Main jet question

[bazwell]

A while ago, before I pulled my carbs apart, I posted a question. In the end I got some 147.5 mains.

I'm doing some carby work now, and it's a little different from what I previously guessed.

My '85 has had the 2 150's changed to 152.5's already. (So it has 152.5's in it.) I guess the rest is stock. (it's a 49 state)
It has a std exhaust with the middle opened up. (Big hole thru the guts, not the holes in the end cap.) I've just added t-boost.

Problem was, it was running rich. A friend told me when I gave it WOT from the traffic lights it would blow black smoke as the revs built up a bit. Actually he said he had to dodge the black shit shooting out the back... oops.

Now that I have it apart, I can see several holes in two of the diaphrams, and all 4 diaphrams are see through around the edge where the metal lip sits.

I have repaired the diaphrams and they look OK now. My guess is that holey diaphrams would make it rich.

My question is, do you think I should put it back together with 147.5's in it? The only other jets I have are the 152.5's.
If I put the smaller jets, and it seems too lean, can shim the needles?


Baz :biglaugh:

 

[tugla]

think you should not bother with the tboost as it only makes it richer in the bottom end without adding much for power for you, yami got the vboost pretty much set up right. so if its still rich then id try to get a set of 150 and go from there, but the 152.5 should work good. at wide open the needle being shimmed wont give you what you want with the 147.5

 

[SpecOps13]

+1

 

[bazwell]

think you should not bother with the tboost as it only makes it richer in the bottom end without adding much for power for you, yami got the vboost pretty much set up right. so if its still rich then id try to get a set of 150 and go from there, but the 152.5 should work good. at wide open the needle being shimmed wont give you what you want with the 147.5

Cheers for that Tugla!

I'm keeping the T-boost though.
I would be surprised if it made any different in the bottom end. It can only possibly affect from 3000rpm and up.

So your saying stick with std or get 150's.

As a side question, does anybody know how I find the picture which shows what affects what at different rev ranges? I have seen it a few times, but I can't find it now! :bang head:

 

[bazwell]

Aaaargh! One of my slides is sticking.... it's got a crack in it.
That may explain some intermittant rough running.

Grrrrrr. Now I need a slide. :teeth angry:

 

[one2dmax]

If you have aftermarket slip-ons or a full header (with no jet kit) then put the 147.5 mains in it. Having holes in the slides would slow down their retraction rate and make it leaner if anything (in the mid and low end).

Sean

 

[sdt354]

Stock exhaust ,I'd use stock jetting. The pipe diameter is still a restriction, even poked out, drilled whatever. They do sell new diaphrams on e-bay which I'd prefer over repaired, myelf, new slides are big $ form Yamaha.(Of course you could just contact Dannymax and get a carb rack ready to bolt on, all blueprinted and like new, for a fair price) I believe he has them ready to ship too. Black soot shooting out the exhaust? Agree with Sean on this, different issue. MPG at a steady 65-70 mph is? You can do it just for a little while to check. I know it's hard and not much fun to do though.But does give a rough indication of a few issues.
Steve-o

 

[sdt354]

Aaaargh! One of my slides is sticking.... it's got a crack in it.
That may explain some intermittant rough running.

Grrrrrr. Now I need a slide. :teeth angry:

Sean, Kyle maybe.

 

[Lew L]

Hi Steve,
I've been asking this question for years------ what could you use to preserve/repair the carb diaphrame????????

Thanks much,
Lew

 

[bazwell]

It only took a few seconds to get rid of the high spot next to the crack in the slide with wet and dry. It'll work for now, and is on my shopping list. Slides feel OK - good enough for now. I'm a bit sick of having to wait for little things from overseas!

Lew, I used Sikaflex 221 thinned with paint thinners and painted on with a little brush. Should work OK. Replacements aren't that pricey, but I'm jacked off with delays in getting my bike back together.

Steve, what are you getting at here? --> "Black soot shooting out the exhaust? Agree with Sean on this, different issue." Seam said use 147.5's (I think). Do you agree?

Sean, in your reply, does a 1" hole in the standard pipes count as aftermarket? So try 147.5's?

I guess it's worth noting that the float levels were all a tiny bit higher than the 1.125" measurement method. All were exactly the same. I set them all down a tiny bit. I'm guessing 0.5mm.

 

[sdt354]

What I agree with Sean on is, the diaphrams leaking are not causing the rich condition.
Nor do I myself think it's the 152.5's mains. IMHO. Float levels came to mind when I herd running THAT rich, but you've checked that.Correct?
You had a cracked slide? was that sticking in the bore? that's a rich issue.
147's? Sean must have used them in this situation-baffle opened up down the center. And,Sean has been around the block tuning Vmax's more times than I regrardless of years as a mechanic. So go ahead. Sean's tuning advice has never steered me wrong.
Myself, Before buying a Mark's system, I drilled 5 - 3/8 holes in each end cap and used the 152.5's with success.It mostly made more noise than extra power, if any. But ran well with good plug read.
I may have comparable dyna jets to 150 Mikuni's if you want to ty them first. I'm a fan of 1 step up or down at a time. Let me know if you'd like me to look for the dyna jets, pretty sure I've got them. Pm me if interestd. I hope I answered your questions.And, let your plugs be your guide. Post plug pics if possible. There is more to this than discussed. A/F screw position, as an example. Wish it were easy. To get my bike to run like I wanted it took many hrs of one change, ride the bike, check the plugs, mpg consideration, a different needle, clip position, shim size. Very time consuming, worthwhile and a lot of fun.
Steve








QUOTE=bazwell;225438]It only took a few seconds to get rid of the high spot next to the crack in the slide with wet and dry. It'll work for now, and is on my shopping list. Slides feel OK - good enough for now. I'm a bit sick of having to wait for little things from overseas!

Lew, I used Sikaflex 221 thinned with paint thinners and painted on with a little brush. Should work OK. Replacements aren't that pricey, but I'm jacked off with delays in getting my bike back together.

Steve, what are you getting at here? --> "Black soot shooting out the exhaust? Agree with Sean on this, different issue." Seam said use 147.5's (I think). Do you agree?

Sean, in your reply, does a 1" hole in the standard pipes count as aftermarket? So try 147.5's?

I guess it's worth noting that the float levels were all a tiny bit higher than the 1.125" measurement method. All were exactly the same. I set them all down a tiny bit. I'm guessing 0.5mm.[/QUOTE]
I don't think it's the main jets causing the smoke. Lot's could cause rich running at low and mid range. High float levels did come to mind.

 

[bazwell]

Thanks for clarity Steve. :worthy:

The cracked sleeve was about 3/8" from the diaphram. Once it had moved up a bit, it was free, but the spring couldn't push it all the way back. I guess it would have been rich most of the time. I was riding 45mins to work in shitty traffic so the carbon would have built up until I gave it revs on that weekend ride. It sounds like a good explanation!

 

[tugla]

+1 a good plug read will help determine a set up, sean pretty must got it figured out there for you.

send some pics of a wide open cut plug shot and what jet you got and see how to help fine tune her

 

[tugla]

+1 a good plug read will help determine a set up, sean pretty must got it figured out there for you.

send some pics of a wide open cut plug shot and what jet you got and see how to help fine tune her

 

[Lew L]

Hi Baz,
I'm not familiar with the Silkaflex product??? Is it a paint or glue and what kind of thinner? Regular paint thinner or laquer thinner.\??

Thanks for the answer,
Lew

 

[bazwell]

Lew,

Sikaflex 221 is a sealant/adhesive similar to silicone products, but it is polyurethane. It is quite hard to 'work', and sticks to basically everything. It dries like rubber.
It is industrial grade and needs to be used carefully in automotive applications, as once it sets it usually requires "mechanical removal". It could be used to form a gasket, but you probably won't be able to pull those 2 parts apart without using destructive forces. You have been warned!

I used it thinned with paint thinners.

http://www.jamestowndistributors.com/userportal/show_product.do?pid=6510

ps. If you get it on your hands, even if you clean your hands with thinners, it will not come out of the fingerprint lines, until the top layer of skin wears off! :biglaugh:

 

[sdt354]

Hi Baz,
I'm not familiar with the Silkaflex product??? Is it a paint or glue and what kind of thinner? Regular paint thinner or laquer thinner.\??

Thanks for the answer,
Lew

Silkaflex is very popular in the boat building and repair business. It's a sealant/adhesive and super durable. Acetone doesn't seam to touch it for removal once set up. I'm not sure about temps it can handle resistance to gas/solvents over a long period. Red hot putty knifes are used to remove it. Yes, wear gloves when using it, it sticks to skin best. Baby oil helps get it off of hands. If it stands up to gas and heat long term I'd think it would be suitable for gasket apps.
Steve

 

[RaWarrior]

You mean something like this?

It's not perfect here, the "valve cutaway" refers to slide-throttle carbs, not CVs like the Vmax uses.

My stock motor with slipons runs dandy on 147.5's. Butt dyno says the top end was a little quicker to rev than with the 150's that were in there, but 2.5 sizes is a pretty small difference, so it's probably just me being optimistic. My bike has been held at WOT for several minutes at a time in top gear as well, water temp barely rises from normal and plugs look nice and toasty, not overheated or white.

 

[bazwell]

Silkaflex is very popular in the boat building and repair business. It's a sealant/adhesive and super durable. Acetone doesn't seam to touch it for removal once set up. I'm not sure about temps it can handle resistance to gas/solvents over a long period. Red hot putty knifes are used to remove it. Yes, wear gloves when using it, it sticks to skin best. Baby oil helps get it off of hands. If it stands up to gas and heat long term I'd think it would be suitable for gasket apps.
Steve

Good stuff isn't it Steve!
I've used it for gluing panels on cars too. :biglaugh:

They did sell it (221) in little toothbrush type tubes here as an automotive sealant for a while. but they removed it from the automotive list.
They had issues with people fixing leaky sump gaskets by using 221 as a form-a-gasket. It works perfectly.
No leaks, no deterioration from heat or oil. No hope of getting the sump off without wrecking it!! unk:

Now that it's not automotive grade, they don't sell little tubes, only big cartridges. It always goes off before I get a chance to use it all. :bang head:

 

[bazwell]

You mean something like this?

It's not perfect here, the "valve cutaway" refers to slide-throttle carbs, not CVs like the Vmax uses.

My stock motor with slipons runs dandy on 147.5's. Butt dyno says the top end was a little quicker to rev than with the 150's that were in there, but 2.5 sizes is a pretty small difference, so it's probably just me being optimistic. My bike has been held at WOT for several minutes at a time in top gear as well, water temp barely rises from normal and plugs look nice and toasty, not overheated or white.

That looks like the one I was looking for!
Except I want to know what that valve cutaway means on a vmax.