float height settings

[fourbarrel]

I've had my carbs apart more times than I care to think about and am well familiar with the inner parts and pieces so what I'm about to ask is embarrassing,but in regards to setting the float height I need to affirm my thought in that the higher the setting the more fuel will be allowed into the float bowl? The range for the SRX is like 11.5-15mm and I have the ones in my 01 SRX set at 14mm and the ones in my 98 I thought were 14 but actually were closer to 13mm.The reason I'm asking this question is that I'm trying to sort out what I believe is a fuel starving issue with my 98 on the top end or larger throttle openings.The last few times out I noticed while running down a fast trail or road at around 70mph plus that I'd lose fire on one cylinder but as soon as the throttle was closed up some it come right back,so I think to myself I have a float that's either set too low or sticking closed a bit.Well yesterday after work I got the chance to try my sled after putting the carbs off my 01 on it and while I only got a chance to try larger throttle openings a couple of times I never once experienced the loss of a cylinder so I figured it has to be the original carbs causing the problem.So tonight I opened up the carbs AGAIN and AGAIN found NO blockages or sticking needles but I did find that the floats weren't at 14mm like I thought but closer to 13 or 13.5,and while this seems like a minimal discrepancy I don't know if it's enough to cause one of the carbs to not allow enough gas in for larger throttle demands.

I used compressed air to blow through every passage and orifice and I'm 100% confident that all three are spotless so if it isn't the float height setting causing one cylinder to not get enough gas then what could be causing it?The sled runs fine at lower throttle inputs,starts great actually better than my 01.

Carb settings are:
01 main specs 150,148.8,148.8
42.5 pilots
fuel screws 1.5
jet needle stock w/shim top and bottom
floats were at 13-13.5mm ( now are 14mm)

 

[roudyroy1]

if it is a starvation problem itsleaning out and could melt a cylinder down. next time it does this pull the plugs, one should be white if its starving. if i remember right, if you make the measurement from carb body to float smaller you will let more fuel in.

 

[Devilin AblueDress!]

I haven't ever had to mess with mine to much BUT I think you have that backwards. Larger number would = less fuel. Think about it in extremes, say at 30mm floats wouldn't ever leave the bottom of the bowls, seat would stay closed and no fuel would flow. Say the number was 0, then the floats would never shut off fuel.

 

[02YamiSxViper]

I haven't ever had to mess with mine to much BUT I think you have that backwards. Larger number would = less fuel. Think about it in extremes, say at 30mm floats wouldn't ever leave the bottom of the bowls, seat would stay closed and no fuel would flow. Say the number was 0, then the floats would never shut off fuel.

You are correct. I just set mine to 14.5mm in my viper. Smaller number is more fuel, higher is less.


Sent from my iPhone using Tapatalk

 

[snomofo]

I've had my carbs apart more times than I care to think about and am well familiar with the inner parts and pieces so what I'm about to ask is embarrassing,but in regards to setting the float height I need to affirm my thought in that the higher the setting the more fuel will be allowed into the float bowl? The range for the SRX is like 11.5-15mm and I have the ones in my 01 SRX set at 14mm and the ones in my 98 I thought were 14 but actually were closer to 13mm.The reason I'm asking this question is that I'm trying to sort out what I believe is a fuel starving issue with my 98 on the top end or larger throttle openings.The last few times out I noticed while running down a fast trail or road at around 70mph plus that I'd lose fire on one cylinder but as soon as the throttle was closed up some it come right back,so I think to myself I have a float that's either set too low or sticking closed a bit.Well yesterday after work I got the chance to try my sled after putting the carbs off my 01 on it and while I only got a chance to try larger throttle openings a couple of times I never once experienced the loss of a cylinder so I figured it has to be the original carbs causing the problem.So tonight I opened up the carbs AGAIN and AGAIN found NO blockages or sticking needles but I did find that the floats weren't at 14mm like I thought but closer to 13 or 13.5,and while this seems like a minimal discrepancy I don't know if it's enough to cause one of the carbs to not allow enough gas in for larger throttle demands.

I used compressed air to blow through every passage and orifice and I'm 100% confident that all three are spotless so if it isn't the float height setting causing one cylinder to not get enough gas then what could be causing it?The sled runs fine at lower throttle inputs,starts great actually better than my 01.

Carb settings are:
01 main specs 150,148.8,148.8
42.5 pilots
fuel screws 1.5
jet needle stock w/shim top and bottom
floats were at 13-13.5mm ( now are 14mm)

Since the float height is set with the carb inverted, the smaller the measurement, the higher the float setting. So you actually lowered the fuel level going from 13mm to 14mm. I've gotten into the habit of setting float heights on the low side of the spec because most auto carbs (Q-junks, Thermoboggs and most Holleys) don't like a high setting. My '01 SRXs carbs set at 13-14mm.

Keep in mind that the higher the rpm/load, the harder it is on the ignition system to light the spark plug. Your squeezing more air on the compression stroke at larger throttle openings which adds resistance against the plug sparking.

I'd swap plugs/caps/coils before going after fuel delivery.

 

[fourbarrel]

I've already tried the carbs from my 01 on the sled and I'm thinking it's in the carbs because I never noticed any starving the other night.I'm hoping to get a decent run in this weekend to say for sure but if I still have the same issue then I'll be looking at the elecrical.

 

[snomofo]

I've already tried the carbs from my 01 on the sled and I'm thinking it's in the carbs because I never noticed any starving the other night.I'm hoping to get a decent run in this weekend to say for sure but if I still have the same issue then I'll be looking at the elecrical.

It sounds rather intermittent so performing an A-B comparision of your '98 vs. '01 carb rack might prove difficult especially if the conditions change (i.e. ambient temps, RH, load conditions). If it does seem to follow the rack, try installing the '98 rack back on to see if the symptom comes back (A-B-A). That would be a better indicator.

Carb vents are clear? Maybe TORS switch on the suspect rack? I don't think it's a float height issue.

Been one heck of a year for you, eh?

 

[fourbarrel]

One heck of a year,yeah that's one way to put it lol.Been one thing after another for me but hopefully I'll at least finish off the season a high note with my 98 at least.

I was just out in my shed putting the mains and bowls back on my original 98 carb rack and noticed that the tps wiring going into the plug on the carb body are all cracked,the insulation that is.I'm in the process of trying to get the wires out of the plug so I can shorten them and solder them back up.Maybe this had something to do with my problem?Don't know.