Unofficial Royal Enfield Community Forum

General Discussion => Tech Tips => Topic started by: Roger on November 11, 2007, 02:23:16 am

Title: Vacuum Leak
Post by: Roger on November 11, 2007, 02:23:16 am
For some time I have suspected there maybe a slight vacuum leak in the line that runs for the block in front of the carburettor and the vacuum pump located in the left hand tool box.

I initially blocked the tube at the carburettor end; I felt this action improved the ability of the engine to idle more reliably. I later noted the small diameter steel tube in the block in front of the carburettor was also slightly loose and while I felt that any leak from here would be very minor I decided to remove the tube altogether.

The tube looked as though it was originally glued in place with some sort of epoxy cement as once removed it was quite loose when placed back into the blocked. (See attached photo)

I tapped a tread (I used an M5x0.8 tap) into the block where the tube was removed, and fitted a suitable length screw after coating the thread with sealing compound. I had some Loctite Power Gasket on hand so I used that.

I removed the plastic tube and the air pump in the tool box, as well the braided line that runs to the exhaust header.

Roger


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Title: Re: Vacuum Leak
Post by: mbevo1 on November 12, 2007, 01:23:21 pm
When I removed the PAV, I put a dap of JB weld in the hole.  Nice and smooth, no leaks.

Mike and Stumpy in Michigan
Title: Re: Vacuum Leak
Post by: LotusSevenMan on November 12, 2007, 06:20:52 pm
I'm just about to do away with the PAV as I have a shorter, less restrictive exhaust coming that has a new header pipe too which has no welded-in PAV takeoff boss   :)
Any tips (apart from the JB-WELD) to removing all this clutter?
Title: Re: Vacuum Leak
Post by: Ofcalipka on November 12, 2007, 07:08:14 pm
I did this modification.  Just remove all the bits of the PAV.  Close up the hole on the intake like Roger detailed and put a rubber vacuum plug on the point where you remove the other end of the PAV line.
Title: Re: Vacuum Leak
Post by: Roger on November 13, 2007, 10:11:11 am
Right after I removed the PAV and the associated plumbing I went for a ride to see if there were any problems, I knew there wouldn't be but I just like riding my RE. I got about a mile down the road and the heavens opened up. It is that time of year here when showers persist (quite heavy ones at times) right up until summer starts. I high tailed it back home and by the time I got the garage door opened I was soaked.

Roger
Title: Re: Vacuum Leak
Post by: cyrusb on December 08, 2007, 02:16:14 am
Your on the right track, don't forget to do the jetting, its mandatory cmw has the parts.Average sizes go like 130 main and like a 29.5 pilot. Don't even start the bike to hear the new pipe before doing this,thats how lean it will be with the stock jets. Instant blue pipe...
Title: Re: Vacuum Leak
Post by: LotusSevenMan on December 09, 2007, 11:17:32 am
What are the stock main and pilot then please?
Title: Re: Vacuum Leak
Post by: Kevin Mahoney on December 10, 2007, 04:33:51 am
Stock main in a 500 is 110 and pilot in same is a 25
Title: Re: Vacuum Leak
Post by: LotusSevenMan on December 10, 2007, 08:22:45 pm
Thanks Kevin!