bridged exhaust port problems

[bluehawkkevin]

is it true that those cylinders with bridged exhaust will eventually "ruin" the rings due to high temperature on those bridges??is it ok to remove or reduce the bridge of the exhaust??

this particular cylinder i used was the MHR and Evo...help me guys

 

[Big B NRG]

No not really, but you should pay some attention to the bridge.

You can sand it down with some oil and sandpaper, another thing you could do is drill 2 small holes in the piston at the place where the piston goes over the bridge. This helps cooling the bridge.

Edit;

Picture;

 

[bluehawkkevin]

thanks Big B , any other feedbacks guy's?? i had a fear that the ring may snag if i remove the bridge , but i think the image ginven by Big has a potential to reduce the "heat" into the bridge.

 

[Areomyst]

Hello sir,

I don't think you want to remove the bridge, as that will cause you to have even worse problems. The reason that the exhaust port has the bridge in the first place, is so that the ring does not expand too far into the exhaust port and break on the roof of the port when on the upstroke.

Without the bridge, the port could not be as wide, and you would have less performance out of your cylidner.

Also, Big B's suggestions are good! Many tuners sand down the bridge a little (or use a diamond tool) to add a little extra clearance that allows more room for the bridge to expand. Usually these things need to be done when the exhaust port has been ported, and the bridge narrowed, but I don't suppose it could hurt much on a stock cylinder. Personally, if it's a stock cylinder I wouldn't worry about the bridge unless it was going to be ported.

Cheers!

~Josh

 

[Big B NRG]

Well, with the Evo's cylinders are quite good from factory, but the malossi needs work on their bridges from factory...

 

[tiba_karotsu]

Well, with the Evo's cylinders are quite good from factory, but the malossi needs work on their bridges from factory...

+1

the exhaust port bridges on the Evo1 kits hardly need any sanding, as for MHR it's the opposite.

 

[bluehawkkevin]

i have reduced the bridge around 4microns side to side , but for the suggestion of big b nrg i have a fear that the said dimples might cause some carbon deposits which may ruin my cylinder in the future..i just do hope it would still give me a long time to use my evo 1

 

[tiba_karotsu]

i have reduced the bridge around 4microns side to side , but for the suggestion of big b nrg i have a fear that the said dimples might cause some carbon deposits which may ruin my cylinder in the future..i just do hope it would still give me a long time to use my evo 1

it will never happen, ever. you'll more likely to ruin your cylinder with cheap oil.

 

[DRXRACING]

i have reduced the bridge around 4microns side to side , but for the suggestion of big b nrg i have a fear that the said dimples might cause some carbon deposits which may ruin my cylinder in the future..i just do hope it would still give me a long time to use my evo 1

Don't use the dimples just drill them all the way thru, then cut a channel about the depth of the dimples from hole to hole. = Lubrication channel.

Cools the exhaust bridge.

 

[Browni]

Don't use the dimples just drill them all the way thru, then cut a channel about the depth of the dimples from hole to hole. = Lubrication channel.

Cools the exhaust bridge.

DRXRACING is right! Dimples are quite useless, use real holes as a cooling channel (but not as big as on the picture). The holes must be smaller than bridge width, because of the sealing surface. Fresh mixture from the crankcase cools down the bridge. But don't forget chamfering the holes inside and outside.

 

[Big B NRG]

This worked for my pretty good guys.

 

[bluehawkkevin]

drx can u send me some pictures of your idea of drilling it?

 

[tiba_karotsu]

i also did this on our 2Fast & MHR Team cilinders & it helps to cool & lubricate the bridge.

i see no need to do it on Evo cilinders as they are not prone to warping but if you insist, find a sharp blade (cutter) that will fit inside the exhaust port, it would be better if the cilinder & piston is installed & tightened down. move the piston to TDC & then scribe a line on both sides of the bridge, make sure the line is visible then you pull out the cilinder & piston, using a pointy center punch put a mark or 2 right between the lines which is dead center on the bridge, drill the mark as straight as possible & you're finished.

 

[bluehawkkevin]

you mean that would be 2 holes on the side of the bridge???

its opposite to the idea of big B nrg....

if we will be using the picture given by big b...the 2 dimples is within the bridge....for tiba he's idea is to put 2 holes at the sides where the bridge goes thru??

clarify your ideas guy's...considering compression , lubrication and others?? can it really help???

as you know i have to make sure of it...piston sets is very costly here in PI.

 

[Big B NRG]

Don't really worry about compression. You ain't gonna notice it.

Don't get rocket science scientific with this.

 

[mt5-ronken]

you mean that would be 2 holes on the side of the bridge???

its opposite to the idea of big B nrg....

if we will be using the picture given by big b...the 2 dimples is within the bridge....for tiba he's idea is to put 2 holes at the sides where the bridge goes thru??

clarify your ideas guy's...considering compression , lubrication and others?? can it really help???

as you know i have to make sure of it...piston sets is very costly here in PI.

He means just like big b's dimples, but the holes go all the way through.
That way fuelmixture and oil can pass through the holes to the bridge.

He didn't mean 2 holes on the side of the bridge...

 

[bluehawkkevin]

got the idea..THANKS TO YOU ALL GUYS

 

[tiba_karotsu]

you mean that would be 2 holes on the side of the bridge???

its opposite to the idea of big B nrg....

if we will be using the picture given by big b...the 2 dimples is within the bridge....for tiba he's idea is to put 2 holes at the sides where the bridge goes thru??

clarify your ideas guy's...considering compression , lubrication and others?? can it really help???

as you know i have to make sure of it...piston sets is very costly here in PI.

you misunderstood my post, i said drill the holes between the 2 lines not on the sides, maybe this picture will help you understand.

 

[bluehawkkevin]

thanks tiba, what specific size the hole would be?? are the holes be on tDC & bdc respectively??

 

[Big B NRG]

You see the picture, copy that image!