Good thought, but tested it already by running with no gas cap. No difference in problem.

Thanks...

Huygens<br><br>Post edited by: huygens, at: 2007/05/19 16:38

Ok let's see .....

- tank adequately vented
- disconnect fuel line at crab and see if fuel flows freely
- remove small filter in carb fuel inlet
- float level
- correct needle valve
- no dirt in needle valve
- 175 main jet - are you sure it's a Mikuni (round large head with square marking)

Doc

What rate should the fuel flow from the tank to the carb? Seems to me I saw somewhere a rate of flow that should be atainable with a direct gravity flow. Cant seem to find it anywhere. Any ideas, I could do a test with a coffee can and a second hand?

As well any opinion on the factory yamaha petcock? Should it be replaced with a higher quality/higher flow rate petcock?

Thanks...

Huygens

Rate for flow.....beats me. When I take mine off the gas comes out fairly fast. You just want to make sure the flow from the tank to the carb is adequate.

The Yamaha petcock is sufficient. You can go to a hi-flo Pingle but you'll be able to tell when you do the test above. BTW .... I have a Pingle and they a tough to fit. I went to it for looks, not to get the higher flow.

Doc

Ok, I am going to document my progress step by step as I go through diagnosing this problem so that if anyone else runs into a similar problem they will have some info here to reflect on.

This morning I did the following:

Removed and flushed tank. Removed Petcock and cleaned/verified cleaned. Removed internal Petcock filters (Thought maybe they were causing a small restriction).

Replaced fuel line with another piece of new fuel line. Fuel line is 5/16 rubber core with outside stainless braid (if that makes any difference).

Reintalled all of the above (less the petcock internal filters).

Filled tank with 2 gallons of fresh fuel. Verified that fuel ran at a steady full stream. Looked good, full flow full size of the fuel line (as before). I read somewhere (now I cannot find it) that someone actually timed the amount of fuel flow from the tank for this configuration (with no fuel pump). I beleive they tested quantity of fuel over time. Does anyone remember reading this? Has anyone tried this?

Tested bike.

Same problem.

Next: I will order a higher volume petcock to replace the factory one. When inspecting the factory petcock I noticed that the inlets (on the inside of the tank) and the internal channels were considerably smaller than the outlet and the 5/16 fuel line. Although I donot believe this is the probem, I want to rule out any possibility that there is a fuel flow problem. At this point, I suspect I have done something wrong internal to the carb, either float setting, or other. I have noticed something in my previous inspections of the carb and forgot to inquire. Notes I have read, both the manual and on this site indicate that the float setting is set with the carb being level and based on the mating surfaces of the bowl and the carb itself. What I preceive as a level carb renders the mating surface as not level. Do I need to set the bowl with the mating surface as level or the carb mounted on the bike and the bike level (ie on a frame lift stand, as I have done), or with the bike on a level surface on its kick stand leaning to the side (which at this point he mating surface would appear to be level)?

Huygens

Possibly a stupid question, but I read all the post and didn't see this asked. How did the bike run before you made these mods? Fine? Could it pull 110-115 before? I'm just curious to know if your issues were there before you started or started after these procedures? BB

Also, on flow rate , it was an 1/8 gallon, Unmodified cap,70 seconds. Modified cap or cap off tank , same amount (1/8 gal.) in 22 seconds. Hope that helped.<br><br>Post edited by: Big Bear, at: 2007/05/20 12:44

Bike was running ok. Not great but not the problem I am experienced now. Could easily pull 110+. Had some carb adjustment problems that I have resolved thanks to this site and advice from DocShadow. I am relatively sure the problem I am experiencing with this is going to end up in the carb. It will be something stupid I did/didn't do and I will wack my head. When I post it here people will chuckle to themselves (or outloud) and say something like 'What a doof. God, I cant believe he missed that.' I will probably be saying the same to myself.

Thanks for the info on the flow rate. I am going to go test right now.

Huygens

Hey huygens

Since you took the filter out of the carb inlet maybe a little piece of junk went in the carb an it's partially blocking the gas flow.

Thanks to Big Bear found the fuel flow properties for the pumpless configuration (22seconds=1/8 gallon fuel). I am right on the money with this, with the tank cap on with the vent mod. Based on this I am not going to replace the petcock.

Next step is the carb. I will pull, clean/verify clean, double check all parts and pieces and settings. Then reinstall.

I have yet to hear if anyone knows if the float setting is to be done with the frame of the bike level, or with the bike on a level surface leaning to the side on the kick stand.

Thanks....

Huygens

huygens wrote:
I have yet to hear if anyone knows if the float setting is to be done with the frame of the bike level, or with the bike on a level surface leaning to the side on the kick stand.

That's because everyones ignoring you.

You can do it on the bench right after buttoning the carb up. Make the mating surface level using a bench vise to hold the carb.

If it's on the bike then level the bike and use the back matting surface as the reference point.

Doc