Acceleration from stop issues

[Nholmes1987]

I am having some problems with the bike needing excessive amounts of throttle in order to take off from a stop. It seems to run ok once driving but revs up to about 4,500 RPM in 5th gear. I want to fix this but am having some issues. The carbs seemed synced and I have checked the ignition timing. Those seem ok. Is it a mixture screw issues? Or could it be caused by air pods being installed? I can't seem to get it right. I'm not sure what to do really...

[TopCatGr58]

It's all elementary my dear Watson!

Sorry for the cliche` but had to!

Okay, I think I had seen you post before, but can't recall exactly.

We need more background info regarding about your bike, have you had it along time, or is it new to you? What level of work have you done to the bike, you say the carbs "seemed" synched , but you say the engine runs up to 4,500 in 5th?? How have you checked the ignition??

Have you actually taken the carbs apart and thoroughly cleaned them?
Pod filters usually don't interfere with the low speed/rpm performance much, mostly the 5-6+ k rpm range, but IF you put pods on when it had an OEM airbox, then it may be running lean and may need rejetting.

Also, are you sure it's running on all 4 cylinders, after warmed up, spritz some water on the headers, should instantly flash to steam, but if one or more are only warm, then you may actually be running on 3 or even 2 cylinders!

OR....your brakes could be dragging severely causing you to need much more throttle to overcome the brake drag! JAT!

T.C.

[natemoen]

TC is right, we need more info, but I am banking on dirty carbs.

[650mark]

poor accel issue

fwiw, have you tried sea foam in the gas yet? it's a gas additive that does a great job of cleaning carbs while you ride. several ounces in a tank, then repeat. i use it all the time on my restoration projects and on several have had the bikes soon running extremely well without touching the carbs. after that, if still having problems, carb disassembly and cleaning may be in order.
for about $10.00 it's certainly worth a try. or course, ymmv.

[BA80]

4500 in 5th. I don't think your firing on all four cylinders.

[Nholmes1987]

Poor accel issue

Ok, sorry guys. I have completely cleaned the carbs and put new float bowls in them, I have not rejetted the carbs at all, though. I just rebuilt both master cylinders and calipers, so the brakes are working fantastically! I changed all the fluids and synced the carbs with a vacuum gauge. The only thing I can think of is adjusting the mixture screws as it must be running lean. The reason it was at 4500 in 5th I believe was due to adjusting the idle up on the road in order to get it to actually start from a stop without dying. Oh, and I checked the pod filters to makes sure they were not blocking the ends of the carbs. Hope this info helps

[Nholmes1987]

accel issue

Also, I just bought the bike in May. It hasn't been ridden in about a year and a half. I checked the ignition timing with a timing light after taking the cover off. Other than that, it all seems to point to the mixture screws and a possible rejetting. Also, any ideas on how to get a broken mixture screw out of the carb???

[cywelchjr]

Also, I just bought the bike in May. It hasn't been ridden in about a year and a half. I checked the ignition timing with a timing light after taking the cover off. Other than that, it all seems to point to the mixture screws and a possible rejetting. Also, any ideas on how to get a broken mixture screw out of the carb???

If you have a broken mixture screw in the carb you're not going to get the idle to work right, or get it to take off from a stop right either until to fix that. I don't remember where they are, but there are several threads on getting stuck idle mixture screw tips out, which include things from freezing the carbs to making a special tool to get the tip out. With that tip in there you're running on 3 which throws everything off, so you gotta fix that.

[BA80]

The mixture screws WON'T affect the off idle performance very much at all. As a matter of fact it's so insignificant it's not even worrying about. I ran my bike for a year before I even knew there was one broken off in there. It wouldn't idle right but it ran like a striped ass ape.

That needs to be addressed but you have something else going on.

[Nholmes1987]

Acceleration issue

I think I have it figured out between the forums and youtube videos about air/fuel mixture. I believe that the problem was that I did not have enough air coming in to enrich the fuel i.e. when I was running my bike it was only pulling 5inches of vacuum and it should be between 15 and 20 inches of vacuum. The carbs are synced 100% spot on and the only other thing that could affect performance like that is the pilot screws. Once those are set correctly and the idle is set to where it "should" actually be, I should be alright. That is, once I get this damn broken idle mixture screw out and the new ones come in!!!


Thanks for you help guys, I really appreciate it. I am almost done with this bike!!!