Exhaust Bridge

[dirtbike59]

Hi i just got a new wiseco piston. in the direction it talks about drilling hole for a exhaust bridge. My question is what is a exhaust bridge? How would i know if i have one on my bike. It is a 93 RMX 250.

 

[keith500r]

looking at your exhaust port, if its a single hole, with nothing dividing it into two holes than you dont have a bridge and dont need to worry about it. Some bikes usuallly larger displacement, have a bridge going up and down in the middle that splits the exhaust port into two separate openings. if you have that its a good idea to follow the directions that came with the piston.

 

[dirtbike59]

Thanks . I do have one but the stock piston on the bike didn't have holes drilled into it. What would my chances of a problem if i don't do this. i have already run the bike for one heat cycle. And this bike is never raced only trail ridden

 

[jmics19067]

The idea drilling the holes for the exhaust bridge I beleive is recommended but not nessecary<sp>It is meant to give a little bit more lubrication and cooling to exhaust bridge. I would ride it since you have the bike back together but the next time you redo the piston and or rings look and see if the piston is scuffed.

I do not know if the differences between the types of pistons make a difference<cast or forged> or that if you have some scuffing that the lack of oil holes are the direct problem.

It is somewhat of a pain to drill those holes. Putting the wrist pin , bearing and piston on the rod , sliding the jug down running a couple of nuts down snug for it, reaching up thru the exaust port with a felt tip pen to the thinnest part of the bridge, slowly turning the engine over marking the piston. Take it all apart again, finding the middle of the two lines you just made, finding the heighth on that center line where you are supposed to drill.
keeping thedrill bit from walking since it is something round you are trying to put a hole thru. I am leary on smacking my psiton with a center punch<call me chicken but thank goodness that it is aluminum and the drill bit shoud bite right in> . Deburring the holes you just drilled, and then recleaning everything
It is a smidgen easier then the way i tried to explain it but if I HAD to do this everytme I installed a piston I would probably buy the stock piston only because the factory didnt think I needed it and I dont have to do it. The majority of my decision resting on the idea of if the piston manufacture says I need it then they should do it when making it. I know that a a particular piston wil usually fit a few different years of a model , some with exhaust bridges some without . But my idea is I am spending My money Your product better fit my needs and nothing more.

 

[DougMXer]

coudn't agree with you more, Exhaust bridges are ****ed , a pain in the arse, and I don't see how they lead to any peformance gains. I totally ****ed a 1990 CR250 , because I thought I was knocking out the seized valve guide from the other hole, whereas in fact I was tonking the exhaust bridge. Totally ****ed a resleeved barrell and had to hock it off for $1000 to some poor cunt. Oh well lifes a bitch and then some !!