Can too much intake??? By scooteraddict (Read 1,986 times)

[scooteraddict]

Can too much intake or air flow through the carberator cause a reduction on the vacuum lines?

Up untill this pass weekend, I was running a K&N filter with a precharger filter over it. (Precharger filter is a net filter used for high dust applications.) Thinking I don't need this anymore, I removed it.

Now it seems that I might have lost my ability to create enough vacuum for the pump to keep up. I use to be able to reach 70mph or so. No problem on the flats or downhills but on hils I would loose a little speed but the pump would keep up (before the changes). After a few rides now, it seems that my carberator seems to start to starve and the bike starts to slow down, or loss of power. My though is that, if the engine has less restriction of air flowing through the carberator and can not produce a good vacuum, can this have an effect on the vacuum?

I would like to add, that I also reset the valves to 0.004" on the intake and 0.005" on the exhaust. Although these are the recomended settings, can the intake valve not be open enough to create enough vacuum for rhe pump to keep up?

I haven't had a chance to check for any vacuum leaks and I know that everything went back together, but I will do that tonight.

[flyangler]

Others will be commenting soon but my quick thought on your situation is that you may be running a little lean maybe a lot lean. With the new intake did you rejet or adjust for a richer mixture, that could be all that's needed

[cruiser]

I tend to agree with flyangler. Did you replace the precharger filter to see if the problem went away? If it does, then I definitely agree with flyangler.

[scooteraddict]

I'll be putting the precharger on tonight, however, I can go for about 1/2 to 3/4 miles going uphill before it starts to loose power. This tells me it's realy not a run lean type of issue but a loss of vaccum which will not allow the pump to keep up.

I can understand that if it were to start when I begin to go up a incline, but it happens 1/2 or so upwards.

[cruiser]

Your analysis sounds good to me, addict. May I call you addict? Let us know what the results are.

[scooteraddict]

Well with the precharger on, it still has a problem keeping up.

I think that with a recent valve adjustment, I must have messed up. Well I'll take the plastics off again and perform an another adjustment. Why o why did I adjust something that didn't need it.

[damin69]

Jul 20, 2011 19:13:23 GMT -6 scooteraddict said:

Well with the precharger on, it still has a problem keeping up.

I think that with a recent valve adjustment, I must have messed up. Well I'll take the plastics off again and perform an another adjustment. Why o why did I adjust something that didn't need it.

Addict, I feel the same way. One of the most important items and I am still trying to learn how to do it correctly the first time and get a scooter to run correctly..

[tvnacman]

Guys , Sprocket posted a great way to adjust the valves forget TDC way (let one valve fully open and adjust the other then vise versa . I think its easyer than TDC one thing less to take apart!!!!!!!!!!!!!!!!

John

[scooteraddict]

Well off came the plastics. Started to do the top intake and noticed that the air cleaner box was not on fully. Check the intake valve anyway and yes it was right. I'm certain that the bottom one is correct as well.

After getting the air intake on correctly, I tested the bike once again. No more sluggish at WOT after a half a minute or so up a hill but I still don't know about top speed on long runs. I want to reroute one of the coolant hoses first before I tighten everything up and take it for a true test.

[scooteraddict]

Well I did a once over and found absolutely nothing wrong with the scooter. For the life of me, I can figure out what might cause such a loss of power on hills all of a sudden. I even had to take the muffler off and replace a broken bolt that held it on and found that the baffles were all broken loose inside. Now you might think that this might be the problem but the in reality, since the baffles have shifted, it created less restriction.

As a last resort, I even went and hooked up my A/F ratio meter to see if I'm running lean and far from it. In fact I run a tad rich. Not a lot be enough. Now I'm wondering that this might be causing the issue at hand. Normally optimum would be 14.7 Air to fuel ratio. Currently I'm running low 12's. Ideally, I should be running high 13's, low 14's for a well tuned bike. Could it be that the rich fuel mixture can cause this loss of power on hills?

[tvnacman]

Scooteraddict ,
Please embellish what are the numbers you are testing , what and how are are you testing . I do combustion analyzing for boilers , I look for stoichiometric combustion (not that that it is obtainable ) how ever I want the leanest burn , with the least excess air and next to no co. .

so talk to me what are the (perfect burn) emission specs for these little engines ?

my biggest concern is riding with the analyzer while doing the testing .

John

[scooteraddict]

On this web page, it explains it best.

.fuelairspark.com/Products/Documentation/C-Com/Help/targetaf.htm" rel="nofollow" target="_blank">.fuelairspark.com/Products/Documentation/C-Com/Help/targetaf.htm

"There is a particular ratio of air to fuel that results in all of the oxygen molecules combining chemically with all of the fuel molecules. This ratio is 14.7:1, meaning 14.7 parts of air for every 1 part of fuel. Running an engine at this particular air/fuel ratio helps to minimize emissions and maximize fuel economy, but this air/fuel ratio is generally not safe to run at high RPM and/or engine load conditions. Since most oxygen sensors produced are only meant to accurately measure a 14.7:1 air/fuel ratio, they shouldn't be used in applications where much richer or leaner target air/fuel ratios are selected. The wide-band oxygen sensor used with this system is capable of accurately measuring a much wider range of air/fuel ratios. This system can measure any ratio from as rich as 9:1 to as lean as 16:1."

[cptk]

So far with my experiences Any chocking , stalling or kicking issues as far as hill climbing ( and trust I have had plenty ) has always led to not enough air or being to restricted..Have not tried yet to just run carb naked on intake side but have run intake without filter for a run or two and always end up putting filter back on. Roads are plenty dirty and dont need that in the bike..Just my Experience.....

[scooteraddict]

Well it turned it that it was too rich to the point that it was quenching the spark. With trying to run under full torque the cylinder might have been so wet that it couldn't burn correctly.

What I found what the problem was, the auto choke wires broke at a heat crimp for the plastic tubing that encompassed them.

I wrote another thread that explained all the issues that I encountered this year due to this issue. Long story short, after putting a new choke in, it make a big difference with the need to and including upping the main jet by one.

The thread, if you want to read it is under the title "A problem and the fix with a 250B" under the 250cc section.