Bonneville America Forums Forums Technical Forums Performance Mods Top End Gone

I rejetted a few weeks ago to 130 mains,pulled the 3 snorkles and cut 1.5" hole in bottom of air box and added UNI filter,pilot is stock I noticed on the New Glarus ride that in 5th gear and runnin about 75/80 that when I rolled on the throttle it just lugged. I tried choking it a bit a couple of times going up hills to see if that helped to no avail. Where did my top end go? Any thoughts? Slould I put some resrtiction back in the air box? How about upping the main?
ModelMaker

From the sound of it you may be too rich. That doesn't make sense though, because your jets choice seems to suggest that you are not too rich. Drop your bowls and look for a clogged/obstructed main jet(s).

i would pull your plugs and take alook at the color.. but when you do this use a set of new plug's and here is a good color chart to use. web page

Did you install new pipes as well? Even with those airbox mods 130's are probably too rich for the stock pipes. When I changed my stock pipes to Epco's I played around with different jets and came down to 130's from 135. I was getting similar problems with the rich jets.

let me explain that better... frist go get a set of new plug's put them in the bike.. ride the bike for at least 15 to 20 min's then bring it back pull the plug's and and then look at the color chart to see how where your plug's fall on the chart web page i hope this helps you out

Ed

Another quick test you can make is to shut off the petcock. If the bike picks up power just before the carbs run dry, you are running too rich.

When I got home last night I closed off the bottom of the UNI filter and reinstalled the front snorkles. I went out for a test ride and it seemed a little better but all of a sudden it just started spitten and sputtering about two miles from home. It smelled all gassy and I assumed it was runnin God awfull rich, missing and runnning from one cylinder to the next, finally died and had to push that 500 lb anchor about four blocks home in 85/85 heat and humidity. It had 110 miles on the tank and I NEVER hit reserve before 120. Came home and checked what went wrong and did'nt see anything out of ordinary. Switched to reserve and she fired right up. (STUPID A$$!!!!). Pulled the front snorks put it back together filled it up and took it out again.
I hit the limiters in 1st and 2nd and quit right at a ton. It's better but still not right. Am I correct in thinking the pilot is controling the back end of the throttle? Should I go from stock (40?) to perhaps a 42 or 43?
I didn't see a real pattern in the spec boards.
Any thoughts on pilots? I'm not sold on effectiveness of TBS needles as there seems to so much "yeh it's great" " I did'nt notice a difference" here.
ModelMaker

The TBS needles will only make a noticable differance in the mid range. If you have a bog or flat spot half way through TBS needles are the way to go. Changing the pilots will have almost no effect on your top end. I'm guessing smaller mains will do the trick.

With all that new air coming in you think going back to stock 120's or up to 125's will help? It struck me that adding air also required adding more gas. It seems that at the high end of the throttle it was starving for fuel.
I was talking to RapidReverend at New Glarus and I think he said he was running 130 mains and 42 pilots.
I think I need to do some more reasearch.
ModelMaker

Access to a dyno would be nice. I'm running 135 mains with snorkel removed + unifilter at almost 2,000 ft elevation. Haven't had it dynoed, but had a sniffer hooked up to it at the dealer and the bike runs great. Seems to me you're mains are too small, but as we know, not all of these bikes are the same.

Per Biker and Dinqua's suggestion I went out yesterday and got two new plugs and installed them at work, rode home the long way and pulled them ( ****** them motor parts are hot).
The new plugs looked like new plugs. The old plugs (since spring) looked to be more white than tan so am I correct in thinking I am running a little lean?
So what's the next step, up the mains to 132 or pilots to 42 or both? Keep in mind the problem presents itself mostly at the end of the throttle.
ModelMaker

That depends. Did you ride home and shut the bike off and pull the plugs? Then the idle circuit, i.e. pilot jet(s) is what you observed. If you had the bike at high rpm in 4th or 5th gear for a bit, while loaded (like going up hill) pulled the clutch in, hit the kill switch and coasted to a stop and pulled the plugs then you are looking at the main jets. Have you read the tps thread?

However, you noted earlier that,

Quote:

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...on the New Glarus ride that in 5th gear and runnin about 75/80 that when I rolled on the throttle it just lugged...

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It sounds like you have fuel starvation problem. Did you try to drop a gear and accelerate? You must have been turning about 4 to 4.5K rpm. Ryan and others had to change out their needles due to a flat spot.

Have you checked your jets and blown them out? Given your ride after reinsertion of the snorks, you were hitting the rev limiter but for what it is worth, Vera had similar symptoms and low and behold i could rev her above 4K in first and second, sometimes, but almost never while in third and up. Check your fuel side as one of my main jets was obstructed by tampoony particulate matter. (cotton). Vera had TSS! Drain the bowls look for trash. Shut off the petcock remove the fuel line hook a hose up to the petcock and the other end place in a clean glass container. Turn the petcock back on and observe fuel flow rate and look at the fuel for contaminates.

Your problem may very well be with your jet selection, but for some reason fuel issues keep nagging me.

PS: Usually, when the pilots are too small a lot of decel popping will occur. How many turns out are your mixture screws? Do you experiance decel popping? More than 3 turns and increasing them won't hurt but will allow you to stay below three turns out.

Sounds like you're too lean. Try 135 mains with 45 pilots.Access to a dyno is a big plus when tuning.

M&M..i see your getting lot's of info about this... maybe to much????? but i am going to give you some more here is the way i look at if your idle is fine then you pilot's jets are good " your pilots jet are for idle to about 3500 RPM.." if you are running good in that range then i would not mess with them..now moe bring up a good point are you even getting the right amount of gas at the higher rpm's i would do as he says and check the flow to the carbs this is easy to check if you get about a 12 FL OZ in about 20 sec or sooner your good and the way i do this is go to parts store get your self some 1/4 rubber hose and hook it right to the petcock and let run in to a clear pop bottle which is about 12 OZ if the amount of flow is not good dran your tank and pull your petcock and see if all clean also let that bottle of gas set for a time and see if see any thing in it like paint chips or dirt or even water..if thats all good pull your float bowls and the pull your float's and the stoper's your stoper is that small part hooked to the back of your float make sure you take note of how it all look's so you can put it back the same way you took it out.. this is all very easy to to do..
then hook your gas line back up to the tank and put a pan or some thing to catch the gas then turn you petcock on for the same amount of time you had it on when you did the first test and then compar the 2 they should be very close to the same amount " if the amount of gas you get from the float test is not even close to amount of gas you get from the petcock test.... then i would look at that small fillter that is in the line right before the T that feds gas to both carb's .. you can also do each carb put a separate cup's under each carb and you can see how much gas each carb is getting and each carb should be getting about the same amount of gas... this will take care of your gas flow so atleast you will know that is not your trouble..also if you can do this test with the bike up right not on the kick stand...and while you have it apart take a look at your main jets and make sure you have nothing blocking them i would also pull the part that hold the main jet and make sure nothing got buy you main *note when pulling this part be very carfull on top of them set's a very small spacer that has a hole through it make sure you put back in the way you took it out....and also now that you have them apart i would pull the top of the carb's and get a can of carb clearner put that lettle tub you get with the can and spary it through the holes where you jet go and make sure you the spary come out the other side "you can do all of this with the carb's right on the bike but put some rag's down under the carb's so you don't get a big mess on the bike now put it all back together and take it for ride if you are still haveing the same trouble and your plugs still look lean i bet you are running lean here is a newer plug chart the other one is from 1977 this one is from 2003.. web page also i belive if you are running a higher grade of gas your plugs will look cleaner i hope all of this helps but i still belive the bottom line on this one is your running lean !!!!!!!

BIKER

I ordered some jets from Brent at lunch. I'm going to try the 42 pilots and see how works. I'm leaving town for a funeral and won't be back till tues or so will try to get new pilots in then.
Till then thanks all for the thoughts and will post when i'm done.
ModelMaker

Well, I think I'm about there now.Last weekend I changed the 130 mains to 132, and the 40 pilots to 42. The airbox is snorkleless (all 3) and a 1.5" hole in bottom of filter case. Top and bottom holes are covered by 3-M Scotchbrite pads. Mix screws are 3.5 turns out. The local Rat(spit) group went on our annual leaf ride yesterday and I had all the juice I needed to keep up with the sporty guys. It pulls like a really fast tractor through 3 gears and still will accelerate nicley in 5th at around 80mph.
I still think I need to do a plug check, will try to get around to that this week.
Thanks for all the input gentlemen.
ModelMaker