Replaced the Vacuum Lines - she feels like a different bike!

[8Track]

Hi all,

At 17 years of age and 52,000 kms I figured it was time to check the vacuum lines under the carb bank. I was dreading the job due to all the reports I heard about how difficult the airbox is to refit.

Anyway I went ahead and got stuck in. Surprisingly, it wasn't such a difficult job after all. I found a couple of tiny pin holes in the tubes to intakes 3 and 4, but the tube going up from the T piece to the Pair valve was in good condition.

I replaced all the lines anyway, put on new sealing caps on intakes 1,2 and 5, and a new line from the petcock to intake 6.

The airbox went in quite easily. I took off the 6 metal sealing collars before taking it out to make sure I didn't scratch the frame, and maybe this made it a bit easier to re-install. The trick to getting it back in is to go around all the snorkels and get them lined up with the carbs before you start doing up the sealing collars. Push them on and make sure they are sitting flush all the way around and you're good to go.

Once it was all back together I hit the starter and could tell right away the engine seemed happier. Quicker response to the starter motor, and less time needed with the choke on. The idle was smoother, not hunting around as much. It does still seem to skip a beat every now and then, not sure why that is.

The real test was on the open road. The engine runs smoother, and delivers more low and midrange power with a crisper throttle response. The bike feels much more lively. Upper end power still feels about the same, however I think the bike is accelerating there faster and climbing the rev range quicker. I also noticed that roll-on acceleration in 4th and 5th is improved quire a bit too.

Not sure what has contributed to the change. Was it just the little pin holes in the vacuum lines that robbed the bike of power, or maybe the airbox wasn't correctly seated before I pulled it out? Who knows? All I can tell you is that the bike has lost its lazy feel and is now much more eager to get up and go.

The next job is to replace the intake runner o-rings and then do a carb sync. After that, I don't think there will be much else I can do to improve things.

Thanks to all the members of this board for all the information they make available. It really helps!

Cheers,

Mark

[Bone]

All I can tell you is that the bike has lost its lazy feel and is now much more eager to get up and go.

There goes your MPG   

[8Track]

All I can tell you is that the bike has lost its lazy feel and is now much more eager to get up and go.

There goes your MPG   

Oh well! It will be fun!

[Paladin528]

What size are the Vacuum lines.  I think I am going to go over them and replace.  If I can find red ones, even better.

[hubcapsc]

I had good luck changing out those lines too 

I did them at the same time as the intake runner o-rings and exploited
having one or another of the runners off while I was fishing around back
in there for the vacuum lines... it really helped reaching some of the rotten
carb drain lines - they don't make the bike run better, but some were rotten...

-Mike

[Patrick]

Not sure what has contributed to the change. Was it just the little pin holes in the vacuum lines that robbed the bike of power, or

end quote






Engines don't like vacuum leaks.  They were probably leaking for a long time.

[8Track]

The size of the vacuum lines is 5/32".

Cheers,

Mark

[Tfrank59]

I bought the Redeye stealth kit over year ago, but I'm so carb non-savvy I have shied away from doing it.  I fear my bike has vacuum leaks too, and that once I get in there I'll be glad that I did the work even though like I said I'm kind of scared to get in there and open her up.  The guys on this forum have already encourage me to do it, and I know I got their help if I get in over my head, so I should probably do it this winter at the latest.

[Bighead]

I bought the Redeye stealth kit over year ago, but I'm so carb non-savvy I have shied away from doing it.  I fear my bike has vacuum leaks too, and that once I get in there I'll be glad that I did the work even though like I said I'm kind of scared to get in there and open her up.  The guys on this forum have already encourage me to do it, and I know I got their help if I get in over my head, so I should probably do it this winter at the latest.

Don't be scared guy just put the parts back where they came from and all will be good.

[Crackerborn]

The air cut valve hoses should be replaced with all the rest of the hoses. You know, the short little suckers on the side of each carb that require hemostats to get off and back on. When they leak, performance really drops off.

[BF]

What size are the Vacuum lines.  I think I am going to go over them and replace.  If I can find red ones, even better.

Just a quick check on eBay, they have it in orange, yellow, blue green AND red. 

http://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H1.Xvacuum+line+5%2F32%22.TRS5&_nkw=vacuum+line+5%2F32%22&_sacat=0

[Kunkies]

thanks for the eBay link, any advantages in using a Stainless Steel hose versus rubber?