was running good but was getting a little bit harder to start and felt like it didn't have the power it used to. So I decided to freshen a few things up adjust valves, rings, piston, cam chain and etc...

I've only ever had adjust my valves when I put the 450 cam in. That was a year ago I am not just finding I need to reshim my intakes as they're getting a little tight and the exhaust are a little loose.

I don't have ready access to do a compression test or leakdown test but I noticed a little more oil start to come out of the breather tube than usual so I figured it might be time for a top end. It probably only needs rings but I decided to do a new piston also.

5valve.jpg

Is this what used valves should look like?

piston.jpg

normal buildup on piston?

I have it all apart now and was wondering if all these parts looked normal enough, as I've never had the head off my bike.

cylinder.jpg

I am not sure if I need to hone the cylinder? It doesn't look like there is much build up or glaze. I think I can still see the cross hatch marks clearly.

Thanks for the help

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Wah there is a lot of carbon in there!

From your valve picture, I'd say everything looks normal except that they seem quite orange... maybe you're running this bike a little hot. My exhaust valves were kind of brown because they run hotter than the intake ones but yours are all orange except one. Is your jetting OK? Might be a little lean.... Just a thought.

Put a small brass brush on your drill and remove carbon traces. Don't put the brush on the surface with which the gasket comes in contact to make sure you won't dammage the surface and have leaks once reassembled.

Clean the top of the piston with the same brass brush and check for cracks or hot spots on the piston. If there is any, replace the piston with a new one.

By the time your sleeve is removed, remove the first two rings and check them. They must be within the specs. You should also check their slot in the piston. The third ring you cannot check. You replace the third ring (oil ring) if the other two show some wear.

Your cylinder doesn't look like it needs to be honed according to me but you'll need to check with a mechanic to make sure.

If you want to check if your valves seal properly, you can blow some break cleaner in the intake port and check if the cleaner leaks from under the head. You can do the same on the exhaust side. If the cleaner does not go through, it is a good indicator that everything seals right. If the cleaner does go through, you'll need to unmount the valves and check everything...

Hope this help

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99 400f and I was thinking the valves looked a little different than some of the others I have seen I asked a machinist friend and he said I'd be fine without honing it. I could be a tad lean, the plug is about the same color as the valves.

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The orange is from gasoline additives, possible oxygenated. Your head looks just like an 98 F-150s engine that we tore down the other day. The only thing I'm wondering about is why the ONE valve is noticeably different in coloration. Either way I have a few questions.

Have you ever torn down the engine? Reason I ask is my bike is used and runs well, so that gives me peace of mind that they really do hold together well.

What engine work have you done since 2000....just adjusting of valves, what about the chain etc?

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I looks like you use regular gas :)

Looks like that to me too. When I had mine apart I had a white dust on my valves, nothing like leaded fuels.

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Looks like that to me too. When I had mine apart I had a white dust on my valves, nothing like leaded fuels.

Sorry guys, you might be right about the regular fuel, but I don't understand why you say that. :) Could you explain please, I'm curious to learn :)

Thanks

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Pump gas tends to leave carbon deposits on the valves, head, and piston. The leaded fuel only leaves a white or grayish residue that cleans off real easy with some carb clean. Theres nothing wrong with pump fuel, your bike will run fine with it. I use leaded race fuel because its exactly the same everytime I buy it (gas stations water down pump gas with chemicals), leaded makes my bike have more snap off idle and pull harder in the midrange aswell, and finally jetting is alot easier with leaded fuels. Oh one other thing, I love how race fuel smells. My fuel of choice is Citgo 110 leaded, it costs almost $5 per gallon, but thats not too bad considering 87 pump gas is $ 2.10 per gallon. :)

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Pump gas tends to leave carbon deposits on the valves, head, and piston. The leaded fuel only leaves a white or grayish residue that cleans off real easy with some carb clean. Theres nothing wrong with pump fuel, your bike will run fine with it. I use leaded race fuel because its exactly the same everytime I buy it (gas stations water down pump gas with chemicals), leaded makes my bike have more snap off idle and pull harder in the midrange aswell, and finally jetting is alot easier with leaded fuels. Oh one other thing, I love how race fuel smells. My fuel of choice is Citgo 110 leaded, it costs almost $5 per gallon, but thats not too bad considering 87 pump gas is $ 2.10 per gallon. :)

Thanks for the info but you guys make me laugh with the price of fuel.. Here the 87 is 3.50 per gallon and the 92 is not any cheaper than your race fuel ( 4.20 per gallon!) We're in Quebec man! Taxes ruin :):p:D:D:lol::D:lame::D:o;):D:D our lives :thumbsup::thumbsup::cry:

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we arent far behind u in Cali, gas prices where i live have gone up to 2.35 or so. This summer its exspected to be up to 2.50(87 octane).

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We're in Quebec man! Taxes ruin our lives :):D:p
But the libs told us that taxes are good for us!! :)

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Ok I have everything torn apart and I finally have time to put it back together.

Thanks for the tip about the brass brush.

I do just run the normal premium pump gas and that could be the cause for all the build up with how long its been on this top end.

I got a wiseco standard compression piston kit to put in and I have a couple more questions I need some help with.

bikepicsrings001.jpg

On the stock piston the thickest darker ring was the top ring.

bikepicsrings002.jpg

And the bronze looking ring was the second ring.

bikepicsrings005.jpg

On the wiseco it looks backwards from the stock piston. The thicker ring is to thick for the top gap on the new piston.

bikepicsrings003.jpg

The bronze ring that I thought was the second ring fits in the top gap perfectly.

bikepicsrings004.jpg

The ring I thought was the top ring fits perfectly in the second notch.

Id the bronze ring suppose to be the top ring ?

Is that how it is on the wiseco or is there something wrong?

Also was wondering if I needed a sealant on the base gasket and head gaskets? (I don't think I do but just checking)

As for engine work done since 2000, almost none the only things I have ever opened the engine up for were a little over a year ago I put in the 450 cam had to re shim for it I also added a flywheel weight. Other than valve checks periodically I haven't had to do anything major. Just now do I need to reshim some other valves the outer intakes needed one smaller shim and the right exhaust needed one size bigger shim. I think I could have gone some more time on the old top end I am just doing this as prevention more than anything.

Not bad for a 6yr old bike. Do the basic maintenance and take care of it and the yamaha thumpers will take care of you.

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Kinda obvious that the bronze ring is the top on the wiseco as that is the only slot it fits in but I found it peculiar and I was just looking for affirmation on my thoughts. Anyone know why it is different?

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Regarding the pistons, I'm tempted to speculate this.

On a stock piston/ring kit, the first ring (the one that goes in the top slot) has to be the one with the smallest overture.

I'm pretty sure that if you look at your wiseco rings closely by putting them both one over the other in your hands, you'll see that one of them has a biggest overture than the other.

The smallest overture ring goes on top and the other goes right under.

Then if the one with the smallest overture is also the one that fits best in the top slot, you have two arguments to put it on top.

I'm pretty sure of what I'm saying but if I were you, I would contact Wiseco and come back posting their answer here in this thread :)

Don't mess with it! :) and keep us informed cause I'm probably going to replace my piston next year with a Wiseco kit so your input will be useful :p

HTH

Math

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Kinda obvious that the bronze ring is the top on the wiseco as that is the only slot it fits in but I found it peculiar and I was just looking for affirmation on my thoughts. Anyone know why it is different?
It's not unusual for the two compression rings to be different. In fact, it's rather more common than for them to be the same.

The top ring is often hard chromed, or otherwise plated or coated to make the wear surface harder. I'm not certain exactly why this is common practice, but I imagine it has to do with the top ring being farther from any lubricant, and closer to the heat and debris of combustion. I am pretty certain that the ring you're looking at has no bronze in it, and that any gold color it has is probably titanium nitride, a very hard substance which is used on cutting tools and your titanium valves. It's also not unusual for the top ring to be thinner.

Make sure that you know if there is an up and down side to each of the compression rings, too. There may not be, but if there is, it will be covered in the information that came with the set.

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all good info now try supermoto! These bikes kick ass on the supermoto tracks/ check misupermoto.com

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I know there isn't any bronze in the ring but that's just the color it looks like.

I just got off the phone with wiseco and they said that is the proper placement of the rings. They do have a top side and the iron looking ring does have the sharp sorta tapered edge like a second ring should.

He didn't explain much about why it was different but said I'd like the difference compared to stock and he gave me the tip to put the piston in the cylinder then slide it down to where the hole is exposed to put the wrist pin in.

I am going to go assemble it hopefully break it in today or tomarrow and I'll post the results.

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