State of things

[Firehawk]

Well, I messed around with the jetting some more after this.

122.5s are shooting unburnt fuel out the tail pipe, but 120s are too lean.

I looked back to the carburetors. The only thing that I haven't messed with: the diaphragms. Perhaps they arent' sealing.

I pushed them up to the top and put my thumb over the inlet, and the just slide down. All four of them do this, about the same.

I took one out and looked it over and didn't notice any holes or cracks. So, I decided that perhaps they weren't sealing properly. I put silicone around the seat to help hold it down and act as a gasket.

It still slides down, but very, very slowly. They are supposed to sit at the same spot when the inlet is covered, right?

[TopCatGr58]

Firehawk,

They will slide down very slowly, cause there's a vent hole down in the middle of the hard slide portion, so air will eventually leak thru there to release the vacuum that is above the slide. But what you found about them sliding down quickly was not good. Surprised that the silicone sealed them around the lip enough!?
Most folks find pinholes as the culprit, not leaking around the lip!

T.C.

[Firehawk]

Well I didn't see any actual problems with the one. There might be problems with the others.

Is there anyway to repair the little holes? Or do I have to drop $70 on each one?

[Firehawk]

The silicone didn't fix carb #1, but I still didn't see any pin holes or anything of the like. I guess I'll see if it's any different after it's "fully" set up, tomorrow morning.

If only this was fuel injected, they're so easy to diagnose...and fix.

[Brian_D]

Firehawk,

use Yamabond #5 and a disposable watercolor paint brush to "paint" the inside and outside of the diaphrams.

total cost = $7.00

[Yamaniac]

Hey Fire.

Did you make it to Pitt this last weekend? I didn't hear from you on Friday, so we didn't end up going down.

I'm still game for helping you get sunk, or synched up, so holler when ready.

[Firehawk]

Yamaniac,

No, I didn't. It was raining and then I hung out with a ladyfriend that night and forgot to call you.

And then I resigned myself to attempting to fix this diaphragm problem. Which, unless I'm just a complete loss with the carburetors, pretty much has to be the last thing to fix with them. All circuits are clean, the spring tensions on are good, no air leaks from anywhere else. Engine is in time, with good compression. So on and so forth.

Unfortunately, this is also finals week. I hate college sometimes.

[Yamaniac]

Finals

I hated them too. I would usually just think, well, if I haven't learned it by now... and then go to the bar. Maybe why I didn't have the highest GPA known to man in college....

Yeah, those carbs sound like they have put you thru the ringer. Dumb question, but you were testing those diaphragms with the top cover on and bolted down tight? Another possibility is that they popped out of the groove they sit in before you got the lid on and tight. I noticed that mine had to be just right before they would stay in place.

[Firehawk]

Yeah, that's what I was doing with the silicone: holding them in place. I found that while it was part of the problem, there may be little holes and stuff I didn't see. I'm gonna coat them with the Yamabond just to be safe and see if that solves the issue.

Another question I have: I put in 120 mains and the bike is too lean and cuts out at topend. If I put in 122.5 mains it gets enough fuel, but my friends report puffs of unburnt fuel during shifting and decelleration. I also have popping and a seemingly lean mixture during decelleration. Anyone have any ideas as to why it's doing this?

[Yamaniac]

Couple things. have you tried messing with your diaphragm needle?


Also, will be down close to your way( Ark City) on Sunday the 21st. I have my cousin's graduation down there. If you have things together by then, let me know and I'll swing by.

[strom]

Are you sure its the carbs?
Check compression and cam timing.
I fiddled with electronics and coils and TCI and pickups for quite some time, before I found out we set the cams wrong. Replaced 2 bent valves and the bike ran fine after that.

LP