Throttle response question.. 78XS

[Diskman01]

Just wondering what everyone elses throttle response is here? Pretty sure something is wrong with my 11....

Say I'm doing 30mph and drop it down to 3rd and QUICKLY wrap the throttle around completely I get no acceleration at all for as long as I hold it wide open. If I try it again and twist it slowly I get some nice acceleration.

I would think that any zealous twisting of the throttle would kick it in the a$$ somewhat. I know these are not fuel injected.

It just feels flat on roll-on and up to about 3500RPM. Messing with the choke during these flat times doesn't seem to help other then load it up with fuel and start stumbling.

[BA80]

Sounds like you may have some carb issues. Have you been through them?

[Diskman01]

Sounds like you may have some carb issues. Have you been through them?

Many many many times.

It's been a long time since I cleaned them. Guess Ill start tonite.

[ViperRon]

When you clean the needles and tubes also check the boots for pin holes, poor slide response can cause this also.

[Diskman01]

I think its my float levels being too rich.. I posted a question on adjusting them in another thread. Will try adjusting levels for a while.

[WSL91]

The 3 bikes I had previous to the XS were all V-Twins which overall have moderately anemic performance but usually have some low end grunt. I'm surprised at the throttle response of the 2 1100s I have. I did not expect the throttle response that they have in the lower rpm range. I really didn't expect much out of them until 4k so it sounds like you have something not right. My Honda VTX has more low end and throttle response than the 1100 but then it's an 1800 and it all ends at around 5500rpm !

[TADracer]

Fuel level in the bowls

I go for fuel level in the bowl being wrong because of your plastic floats. Unless you have later carbs installed you should have brass floats. The plastic ones when installed in earlier carbs work well but require a different static height from the stock 25.7mm. Not sure what the level is supposed to be but it is mostly always a trial and error thing.

[TopCatGr58]

Hey Mike/Tad,

Folks have reported using the plastic floats in place of the brass ones, and they used the later carbs float levels ~23mm's vs. the 25.7. As you stated, may still require some adjustment/tuning, but that's where I would suggest starting.

But yes Diskman, if you haven't been in there in a while, they can easily and quickly gum up and such. These bikes/engines do have a decent amount of low end grunt and fairly brisk throttle response if you're not in too high a gear when you're trying the WOT action. But if you have aftermarket pipes ie. 4-1's it's known to adversely affect the low end throttle response a bit.

T.C.

[petejw]

I think its my float levels being too rich.. I posted a question on adjusting them in another thread. Will try adjusting levels for a while.

yep that would do it, check out ur spark plugs
thatl give u some indication, personally id be getting the stock
floats that are suited to ur carbs (brass) and putting them
in, otherwise itll be trial and error till u get it rite.

[gryphon51]

I have to look into this, I have the same problems... my DL1000 will eat this bikes lunch, and that should not be the case for a 1000 VTwin...

[Rasputin]

You could always get some metric grease zerks. Drill out the ball and spring portion so you have a hole clean through the zerk. Then use clear tubing pushed over them to set the float hieghts the same way as the later carbs are supposedly set. That way you can set the fuel level in the bowl to the proper hieght even with the newer plastic floats.

[Diskman01]

Problem was a combination of issues. The MAJOR one was that the cams were off by 1 tooth . Been that way as long as I have owned it I figure. I noticed something was up when I did the auto cam tensioner mod and I really got it out of "time".

First off, the spark timing was waaay off. Not sure of the degrees, but someone before me had marked the plate and the case with sharpie and it was nowhere NEAR those marks. Someone was trying to adjust for either the intake or exhaust timing off slightly.

Anywho, I reset the chain and the marks to where they were supposed to be. MAN, what a difference! No more popping out the carbys, backfiring and general wimpyness! Then I tackled the ignition timing. Move it to the previous sharpie mark and by god she screams and actually idles smooth. At idle it always sounded like a 3 cylinder 5 stroke or somethin'. I can get a bit more aggressive on the timing but it's running fantastic for now and the old girl deserves a mellow life. Setting the timing is a slight pain as I need to remove the crash guards before accessing the cover. lol.

I vaguely remember the PO mentioning that he messed with the CCT at some time. Something jumped I imagine. Odd that it was between cams. But, it's all better now! Compression test actually went UP since the day I bought it. Imagine that.

On another related topic: I found out that my clutch slips. I guess that COULD be a good thing? Im generating enough oomph to get slippage. New springs this winter.

[ViperRon]

Do yourself a favor when you put springs in and take the clutch basket appart and clean things they can build up a lot in 30 years and while you have it appart might as well make a good job of it.

TC has a good pictorial help of how to do the clutch here in the tech section.
Glad you got the power fixed.