Carb diaphrams

[frankd]

Adjusted the one tight intake valve on my 89, and figured that seeing that the Tupperware was all off, I may as well check the carb diaphrams. I had small holes in 3 of them---my bike only has 58K miles on it. I looked up Sirius and found that they were out of stock on diaphrams until the end of the month. While doing searches here on this site, I came across Snagletooth's message about using Plasti coat to make a temporary repair. Home Depot carries Plasti coat, so this morning I followed Snagletooths' proceedure and this afternoon I re-installed the sealed diaphrams. In addition to the Tupperware, both heat shields (the ones that are over each valve cover) were out, so it was real easy to change the spark plugs. Heck, I also found an open plug cap. I ordered replacements, but I took the bad one apart and convinced it to work by cleaning everything up. The resistance is a bit high (the resistor itself reads high), but it'll work until the new ones get here.

 

Then the fun began. I started the bike up, and it sounded good when you opened the throttle, but it idled badly and slowly. I checked the carb sync, and it was all over the place. I synced the carbs (both on the right side were almost completely closed) and I had to slow the idle speed down quite a bit. I also had to adjust the idle mixture screws. Now it's idleing great. Those holes in the diaphrams sure had an effect on how the bike idled. BTW, I had adjusted the carb sync in May, and it was idleing what I thought was OK before I started on the diaphrams. Tomorrow morning I'll put it all back together and if it's not raining like they predict, I'll take it for a ride.

[saddlebum]

Try the set offered by JBM industries. I bought a set found them easier to instal than the OEM style and so far have worked great. Their delivery was fast and price reasonable.

Here is their link

http://www.jbmindustries.com/index.html

[twigg]

I tried plastikote, or similar, on the diaphragms.

 

It was a colossal failure. They ended up so stiff they would barely flex at all.

[frankd]

Thanks Ben for that info. I sent them an Email and I should hear from them in the morning.

 

 

Also, one more thing I found today......When I was on the right side pulling the rubber plugs to connect the vacuum gauges, I saw that the outer screw for one of the carb. holders had worked loose and the head was about 1/2" above the holder base. Before I put the plastic back on, I'm going to make sure that all 4 holders have both screws tight.

 

Frank D.

[frankd]

Twigg==I goofed with the name of the product I used. I should have said Plasti Dip, and I was surprised how flexible the diaphragms were after being sprayed. I really couldn't tell any difference.

 

Frank

[frankd]

Yesterday, I took it for a 20 mile test ride. After fixing the holes in the diaphragms, as I expected it was a lot smoother and somewhat faster. But the real surprise was how much quieter it was. I ordered a new set from JBM as Ben suggested, and hopefully they'll be in tomorrow's mail. If not, they should be here tomorrow. The new NGK plug caps were in today's mail, but I'll wait until I have the pastic off for the diaphragms to install them.

[saddlebum]

Yesterday, I took it for a 20 mile test ride. After fixing the holes in the diaphragms, as I expected it was a lot smoother and somewhat faster. But the real surprise was how much quieter it was. I ordered a new set from JBM as Ben suggested, and hopefully they'll be in tomorrow's mail. If not, they should be here tomorrow. The new NGK plug caps were in today's mail, but I'll wait until I have the pastic off for the diaphragms to install them.

Be sure to follow the instal directions in this link http://www.jbmindustries.com/Yamaha650.html speacially the part about the open hole location.

[Snaggletooth]

Twigg==I goofed with the name of the product I used. I should have said Plasti Dip, and I was surprised how flexible the diaphragms were after being sprayed. I really couldn't tell any difference.

 

Frank

 

Glad it's working for ya. I'm still running the treated ones in mine and they are doing better than I ever expected. Should be getting my new set from SCI before too much longer.

 

Mike