Carb slides do not move at the same speed (GS450)

[Guest]

Hi Guys,

I'm rebuilding my GS450 carbs and have reached the final stages of putting it back together. I also changed out the slide diaphragms as they had tiny holes in them. The new diaphragms are aftermarket, but fit in size and shape.

However I have noticed that when I push both slides all the way up with my fingers and let go, they don't get down at the same time. I reckon there is 0.2 to 0.4 sec difference between them, but both run smooth with no "jerking" on the way down.

Will that have any effect on the engine performance? I could imagine stuff will be less synchronised somehow, and will have some odd spots when revving up and down?

Thanks,

 

[Tom R]

Maybe it’ll have a small effect.... but nothing you could notice. Did you try putting a light oil on the slides? Are both springs the same?

 

[Gorminrider]

First off, I see the caps of the diaphragm look like they're not seated. Did you get the diaphragms' tabs in their recesses?

How do you measure 0.2 seconds? but I guess you mean one side lags a little. One slide or its channel might be a little more worn than the other-you could try swapping them backnforth but I doubt the slides jump to the very top very often and these bikes don't exactly leap into the sky when you goose the throttle anyways.

But for fun, try blocking the long sausage shaped port with your thumb while playing with them.... it's a better test of the passages and fit of the slides I think.

a bit of oil might help for a little while but you would want very thin and never-go-gummy oil like a clock oil plus a good airfilter so dirt doesnt glue onto them

 

[TeamDar]

First off, I see the caps of the diaphragm look like they're not seated. Did you get the diaphragms' tabs in their recesses?

How do you measure 0.2 seconds? but I guess you mean one side lags a little. One slide or its channel might be a little more worn than the other-you could try swapping them backnforth but I doubt the slides jump to the very top very often and these bikes don't exactly leap into the sky when you goose the throttle anyways.

But for fun, try blocking the long sausage shaped port with your thumb while playing with them.... it's a better test of the passages and fit of the slides I think.

a bit of oil might help for a little while but you would want very thin and never-go-gummy oil like a clock oil plus a good airfilter so dirt doesnt glue onto them

The caps aren’t seated....because there appears to only be one screw holding them on.

 

[grcamna2]

I have massaged both carb slide rubber diaphrams with plenty of silicone which treats the rubber a bit:when those age,the rubber dries-out and it slows them down,although new slides are expensive,it brings back that responsiveness we all like.

 

[Guest]

Thanks for the replies Guys - as always very useful and constructive.

Maybe it?ll have a small effect.... but nothing you could notice. Did you try putting a light oil on the slides? Are both springs the same?

Both springs are the same, but I'll try switching them around. I have given the slides oil.

First off, I see the caps of the diaphragm look like they're not seated. Did you get the diaphragms' tabs in their recesses?


How do you measure 0.2 seconds? but I guess you mean one side lags a little. One slide or its channel might be a little more worn than the other-you could try swapping them backnforth but I doubt the slides jump to the very top very often and these bikes don't exactly leap into the sky when you goose the throttle anyways.


But for fun, try blocking the long sausage shaped port with your thumb while playing with them.... it's a better test of the passages and fit of the slides I think.


a bit of oil might help for a little while but you would want very thin and never-go-gummy oil like a clock oil plus a good airfilter so dirt doesnt glue onto them

Actually I filmed it and counted the frames. It was around 0.3 sec every time. Nerdy I know


I'll try what you suggest with the port, and also switch things around to see if things change.

The caps aren?t seated....because there appears to only be one screw holding them on.

Actually 2 screws, both on the same side. Because I haven't put the "brace" in-between the carbs. Honestly I thought 2 would be enough for the test, but I'll try putting all 4 in.

I have massaged both carb slide rubber diaphrams with plenty of silicone which treats the rubber a bit:when those age,the rubber dries-out and it slows them down,although new slides are expensive,it brings back that responsiveness we all like.

Will try this as well

 

[Guest]

Hi All,

Here's an update. I took them apart again and massaged the diaphragms like it was a night with the misses. It seems to have helped as the time difference between them sliding down is barely noticeable. I believe this will be fine.

 

[Gorminrider]

Funny! but gee, I'll have to try that...Thanks for reporting back

 

[grcamna2]

Hi All,

Here's an update. I took them apart again and massaged the diaphragms like it was a night with the misses. It seems to have helped as the time difference between them sliding down is barely noticeable. I believe this will be fine.

I've also experimented with old slide diaphrams(once that rubber hardens/shrinks with age,it's difficult to really bring them back to 100%..)with wintergreen oil and water,using different ratios and amounts of time spent immersed in the solution:it helps soften old rubber a little,although the effects may not last.Be careful not to leave them in too long otherwise the rubber can become too blown-up.