[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Lets get back to oilheads... throttle body question

John,  Just a thought, but I may be going to Parkers on Monday morning. 
  Perhaps we could hook up to deliver the part if needed?

Bob Hadden

On Sep 3, 2005, at 7:57 AM, John Van Deren wrote:

> Hi Bob,
> Yeah, I'll check TPS voltage too...haven't done that in a looong time. 
>  I was hoping to ride on this beautiful morning but I guess I have 
> some work to do.  Thanks for your thoughts (and replacement TPS if I 
> need it!).
> John Van Deren
> Montpelier, VT
> Bob Hadden wrote:
>> John,  The setting of the tps affects the idle speed.  Perhaps, with 
>> the mileage on your bike, the throttle stop has loosened up or the 
>> tps is wearing and not getting down to the proper level.  You should 
>> check the throttle stop to be sure it is not loose, and check the tps 
>> voltage to be sure it is still where you want it.
>> Incidentally, I have a tps new in the plastic if you need it.
>> Bob Hadden '05R12GS, '62R27
>> On Sep 3, 2005, at 7:37 AM, John Van Deren wrote:
>>> Thanks, Andrew,
>>> I wish we could post photos.  If the 28 feet of tubing are in a "u" 
>>> shape on the four foot board (using what sounds like about 10 feet 
>>> of the tubing), where is the remainder of the 28 feet?  I'm having a 
>>> little trouble visualizing what your vacuum gage looks like.  
>>> Anyway, I'll test for air leakage w/carb cleaner.  The tube clamps 
>>> are tight. I do have an old Carb Stik w/mercury that I never liked.  
>>>  I may break it out and see if I can adjust the throttle stops as 
>>> you suggested.  I've never removed the BBSs and cleaned them so I'll 
>>> do that too.  I had done a careful valve adjustment (OVAD).  The 
>>> engine runs smoothly, but I'd like to determine why the BBSs are so 
>>> uneven in their setting and get the idle down a bit.  Thanks for 
>>> your ideas.
>>> John Van Deren
>>> Montpelier, VT
>>> andrew johnson wrote:
>>>> At 1:46 PM -0400 9/2/05, John Van Deren wrote:
>>>>> Hi listers,
>>>>> Today I was adjusting the throttle body synch on my 94 RS (110K 
>>>>> miles) and noticed that the right brass air bypass screw needed to 
>>>>> be almost closed (clockwise) to attain balance on the Twinmax. The 
>>>>> left screw is a couple of turns out.  I cannot get the idle low 
>>>>> enough to suit me...about 1400 rpm is as low as I can get it.  
>>>>> Does this indicate that the right throttle body has a problem 
>>>>> (wear)?  Do I have an air leak perhaps on one side?  Any wisdom 
>>>>> from the pros out there would be greatly appreciated.  BTW, I use 
>>>>> GS tubes.
>>>>> John Van Deren
>>>>> High and dry in Montpelier, VT
>>>> Could be an issue with your throttle body, the butterfly shaft can 
>>>> wear and allow air to pass through its bore in the cast body. 
>>>> Conventional wisdom says squirt carb cleaner on the throttle body 
>>>> near the shaft's bearing points and see if any change in idle.
>>>> I finally tossed the TwinMax. It had developed a preference to lean 
>>>> off to one side, indicated by swapping hoses and seeing a whole 
>>>> different reading from the last set zero. I was also looking for 
>>>> something better for adjusting the throttle stop screws.
>>>> I made up a water gage, about 28 feet of 3/16 I.D. vinyl tubing, in 
>>>> a "U" shape along a four-foot wood board, with exactly the same 
>>>> lengths from bottom of "U". I filled it with colored water to half 
>>>> the height of the board. When I attach this to the vacuum ports I 
>>>> get a very clear and stable indication of whether the engine is in 
>>>> balance or not.
>>>> My adjustment process is as follows:
>>>> 1. Valves dead-on, cold, OVAD style with four guages, engine set at 
>>>> TDC with home-built TDC flywheel locking tool.
>>>> 2. Remove and clean the Big Brass Screws (BBS) and their bores with 
>>>> carb cleaner. A faint dab of silicone grease on the O-ring, then 
>>>> back in.
>>>> 3. With engine fully warmed up, and throttle cables slack against 
>>>> their adjustment barrels, the BBS are fully and gently seated 
>>>> (turned in clockwise until they stop).
>>>> 4. Engine running (roughly and slowly) I adjust the right hand side 
>>>> throttle stop screw until I have perfect balance in the water tubes 
>>>> (or TwinMax). The water tubes take a while to settle, be patient. 
>>>> When the engine is balanced at this stage, you will feel and hear a 
>>>> discernable relaxing of the roughness, even though it's idling at 
>>>> 600 RPM.
>>>> 5. I back both BBS out two full turns, then adjust for balance at 
>>>> idle (throttle cables still slack).
>>>> 6. I finally adjust for off-idle balance by moving the right hand 
>>>> side throttle cable adjustment barrel, as needed. Take it to 1500 
>>>> RPM for basic measurement, higher if you wish.
>>>> This is what I do. The left side throttle stop is fixed, TPS is set 
>>>> at 0.390 volts, I don't mess on that side except BBS.
>>>> Bike runs so smooth now, the water gage helped me get the throttle 
>>>> stops in perfect balance, as never before.