[hondarider]

Hey guys I was just wondering if anyone might know what type of jug this is it has est head and all but not sure if it is esr jug any help is greatly appreciated
IMG081.jpg
Phone will not let me put pic will put one on when I get home sorry

 

[kerryaldridge]

Looks like ESR. Usually on bottom side of exhaust or carb port it will have what type of ESR exhaust it has been ported for engraved on it

 

[hondarider]

It has CT racing exhaust on it but ill check when I get home thanks kerry

 

[PORTED R 22]

looks like you have one the first generation prox design cylinder ,its a cylinder that ct or esr used
the reason why i say first and older generation cylinder is becasue you dont have a brace on the reed block area of the cylinder

 

[PORTED R 22]

ok heres a picture of a newer design prox cylinder ,you see the bridge that runs almost up and down on the reed block area ,that acts like a brace ,i geuss those older cylinders would crack over time

 

[etccb]

The next time that you have it down for any work being done to it you should add some braces to that area simular like you see on the newer prox and esr's cyl. Just for safety being that they were added to them for a reason.

edit=crap...I thought that pic had braces added in it as well..You may be able to find a photo of one that was braced to use as a guide if not being done by someone that is very familier with it. I will keep my eyes open for one as well.

 

[PORTED R 22]

ive heard that LED does the mod to the cylinder,im pretty sure other builders do it aswill

 

[etccb]

Yes I am sure there are several that have or know about it and will. Your next bore send it to someone that will do that for you while they have it. The sooner the better though......

 

[kerryaldridge]

Why does it crack? Is it from using eliminator kit without a brace?

 

[PORTED R 22]

not sure i think its from cylinder pressure itself ,like the compression

 

[acecarlos]

View attachment 8064


Hey guys I was just wondering if anyone might know what type of jug this is it has est head and all but not sure if it is esr jug any help is greatly appreciated
IMG081.jpg
Phone will not let me put pic will put one on when I get home sorry

Yup; it is an early ProX, without the support ribs like Ported R22 stated. They crack due to the thin wall section, and lack of support to the rear cylinder base bolts. Keep in mind; ProX developed this cylinder, the castings, and the use of a BB aftermarket cylinders for 250R's way back when...lot's of development work when into BB cylindrs for 250R's.

The New ProX cylinders as well as the Copies of 'Low Cost' cylinders now in production are a newer version derieved from the latest ProX cylinders. Not all of these early cylinders without the support ribs cracked, most did not. The support ribs was added as a 'safety' measure, if yours has any amount of run time, it will likely be fine and not develop any cracks. As an added 'make you feel good' measure, you can get the support ribs added/welded in place.

Carlos

 

[atv fan 28]

 

[C-Leigh Racing]

I can add something else about those old model cylinders.
You see in the pic how thick the mounting area is for the reed cage, even though it is that thick, it will sit the end of the reed cage closer to the back side of the sleeve & cause the tips of the reed petals to strike the sleeve or what is left of the cylinder casting. The newer model casting that reed cage mounting area is moved back a bit more so the reed petals cant touch.
Always use a reed spacer on those old castings, between the cylinder & reed cage if your using the Boysene Rad Valve, because it is a bit longer than normal reed cage & the tips of the petals will hit the sleeve.
Neil

 

[acecarlos]

Yup, use a 1/4" or 3/8" reed spacer plate on the old ProX jugs with the Boyesesn reed Assy, I would also use it with all other Reed assemblies as well on these older ProX's.

Carlos

 

[udontknowme]

cr500 has same problem with radvalve. puts the cage right on the piston. completely covers the boyesen ports also. the design doesnt appear to be well thought out. stock cage or vf3 seems to be a better option on the 500 jug. swapped a rad valve for some vf3 and never looked back