Slides and diaphrams - Need Expert Advise

[MasterGuns]

Just pulled two of the four carb sliders/diaphrams and each had three or four tiny pin holes and I suppose need replaced. My question is, I have a second set of carbs with unknown issues and want to ask if the entire diaphram assembly can be exchanged from one set of carbs to another? Looking at things and considering all things, I don't see why not. However, I don't consider myself an expert on things of this nature and just want to ask those that are.

 

Second question is, I just had the Carbtune hooked up and all four carbs showed really low on the tubes. All seemed to be even but just way, way low. I tried turning the idle up but no improvement. What is this indicating and what must I do to raise them. I thought I know how to sync carbs but I guess I don't.

 

Thanks

[MiCarl]

There shouldn't be any issues switching slides carb to carb.

 

When vacuum is low across the board the usual culprit is one or more cylinders not firing. This can be caused by fouled plugs, coil/wire issues or fuel mixture. Your leaking diaphragms could potentially bleed enough air to prevent cylinder(s) from firing.

 

If it were me I'd get good diaphragms in, replace the plugs and try again.

[SapperMedic]

I have just been out trying to change my diaphragms. so far I have only taken 2 off and both don't have any holes at all. But my questions are:

1. do the slides have to be put back in exactly the same way, ie if they are rotated slightly to line up the little tab on the carb body, does that mess them up.

2. The old diaphragms seem to seat easily in the outside groove of the body but the new ones seem more springy and I worry that as I tighten the cap down that I won't seat them correctly, kinda like a car head gasket without alignment pins.

 

Am I paranoid? (bad question)

 

I just worry that part of the diaphragm goes inside and doesn't seal

[SapperMedic]

BTW, Micarl, is that a Gemini SST on your avatar?

[Dragonslayer]

Just pulled two of the four carb sliders/diaphrams and each had three or four tiny pin holes and I suppose need replaced. My question is, I have a second set of carbs with unknown issues and want to ask if the entire diaphram assembly can be exchanged from one set of carbs to another? Looking at things and considering all things, I don't see why not. However, I don't consider myself an expert on things of this nature and just want to ask those that are.

 

Second question is, I just had the Carbtune hooked up and all four carbs showed really low on the tubes. All seemed to be even but just way, way low. I tried turning the idle up but no improvement. What is this indicating and what must I do to raise them. I thought I know how to sync carbs but I guess I don't.

 

Thanks

Old diaphrams can be repaired by spraying both sides with Plasti-dip aerosol rubber spray and let dry throughly before reinstalling them.

[MiCarl]

1. do the slides have to be put back in exactly the same way, ie if they are rotated slightly to line up the little tab on the carb body, does that mess them up.

I'd put the new diaphragms on so they maintained their orientation in the bore.

2. The old diaphragms seem to seat easily in the outside groove of the body but the new ones seem more springy and I worry that as I tighten the cap down that I won't seat them correctly, kinda like a car head gasket without alignment pins.

What I like do do is get one half of the lip in then put the cap on slightly offset to that side. Then slide the cap into position should drag the lip into the slot. You can move the cap in a slight orbital motion to make sure everything is in.

 

Am I paranoid? (bad question)

Hey, I'd be paranoid too, if everyone were out to get me!

 

BTW, Micarl, is that a Gemini SST on your avatar?

 

Honda Mini Trail 50. Same as my first scoot.

Edited May 16, 2009 by MiCarl

[Marcarl]

I have just been out trying to change my diaphragms. so far I have only taken 2 off and both don't have any holes at all. But my questions are:

1. do the slides have to be put back in exactly the same way, ie if they are rotated slightly to line up the little tab on the carb body, does that mess them up.

2. The old diaphragms seem to seat easily in the outside groove of the body but the new ones seem more springy and I worry that as I tighten the cap down that I won't seat them correctly, kinda like a car head gasket without alignment pins.

 

Am I paranoid? (bad question)

 

I just worry that part of the diaphragm goes inside and doesn't seal

In order to get them to seat properly, stick your finger inside the carb and hold the slider out a little so that the diaphram can seat well. As you do this, you can install the cover and put in a screw or two. Also double check that you have the little o-ring installed that goes in near the bottom.

Hope this Helps

Carl

[SapperMedic]

Thanks again, I got all 4 done in about 2 hours even with cleaning everything good and then putting it back together with the stainless hex screws. I took the advice to coat them with rtv silicone to try to keep the chemical reaction down between the stainless and the aluminum. Just as I was warming it up, the sky opened up and it is raining HARD. Oh well, I didn't find any pin holes or anything in any of them, and I have a sneaking suspicion that the prior owner had changed them awhile back. Now I just need to fine tune with the carb sync. Every time I work on this bike, I respect how lovingly the guy I bought it from took care of it. He is a lot more Type A than me, I changed the oil and found out that he only used synthetic in all the cases thoughout.