check valves

[addicted]

we all know that the 65U carbs are really suceptable to creasing. Question is, what can be done to minimize that? longer pulse lines? softer pulse line hose?

[J-ME]

Get block off plates (available from Hot Products) and run and external pump.
You may also be able to just remove the diaphragms, and install an external pump (Raider 1100 style) and run a return line restrictor.

[oldmanraider]

Do you think this could work. http://www.groupk.com/sep.htm

[CatRunner]

we all know that the 65U carbs are really suceptable to creasing.

Can someone give me a brief description of what that is? thanks.

[Metal4130]

OMR, I think that group k set-up will work. In the product description it says it eliminates the stock fuel pumps.

[Duke]

we all know that the 65U carbs are really suceptable to creasing. Question is, what can be done to minimize that? longer pulse lines? softer pulse line hose?

The only time I ever creased a 65U AC pump disc was during a hard backfire on a tripple pipe. Mike you must have had something dramatic happen IMO.

External fuel pumps were way more trouble then they were worth!! my .02

[addicted]

Well, this is the second set of check valves that went bad on me with these carbs in less than 1 year. I was thinking about running a seperator, mainly because i like to run it low on gas, but i don't like the idea of an external pump. what bugs me the most is that the fuel pumps, internal or external are identical on the inside, so why is it that the carb mounted ones blow?

I *think* i got bad gas or a mystery additive at the bug and it caused a backfire or 3. i still have to check the riva flywheel to make dure it didn't crack and throw the timing off.

[Flying Scotsman]

Sounds like a flywheel crack but it could be your gas lines started to melt are they oem or other.

[jdog800]

I would also say that its more thatn likely not the fuel pump....Internal or external both fuel pumps work the same way. They both take signal off of a pulse line only one is mounted directly to the carbs and one is not. I couldnt see how one would be any different than the other.
Backfire usually points to bad timeing or bad mixture ratio. I would check your flywheel key and make sure it hasnt been bent over a little bit making you advanced. You may also want to index your crank to make sure its not twisted. This would also cause a missfire in one cylinder.
Addicted I also am wondering if I didnt get some bad gas at the bug. My bike has been riddled with strange running properties. I still have a portion of that gas in my bike now. This could be the grimlin we have been looking for. Just my 2cents. JDog

[97GPSLEEPER]

Something is causing your check valves to crease so often. I rebuilt my carbs over the winter (after 5 years, I was pushing it), and my check valves were not creased. I have heard of some people installing two check valves, this would make it less likely to crease, but you need to find out what is going on.