300ex valves and cam

[Rob_Tapp]

A piece of the choke butterfly broke off on my 94 300ex, it sucked into the head. It bent the gap in on the plug and came out in the exhaust pipe in a bunch of chunks. I took the head off and thought there would be some damage. The cylinder wall looks fine, nothing wrong with the piston, the valves look good. I can tell where the valves hit it, but no signs of damage. It was a small piece, about 1/4" long by 1/8".

My question is, while I have the head off, are there any mods like another cam or valve work that I can do that I dont have to change the carb or the piston? Just something that might give a little more punch. 94 300ex, 4" Supertrapp, smaller front sprocket, 20" shredders on rear.

[dirtmomma]

You could have some porting work done, is it a stock cam?? If so you could get a WEB cam, I run a stage 3 & LOVE IT!! Also you could go w/ hardened rockers Good Luck

[Aceman]

Since your quad has no motor work done to it, my advice would be to try a White Bros all around cam, I think they are a drop in cam. With a Web Cam you have to get hardfaced rocker arms with it, which really adds up. I don't think I would go for the port and polish ,too spendy for that stock motor. A KN filter with some holes in the lid, that cam and your pipe should make some more power. To really make some decent power, a high comp piston and a cam would be ideal.

[dirtmomma]

now i don'think the porting is a waste of $$ & as for the cams WEB has a "drop in" cam it's a stage 1, if you hunted around you may be able to find a good deal on some hard faced rockers :) I did! I guess maybe the porting is excpensive, I got my done FREE :D And YEP onthe high comp piston I'm just one over so it's not that big, but it just had to have a cleanup bore :)

[sjc115]

The porting will make a huge difference on that motor. The 300ex actually uses a 250 head, so it will benifit greatly from some port work.

You should be able to get a good port job for around $100. I think I saw pricing on the Hetrick Racing website (www.hetrickracing.com) for all kinds of 300ex motor mods. That would be a good indicator of what it might cost you for the different upgrades.

[buster369]

I have a 93 with a web cam- cam, rocker arms, and springs. I also ported and polished the head and did a valve job on it. you could bored out the values and get bigger ones if u want. The engine work with a .020 weisco piston made a great difference. It was expensive but it was well worth it.

[Rob_Tapp]

I just checked the head out and everything was good. I just got a new head gasket and replaced the head, put it back stock. When I fired the bike back up, it seems to tick a bit more in the valves than it used to. I am pretty sure the cam timing is set right. The marks on the cam sprocket werent exactly lined up with the case. I got it as close as I could, move the sprocket on tooth forward it was too much, backward and it was too much. Can the cam chain be moved on the sprocket at the crank? I tried to slack the chain and move it a tooth or two on the crank but couldnt, is the case made so that there isnt enough clearance to get the chain over the sprocket? I think this might be what is causing my tick. The bike starts and revs fine, just a slight tick. Any suggestions?

Thanks Rob

[buster369]

ur timing chain could be to stretched out due to overheating or just wear. or it could be loose becasue the cam chain adjuster on the back of the cylinder is not functioning properly