Valve Problems

[Rusty91o]

My 300ex has stuck valves. How do I fix that?

[250X_project]

well.....first elaborate more. How do you know it is "stuck"? Do you have the covers off?...we will go from there with a little more info.

Also intake or exhaust and how many?

[2muchquad]

If you had hydraulic lifters like a small block chevy then maybe.A 300ex has rocker arms to open the valves.Unless your lobes are worn completely off your cam.:( You could have a bent valve from piston damage but...

[Rusty91o]

I'll have to get back to you guys with some more info then.

[250X_project]

I'll be waiting. The only way I can think of a valve sticking is if you had a 250X instead, with a kick start and decompression on the ex. valves....unless you bumped the piston :(

[Rusty91o]

Yeah the exhaust valve is stuck I guess, I still haven't looked at it myself. The guy I got it from says If I were to just get a new valve it would be fine. Does any of this make sense? Any advice?

[250X_project]

Well if you have a stuck valve that must be replaced then it is most likely because the stem is bent, This is probably because it dropped and hit the piston. IF so than you may be able to just replace a valves and be fine.....or you may have head damage, piston damage, cylinder or other damage depending on if pieces of the valve went into the engine. I've seen both.

But until I know for sure what even is the matter I can't tell you for sure....I'm just stabbing in the dark here.

Just take the cover off of the head and take a look and tell us for some better help.

[Rusty91o]

Ok. I was able to look at it for myself early today. One of the intake valves hit the piston. The piston only has a very small barely noticable scratch in it. The Valve is slightly bent, and the sleeve for it is cracked. It looks like all I will need is a new valve. (what the previous owner said) But, If I get a new valve, what next? Won't I have to figure out the timing, or adjust the valves? I'm just not quite sure what all this involves. (Is this a reasonable do it yourself job, I am a very mechanically inclined person) Please give me as much info as you can. Thanks.

[Mud_Slinging]

Welp, I don't know a whole lot about 300ex's, but I do all the motor work on my quad. If you change out the bent valve, I would probably recommend putting a new valve seal in if it's worn. Once the valve is in with the valve springs, you have to set the valve with a feeler gauge. Then most likely set the timing again. It's really not that difficult to do. Do you have a Clymer manual or a Service Manual for your quad? If so, the book will tell you exactly what to do, step by step. All in all, if you take your time. It's not a hard thing to fix.


*edit*
Ok...I just looked up a 2000 Honda 300ex for an example. It seems they have 4 valves with one cam. That would be pretty darn easy to do compared to my DOHC 4 valve....

If I'm correct on this quad...here would be my rough step by step help...

1. Remove Cylinder head cover
2. Take out cams, then remove cylinder head.
3. Figure out a way to take off valve springs, I use a socket and c-clamp
4. Remove damaged valve. (And seal if damaged)
5.Clean everything thoroughly
6. If a new seal has been purchased install it as well as the washers underneath the springs.
7. Then install new valve, then install springs
8. Check over everything to make sure it is correct.
9. Install cylinder head
10. Get motor at TDC (Top dead Center)
11. Set cams to manufacturer spec
12. Once cams are set, check valve clearance with a feeler gauge.(One can be purchased at an automotive store for like $5
13. After clearance has been set to manufacturer spec, put cover cylinder head cover back on, and give it a crank....
14. Hope for the best
:)

[Rusty91o]

Good thanks. Yes I have the Clymer manual for the EX. I'll frobably have to get some of the required tools then. But it looks as if I will be able to do this job myself, and without spending alot of money. BTW, I had a Mojave too. :) But It was stolen :mad: Worst day of my life

[Mud_Slinging]

:( Thats horrible!!! I don't know what I'd do if someone stole my Mojave....lol


But anywho..about that EX

The clymer will give you step by step guidelines to go by while fixing your quad. The only tools you will most likely need depending on how crafty you are would be ratchet,appropriate sockets, needle nose pliers, feeler gauge, c-clamp, and a lot of patience...

The way I used the c-clamp and socket rigging for removing the springs might require 4 hands...but I manage to do it by myself with patience. What you do is,

1.Position a decent sized socket on the base of the valve you are removing
2.Take the c-clamp and put the solid end on the socket and then take the screwing in part of the c-clamp and press down on the springs to remove them.
3.Take your time, and wear eye protection, if one of those springs flies off and gets you in the eye you're gonna be hurting haha
4. Once you removed the springs and replaced everything, you basically repeat the process, but installing the springs and valves. It's not a very difficult thing to pull off. It is much easier than going out and spending a ridiculous price for a tool you might only use twice....lol Just my $.02 on that comment...lol

[250X_project]

"The Valve is slightly bent, and the sleeve for it is cracked."

What do you mean by this? Is it the valve guide of the actual head? You can not leave it like this.

There is no sense in replacing only one seal. Replace all 4. They come in a good top end kit anyway. $25 off eBay.

SPRING REMOVAL- just hit them with a hammer and socket and don't loose the keeper. :D

ADJUSTING VALVES- you can't exactly do that with the head cover off as the rockers are in the head cover.... :huh .004 is spec for BOTH intake and exhaust.

TIMING- TDC as said, and both lobes on came faces down at about 4 and 8'oclock with lines on cam sprocket flush with the head. ;)

[Mud_Slinging]

Originally posted by 250X_project
ADJUSTING VALVES- you can't exactly do that with the head cover off as the rockers are in the head cover.... :huh .004 is spec for BOTH intake and exhaust.

Sorry, I was just going by what I know doing my valves and cams...Like I said, I'm not familiar with the 300ex....:(

[Rusty91o]

Yes, I believe it is the Valve guide that is a little cracked. When I buy these things off of Ebay, will I have to find a top end kit, then a replacement valve? Or will it all come together. Or... would it actually be much better/easier to get a whole new head, because I found one.

[250X_project]

Mud_Slinging- What do you have that has the head cover off to adjust the valves??

If you stick with the old head you can find the top end gasket set for about $24shipped w/ seals. Valve guide for $10+shipping. And $24 shipped for the intake, or $35shipped for exhaust. Are you 100% sure of which it is? ...Grand total of $58+guide shipping, if it is intake and all your work or mechanic/machine shop work. How much for the new head. Is it NEW NEW?

[Mud_Slinging]

I have a 1991 Kawasaki Mojave DOHC 4-Valve
I can take off my cylinder head cover, and have access to my cams,cam chain,rockers,and adjusting valves...

[Rusty91o]

I have a couple of options. One is slightly used, less than mine. For very cheap, looked good. Total of about 35$ including shipping. Another was absolutely brand spanking new, for 60$ maybe about 75$ with shipping, if I were able to get it. I'd say go for the cheaper one, not to mention there's more of a chance to actually get it. (Ebay we're talking)
And yes Mud is right, on the Mojave you do have access to everything with the cover removed.

[250X_project]

Yeah, just inquire about the valve faces- that goes for the head you have now too. These engines eat valves.

That's wierd I didn't know the mojo was a dual cam....:huh

[Rusty91o]

Alright, I guess I 'll try to get this whole new head. If I get it, the next problem will be trying to wait until it arrives. lol
I thought Kawasaki did such an awesome job with the Mojave. I was impressed with just about everything about it. (Mine couldn't be killed) I don't think the Lakota had DOHC though. Since the Lakota was the next ring up from the Mojave.

[Mud_Slinging]

The Lakota was SOHC unfortunately...The Mojave was way ahead of its time, 1987 DOHC 4-Valve 250cc 4-stroke...Can you say a bit advanced for its time?? lol
It's a real shame they quit production of them tho :(

[Rusty91o]

I know really. Didn't they put electric start on the last 04' models?

[Mud_Slinging]

Nope, they were kickstart strictly from 87-04....I think if they had the electric start they would still be in production...

[Rusty91o]

They should put it back into production. Kawasaki is lacking variety with sport ATVs now. They don't make the KFX 400 anymore. The KFX 450 is yet to come, the KFX 700 is awesome, and will be around for a while I think, and they still make the KFX 50, and 90. But they are styled after the new 450. Bring the Mojave back, restyle it a little, add electric start and whatever else. I'd definitely buy one.

[250X_project]

Mud_Slinging- I wanted to apologies about the head cover thing. I know what you mean know, I'm working on an XR bike right now with that set up. :D

[Mud_Slinging]

It's alright man..You didn't know about the Mojave...And I didn't know about the 300ex either...:D

[Rusty91o]

I'm so glad I found this place. Intelligent people, and ones that can admit mistakes, apologize, and take things simply and lightly. And not act like little kids fighting in a sand box. lol

[Rusty91o]

Oh yes. And I ordered the new head, and a brand new Gasket Kit as well. Hopefully, (depending on when they parts come in) I should have my EX running in about a week.:D

[250X_project]

Yes this forum is deffinently my favorite. I love it. Great people!